PHOSPHORUS YLIDS By BRIAN JOHN Y/ALKER - … · · 2015-11-20PHOSPHORUS YLIDS By BRIAN JOHN...

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Of

PHOSPHORUS YLIDS

By

BRIAN JOHN Y/ALKER

A T h e s i s s u b m i t te d f o r th e d e g re e o f D o c to r o f P h i lo s o p h y

o f th e

U n i v e r s i t y o f L e i c e s t e r

1966

UMI Number: U 296388

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STATEMENT

The work d e s c r i b e d i n t h i s t h e s i s was c a r r i e d o u t by th e

a u th o r i n th e D epartm en t o f C h e m is try o f t h e U n i v e r s i t y

o f L e i c e s t e r u n d e r th e s u p e r v i s i o n o f D r. S . T r i p p e t t .

No p a r t o f i t i s c o n c u r r e n t l y b e in g s u b m i t t e d ’f o r any

o th e r d e g re e .

O c to b e r 19^3 — May 1966

S ig n e d

(B . J . V /alker)

ACKNO\YLEDGEMENTS

The a u th o r would l i k e to r e c o r d h i s s i n c e r e th a n k s to

D r. S . T r i p p e t t f o r h i s s u p e r v i s i o n an d c o n s t a n t

e n c o u ra g e m e n t , t o t h e S c ie n c e R e s e a rc h C o u n c i l f o r th e

aw ard o f a R e se a rc h S t u d e n t s h ip and to M iss R. E. O’N e i l l

f o r th e ty p in g in v o lv e d .

CONTENTS

Summary

I n t r o d u c t i o n 1

P h o sp h o ran e s and P h o sp h o ru s Y l i d s 1

The p r e p a r a t i o n o f P h o sp h o ru s Y l id s k

R e a c t io n s o f P h o sp h o ru s Y l id s 19

( a ) P h o sp h o ru s Y l id s i n th e W i t t i g R e a c t io n 19

(h ) O th e r R e a c t io n s o f P h o sp h o ru s Y l id s

p ro c e e d in g v i a I n t e r m e d i a t e B e ta in e s 22

( c ) R e a c t io n s o f P h o sp h o ru s Y l i d s n o t

p ro c e e d in g v i a I n t e r m e d i a t e B e ta in e s 1+3

The R e a c t io n s o f P h o sp h o ra n e s w i th A c t i v a t e d T r i p l e

Bonds 53

E x p e r im e n ta l 71

Some R e a c t io n s o f P h o sp h o ru s C o n ta in in g B e ta in e s

i n W i t t i g R e a c t io n s 83

The Mechanism o f th e W i t t i g R e a c t i o n 83

R e a c t io n s o f I n t e r m e d i a t e B e t a in e s i n th e W i t t i g

R e a c t io n o t h e r t h a n O l e f i n F o rm a t io n 87

Abnormal R e a c t i o n s o f t h e B e ta in e s

RgP-C H s ~C H (5)R 98


A bnorm al Q u a r t e r n i s a t i o n R e a c t io n s o f Some

A c t i v a t e d A lk y l H a l id e s 1 2 0 (a )

( a ) R e a c t io n s P r o c e e d in g v i a E no l-P hosphon ium

S a l t s 120 (a )

(b ) The Mechanism o f E no l-P hosphon ium S a l t

f o r m a t io n 127

( c ) The R e a c t io n o f T r ip h e n y lp h o s p h in e w i th

1 - B r o m o - l - N i t r o a lk a n e s 128


The R e a c t i o n o f A ld eh y d es and K e ton es w i th

T r i v a l e n t P h o sp h o ru s Compounds 1 4 3 (a )

E x p e r im e n ta l 154-

R e f e r e n c e s 157

SmiMARY

Both th e m ethods o f p r e p a r a t i o n , and th e r e a c t i o n s ,

o f p h o sp h o ru s y l i d s a r e re v ie w e d .

The r e a c t i o n s o f a c t i v a t e d t r i p l e bonds w i th

p h o sp h o ru s y l i d s a r e s t u d i e d and shown to g iv e r e a r r a n g e d

p r o d u c t s , p r o b a b ly v i a a fo u r-m em b ered c y c l i c t r a n s i t i o n

s t a t e .

A b r i e f o u t l i n e o f th e m echanism o f th e W i t t i g

r e a c t i o n i s g iv e n , and r e a c t i o n s o f i n t e r m e d i a t e b e t a i n e s i n

th e W i t t i g r e a c t i o n , o t h e r th a n o l e f i n f o r m a t io n , a r e s t u d i e d .

The r e a c t i o n o f p h o s p h in e s w i th e p o x id e s i s u se d to d e m o n s t r a te

b e t a i n e d i s s o c i a t i o n and r e a r r a n g e m e n t .

F o l lo w in g a re v ie w o f ab n o rm a l q u a t e r n i s a t i o n

r e a c t i o n s o f a c t i v a t e d a l k y l h a l i d e s , th e r e a c t i o n o f t r i p h e n y l

p h o sp h in e w i th 1- b r o m o - n i t r o a l k a n e s , t o g iv e a -h y d ro x y im in o -

a l k y l phosphonium s a l t s , i s d i s c u s s e d .

A b r i e f rev ie w o f th e r e a c t i o n s o f a ld e h y d e s and

k e to n e s w i th t r i v a l e n t p h o sp h o ru s compounds i s f o l lo w e d by a

more d e t a i l e d s tu d y o f th e r e a c t i o n o f a m in o p h o sp h in es w i th

a ld e h y d e s and k e to n e s to g iv e r e a r r a n g e d p r o d u c t s .

- 1 -

INTRODUCTION

P h o sp h o ra n e s and P h o sp h o ru s Y l i d s .

P h o s p h o ru s , u n l i k e n i t r o g e n , i s a b l e to e x i s t

i n th e q u in q u e v a le n t s t a t e b e c a u s e i t h a s r e a d i l y a v a i l a b l e

d o r b i t a l s i n t o w hich i t s o u t e r s h e l l c an e x p an d . The term

ph o sp h o ran e i n c o r p o r a t e s any compound c o n t a i n i n g f i v e v a l e n t

p h o sp h o ru s .

W ith in th e g e n e r a l g ro up o f compounds known a s

p h o sp h o ra n e s t h e r e a r e two d i s t i n c t t y p e s . The f i r s t

c o n t a i n q u in q u e v a le n t p h o sp h o ru s bonded c o v a l e n t l y t o f i v e

s e p a r a t e g r o u p s , w h i le th e se c o n d have f o u r c o v a l e n t bonds

and a f i f t h , c h a rg e s e p a r a t e d , bond .

The p a r e n t compound o f t h e f i r s t ty p e c a n be

c o n s i d e r e d to be p h o sp h o ru s p e n ta h y d r id e (P H ^). B o th th e1 ,2

t h e o r e t i c a l p o s s i b i l i t y , and th e a c t u a l e x i s t e n c e o f t h i s

compound have b e e n s t u d i e d . The e v id e n c e p o i n t s t o th e f a c t

t h a t i t h a s no f i n i t e e x i s t e n c e even a t t e m p e r a tu r e s a s low

a s —100®C. I t i s s u g g e s te d t h a t i n th e f r e e p h o sp h o ru s

atom th e 3 d o r b i t a l s a r e to o d i f f u s e f o r good b on d ing w i th

h y d ro g en .

The se co n d ty p e o f p h o sp h o ra n e s a r e known a s y l i d s

-2 -

and have a s t r u c t u r e b e s t r e p r e s e n t e d a s a r e s o n a n c e h y b r i d

o f t h e c o v a l e n t and i o n i c fo rm s ( l a ) and ( l b )

RqP = X < --------> R g P -X

( l a ) ( l b )

X c a n be c a r b o n - th e a l k y l i d e n e p h o s p h o ra n e s ( 2 ) , o r

n i t r o g e n - t h e im in o p h o sp h o ra n e s ( 3 )#

R3.P = CRg R3 P = NR

(2 ) (3)

B oth th e s e g ro u p s o f compounds ov/e t h e i r r e a c t i v i t y to th e

a n i o n i c c h a r a c t e r o f t h e i r X atom and were o r i g i n a l l y* ,5

p r e p a r e d by S t a u d i n g e r i n 1919.

Some y l i d s do n o t e x i s t a s shown i n ( l a ) and ( l b ) ,

T hese a r e p h o sp h o ru s y l i d s h a v in g a p - c a r b o n y l g ro up ( 4 ) ,

w hich g i v e s a f u r t h e r p o s s i b i l i t y f o r r e s o n a n c e s t r u c t u r e s .

R3 P = CR — C — R 0

(4 )

A l th o u g h i n many o f t h e i r r e a c t i o n s y l i d s o f t h i s

ty p e behave a s i f t h e y a r e i n th e form (4 ) , t h e r e i s

c o n s i d e r a b l e e v id e n c e to show t h a t th e y a r e i n f a c t b e s t

- 3 -

r e p r e s e n t e d by t h e re s o n a n c e h y b r i d o f fo rm s ( 4 ) and ( 3 ) .

RqP = G E - C - R <---------- > R o P -C E = C - R& L

(W C5)

6A skn es h a s shown t h a t i n compounds o f t h i s ty p e th e

c a r b o n y l s t r e t c h i n g f r e q u e n c y f a l l s t o th e 1 ,6 0 0 cm~^ r e g i o n ,

w hich s u g g e s t s a c o n s i d e r a b l e c o n t r i b u t i o n from th e form

(3 ) » The o r i g i n a l s u g g e s t i o n o f th e p h o s p h o b e ta in e form7

(5 ) was b a se d on d i p o l e moment m e a su re m e n ts . The a c e ty l e n e8 . .

s y n t h e s i s o f T r i p p e t t i s b a s e d on th e a s s u m p t io n t h a t (5 )

h a s a c o n s i d e r a b le c o n t r i b u t i o n .

The P r e p a r a t i o n o f P h o sp h o ru s Y l i d s .

*The f i r s t p r e p a r a t i o n o f a p h o sp h o ru s y l i d

i n v o lv e d t r e a t i n g t r ip h e n y lp h o s p h i n e w i th a d i a z o - a l k a n e

and h e a t i n g th e p h o s p h in e a z in e ( 6 ) fo rm ed .

Pha P + NoCR=^R2 _► P haP = K - N = CR^R213;J

iPh3..P=CE^R® + Ha

9B estm ann h a s a l s o p r e p a r e d p h o s p h in e a z in e s by th e a c t i o n o f

d ib r o m o t r ip h e n y lp h o s p h o r a n e ( 7 ) on h y d ra z o n e s i n th e p r e s e n c e

o f a b a s e such a s t r i e t h y l a m i n e .

PhafBrg + H H 8-H = CEs: PhaP = N - N = CR3

(7)

I t i s s u g g e s te d t h a t p h o sp h o ra n e s a r e fo rm ed from

p h o s p h in e a z in e s v i a t r ip h e n y lp h o s p h in e and th e c a rb e n e :GR^R®,

w hich combine t o g iv e th e p h o sp h o ra n e . D i r e c t r e a c t i o n be tw een

t r ip h e n y lp h o s p h in e and c a r b e n e s h a s b e en r e p o r t e d ,10 ,1 1

C h lo ro m e th y le n e w i th t r ip h e n y lp h o s p h in e a t -30®C gave a 63^10 ,11

y i e l d o f c h lo r o m e th y le n e t r ip h e n y lp h o s p h o r a n e ( 8 ) , w hich

c o u ld be r e a c t e d w i t h a ld e h y d e s a n d k e to n e s i n a W i t t i g

r e a c t i o n to g iv e v i n y l c h l o r i d e s .

-5 -

C3îa:Cls + LlC^Ha -» :GB3 1 P % P = CECI

( 8 )

a ld e h y d e s o r k e to n e s

R^E®C= CHCl + Pha PO

11 ,1 2 l aD ic h lo ro m e th y le n e and m e th y le n e a l s o r e a c t w i th

t r ip h e n y lp h o s p h i n e to g iv e t h e c o r r e s p o n d in g y l i d s .

D ic h lo r o m e th y le n e t r ip h e n y lp h o s p h o r a n e (9 ) h a s

a l s o b e e n p r e p a r e d by th e r e a c t i o n o f t r i p h e n y lp h o s p h i n e / 14w i th c a r b o i y c e t r a c h l o r i d e . T h is r e a c t i o n a p p e a r s t o p r o c e e d

w i th a t t a c k o f p h o sp h in e on h a lo g e n to g iv e th e phosphonium

s a l t ( l O ) , e l i m i n a t i o n o f c h l o r i d e l e a d s t o d i c h l o r o t r i p h e n y l -

p h o sp h o ra n e and d i c h lo r o c a r b e n e w hich can r e a c t w i th more

p h o sp h in e to g iv e d i c h lo r o m e th y le n e t r ip h e n y lp h o s p h o r a n e ( 9 ) .

P h g f : + C l - C C l a P h ^ P - C l CCI3"

( 1 0 )PhaPC la + tCCl-B > PhaP = CClg

C9)

The r e a c t i o n o f c a rb o iy te t ra b ro m id e w i th t r i p h e n y lp h o s p h i n e i s 16 /

s i m i l a r . However i f t h e p r o d u c t i s t r e a t e d w i th h y d ro g e n

b rom ide t o g iv e th e phosphonium s a l t ( l l ) , t h i s w i l l u n d e rg o

r e a c t i o n w i th t r i p h e n y lp h o s p h i n e t o g iv e b ro m o m e th y le n e -

t r ip h e n y lp h o s p h o r a n e (’12 ) .

- 6 -

P h g f = CBra PhaP-C H B ra Bi>“

( 11)

PhaPf

PhgjP = CHBr + Phg PBPg

( 12)

P h o sp h o ru s y l i d s c a n a l s o be p r e p a r e d from d ih a lo p h o s p h o r a n e s16

o f th e ty p e EgPGlg. H o rn e r an d O e d ig e r h av e shovm t h a t i n

th e p r e s e n c e o f t e r t i a r y am ines d ih a lo p h o s p h o r a n e s w i l l r e a c t

w i th a c t i v e m e th y le n e g ro u p s t o g iv e p h o sp h o ra n e s ( 1 3 ) .

EaPClg + CHb RaP = C (1 3 )\ y

V/here X and Y a r e e l e c t r o n w i th d ra w in g g ro u p s .

A f u r t h e r i n d i r e c t m ethod o f p r e p a r i n g p h o sp h o ra n e s

h a s b e e n d e v e lo p e d by B estm ann. I n a s e r i e s o f17 ,18 ,19 ,20 ,21 ,22 ,23

p a p e r s he h a s shown t h a t a l k y l a t i o n and

a c y l a t i o n o f p h o sp h o ra n e s l e a d s t o c x - s u b s t i t u t e d p r o d u c t s .

T re a tm e n t o f a l k y l i d e n e p h o sp h o ra n e s (1 4 ) w i th a l k y l h a l i d e s

l e a d s t o a - s u b s t i t u t e d phosphonium s a l t s ( 15 ) .

PhaP= CHE + Ri^I -» PhaP-CHEiR^ l “

(1 4 ) (1 5 )

T h is i s a l s o t r u e f o r a c y l a t i o n . H ow ever, i f t h e a -h y d ro g e n

-7 -

i n th e phosphonium s a l t ( 1 5 ) i s more a c i d i c t h a n t h a t

i n th e phosphonium s a l t , o b t a i n e d on t r e a t i n g t h e p h o sp h o ra n e

(li+) w i th a c i d , t h e r e a c t i o n d o es n o t s to p a t t h i s p o i n t .

The phosphonium, s a l t (1 5 ) i s d e h y d ro h a lo g e n a te d by th e

p h o sp h o ran e ( l 4 ) t o g iv e ( l 6 ) and ( 1 7 ) .

PhaP-G H E^R I" + P h g P = CRR PhaP=CER^ + P h aP -C H gR I ~

(15 ) (1 4 ) ( 16 ) ( 1 7 )

T h is r e a c t i o n i s known a s t r a n s y l i d a t i o n and t a k e s

p l a c e when i s an e l e c t r o n w ith d ra w in g g ro u p . I n c a s e s o f

t h i s ty p e o n ly a 50^ e q u i v a l e n t o f R^I i s added i n o r d e r t o

a v o id th e c o m p l i c a t io n s o f a d d i t i o n to ( l 6 ) .

P h o sp h o ra n e s w i th a l a r g e ra n g e o f a - s u b s t i t u e n t s17 ,1 $ so

c a n be p ro d u c e d by t h i s m ethod , e . g . —COR,84 85 38 2 3

-CH O , - B r , - T , -COOR.

P h o sp h o ra n e s may a l s o be p r e p a r e d f r o n u n s a t u r a t e d2 7/ 28

compounds. Oda and Hoffm ann have shown t h a t p h o s p h in e s

w i l l add to a c t i v a t e d d o u b le b o n d s , i n e t h a n o l , p re su m a b ly

i n i t i a l l y fo rm in g th e b e t a i n e ( 1 8 ) which th e n t a k e s u p , and

l o s e s , a p r o t o n f ro m , and t o , th e s o l v e n t to g iv e t h e more

s t a b l e p h o sp h o ra n e ( 19 ) .

—8—

+ —»Rq;P + CHa = CHX —> R s P - C H a - G E - X

(18) Eton

E g P s CH— C%X + EtOE <---- R a P -C H g ,-C H a -X EtO

(1 9 )

Where X can be — CE> — COOEt, — GOEHg .

Hoffmann c a r r i e d o u t t h e s e r e a c t i o n s i n th e p r e s e n c e o f

a c i d and i s o l a t e d th e c o r r e s p o n d in g phosphonium s a l t s ,

w h i le Oda add ed a ld e h y d e s and i s o l a t e d th e o l e f i n s p ro d u c e d

from a W i t t i g e l i m i n a t i o n ( s e e p . 83 )•8 9 3 0

O such, and o t h e r w o r k e r s , have ad d ed

t r ip h e n y lp h o s p h in e t o m a le ic a n h y d r id e t o g iv e t h e phospho

b e t a i n e ( 2 l ) . T h is r e a c t i o n p re su m a b ly t a k e s p l a c e by a

m echanism s i m i l a r t o t h a t d e s c r i b e d a b o v e , i n i t i a l f o r m a t io n

o f t h e b e t a i n e ( 2 0 ) and p r o t o n t r a n s f e r to g iv e th e

p h o s p h o b e ta in e .

PhaP

PbgP

( 20 ) ( 21 )The r e a c t i o n o f me th y le n e t r i p h e n y l p h o s p h o r a n e w i t h

t e t r a m e t h y lc y c l o b u t a d i o n e l e a d s t o th e p h o s p h o b e ta in e ( 22 ) ,

-9 -

p e r h a p a by i n i t i a l a t t a c k a t a c a r b o n y l g rou p f o l lo w e d by

r i n g open in g and a p r o t o n t r a n s f e r .Me

Me

Me"Me

Phr Me

. ? SP i% T -G E = C C ^ M e <-

C GH/ \ \

Me Me Me

( 22)

OT Me

P —f GH C — C —

^ 4 'M e yMe

Me* i ^ M e

P h a ,? CH— C

Me I

32S e y f e r t h h a s added d ip h e n y lm e th y lp h o s p h in e t o

benzyne t o p ro d u c e m e th y le n e t r ip h e n y lp h o s p h o r a n e ( 2 3 ) , w hich

was t r a p p e d w i th c y c lo h ex a n o n e i n a c o n v e n t io n a l W i t t i g

r e a c t i o n .

P h g P -C H a +

+ Pha,PO « Pha.P = CHa

-1 0 -

A l l t h e s e m e thod s may be u s e d t o p ro d u ce

p h o s p h o r a n e s , how ever t h e m ost g e n e r a l m ethod o f p r e p a r a t i o n

i s the t r e a tm e n t o f t h e c o r r e s p o n d in g phosphonium s a l t w i th

a s u i t a b l e b a s e .

+■ —Ea,P-CHR^R® + B ^ R aP sC R ^E ® + BH

33A w ide ra n g e o f b a s e s a r e a v a i l a b l e and th e

c h o ic e d ep en d s on th e ty p e o f p h o sp h o ra n e t o be p r e p a r e d , i t s

s t a b i l i t y t o f u r t h e r r e a c t i o n w i th t h e m ed ia and th e e a s e o f

rem o v a l o f th e a —p r o t o n i n th e phosphonium s a l t .

G e n e r a l l y p h o sp h o ra n e s c a n be d i v i d e d i n t o two

g r o u p s , " s t a b l e * * and * * u n s tab le **. The ** s t a b l e ** p h o sp h o r

a n e s a r e th o s e i n which th e n e g a t i v e c h a rg e r e s i d i n g on th e

a —c a rb o n atom i s d e l o c a l i s e d to some e x t e n t by s u b s t i t u e n t s .

When t h i s d e l o c a l i s a t i o n i s n o t p r e s e n t we h av e th e **u n s t a b l e **

p h o s p h o ra n e s . The e l œ t r o n w i th d ra w a l by s u b s t i t u e n t s which

s t a b l i s e s t h e p h o sp h o ra n e w i l l a l s o a i d rem o v a l o f a p r o t o n

from th e phosphonium s a l t , th u s th e p r o d u c t i o n o f **u n s t a b l e **

p h o sp h o ra n e s r e q u i r e s a more p o w e r f u l b a se t h a n t h a t o f

**8 t a b l e ** p h o s p h o ra n e s .

B a se s u s e d t o p ro d u c e * * u n s tab le ** p h o sp h o ra n e s a r e

u s u a l l y m e t a l a l k y l s , commonly l i t h i u m a l k y l s . The m echanism

o f p h o sp h o ra n e f o r m a t io n u s in g t h e s e b a s e s h a s y e t t o be f u l l y

-1 1 -

e x p l a i n e d , an d a number o f s i d e r e a c t i o n s h a v e b e e n shown

t o t a k e p l a c e . I n th e r e a c t i o n o f m e th y l t r ip h e n y lp h o s p h o n iu m3 4r ,3 6

brom ide w i th n - b u t y l - l i t h i u m , S e y f e r t h h a s shown

t h a t , a s w e l l a s b u t a n e , a 2.0fo y i e l d o f b e n ze n e i s p ro d u c e d

and t r e a t m e n t o f te t r a p h e n y lp h o s p h o n iu m b rom id e w i th

m ethy1- l i t h i u m g i v e s a t l e a s t ^8^ o f m e t h y l e n e t r i p h e n y l -3 4 , 3 6

p h o sp h o ra n e . H ow ever, i f the b a se i s chan g ed to

v in y 1- l i t h i u m th e p r o d u c t s from t h i s r e a c t i o n a r e s t y r e n e and36

t r i p h e n y lp h o s p h i n e . S e y f e r t h h a s p ro p o s e d th e q u in q u e -

v a l e n t p h o sp h o ru s d e r i v a t i v e i 2 k ) a s th e i n t e r m e d i a t e i n

th e s e r e a c t i o n s .

Ph Ph I Ph

+ - \ I /P h tP Br + CEiaLi ^ ^P Ph@P = GH&

/ ^ P h

C 2 k )

The r e a c t i o n o f l i t h i u m - a l k y l s w i th h a l o m e t h y l t r i p h e n y l -37

phosphonium s a l t s i s a l s o com plex . A l th o u g h c h lo r o r a e th y l -

t r ip h e n y lp h o s p h o n iu m b rom id e gave o n ly c h lo r o m e t h y l e n e t r i p h e n y l

p h o sp h o ra n e and b e n ze n e on t r e a t m e n t w i th l i t h iu m - p h e n y 1 ,

b ro m o m e th y l t r ip h e n y lp h o sp h o n iu m brom ide gave b e n ze n e ( 39^ ) and

-1 2 -

■bromobenzene u n d e r th e same c o n d i t i o n s , p re s u m a b ly by

a t t a c k a t b o th c a rb o n —h y d ro g en and c a rb o n -b ro m in e b o n d s .

Pha P— C H a - C l Br"

Phg P — GHg. — Br , Br

PhLi » PhaP = GHGl Hr PhH + L iB r

P haP = CHBr + PhH + L iB r

PhgP = GHg + PhBr L iB r

When th e r e a c t i o n i s e x te n d e d t o i o d o m e th y l t r i p h e n y lp h o s -

phonium i o d id e th e p r o p o r t i o n o f a t t a c k on th e h a lo g e n - c a r b o n

bond i s i n c r e a s e d s t i l l f u r t h e r , t h e p r o d u c t s b e i n g b enzene

( 2 % ) and io d o b en z en e ( 7 0 ^ ) . T h is t r e n d i s i n ag reem en t w i th

th e o b se rv e d r e a c t i v i t y o f c a rb o n h a lo g e n b onds to w a rd s38 39

l i t h i u m h y d r o c a rb o n s . K o b r ic h h a s fo u n d t h a t c a r b o n -

•h a lo g e n c le a v a g e i s m in im is e d by th e u se o f p i p e r i d y 1- l i t h i u m

a s th e b a s e . He o b ta in e d a 70^ y i e l d o f o l e f i n from th e

r e a c t i o n s o f p—iono ne w i th b ro m o m e th y le n e t r ip h e n y lp h o s p h o ra n e

p ro d u c e d i n t h i s way.

LiCaHgHPhaP — GHg: — Br Br PhaP= GHBr

—13-

I n a l l t h e s e r e a c t i o n s a n e x c e s s o f l i t h i u m

h y d ro c a rb o n m ust be a v o id e d b e c a u se th e a n io n ( 2 5 ) may be40

p r o d u c e d , which c a n u n d e rg o r e a r r a n g e m e n t t o g iv e t h e

b e n z y l id e n e p h o s p h o ra n e ( 2 6 ) .

/PhPh3 P = a i C l P h a P ^ C T ------------ >• PhgRP = OHPh

( 2 5 ) ( 2 6 )

To p ro d u c e ** u n s t a b l e ** p h o s p h o ra n e s , v e r y r e a c t i v e b a s e s

su ch a s th e l i t h i u m h y d ro c a r b o n s m ust be u se d , and i t i s j u s t

t h i s r e a c t i v i t y t h a t h i n d e r s t h e i r u s e i n th e p r o d u c t i o n o f

many p h o s p h o ra n e s . I f t h e phosphonium s a l t c o n t a in s a

g rou p w hich w i l l r e a c t w i th t h e l i t h i u m h y d ro c a rb o n ( e . g .

c a r b o n y l ) t h e n a l k a l i - m e t a l a l k o x i d e s c a n be u s e d . These

may be em ployed i n a v a r i e t y o f s o l v e n t s ( e . g . t h e p a r e n t

a l c o h o l , H ,N -d im e th y lfo rm a m id e , h e x a m e th y lp h o s p h o r ic

t r i a m i d e ) and on a d d i t i o n o f th e phosphonium s a l t an

e q u i l i b r i u m i s e s t a b l i s h e d : —

Ph. .f-CHR^R® + "OR si Ph«P=CR^R® + ROH

Some phosphonium a l k o x i d e s c a n decompose to p h o sp h in e

o x id e s ( s e e p . 3h) and so th e p h o sp h o ra n e i s b e s t u s e d

q u i c k l y .

-1 4 -

A n o th e r b a se w hich i s becom ing w id e ly u se d h a s

b e e n d e v e lo p e d by C o rey . Sodium h y d r id e d i s s o l v e s i n

d im e th y ls u lp h o x id e ( 2? ) to g iv e th e s u lp h o x id e a n io n (28 )

and h y d ro g e n .

CHa CHg\fN = 0 - S S Ë » ' ^ s - o + %

CI% CEo N a*

(27) . (28)

T h is a n io n i s a n e x t r e m e ly p o w e r fu l b a s e and th e sy s tem h a s

th e a d v a n ta g e t h a t d im e th y ls u lp h o x id e i s c o m p le te ly m i s c i b l e42

w i th w a te r . How ever, t h e a n io n w i l l r e a c t w i th k e to n e s

and t h i s can c a u se c o m p l i c a t i o n s .

Sodium h y d ro x id e a n d e v e n , i n e x c e p t i o n a l c a s e s ,

sodium b i c a r b o n a t e , c a n be u s e d a s a b a s e , b u t o n ly to p ro d u ce

th e more s t a b l e p h o s p h o ra n e s . E th o x y c a r b o n y lm e th y le n e t r i -/ \ * 3p h e n y lp h o s p h o ra n e ( 2 9 ) c a n be p ro d u c e d i n t h i s way, a t

0®G i n aqueous s o l u t i o n .

. Br~ HaOH.P h a f - CHa -COOEt ""o^C = CH-COOEt

Not a l l p h o sp h o ru s y l i d s may be p r e p a r e d by th e

—15-

t r e a tm e n t o f a phosphonium s a l t w i th th e a p p r o p r i a t e b a s e .

I f a lk y l t r ip h e n y lp h o s p h o n iu m s a l t s , h a v in g i n th e p - p o s i t i o n ,

i n th e a l k y l g ro up a g r o u p ,w hich i s c a p a b le o f s t a b l e e x i s t e n c e

a s an a n io n o r u n c h a rg e d m o le c u le , a r e t r e a t e d w i th b a se t h e y

may e l i m i n a t e t h i s g ro u p to g iv e a v in y l t r ip h e n y lp h o s p h o n iu m

s a l t .

Pha P - C H a - C H a P h a P C H g ,

+ iP h a ,P -C H = CHa X

+ 44 46 45T h is o c c u r s w here X i s : - P hgP , — OEt, h a lo g e n , and

46h y d r o x y l , and i s r e v e r s i b l e u n d e r th e c o r r e c t c o n d i t i o n s .

I t i s ev en p o s s i b l e f o r t h i s e f f e c t t o be t r a n s m i t t e d th ro u g h46

a c o n ju g a te d sy s te m .

P haP = C H - GH= C H - C% - PPhg ^ P h a P - CH= C M - CH= GHg + P h g?

X“ X”

47 2 1 ,4 8Mondon, and o t h e r w o r k e r s , have shown t h a t a s i m i l a r

r e a c t i o n t a k e s p l a c e w i th CO"" b ro m o b u ty l t r ip h e n y lp h o s p h o n iu m

b rom ide on t r e a tm e n t w i th p h e n y l - o r b u t y l - l i t h i u m . The

e x p e c te d p h o sp h o ra n e (3 0 ) b e in g p ro d u c e d i n i t i a l l y and th e n

u n d e rg o in g s e l f a l k y l a t i o n to g iv e e y e lo b u ty l t r ip h e n y lp h o s p h o n iu m

b ro m id e .

-1 6 -

Pha p - (CHj >4, - B r B r PhgP ÇH» - ^ r

( 3 0 ) CHg— GHg

IP h a P -C H -C H g Br

CHg-CHg46 ,49

V a r io u s w o rk e rs h av e shown t h a t v i n y l -

phosphonium s a l t s th e m se lv e s b ehave a b n o rm a lly i n th e p r e s e n c e

o f b a s e . Keough and G rayson t r e a t e d th e v iny Iphosphon iu rn

s a l t (.3 1 ) w i th a s e r i e s o f a n io n s and showed t h a t a d d i t i o n

o c c u r r e d a c r o s s th e d o u b le bond i n p r e f e r e n c e to th e rem oval

o f an a - p r o t o n .

+ - X“ +E3 P - C E = GHg Y ■■> R3 P - G H 2 - C H g - X Y

(31 )

46 ,49 46 ,49 46, 49X c o u ld be c a rb o n , n i t r o g e n , oxygen , s u lp h u r

46o r p h o s p h o ru s .

49S ch v /e ize r and L ig h t h av e a l s o shown t h a t inhen

XH i s th e s u b s t i t u t e d p y r r o l e ( 3 2 ) , th e i n i t i a l M ic h ae l a d d i t i o n

p r o d u c t u n d e rg o e s an i n t e r n a l W i t t i g r e a c t i o n to g iv e compound

( 3 3 ) i n h ig h y i e l d .

-1 7 -

n -

^ C H O

NaHEtgO a

Br~P h a P - c m = cais,

N ' CHOHa+

(32)

a H I0=0

I ^ +GHg - GH - PPhg

VL C m . . -

CHo - & - PPho

(33)

T h is ty p e o f r e a c t i o n h a s b e e n d e v e lo p e d i n t o a g e n e r a l r i n g5 0

s y n t h e s i s .

V/hen phosphonium s a l t s w i th a k e to g ro up i n th e

0 p o s i t i o n a r e t r e a t e d w i th sodium a lk o x i d e s th e p h o sp h o ra n e

i s i n i t i a l l y f o r m e d ,b u t th e n u n d e rg o e s an i n t e r n a l W i t t i g& ±.

r e a c t i o n to p ro d u c e a c y c l i c o l e f i n .

P1% P = C E - (CHa )3 - G O - P b P h aP O + P h - C H - ( C H a ) a

'^ C H

A s e r i e s o f t h e s e r e a c t i o n s have b e e n c a r r i e d o u t

-1 7 a -

on phosphonium s a l t s o f t h e ty p e (3U)

PhcP-C H a - (C H a ) j j - COPh B r“

L3k)

When n = l^ a n d sodium e th o x i d e i s u se d a s a b a s e , a p - e l i m i n a t l o n62

t a k e s p l a c e t o g iv e t r i p h e n y lp h o s p h i n e .

P h s , :^ GHg: CO - Ph -* Phg^P + CH3 = C E - COPh

OEt

H ow ever, i f l i t h i u m p h e n y l i s u s e d a s th e b a s e , 1 ,452

diphenyl-1,4 -c y c lo h e x a d ie n e i s fo rm e d , p re s u m a b ly by an

i n t e r m o l e c u l a r r e a c t i o n #

When n = 2 , no o l e f i n i s fo rm ed u n d e r a n y c o n d i t i o n s ,53

and o n ly i n s m a l l y i e l d when n = 4 .

phosphonium s a l t s w i th e s t e r g ro u p s i n th e ^ j S and £ p o s i t i o n s i n t h e s i d e c h a in g iv e a c y l a t e d p h o s p h o ra n e s

6 4when t r e a t e d w i th sodium a lk o x i d e s .

P h o P = C H - ( C % ) n - C ( -4 P h 3 P = C ^ ^ F ^ ) n^ O E t 3 0 - ^

0 ^n = 2 , 3 , 4 .

66Bestm ann h a s a l s o shown t h a t p y r o l y s i s o f th e

l a c t o n e ( 3 3 ) l e a d s t o d e c a r b o x y l a t i o n and th e f o r m a t io n o f

—18-“

th e c y c lo p ro p y lp h o sp h o n iu m s a l t (36)#

CHg — Œ — PPha; 180 -

B r 190®G^ COg + CHs — ,

GH<

GH PPhaBp-

(36)

-1 9 -

R e a c t i o n s o f P h o sp h o ru s Y l l d s #

( a ) P h o sp h o ru s Y l l d s i n th e W i t t i g R e a c t io n

The enorm ous i n t e r e s t i n t h e r e a c t i o n s o f

p h o sp h o ru s y l i d s , o v e r t h e p a s t d e c a d e ,s t e m s m a in ly from th e5 6

d e v e lo p m e n t , by W i t t i g , o f a g e n e r a l o l e f i n s y n t h e s i s

i n v o lv i n g th e s e compounds.

A l a r g e number o f r e v ie w s on th e W i t t i g r e a c t i o n33 ,46 ,6T ,68 ,69 ,6 0 ,6 &

h av e a p p e a re d , t o g e t h e r w i th more th a n

one h u n d red and f i f t y p a p e r s . A d i s c u s s i o n o f th e mechanism

o f th e W i t t i g r e a c t i o n w i l l be fo u n d below ( p . 83 ) and h e r e

i t s g e n e r a l a p p l i c a t i o n s w i l l be d i s c u s s e d .

I n th e W i t t i g r e a c t i o n a k e to n e o r a ld e h y d e i s

r e a c t e d w i th a p h o sp h o ra n e to g iv e an o l e f i n and a p h o sp h in e

o x id e . The c a r b o n y l compound may c o n t a i n any o f th e f o l lo w in g6 3 6 3 6 9 6 4

g r o u p s : - h y d ro x y , a c e to x y , m ethoxy , a c e t a l ,64 66 66

t e t r a h y d r o p y r a n y l , d im e th y la m in o , t e r m i n a l a c e t y l e n i c ,43 43 6 6

h a lo g e n , e s t e r and n u c l e a r h a lo g e n and n i t r o .

The r e a c t i o n h a s p r o b a b ly fou nd m ost u se i n p o ly e n e6 7’ 6 8 6 9

s y n t h e s i s . S g u a le n e , V i ta m in A e s t e r , l y c o p e n e ,6 9 6 9

1 5 , 1 5 * -d eh y d r0- l y c o p e n e , 1 5 ,1 5 *- c i s - l y c o p e n s ,6 9 7?0

1 5 , 1 5 *- d e h y d r 0- 0 - c a r o t e n e and n o r b i x i n and c r o c e t i n d i e s t e r s

h av e b e e n p r e p a r e d u s i n g th e W i t t i g r e a c t i o n .

-2 0 -

The r e a c t i o n h a s b e en u s e d e x t e n s i v e l y i n th e

V ita m in D f i e l d . C a l c i f e r o l and o t h e r r e l a t e d s t e r o i d s have

b e e n p r e p a r e d f o r u se i n l i g h t a b s o r p t i o n s t u d i e s by m ethods6 2 , 6 8

i n v o lv i n g W i t t i g r e a c t i o n s .26

Bestm ann h a s u se d th e W i t t i g r e a c t i o n to

s y n t h e s i s e t r i t i a t e d o l e f i n s w i th p h o s p h o ra n e s h a v in g a

t r i t i u m atom a s th e m e th y le n e c a rb o n a tom . T hese p h o sp h o ra n e s

were p r e p a r e d by t r e a t i n g th e c o r r e s p o n d in g n o n - t r i t i a t e d

phosphonium s a l t w i th sodium e th o x id e i n t r i t i a t e d e t h a n o l : -

PhaP-C H gR > PhaPdCER + EtOHEtOT

Ph&P=GTR ^-------------} PhaP-GHTR + EtO~

I R*CHO

R»CBI= GTE

4A l i é n é s hav e a l s o b e en p r e p a r e d . S t a u d in g e r and

71. 72W i t t i g r e a c t e d k e te n e s w i th p h o s p h o ra n e s , w h i le Gilman

u s e d th e p h o sp h o ra n e (37 ) and k e to n e s t o g iv e a l i é n é s .

P h sP = 0 = CR= R® Hr R ^ R ^ C sO R^R*G= G = GR^R^ 4 PhoPO

(37)

L e v i n e , W i t t i g ^ * and Z b i r a l^ ^ have shown t h a t

-2 1 -

th e W i t t i g r e a c t i o n c a n be u s e d a s an a l t e r n a t i v e t o th e

g l y c i d i c e s t e r s y n t h e s i s , f o r th e c o n v e r s io n o f an a ld e h y d e

o r k e to n e i n t o i t s n e x t h i g h e r hom ologue. A ld e h y d e s and

k e to n e s r e a c t w i th m e th o x y m e th y le n e t r ip h e n y lp h o s p h o ra n e s t o

g iv e v i n y l e t h e r s , w hich a r e r e a d i l y h y d r o ly s e d by a c i d t o

a ld e h y d e s .

PhgiP= CHCOCH» * R*R®C=0 -» R=^E®C= CHCOCH;3

/R^R®Cai.CHO

76S i e m i a r t y c k i h a s u s e d c e r t a i n s u b s t i t u t e d b e n z y l i d e n e -

p h o s p h o ra n e s a s s e l e c t i v e r e a g e n t s f o r th e d e t e r m i n a t i o n o f

a ld e h y d e s .

R e c e n t ly f l u o r o o l e f i n s h av e b een p r e p a r e d by a77 ,78

m ethod w hich i n v o l v e s t h e W i t t i g r e a c t i o n . When a

p h o s p h in e , a c a r b o n y l compound and sodium d i f l u o r o c h l o r o -

a c e t a t e a r e h e a t e d i n a p o l a r s o l v e n t d i f l u o r o o l e f i n s a r e

p ro d u c e d . The d i f l u o r o c a r b e n e p ro d u c e d f r o n th e sodium s a l t

p re s u m a b ly r e a c t s w i th th e p h o sp h in e to g i v e t h e p h o sp h o ra n e

(3 8 ) w hich t h e n u n d e rg o e s a n o rm al W i t t i g r e a c t i o n t o g iv e

th e p r o d u c t s .PhgP

GlCPg -CDONa GOg + NaCl + :GFg --------- > Phg P = CPg(3 8 )

I R a C ORgC = GPg + PhgPO

-2 2 -

( h ) O th e r R e a c t i o n s o f P h o s p h o ru s Y l ld s P ro c e e d in g

v i a I n t e r m e d i a t e B e t a i n e s .

The W i t t i g r e a c t i o n i s a s p e c i f i c exam ple o f a

g e n e r a l r e a c t i o n o f p h o sp h o ru s y l i d s p r o c e e d in g th ro u g h an

i n t e r m e d i a t e b e t a i n e ( 3 9 ) .

+ —Ra.,P=CHE + X = Y R g P - C H R - X - Y

i (3 9 )

p r o d u c t s

A lth o u g h p h o sp h o ra n e s r e a c t by th e no rm al W i t t i g

r o u t e w i th a y 0 - u n s a t u r a t e d k e to n e s i n m ost c a s e s , some

a n o m a l ie s , i n v o lv i n g 1 , 4 - a d d i t i o n , have b e en fo u n d . I n t h e s e

c a s e s th e b e t a i n e (40 ) i s i n i t i a l l y p ro d u c e d , w hich can

decompose i n v a r i o u s ways d e p e n d in g upon th e g ro u p s R.

ft* R*\ R ® I

C

■I — ^ I *CH ^ ( ' - ^ P P b a CH P P h j

I IR i

(ao)

-2 3 -

When ( 4 0 ) i s d e r i v e d from th e r e a c t i o n o f 1 oxo-1,5

d i p h e n y l p e n t - 2 ,4 - d i e n e ( 4 l ) and s t y r y l i n e t h y l e n e t r i p h e n y l -

p h o sp h o ra n e i t decom poses t o g iv e th e t r i e n e ( 4 2 ) ,79

p h e n y la c e ty le n e and t r ip h e n y lp h o s p h in e o x id e .

Ph

( 4 1 )CH 3 0

P h - GH= CH - GH ^PPhokT ^

GH

PhGH = CH

Ph

PhGH = GH- GH

^ GHI

GH= GH

PPhe

Ph/

P h - CH= C H - GH = C H - GH= CH- Ph

+ (42 )

P h-C sG H + PhgPO

vVhen (40) i s d e r i v e d from 2 -m e th y le n e c y c lo h e x a n o n e and

c y c l o h e x y l i d e n e e t h y l id e n e t r i p h e n y l p h o s p h o r a n e any r e a r r a n g e m e n t

s i m i l a r t o t h a t above w ould p ro d u c e c y c lo h e x y n e . As t h i s i s

u n fa v o u ra b le th e d e c o m p o s i t io n f o l lo w s a d i f f e r e n t p a th80

l e a d in g to th e t r i e n e (4 3 ) and t r i p h e n y lp h o s p h i n e o x id e ,

p r o d u c t s w h ich can be e x p l a i n e d by a 1 ,3 h y d r i d e s h i f t .

-2 4 -

,CH:

C \ /P P h 3

+ P113PO

The t h i r d and f i n a l r e c o r d e d exam ple o f c o n ju g a te a d d i t i o n

o f a p h o sp h o ra n e t o a n u n s a t u r a t e d k e to n e h a s b e en81 .

d e m o n s t r a te d by F reem an. When m e th y le n e t r ip h e n y lp h o s -

p h o ran e r e a c t s w i th b e n z y l id e n e a c e t o m e s i t y l e n e (44)*

t r ip h e n y lp h o s p h in e i s e l i m i n a t e d and th e c y c lo p ro p a n e d e r i v a t i v e (4 6 ) i s p ro d u c e d . T h is may be e x p l a i n e d by

e l e c t r o n s h i f t s a s shown i n ( 4 5 ) .

—25'“

P h

CHl)

' ^ P P h a ^

(4 4 )

PhOH GH

P h

PhgP

CHgGH

CH GGHg-

(4 6 )

GH

C o n s id e r a b le work h a s b e en c a r r i e d o u t on th e r e a c t i o n s o f82

e p o x id e s w i th p h o sp h o ru s y l i d s . Denney and B o sk in h av e

shown t h a t e th o x y c a r b o n y lm e th y le n e t r ip h e n y lp h o s p h o r a n e and

s t y r e n e o x id e g i v e , a t 200*0, t r ip h e n y lp h o s p h i n e o x id e

and th e c y c lo p ro p a n e (4 7 ) ( 2 3 ^ ) .

Phg P = GH - GOOEt. + P h - G H - GHg

^ 0P h - GH - GHg + PhgPO

\ /^GH

IGOOEÿ

(4 7 )

McEwan83

fo u n d t h a t when th e o p t i c a l l y a c t i v e phosphonium

-2 6 -

s a l t (4 8 ) was c o n v e r t e d to th e p h o s p h o ra n e , and t r e a t e d

w i th s t y r e n e o x id e , a p r e c i p i t a t e was fo rm e d . T h is was

shown to be th e l i t h i i m i o d i d e a d d u c t o f th e b e t a i n e (4 9 ) •

P h Ph Ph Q-

1+ *■ 1 . L iP h 1 + 1 /CHa— P — CHa------- P h ------------------------------GHg-------P -------GH------ GHg GH

I 2 . Pb-GH-GHa I \I T - \ / ' PhCsHa ^ ^ 0 GgHa

( W ) (4 9 )

When t h i s was h e a t e d t o 190-200*0 f o r t h r e e h o u r s a com plex

m ix tu r e o f p r o d u c t s r e s u l t e d , i n c l u d i n g ra c e m ic e th y l m e t h y l -

p h e n y lp h o s p h in e (3 9 ^ ) and b e n z y la c e to p h e n o n e (5 0 ) ( 1 2 - 3 0 ^ ) .

Use o f i s o t o p i c a l l y l a b e l l e d c a rb o n i n th e phosphonium s a l t

( 4 8 ) , a t th e p o s i t i o n s t a r r e d , p r o v e d t h a t t h i s k e to n e c o u ld

n o t hav e a r i s e n v i a th e s y m m e tr ic a l i n t e r m e d i a t e ( 5 l ) s i n c e

th e l a b e l l e d c a rb o n was fo u n d o n ly a t th e p o s i t i o n (3 t o th e

c a r b o n y l g rou p

-2 7 -

CRr

PhIP

Ph __0 + *0 \

HGH CH— Ph

CgHg\

(4 9 )

GH,

P h - C - G H g -O H Ph

0II

P h ^ ^ ^ C H g ^ P h \

(5 1 ) IJ PhMeEtP

/ U P h ^ - G H s - C - P h

BH

P h - G - G H g - C H g P h

BH

P h - GHg - GHg

0- & - P h

(5 0 )

When h e n z y l id e n e t r ip h e n y lp h o s p h o r a n e was u s e d i n t h i s r e a c t i o n ,

v e r y l i t t l e o f th e k e to n e (50 ) was p ro d u c e d , t h e m ain p r o d u c t s

b e in g t r ip h e n y lp h o s p h in e ox ide (,8C^) and 1 ,3 - d i p h e n y lp r o p e n e .84

Work by Z b i r a l h a s c o n f i rm e d t h i s and a l s o shown t h a t

p -m e th o x y p h e n y le th y le n e o x id e r e a c t s w i th t h i s p h o sp h o ra n e to

g iv e l - p - m e th o x y p h e n y l - 3 -p h e n y lp ro p e n e , th u s e s t a b l i s h i n g th e

p o s i t i o n o f th e d o u b le bond i n r e l a t i o n to t h e p h e n y l g ro u p s .

PhgP = GHPh + p-MeO-GgH* - GH - GHg

p - MeO — Cg Ht — GH = C2I— GHg, — Ph

Z b i r a l h a s a l s o shown t h a t c y c lo h e x e n e o x id e r e a c t s w i th

—28—

b e n z y l id e n e t r ip h e n y lp h o s p h o r a n e t o g iv e th e o l e f i n ( 5 2 ) and

th e h y d ro c a rb o n ( 53 )

Ph3.P=GHPh; ♦ -> P h -C m = Œ —

+

0 “(52 )

(5 3 )

A l l t h e s e r e s u l t s may be e x p la in e d i n th e f o l lo w in g

m anner . The i n i t i a l r e a c t i o n i n a l l c a s e s i s n u c l e o p h i l i c

a t t a c k o f th e a ^ c a r b a n io n i n th e p h o sp h o ra n e on th e ep o x id e t o

g iv e th e b e t a i n e ( 5 4 ) . When = a l k y l th e e l e c t r o p h i l i c

c h a r a c t e r o f th e p h o sp h o ru s i n th e b e t a i n e i s d e c r e a s e d , th u s

h i n d e r i n g a t t a c k o f 0 s u f f i c i e n t l y t o a l lo w a 1 ,3 h y d r id e

s h i f t t o t a k e p l a c e , l e a d in g to t h e k e to n e ( 5 5 ) and th e

p h o sp h in e R^gP.

■ " - U\ +

R=^3:P = CHE®- + R®CE — CHE* E ^ g P y CHE* - CHE®

R'

(5 4 )

E^3 P + E ® C % .CÏÏR3 .COE*.

(55)

—29—

85A s i m i l a r r e a c t i o n h a s b e e n r e p o r t e d by W i t t i g and B o l l .

B u ty ra ld é h y d e r e a c t s w i th b u to x y m e th y le n e t r ip h e n y lp h o s p h o ra n e

t o g iv e th e b e t a i n e ( 5 6 ) w hich u n d e rg o e s a 1 ,2 h y d r id e s h i f t

t o g iv e th e k e to n e ( 5 7 ) and t r ip h e n y lp h o s p h in e .

PhaP= CH - OBu

+

G3H7 - GHG

PhgPyGH i-G Bu

IGg H7

( 56 )

PhgP+

GHg, - 0 - B u

0 = 0

Cg Ht>(5 7 )

I n a l l o t h e r o a s e s c y c l i s a t i o n o c c u r s t o g iv e (58 ) w h ich can

th e n u n d e rg o e i t h e r P —C o r 0 —G f i s s i o n .

0GHR-

R% P

(5 8 ) GHR'

GHR® /

(B)

GHR® ^

•QR^.,P

CHR*

GHR® (5 9 )

r /“ g h e ®

\ CHE*E%,PO + / \ ^

E®GH-— >CHE®

E^aPO + GHR® = CE®-GHgE*

( 60)

-3 0 -

When s t a b l e p h o sp h o ra n e s a r e i ised w i l l be a n e l e c t r o n

w ith d ra w in g g roup and w i l l be a b l e t o s t a b l i s e th e c a r b a n io n

( 5 9 ) , th u s i n th e c a s e o f s t a b l e p h o sp h o ra n e s p a th (A) to g iv e

th e c y c lo p ro p a n e w ould be e x p e c te d . I n o t h e r c a s e s p a th (Bl)

w i l l be f o l lo w e d p ro d u c in g th e o l e f i n ( 6 0 ) , e x c e p t where R^

and R® a r e h e l d i n a f i x e d c o n fo r m a t io n such t h a t R® i s t r a n s

to th e 0 — C bond . T h is i s th e c a s e i n th e i n t e r m e d i a t e ( 6 l )

from c y c lo h e x e n e o x id e , and th e r e a r r a n g e m e n t shown can ta k e

p l a c e l e a d in g t o th e o l e f i n (62 )

R

CH

(61) R -G H = CH

(62)C e r t a i n p h o sp h o ra n e s c an th e m s e lv e s e x i s t i n a b e t a i n e fo rm .

T h is i s th e b a s i s o f th e a c e ty l e n e s y n t h e s i s o f T r i p p e t t and , 8

Gough. One c o n t r i b u t i n g s t r u c t u r e i n p -k e to p h o s p h o ra n e s c an

be c o n s id e r e d t o be th e p h o s p h o b e ta in e form (6 3 ) ( s e e p . 3 )

and an h e a t i n g to ^ 200®G t h e s e compounds e l i m i n a t e p h o sp h in e

o x id e to g iv e th e c o r r e s p o n d in g a c e t y l e n e .

-3 1 -

/ R "

l \ ^ l l ■ - — Ra. PO + IIV C C

■O V A:

(6 3 )

F o r th e y i e l d s t o be good i n t h e s e r e a c t i o n s o r R®

m ust be a b l e t o c o n ju g a te w i th th e d o u b le bond i n th e

b e t a i n e (Ri o r Rg = -P h , -COR, -GOOR, -C N ), t h i s i s

p r o b a b ly b e c a u s e th e a c e t y l e n e fo rm ed r e q u i r e s t o be

s t a b l i s e d somewhat to s u r v i v e th e r e a c t i o n c o n d i t i o n s .86

Zimmerman h a s p y r o ly s e d t h e p h o sp h o ra n e (64 )

a t 220-260®C t o g iv e th e e x p e c te d a c e t y l e n e ( 6 5 ) and th e

m uconic e s t e r ( 6 6 ) .

Pho 5 COOMe MeOOC - C = C - ( CHg ) — COOMe^ (6 5 )

II 220°C +G C%

“ 0 CHa COOMe Me03C-CH = CH-CH = CH-COOMe

( 6 4 ) (6 6 )

The r e a c t i o n o f p h o s p h in e s w i th £ -b e n z o q u in o n e s l e a d s t o

b e t a i n e ( 6 7 ) a n a lo g o u s t o ( 6 3 ) . T hese a r e e x t r e m e ly

-3 2 -

t h e r m a l ly s t a b l e and w i l l n o t e l i m i n a t e p h o sp h in e ox ide

even a t t e m p e r a tu r e s >280°G .

(67);

The r e a c t i o n o f p h o s p h o ra n e s w i th p h e n y l i s o c y a n a te was

f i r s t r e p o r t e d by S t a u d i n g e r , and h a s s i n c e b e en f u l l y89

i n v e s t i g a t e d by T r i p p e t t . The g e n e r a l r e a c t i o n may be

f o r m u la te d a s a t y p i c a l W i t t i g r e a c t i o n p ro c e e d in g v i a th e

b e t a i n e ( 6 8 ) . When and R^ a r e p h e n y l , th e b e t a i n e (6 8 )

e l i m i n a t e s p h o sp h in e o x id e to g iv e 1 , 1 - d i p h e n y l - 2 - p h e n y l -

im id o e th y le n e (6 9 ; R = R® = P h ) .

l^R^

PHqP

R^R^G C II + II

NPh

, R"^R®C-7-C^ ' - V I

• / 0P h g P + ^ J

H

Ei^O -C -H H Ph

;HPh

(68)

R^R^C= C = NPli

(6 9 )Phg P 0

(70)

-3 3 -

However i f o r R® a r e h y d ro g en a p r o t o n t r a n s f e r t o

n i t r o g e n o c c u r s , t o g iv e th e more s t a b l e p h o sp h o ra n e ( 7 0 ) .

N i t ro s o b e n z e n e a l s o r e a c t s w i th p h o s p h o ra n e s v i a

a n i n t e r m e d i a t e b e t a i n e (71 ) to g iv e p h o sp h in e o x id e and90

S c h i f f * s b a s e .

Phg^P = GHR Pho P . Pho PO

j - r -

^ ^ N P h4 +

CURIINPh

0 = N - P h 0

(71 )

T h is r e a c t i o n a p p e a r s t o be g e n e r a l f o r s t a b l e and

u n s t a b l e p h o s p h o r a n e s , how ever p -d im e th y la m in o n i t r o s o b e n z e n e

h a s been shown t o g iv e p h o s p h in e , and w hat i s th o u g h t t o be91

th e n i t r o n e ( 7 2 ) , w i th p h o sp h o ru s y l i d s . T h is i s

p re su m a b ly due t o t h e + M e f f e c t o f th e £ - d im e th y la m in o

g roup f a c i l i t a t i n g th e e l e c t r o n s h i f t s shown i n ( 7 3 ) .

. / = \ I ■ / = v ?■(C H 3 )2 N -^ ^ ^ N - j -CHR -♦ PhaP + (C H 3 )a N -^ ^ ^ H = C H R

(7 3 ) (7 2 )

Garbon d i s u l p h i d e r e a c t s w i t h p h o sp h o ra n e s t o g iv e

t r i p h e n y lp h o s p h i n e s u l p h i d e and t h i o k e t e n e s , * p re s u m a b ly

-3 4 -

v i a th e b e t a i n e (.74) •

Pho P = GRg + GSja -> Pho;P,TT“ CRg Rg C = C = S_ +

8 — 0 = 8 PhoPS

(74)

92Bestm ann and Seng h av e shown t h a t p h o sp h o ra n e s r e a c t

w i th S c h i f f ’ s b a s e s by two d i f f e r e n t r o u t e s d e p en d in g on

th e p h o sp h o ra n e . When p h o sp h o ra n e s o f th e ty p e ( 7 3 ) , w i th

a — CHg — g ro u p i n th e p - p o s i t i o n o f t h e s i d e c h a i n , were

r e a c t e d w i th b e n z y l i d e n e a n i l i n e th e p r o d u c t s w ere p h o s p h in e ,

a n i l i n e and a l i é n é s o f th e ty p e ( 7 6 ) .

P h o P = GH-GHg - R + P h “ C H =N P h P hgP + PhNHg+PhCH = G = GHR

(7 5 ) (7 5 )

As y e t no m echanism h a s b e e n p o s t u l a t e d f o r t h i s r e a c t i o n .

When th e p h o sp h o ra n e i s o f t h e ty p e ( 7 7 ) , w i th

no p — GHg — g r o u p , t h e e l i m i n a t i o n p r o c e e d s v i a th e b e t a i n e

(7 8 ) to g iv e th e im in o p h o sp h o ra n e (7 9 ) and th e o l e f i n (8 0 ) ,

-3 5 -

PhgPs.P h a P = C H - R + H^CH = NPH -* + T^CH

(77 )(78)

CHPh '^R^

Pha,P = NPh ( 7 9 ) +

RCH = CHRi

(80)

Bestm ann h a s a l s o s t u d i e d th e a u t o x i d a t i o n o f p h o s p h o ru s9 4, 9 6, 96

y l i d s . B e n z y l id e n e t r ip h e n y lp h o s p h o r a n e (8 1 ; R = P h )

r e a c t s w i th oxygen to g iv e t r i p h e n y lp h o s p h i n e o x id e ( 8 0 ^ ) ,

c i s - s t i l h e n e (2 0 ^ ) and t r a n s - s t i l b e n e (35% ).

The i n i t i a l s t e p i s p o s s i b l y th e f o r m a t io n o f th e b e t a i n e

( 8 2 ) , d e c o m p o s i t io n o f which l e a d s t o p h o sp h in e o x id e and

b e n z a ld e h y d e w hich c a n th e n r e a c t w i t h th e o r i g i n a l p h o s

p h o r a n e , by a n o rm al W i t t i g r e a c t i o n , t o g iv e s t i l b e n e

(8 3 ; R = P h ) .

P hgP = CHR ____ . P h g V PhgPO

+ (8 1 ) . Vy(8 2 )

R— CHO

PhgP= CHR

Phg.PO + RCH - CHR

(83)

-3 6 -

S ty r y lm e th y le n e t r ip h e n y lp h o s p h o r a n e (8 1 ; R = P h —CH = CH— )

s i m i l a r l y gave 1 ,6 - d i p h e n y l h e x a t r i e n e (83 ; R = P h —GE= GH—) .

T h is r e a c t i o n h a s c o n s i d e r a b l e a p p l i c a t i o n s i n p o ly e n e96

s y n t h e s i s and Bestm ann h a s c o n v e r t e d v i t a m in A i n t o

g_-ca ro ten e i n 35^ y i e l d by th e f o l lo w in g m ethod .

GHjjOH>

HX

CHsPPhg

1 . B ase

R# Og

C y c l i c o l e f i n s , i n c l u d i n g a c e n a p h th y le n e (8 U ), h av e b e e n96

p r e p a r e d by a u t o x i d a t i o n o f b i s - p h o s p h o r a n e s .

-3 7 -

CH = PPh.

(8 4 )

The a n a lo g o u s r e a c t i o n o f p h o s p h o ra n e s w i th s u lp h u r l e a d s

to p h o sp h in e s u l p h i d e s and t h i o k e t o n e s .

S t a b l e p h o s p h o ra n e s (8 5 ) have a l s o been o x i d i s e d97

w ith p e r a c e t i c a c i d t o g iv e o l e f i n s , p r o v id in g = H.

wCHaCOaH

PhoE = CR^E® ---------------^I n

CaJaCOOH

PhaPO + R^R®G = CRiR®

(8 5 )

Thus e th o x y c a r b o n y I m e th y le n e t r ip h e n y Ip h o s p h o r a n e

(8 5 ; = H, R® = —COOEt) gave d i e t h y l f u m a r a t e ( 4 3 ^ ) , b u t

a - e t h o x y c a r b o n y le t h y l i d e n e t r ip h e n y lp h o s p h o r a n e (8 5 ; R ^ = Me ,

R® = — COOEt); gave o n ly 1% o f th e e x p e c te d o l e f i n . When l e s s

s t a b l e , more b a s i c , p h o sp h o ra n e s were u s e d i n t h i s r e a c t i o n

phosphonium a c e t a t e s w ere fo rm ed , w h ich u n d e rw en t h y d r o l y s i s

to th e p h o sp h in e o x id e .

When b e n z o y lp e ro x id e was u s e d a s th e o x i d i s i n g

a g e n t , a c i d a n h y d r id e s o f th e ty p e (8 6 ) were fo rm ed .

-3 8 -

0 0I I

PhoP= C H - C O - P h + 2 P h - G - O - O - G - P h

-» PhgPO + CPhCO)a.O + PhGO - 0 - GO - GHPh

0 - GO- Ph( 86)

A p o s s i b l e m echanism f o r t h i s r e a c t i o n i n v o lv e s th e

i n i t i a l p r o d u c t i o n o f th e phosphonium s a l t ( 8 7 ) , a t t a c k

o f b e n z o a te on t h i s to g iv e th e b e t a i n e (88 ) and e l i m i n a t i o n

o f p h o sp h in e l e a d i n g t p (8g)^ which r e a r r a n g e s t o t h e p r o d u c t

( 86).

PhGOO"

Phg P = GH-GO - Ph + (PhGOO)a -*■ Ph - GO - GH— PPhg

0 -G -P h (87 )

n► P h — G — GH-T-PPhQ

/ \ ^ Ph-CO—-0 0 — C — Ph

n0

( 88)

Ph—GO—0

A+ PhaP

0 - GO - Ph

(8 9 )

P h - G B - GO - 0 - GO - Ph P h - G O - 0

( 86)

The t r i p h e n y lp h o s p h in e i s o x i d i s e d by th e s e c o n d m o le cu le

-3 9 -

o f p e ro x id e and i s o l a t e d a s t h e o x id e . An a l t e r n a t i v e

e x p l a n a t i o n i s t h a t th e b e t a i n e (8 8 ) e l i m i n a t e s p h o sp h in e

o x ide to g iv e an o l e f i n , w h i c h i s e p o x id i s e d by th e se c o n d

m o le c u le o f p e ro x id e to ( 8 9 ) .99

Z b i r a l h a s o x i d i s e d p h o sp h o ra n e s w i th l e a d

t e t r a a c e t a t e t o g iv e p h o s p h in e o x id e s and c a r b o n y l com pounds.

Pb(OAc)*P h a = C - G O - R > RCO'COOMe + PhoPO

OMe

O z o n o ly s is o f ^ - k e t o a l k y l id e n e p h o s p h o r a n e s l e a d s 100

t o a - d i k e t o n e s . When t r e a t e d w i th ozone a t -70® i n

m e th y len e c h l o r i d e , p h e n a c y l i d e n e - t r ip h e n y lp h o s p h o r a n e gave

96^ o f t r i p h e n y lp h o s p h in e o x id e and 88^ o f p h e n y lg ly o x a l ( 9 0 ) .

O3Pho P = CH - CO - P h ------------- > Pha PO + FhCO • CHO

CHgClg-70® C ( 9 0 )

10a.M ark l h a s c a r r i e d o u t t h e r e a c t i o n o f b e n z y l id e n e -

t r ip h e n y lp h o s p h o r a n e w i th a l i p h a t i c d iazocom pounds. The

b e t a i n e (9 2 ) was i n i t i a l l y fo rm ed , e l i m i n a t i o n o f t r i p h e n y l

p h o sp h in e t h e n gave th e a z i n e ( 9 3 ) . The t r i p h e n y lp h o s p h i n e

e l i m i n a t e d was a b le to r e a c t w i th a n o th e r m ole o f d i a z o

compound t o g iv e th e p h o s p h in e a z in e ( 9 4 ) »

-4 0 -

+ +Pha p = c m + R2 C 0 « C E - f = I l -» Pha P jC H R

(9 1 ) A - H = GREGOR®

I (9 2 )

, , R®COCEl=K * ,Pha = R - H = CR^COR® *------------------- Pha.P + RCH = N - K = CR GOR®

(9 4 ) (9 3 )

M ark l c la im e d t h a t th e more s t a b l e p h o sp h o ra n e s (9 1 ;

R= — GOOGHs, — CO —P h, —GO—CHa) d id n o t r e a c t w i th

a l i p h a t i c d ia z o compoimds. S t r y e l e c k a , S i e m i a t y c k i , and 102

P r é v o s t h a v e , h ow ever, r e p o r t e d t h a t h e n z o y l d i a z o -

m ethane and p h e n a c y l id e n e t r ip h e n y lp h o s p h o r a n e (91 ; R = — COPh)

r e a c t to g iv e 4 - h e n z y l id e n e - 2 ,6 - d i p h e n y l p y r a n (95 ) and

t r ip h e n y lp h o s p h in e o x id e . GHPh

2Ph3? = CHCO- Ph 4f PhCO-CHNa

PhPh

4r PhoPO

(9 5 )

P y r i l i i m s a l t s (96 ) have b e e n shown to r e a c t w i th p h o sp h o ru s1 03

y l i d s t o g iv e s u b s t i t u t e d benzene d e r i v a t i v e s by a

m echanism in v o lv in g a W i t t i g ty p e e l i m i n a t i o n .

-4 1 -

+ 2 P h s P s CHR

+

BF%

(9 6 )

^ r3 P h o P -C H g R B P ^

R3

PhaPO

R3

104D im ro th , W olf and Wache have e x te n d e d t h i s r e a c t i o n

to th e p r e p a r a t i o n o f a z n le n e d e r i v a t i v e s by u s in g o n ly

h a l f a mole eg_u iva len t o f p h o sp h o ra n e .

"42-

R2

R2fj %PhoP=CH« p Q

" ^ 0 ^ ^ j ' ^+

b p : R"

B f ' (97 )

0 R3

PPho

p i + PhgP

<R0 — \ R " ' " C

ii r p p h o

R2-VI.

b c

P P h ,

( 98)

-4 3 -

The a u th o r s s u g g e s t t h a t th e I n t e r m e d i a t e (97 ) i s

i n i t i a l l y fo rm ed , w h ich , on r i n g o p e n in g , a l d o l c o n d e n s a t io n ,

t r a n s a n n u l a r r e a r r a n g e m e n t and l o s s of w a te r l e a d s to th e

a z u le n e ( 9 8 ) .

P h o sp h o ra n e s a l s o g iv e a d d u c t s w i th e l e c t r o n 106 ,1.06

d e f i c i e n t compounds, e . g . d ib o ra n e r e a c t s w i th+ —

m e th y le n e t r ip h e n y lp h o s p h o r a n e to g iv e PhgP — CHg — BH3 .

T hese a d d u c t s a r e s t a b l e t o w a te r , b u t l i b e r a t e h y d ro g e n

on t r e a t m e n t w i th d i l u t e a c i d . D ecaborane and b o ro n

t r i f l u o r i d e g iv e s i m i l a r s a l t s .

(c ) R e a c t i o n s o f P h o sp h o ru s Y l id s n o t P ro c e e d in g

v i a I n t e r m e d i a t e B e t a i n e s .

R e a c t io n s o f t h i s ty p e may be r e p r e s e n t e d b y : -

R a P = C H E * X - Y -+ E a f - C H R - X + Y "

A l l p h o sp h o ru s y l i d s a r e L ew is b a s e s and a s su ch w i l l r e a c t

w i th i n o r g a n i c a c i d s to g iv e t h e c o r r e s p o n d in g phosphonium

s a l t .

P h g P s CHa + HCl PhoP-CHa. C l”1 07

B estm ann h a s s t u d i e d th e s t a b i l i t y o f p h o sp h o ra n e s an d

shown t h a t an e q ^ u i l l ib r iu m i s e s t a b l i s h e d b e tw een a

p h o sp h o ra n e and a phosphonium s a l t :

-4 4 -

Pha P - CHg - R X" + Pha;P = CHR^ # Phg P = CHR + PI13 P - CHg-R^^ X"

T h is r e a c t i o n i s known a s t r a n s y l i d a t i o n ( s e e p . 6 )

and th e e g u i l l i h r i u m l i e s to w a rd s th e m ost s t a b l e , l e a s t

b a s i c , p h o sp h o ra n e .

P h o sp h o ru s y l i d s u n d e rg o h y d r o l y s i s , t h e l e a s t

s t a b l e i n c o ld w a te r , th e more s t a b l e i n b o i l i n g w a te r o r

a l k a l i , t o g iv e th e c o r r e s p o n d in g h y d ro c a rb o n o f t h a t

g roup a t t a c h e d to th e p h o sp h o ru s which i s m ost s t a b l e a s

an a n io n , and a p h o sp h in e ox ide*

Ph3;P = CHR + HgO P h o P - C H g - R OH”

0 iIIPhgPCHgR + PhH

Only c y c lo p e n t a d i e n y l i d e n e t r i p h e n y l p h o s p h o r a n e i s

u n e f f e c t e d by t r e a tm e n t w i th h o t a l k a l i .

The a l k y l a t i o n o f p h o sp h o ra n e s h a s a l r e a d y b e e n

d i s c u s s e d (p* é ) • Work h a s a l s o b e e n c a r r i e d o u t on sy s te m s

where a l k y l a t i o n and W i t t i g e l i m i n a t i o n s h o u ld be c o m p e tin g

r e a c t i o n s . I n m ost c a s e s th e W i t t i g r e a c t i o n i s more

f a v o u r a b l e . When 4 -h a lo m e th y lb e n z a ld e h y d e i s r e a c t e d w i th

s u b s t i t u t e d b e n z y l id e n e t r i p h e n y l p h o s p h o r a n e s , s u b s t i t u t e d1 08

s t i l b e n e s a r e fo rm ed .

-4 5 -

CHO

+ P h g P = C a - G g H t - R -+ X - C H g - Z ~ ^ - C H = C E - C e H * -R

CHaX

S i m i l a r l y a -b ro m o p ro p io n a ld e h y d e r e a c t s w i th e th o x y c a r b o n y l -

m e th y le n e t r ip h e n y lp h o s p h o r a n e to g iv e th e a , p - u n s a t u r a t e d^ 109

e s t e r (,99) i n GLj y i e l d .

CHa.CHBr.CHO + Phg^P = CH.COOEt CHa. CHBr. CH = CH. COOEt +PhaPO

(9 9 )

110B estm ann h a s c a r r i e d o u t a s e r i e s o f r e a c t i o n s w i th

a -b ro m o k e to n e s and m e th o x y c a r b o n y lm e th y le n e t r ip h e n y lp h o s -

p h o r a n e . K e to n es w i l l n o t underg o W i t t i g r e a c t i o n s w i th

s t a b l e p h o sp h o ra n e s u n d e r th e c o n d i t i o n s o f th e r e a c t i o n and

so t h e f i r s t s t a g e i s a l k y l a t i o n o f th e p h o sp h o ra n e to g iv e

th e phosphonium s a l t ( lO O ) . A se c o n d mole o f p h o sp h o ra n e

th e n rem oves a p - p r o t o n t o g iv e th e b e t a i n e ( l O l ) ,w h i c h

e l i m i n a t e s t r ip h e n y lp h o s p h in e t o g iv e th e o l e f i n (1 02 ) i n

60 -8 0 ^ y i e l d .

E - C O - CHgBr + Phg P = CH- COOCHa Phg P - C H - COOCH3

B r” GHg — C 0 — R

I (100)PhaP + RCOCH= CHCOOCH3 -f P h o ^ C H — COOCH3

-46 -

111S ie m ia ty c k î and S t r y e l e c k a have c a r r i e d ou t th e

a n a lo g o u s r e a c t i o n b e tw ee n p h e n ac y lb ro m id e and ph en a-

c y l i d e n e t r i p h e n y lp h o s p h o r a n e . They fo u n d t h a t a s w e l l

a s th e e x p e c te d o l e f i n ( 1 , 2- d i b e n z o y le t h y le n e ) and

p h e n a c y l t r ip h e n y lp h o s p h o n iu m b ro m id e , a 1% y i e l d o f th e

c y c lo p ro p a n e ( 103) was fo rm ed .

PhQP= GHCOPh + PhCOCHgBr -> PhCO.GBI= GH.COPhCOPh

COPh\Pha,P - CHa - COPh +

(103 )

A p o s s i b l e e x p l a n a t i o n o f th e f o r m a t io n o f th e c y c lo p r a n e

d e r i v a t i v e i s t h a t t h e 1 ,2 d ib e n z o y le th y le n e f i r s t fo rm ed

r e a c t s w i th th e o r i g i n a l p h o sp h o ra n e t o g iv e th e b e t a i n e

( 1 0 4 ) . E l e c t r o n s h i f t s a s shown w i l l g iv e th e c y c lo p ro p a n e

and t r i p h e n y l p h o s p h i n e , w hich would be e x p e c te d t o form

th e p henacy lph osp hon ium s a l t w i th th e p h e n a c y lb ro m id e

p r e s e n t i n th e r e a c t i o n m ix tu r e .

Phg P = GHGOPh + PhCO.CH= CE.COPh

— > P h ^ P j GHCOPh ----------> PhgP + GHCOPh

GHCOPh PhCOCH----- — CHCOPh

- CHCOPh

(1 0 4 )

■-47—

The no rm al r e a c t i o n p a t h f o r b e t a i n e s o f th e

ty p e ( 10 4 ) i s a 1 ,3 p r o t o n t r a n s f e r to g iv e th e s t a b l e

p h o sp h o ra n e (105 ) (S ee p . 54 ) how ever th e c y c lo p ro p a n e

i s o n ly p ro d u c e d i n v e r y low y i e l d .

Ph3;P= C R -G H R -C H gR R = - C O - P h

An a l t e r n a t i v e e x p l a n a t i o n i n v o lv e s t h e p r o d u c t i o n o f t h e

c a rb e n e PhCO— CH, p o s s i b l y b y th e a c t i o n o f th e p h o sp h o ra n e

on p h e n a c y l b ro m id e , a n d a t t a c k o f t h i s on th e 1 , 2- d ib e n z o y l -112

e t h y l e n e . B estm ann h a s shown t h a t w h i l e b r o m o a c e ta te s

g iv e o l e f i n and p h o s p h in e , a s a b o v e , c h l o r o a c e t a t e s g iv e

th e c y c lo p ro p a n e d e r i v a t i v e s c o r r e s p o n d in g t o ( 103 ) , w i th

p h o s p h o ra n e s .69

T r i p p e t t h a s shown t h a t 2 -b ro m ocyc lo hexanon e

r e a c t s w i th th e p h o sp h o ra n e ( 106 ) t o g iv e th e t r i e n e ( 107 ) .

-I- P h sP = CH-CHcc(106)

(107)

-4 8 -

As y e t no m echanism h a s b e en s u g g e s te d f o r t h i s

r e a c t i o n , b u t i t i s p o s s i b l e t h a t th e d ie n e (10 8 ) i s f i r s t

fo rm ed by a n o rm a l W i t t i g r e a c t i o n and t h i s i s t h e n

d e h y d ro h a lo g e n a te d by th e p h o sp h o ra n e ( 106 ) .

+ PhQP= O S - CE

( 106)Br

(108)

(107);

+ BH B r

113M arkl h a s r e a c t e d p h o sp h o ra n e s w i th c h lo ro a m in e s o f

th e ty p e ( 1 0 9 ) . The phosphonium s a l t ( l l O ) i s i n i t i a l l y

fo rm ed , and u n d e rg o e s d e h y d ro h a lo g e n a t io n by th e o r i g i n a l

p h o sp h o ra n e to g iv e th e enam ine phosphonium s a l t ( i l l ) .

PhoP=CHR + CHCla-NMes

(1 0 9 )

GHCl- meg; PhsP-CHH(110) Gi

( 110)

PhgP = CHE

CN "FMe*+ II

PhgP - CE G1 + P l ^ P - C H g - E

( 111)

These compounds c an be u s e d t o p ro d u ce a w ide ra n g e o f

-49—

phosphonium s a l t s .114

S e y f e r t h ^ hav e shown t h a t p h o sp h o ra n e s

w i l l r e a c t w i th m e t a l l i c , a n d o r g a n o m e t a l l i c , h a l i d e s to g iv e

s u b s t i t u t e d phosphonium s a l t s o f th e ty p e ( 112 ) .

PheP = CR^R2 + M - B r P h a P -C R ^ R ^ -M Br

( 112)

114 115 , . 114T h is o c c u r s when M= (CH3 ) a 8 i " , Ph@P-, ( CH3 )g 8n - ,

114and PhgGe.

V/hen d i h a l i d e s a r e u se d th e r e a c t i o n g i v e s th e

d i phosphonium s a l t s (1 13 ) f o r M =Zn’*’**’, Hg’*”*',116 , . 114

PhP and ( CH3 ) g 8n .

+ +PhaP= CR^R^ + B r - M - B r PhgP- CR^R^ - M- CR^R^ - PPhg

2Br~

(1 1 3 )

S t a b l e p h o sp h o ra n e s r e a c t w i th h a lo g e n s to g i v e ,

i n i t i a l l y , th e phosphonium s a l t ( l l 4 ) , w h ich t h e n u n d e rg o e s25 , 1 1 7 ,118

t r a n s y l i d a t i o n to g iv e th e p h o sp h o ra n e ( 115 ) .

+ «

PhQ P = CH - COOCH3 + Xg -► Phg P - CHX - COOCH3 XiPhaP= C X - COOCH3

( 115 )

-5 0 -

H a lo g e n a te d p h o sp h o ra n e s a r e u s e f u l f o r the

p r e p a r a t i o n o f v i n y l h a l i d e s by a W i t t i g r e a c t i o n . I f

e x c e s s h a lo g e n i s u s e d th e p h o sp h o ra n e ( 115 ) r e a c t s

f u r t h e r to g iv e t h e phosphonium s a l t

Pha P - CXg - COOGH3 X”

D iazonium s a l t s w i l l r e a c t w i th s t a b l e p h o sp h o ra n e s

to g iv e s a l t s ( I I 6 ) , w h ich may be c o n v e r t e d t o h i g h l y

c o lo u r e d p h o sp h o ra n e s (1 1 7 ) by t r e a tm e n t w i th aqueous119

sodium h y d r o x id e .

PhoPr: CHR + -N .= N X” P h g P - C H R - R = N-R=^x“ (116)

0H~PhaP= C R -N = H - R i

(1 1 7 )

How ever, when b e n z y l id e n e t r ip h e n y lp h o s p h o r a n e v/as r e a c t e d

w i th d iazon iu m s a l t s th e s a l t (118 ) was p ro d u c e d .

P h 3 P - C - K = N - P h X ^ N = N - P l t

( 118)

C y c lo p e n ta d i e n y l id e n e t r ip h e n y lp h o s p h o r a n e a l s o

b e h av e s d i f f e r e n t l y i n t h a t s u b s t i t u t i o n t a k e s p l a c e a t th e

P p o s i t i o n to g iv e the azo dye ( I I 9 ) , w i th b en zen e d iazon iu m

-5 1 -

120c h l o r i d e i n a sodium a c e t a t e b u f f e r .

PhaP — L > PhgP X“ PhaP

N = H - P h N = K - P h

(119)

121A c c o rd in g to S a u n d e rs and Burchmann, p h o sp h o ru s y l i d s

can be re d u c e d w i t h l i t h i u m alum in ium h y d r id e t o p h o s p h in e s .

PhaP= CHR + LiAlH* -* > PhaPCHgR

+ PhH

Even p - k e to p h o s p h o ra n e s can be r e d u c e d i n t h i s

way v ; i th o u t r e d u c t i o n o f t h e c a r b o n y l g ro u p .

Z inc and a c e t i c a c i d a p p e a rs t o work d i f f e r e n t l y ,

r e d u c in g p - k e to p h o s p h o ra n e s to t r i p h e n y lp h o s p h i n e and a122 ,123

k e to n e . The r e a c t i o n i s th o u g h t t o p ro c e e d by

a t t a c k o f z in c on the c a r b o n y l g roup o f th e i n i t i a l l y

fo rm ed , t r a n s i e n t , phosphonium a c e t a t e .

CHa COOH +Phg P = CH*CO*R ---------------> Phg CHg CHq COO

C aZn‘-1 0 I R

HgO ■TRGOGHa ------- ( GHaGOO)Zn(0 - GR = GHg ) + PhaP

—52—

A tte m p ts to e x te n d t h i s r e a c t i o n to th e p r e p a r a t i o n o f1 2 4

P -k e to e s t e r s have f a i l e d .

-5 3 -

The R e a c t i o n s o f P h o sp h o ra n e s

w i th A c t i v a t e d T r i p l e Bonds

A c t i v a t e d m u l t i p l e bonds a r e h i g h l y s u s c e p t i b l e

to n u c l e o p h i l i c a t t a c k . V a r io u s p h o sp h o ru s c o n t a i n i n g

n u c l e o p h i l e s have b e en u se d i n t h i s way, n o t a b l y125

p h o s p h in e s and p h o s p h o ra n e s .126

Jo h n s o n and Tebby have shown t h a t p h o s p h in e s

r e a c t r e a d i l y w i th a v a r i e t y o f u n s a t u r a t e d com pounds,w i th

i n i t i a l f o r m a t io n o f th e M ic h a e l a d d i t i o n p r o d u c t s .

T r ip h e n y lp h o s p h in e r e a c t e d w i th th e d i e s t e r o f a c e t y l e n e -

d i c a r b o x y l i c a c i d to g iv e ( 1 2 0 ) , w hich th e n r e a c t e d w i th

a f u r t h e r m o le c u le o f a c e t y l e n e to g iv e th e 1 , 5 - d i p o l e

( 1 2 1 ) , w hich was i s o l a t e d a s i t s h y d r o i o d id e .

.COOR PhaP .COOR

PbgP + '

COOR

COOR

COOR

COOR

COOR ^COOR ^C O O R

( 120) ( 121)

27 28Oda and Hoffm ann hav e shown t h a t p h o s p h in e s

r e a c t r e a d i l y w i th a c t i v a t e d do u b le b o n d s , a g a i n i n i t i a l l y

fo rm in g th e M ic h ae l a d d i t i o n p r e c u r s o r , a n a l o g o u s to ( 1 2 0 . )

-5 4 -

(See p . 7 ) •

I n th e r e a c t i o n s o f p h o sp h o ra n e s w i th a c t i v a t e d o l e f i n s ,127 ,128

t h r e e p o s s i b l e p a th s h av e b e en s u g g e s t e d , a l l o f

which i n i t i a l l y in v o lv e M ic h a e l a d d i t i o n o f th e p h o sp h o ran e

c a r b a n io n to th e d o u b le bond to g iv e ( 1 2 2 ) .

Ra P = CHR + R®R®G = GR^R® -* RaP - GHR" - GR^R® - GR*R®

( 122)

T h is c a n th e n r e a c t f u r t h e r by;

( a ) a p r o to n s h i f t from th e a - c a r b o n to th e ^ - c a r b o n

to g iv e th e p h o sp h o ran e (123)

Ra P = GR^ - GR2R® - GHR*R®

(123)

(b ) r i n g c l o s u r e and e l i m i n a t i o n o f p h o sp h in e t o g iv e

th e c y c lo p ro p a n e ( 1 2 4 ) ,

^ G H R ^RaP'

GR^R® CRSRS

(124)

and ( c ) i f R® c a n form a s t a b l e a n io n , th e l o s s o f ( R^)

and f o r m a t io n o f ( 125 ) w hich l o s e s a p r o t o n to

g iv e th e p h o sp h o ra n e ( 1 2 6 ) .

-5 5 -

+ l ' a . - +p — nw pi — np3 — m

'R2

R 3 P - CHR - CR - CR*R® -> R 3 P - CHR - CR® = GR*R®

' ( 1. 3 )

Rs P = CR^ - CR® = CR*R®+ (126)

R*H

A i l t h e s e p a th s have b e en o b se rv e d .

These t h r e e ty p e s o f r e a c t i o n a l s o a p p ly when

p h o sp h o ra n e s r e a c t w i th a c t i v a t e d a c e t y l e n e s . H ow ever,

i n t h e s e c a s e s t h e r e i s th e p o s s i b i l i t y o f a f u r t h e r ty p e

o f r e a c t i o n i n v o lv i n g th e f o u r membered t r a n s i t i o n s t a t e

( 127 ) and l e a d in g to th e p h o sp h o ra n e (1 2 8 ) .

RaPsCHR^ + X - C = C - X -, RaP-|-CHR^

- J b y i (1 27)

R3P= csc-cx= c h r '

(1 2 8 )

127 129T r i p p e t t and H e n d r ic k s o n h av e b o th

c a r r i e d o u t r e a c t i o n s o f p h o s p h o ra n e s o f th e ty p e (1 29 )

w i th d i m e t h y l a c e t y l e n e d i c a r b o x y l a t e .

R3?= CHR"

( 129 )

—5 ""

H e n d r ic k so n fo und t h a t p h e n a c y l i d e n e t r i p h e n y l -

p h o sp h o ran e (129 ; R = Ph; R = — CO — Ph) gave an a d d u c t , f o r

which he s u g g e s te d th e s t r u c t u r e (1 3 0 ) .

Ph.

PRa

-COOCHa

COOCHa

( 130)

He a l s o showed t h a t on p y r o l y s i s th e a d d u c t gave an

a c e t y l e n e o f s t r u c t u r e ( I 3 l ) .

P h - C = C - C = CH/ \

GHa0 0 0 COOCHa

(1 3 1 )

The a c e t y l e n e s y n t h e s i s o f T r i p p e t t and Gough i n v o lv i n g

p h o s p h o b e ta in e s o f th e ty p e (132) h a s a l r e a d y b e en d i s c u s s e d

(S ee p . 3o ) . A p p l i c a t i o n o f th e s e r e s u l t s to H e n d r i c k s o n 's

( 132)

compound s u g g e s t a s t r u c t u r e (133),® which w ould p re s u m a b ly

-5 7 -

g iv e th e a c e t y l e n e (131) on p y r o l y s i s .

COOMe

COOMePhgP . C = G H - CI

- 0 (133)

T h is a d d u c t would be fo rm ed by a p a th a n a lo g o u s to ( a )127

above . T r i p p e t t o b t a i n e d s i m i l a r a d d u c ts w i th o t h e r

p h o sp h o ra n e s and d i m e t h y l a c e t y l e n e d i c a r b o x y l a t e and

s u g g e s te d a n a lo g o u s s t r u c t u r e s f o r them a l l . I n a l a t e r13 0

p u b l i c a t i o n H e n d r ic k so n a l s o s u g g e s t s t h e s e s t r u c t u r e s .

P a th s ( a ) , (b ) and ( c ) above have a l l b e e n

o b s e rv e d , b u t th e f o u r t h s u g g e s t e d p a t h , w hich can o n ly work

f o r th e a c e ty l e n e c a s e , h ad n o t . However, H uebner andl 3 l 1 3 2 ,133 ,134:

Dorfm ann, and a number o f o t h e r w o rk e rs ,

have shown t h a t t h e a d d i t i o n o f b o th a c t i v a t e d and

n o n - a c t i v a t e d a c e t y l e n e s to en am in es in v o lv e d a c y c lo b u te n e

i n t e r m e d i a t e ( 1 3 4 ) , w hich c o u ld even be i s o l a t e d i n c e r t a i n

c a s e s . T h is c a n be r e a d i l y s e e n to be a n a lo g o u s t o th e

f o u r t h p o s s i b l e r e a c t i o n p a th i n th e p h o sp h o ra n e c a s e .

J COOR COOR‘COOR

-5 8 -

T h is r e a c t i o n h a s b e en u s e d t o expand R ing A134:

o f th e s t e r o i d a l n u c l e u s .

To i n c r e a s e t h e p o s s i b i l i t y o f th e f o u r t h r e a c t i o n

p a th th e o t h e r r e a c t i o n p a t h s w ere made im p o s s ib l e o r , a t

l e a s t , d i f f i c u l t .

The p o s s i b i l i t y o f p a th ( a ) was e a s i l y rem oved by

s u b s t i t u t i o n o f th e a -h y d ro g e n b y a l k y l i n th e p h o sp h o ra n e .

E l i m i n a t i o n o f p a t h (b ) was f a r more d i f f i c u l t , a l th o u g h 128

Bestm ann s u g g e s t s t h a t p a t h (b ) becom es l e s s l i k e l y

i f th e p h o sp h o ran e h a s e l e c t r o n w i th d ra w in g g ro u p s on t h e

a - c a r b o n a tom . F o r t u n a t e l y , p a th ( b ) ,w h i c h would l e a d t o

a c y c lo p ro p a n e d e r i v a t i v e , a p p e a r s u n im p o r ta n t i n th e

a c e t y l e n e c a s e . P a th ( c ) c a n n o t o p e r a t e b e c a u se no g ro u p

v/hich c an form a s t a b l e a n io n i s p r e s e n t .

T h ree p h o sp h o ra n e s were r e a c t e d w i th d im e th y l

a c e t y l e n e d i c a r b o x y l a t e , a —e th o x y c a rb o n y l e t h y l i d e n e t r i p h e n y l -

p h o sp h o ran e ( 1 3 5 ) , a - b e n z o y l e th y l i d e n e t r i p h e n y lp h o s p h o r a n e

( 136 ) and a - c y a n o e th y l id e n e t r ip & e n y lp h o s p h o r a n e (1 3 7 ) .

Me Me MeI I I

PhaP= G-COOEt PhaP= C - CO - Ph P haP = C -C N

( 135 ) ( 1 3 6 ) ( 137 )

I t was o r i g i n a l l y i n te n d e d t h a t th e m e th y l e s t e r

“59-

would be u s e d i n p l a c e o f ( 1 3 5 ) . However, a l th o u g h th e

phosphonium s a l t from m e th y l a -b ro m o p ro p io n a te and

t r ip h e n y lp h o s p h in e was r e a d i l y p r e p a r e d , a l l a t t e m p t s to

form th e p h o sp h o ran e from t h i s l e d to d e c a r b o x y l a t i o n and

th e f o r m a t io n o f th e e th y l t r ip h e n y lp h o s p h o n iu m s a l t . The

phosphonium s a l t o f t h e e t h y l e s t e r , h o w e v e r , r e a d i l y

form ed th e c o r r e s p o n d in g p h o sp h o ra n e on t r e a tm e n t w i th one

e q u i v a l e n t o f aqueous sodium h y d ro x id e a t 0°C . A p o s s i b l e

e x p la n a t i o n o f t h i s i n v o lv e s th e c a s e o f h y d r o l y s i s o f th e1 3 5 ,136 ,137

e s t e r g ro u p s . C o n s id e r a b le p r e v i o u s work h a s

d e m o n s tra te d th e i n s t a b i l i t y o f phosphonium s a l t s c o n t a i n i n g

a n a - c a r b o x y l a t e a n io n . I f t h i s a n io n i s p ro d u c e d , by th e

h y d r o l y s i s o f th e e s t e r g ro up b e in g f a s t e r t h a n th e f o r m a t io n

o f th e p h o sp h o ra n e , d e c a r b o x y l a t i o n w i l l r a p i d l y t a k e p l a c e .

T h is a p p e a r s to be th e c a s e w i th th e m e th y l e s t e r , w h i le th e

e t h y l e s t e r p re su m ab ly l o s e s an a - p r o t o n more r a p i d l y . These

r e s u l t s a r e i n ag reem en t w i th th e g e n e r a l r e a c t i v i t y o f e s t e r s

to w ard s h y d r o l y s i s .

The p h o sp h o ra n e s ( 1 3 5 ) , (1 3 6 ) and (137) a l l r e a c t e d

w i th d i m e t h y l a c e t y l e n e d i c a r b o x y l a t e t o g i v e , a f t e r c h ro m a to

g ra p h y , p a l e y e l lo w , c r y s t a l l i n e a d d u c t s .

The N.M.R. s p e c t r a o f t h e s e a d d u c t s were t a k e n .

—60*“

The compound from a - h e n z o 'y l e t h y l i d e n e t r i p h e n y l p h o s p h o r a n e

and th e a c e t y l e n e gave a sp e c tru m w hich c o u ld be e x p la in e d

on th e b a s i s o f compound (1 3 8 ; R= — CO —P h ) , w hich would

be th e e x p e c te d p ro d u c t from a r e a r r a n g e m e n t a n a lo g o u s t o

( 1 2 7 ) . A d o u b le t a t 7.^8'!^( J p = 3 c . p . s . ) due to th e

t e r m in a l m e th y l , a s i n g l e t a t 7 . 2 ^ due to one e s t e r m e th y l ,

and th e o t h e r e s t e r m e th y l a t 6 , 5 ^ ( a d i f f u s e s i n g l e t ) ,

c o u ld be d i s t i n g u i s h e d .

COOMe

PhaPI= c— - c = c

/COOMe ^

( 138)

However, when th e sp ec tru m o f th e a d d u c t from

a - c y a n o e th y l id e n e t r ip h e n y lp h o s p h o r a n e was s t u d i e d ^ i t

a p p e a re d t h a t a m ix tu r e o f two compounds v/as p r e s e n t . The

f i r s t , p r e s e n t i n 60 ^ , h ad a d o u b le t a t 8 . 0 ^ , J p = 3 c . p . s . ,

and two s i n g l e t s , one a t 6 .6 ^ and th e o t h e r a t 6 . 7 ^ . The

s e c o n d , p r e s e n t i n 3 0 ^ , h a d a s i m i l a r s p e c t ru m , b u t th e

d o u b le t was a t 8 . 3 ^ , J p = 4 c . p . s . , and th e two s i n g l e t s

a t 6 . 3 ^ and 6 .6 3 ^ r e s p e c t i v e l y . T h is c o u ld p o s s i b l y be

e x p la in e d by g e o m e t r i c a l i s o m e r i s o n . a c r o s s th e C —C d o u b le

bond i n (13 8 ; R = — CH), t h e d o u b le t s a t 8 . 0 ^ and 8 . 3 ^

—6 l—

b e in g due t o th e t e r m i n a l m e th y ls i n th e tv/o i so m e rs and

th e s i n g l e t s a t 6 , 6 ^ and 6 . 7 ^ , and 6 . 5 ^ and 6 . 65^ , t o

th e e s t e r m e th y l g ro u p s .

The c a s e o f th e a d d u c t from a - e t h o x y c a r b o n y l -

e t h y l i d e n e t r ip h e n y lp h o s p h o r a n e (1 3 8 ; R= — COOEt) a m ix tu r e

o f compounds a g a i n a p p e a re d to be p r e s e n t , a l t h o u g h one

p re d o m in a te d ( ^ 9 0 % ) . One iso m e r h ad a s i n g l e t a t 6 . 3T

due to th e two e s t e r m e th y l g r o u p s , w h i le t h i s was a t 6 . 6 T

i n th e o th e r i s o m e r . The t e r m i n a l m e th y l shov/ed a s a

d o u b l e t , a t 8 . l 0 ^ ( J p = ij. c . p . s . ) i n one i s o m e r , and a t

8 . 2 ^ ( J p = i+ c . p . s . ) i n th e o t h e r .

The p r o p o r t i o n s o f th e iso m e rs p r e s e n t i n each

c a se i s f u r t h e r e v id e n c e f o r g e o m e t r i c a l fo rm s b e in g

p r e s e n t . The p h e n a c y l c a s e (138 ; R = — COPh) was a p u re

compound, and w h i le t h e e s t e r p h o sp h o ran e a d d u c t (138 ;

R= — COOEt) was a 9 :1 m i x t u r e , th e n i t r i l e p h o sp h o ra n e a d d u c t

( 138 ; R = — CN) was a 3 : 2 m ix tu r e . As th e s i z e o f R d e c r e a s e s

i n t h i s o r d e r th e e f f e c t a p p e a r s t o be s t e r i c , and may be

due t o th e l a r g e p h o s p h o r u s - c o n ta in in g s u b s t i t u e n t a t th e

d o u b le bond a l lo w in g th e R g roup t o become c i s to i t i n th e

c a s e o f R = — CN, and t o a l e s s e r e x t e n t when R = — COOEt.

By r e p e a t e d r e c r y s t a l l i s a t i o n p u re sam p le s o f th e m a jo r

i so m er o f each a d d u c t were p r e p a r e d . However, when t h e s e

-62-

8am ples were t r e a t e d w i th p e r c h l o r i c a c i d , t h e N.M.R. s p e c t r a

o f th e s a l t s p ro d u ce d showed them a l s o to he m ix t u r e s .

Assum ing t h a t the a d d u c t s a r e of the form ( 1 3 8 ) , p r o t o n a t i o n

c o u ld t a k e p l a c e i n two w ays, a t th e a - c a r b o n , t o g iv e th e

p e r c h l o r a t e ( 1 3 9 ) , o r a t t h e ^ - c a r b o n , t o g iv e ( l 4 0 ) .COOMe

a p r o t o n a t i o n + | ^ 0 %

:OOMe 1 ' 'Rr + I /^ P h g P - C H - G :

PhaP= G - G = Q/ G i o r COOMe (13 9 )

^ , P h a ' t - G = G - C i r ^ ° X - p r o t o n a t i o n I

C lO r GOOMle (140)

T h ere a r e s e v e r a l r e c o r d e d exam ples o f e l e c t r o p h i l i c a t t a c k

a t th e ^ —c a rb o n i n a l l y ^ i c p h o s p h o ra n e s . Bestm ann h a s shown

t h a t t r e a tm e n t o f th e a l l y l i c p h o sp h o ran e ( l 4 l ) w i th23

c h lo r o c a rb a m a te s l e a d s to aQ - s u b s t i t u t e d p r o d u c t , a s d o es26

t r e a tm e n t w i th t r i t i a t e d w a te r .

TP h 3 P = C H - C H = CHg

(141) Cl-COOMe

G H = G H - G H o T

Phg f - GH = GH - GHg - GOOMa G1

T rea tm en t o f th e p e r c h l o r a t e m ix tu r e s w i th

aq u eo u s sodium h y d ro x id e gave back th e o r i g i n a l a d d u c t s .

—63-

h o w ev er , th e y a g a i n a p p e a re d t o he m ix tu r e s o f g e o m e t r i c a l

i s o m e r s , even th ough p u re sam p les were u se d i n th e p r e p a r a t i o n

o f th e s a l t s .

I n th e hope o f o b t a i n i n g f u r t h e r i n f o r m a t i o n from

N.M.R. s p e c t r a a t t e m p t s were made to h y d ro g e n a te th e

p e r c h l o r a t e s o f th e a d d u c t s . Adam 's c a t a l y s t , p a l l a d iu m on

c h a r c o a l , p la t in u m on c h a r c o a l , and Raney N ic k e l were a l l

t r i e d u n d e r v a r i o u s c o n d i t i o n s w i th a s i n g u l a r l a c k o f

s u c c e s s . A c o n t r o l e x p e r im e n t showed t h a t i t v/as im p o s s ib le

t o h y d ro g e n a te c in n a m ic a c i d i n th e p r e s e n c e o f phosphonium

s a l t , p re su m ab ly b e c a u s e th e s a l t p o i s o n e d th e c a t a l y s t i nL3 8

some way. S in c e o u r w ork , H e n d r ic k so n h a s su c c e e d e d i n

h y d r o g e n a t in g th e a d d u c t s th e m s e lv e s .

A t te m p ts to m e th y la te th e a d d u c t s u s in g m e th y l

io d id e were u n s u c c e s s f u l , th e a d d u c t b e in g r e o b t a i n e d i n

h ig h y i e l d .

A lth o u g h th e a d d u c ts were o n ly r e o b t a i n e d i n lov/

y i e l d from a t t e m p te d a c i d h y d r o l y s i s r e a c t i o n s u s in g

c o n c e n t r a t e d h y d r o c h l o r i c a c i d , no o t h e r c r y s t a l l i n e p r o d u c t

was i s o l a t e d . However, t r e a tm e n t o f the m o th e r l i q u o r s o f

t h e s e r e a c t i o n s w i th d i l u t e a l k a l i gave a f u r t h e r s m a l l

amount o f a d d u c t , show ing t h a t some c o n v e r s io n o f t h e a d d u c t

t o i t s s a l t had t a k e n p l a c e .

-6 4 -

The a d d u c ts r e a c t e d r e a d i l y w i th brom ine to g iv e

compounds which c o u ld n o t be s a t i s f a c t o r i l y p u r i f i e d .

D e g r a d a t io n o f t h e a d d u c t s was fo u n d to be d i f f i c u l t ,

p ro lo n g e d r e f l u x i n g w i th c o n c e n t r a t e d a l k a l i b e in g n e c e s s a r y .

The a d d u c t from a - b e n z o y le t h y l i d e n e t r ip h e n y lp h o s p h o r a n e

( 138 ; R= — COPh) was d e g ra d e d b o th b e c a u se i t was e a s i e s t

to p u r i f y and c o n ta in e d a p h e n a c y l g ro u p , w hich i s s t a b l e

to h y d r o l y s i s . The p r o d u c t s were t r ip h e n y lp h o s p h in e o x id e ,

i n h ig h y i e l d , a c r y s t a l l i n e a c i d i n v e r y low y i e l d and

t r a c e s o f p ro p io p h en o n e and a compound w hich h a d an

i n f r a r e d sp e c tru m s i m i l a r t o t h a t o f fu m a r ic a c i d .

The u l t r a v i o l e t sp e c tru m o f th e c r y s t a l l i n e a c i d

showed a d e f i n i t e s i m i l a r i t y to t h a t o f p - b e n z o y l a c r y l i c

a c i d ( 142 ) .

Ph - CO - CH = CH - GOOH

( 142)

The compound a n a ly s e d f o r CigHigOg and showed two

c a r b o n y l g ro u p s (one o f w hich a p p e a re d to be due to a

c a r b o x y l i c a c i d ) , a d o u b le bond and a m o n o - s u b s t i t u t e d

benzene r i n g , i n th e i n f r a r e d . On h y d r o g e n a t io n th e

compound to o k up 1 .7 m o les o f h y d ro g en p e r m ole and

t i t r a t i o n w i th a l k a l i gave an e q u i v a l e n t w e ig h t o f 1 9 4 - 10.

-6 5 -

The m ass sp e c tru m o f th e a c i d showed what

a p p e a re d to be a m ass p e a k a t m/e = 193>, and s t r o n g p e a k s

a t m /e = 77 (p h e n y l ) and m/e = 105 (B e n z o y l ) ,

T h is e v id e n c e p o i n t s t o two p o s s i b l e s t r u c t u r e s

f o r th e a c i d , (143) and ( l 4 4 ) , one o f w h i c h , ( 1 4 4 ) , c o u ld

HOOC-CHg GO - Ph HOGG G Q -P h

>K ><H CHs CHa CHg

(143) (144)

have b e en fo rm ed by d e c a r b o x y l a t i o n o f th e o r i g i n a l

h y d r o l y s i s p r o d u c t o f th e a d d u c t .

A t te m p ts to c a r r y o u t th e N.M.R. sp ec tru m o f

th e sodium s a l t o f t h i s a c i d i n d e u te r iu m ox id e l e d to

d e u te r iu m e x c h a n g e , a l t h o u g h th e i n d i v i d u a l o r t h o , m eta

and p a r a p r o t o n s o f t h e m o n o s u b s t i t u t e d benzene r i n g

c o u ld be p ic k e d o u t . The a c i d was n o t v e r y s o l u b l e i n

d e u te r o c h lo r o f o r m , b u t s p e c t r a were o b ta in e d a t 50°G.

The q u a l i t y was p o o r , b u t a d o u b l e t , due to a m e th y l g ro u p ,

a t 8 . 3 ^ ( j ^ = 7 c . p . s . ) and a m u l t i p l e t , p r o b a b ly due t o a

— GHg —, a t 6 . l Y c o u ld be d i s t i n g u i s h e d . The p e ak a t 6 . . l O ^ i n t e g r a t i n g f o r two h y d ro g en s and th e s p l i t t i n g o f 7 c . p . s .

o f th e m e th y l g ro u p s u g g e s t t h a t s t r u c t u r e ( l 4 3 ) i s th e

-66—

c o r r e c t o n e .

S in c e t h i s work h a s b e en c a r r i e d ou t a

c o n s i d e r a b l e amount h a s b e en p u b l i s h e d on a d d u c ts o f1 3 8 ,139

t h i s t y p e , a d d u c t s o f im in o p h o sp h o ra n e s w i th

a c e t y l e n e d i c a r b o x y l a t e (w hich a p p e a r t o be a n a lo g o u s )1 4 1

and a d d u c t s o f p h o sp h o ra n e s w i th b e n zy n e . The e v id e n c e

from t h i s work i s t h a t p h o sp h o ra n e s w i th o u t a - h y d r o g e n s ,

and p h o s p h o im in e s , r e a c t w i th d i m e t h y l a c e t y l e n e d i c a r b o x y l a t e

v i a a f o u r membered t r a n s i t i o n s t a t e l e a d i n g to p h o sp h o ra n e s

o f th e ty p e ( l4 3 ) *

PhgPz: C,\ j j 3

•COOMe

COOMePhoP

COOMe

COOMe'4

Pha,P= C - C = CR^R*

COOMe

(145 )

Z b i r a l s u g g e s t s t h a t th e f i r s t s t a g e i n th e r e a c t i o n o f

p h o s p h o ra n e s w i th benzyne i s i d e n t i c a l w i th t h a t a b o v e ,

a t t a c k o f th e y l i d c a r b a n io n a t one end o f t h e benzyne

-6 7 -

**t r i p l e " bond to g iv e th e b e t a i n e (1 4 6 ) . T h is c a r b a n io n

th e n a t t a c k s one of th e p h e n y l g ro u p s on th e p h o sp h o ru s

t o g iv e t h e p h o sp h in e ( 1 4 7 ) .

P h a P = C H - P h +- II P h a l CH Ph

PhcP — GH Ph

( 146)

(147)

T h is r e a r r a n g e m e n t i s a n a lo g o u s to t h a t i n th e r e a c t i o n o f

t r i p h e n y lp h o s p h in e w i t h d im e th y l a c e t y l e n e d i c a r b o x y l a t e

(See p . 5 3 ) , where th e i n i t i a l l y fo rm ed 1 , 5 - d i p o l e c a n

r e a r r a n g e to g iv e t l 4 8 ) by th e a t t a c k o f th e c a r b a n i o n a s

a p h e n y l g ro u p .

-68-

PhgP +

'GOOMe

‘COOMe

COOMe^GOOMe

GOOMeGCOMe

GOOMe

G ^m eGOOMe

GOOMe

GOOMe

OOMe

GOOMeGOOMe

( 148)

McEwen h a s s t u d i e d th e r e a c t i o n o f b e n z o n i t r i l e w i th

p h o s p h o ra n e s . I n th e c a s e o f b e n z y l id e n e t r i p h e n y lp h o s p h o r a n e

th e p r o d u c t s . C a f t e r a l k a l i n e h y d r o l y s i s ) were d e o x y b e n z o in

and p h o sp h in e o x id e . The f o l lo w in g r e a c t i o n p a t h h a s b e en

s u g g e s t e d .

-6 9 -

Ph3P = C H -P h + PhCN

D i l u t ePhaPO

[ P h - CH= G - PlQ NaOH' HHgI

P h - C H a - C - P h

Ph —r

PhaP CH

: IH T Z Z C

Ph —J

PhaP:

HN-

I t seemed p o s s i b l e t h a t by r e p l a c i n g th e a -h y d ro g e n atom

i n th e o r i g i n a l p h o sp h o ra n e by an a l k y l g ro u p , W iich

c a n n o t e a s i l y m i g r a t e , a r e a r r a n g e m e n t a n a lo g o u s t o t h a t

above m ig h t be f o r c e d to ta k e p l a c e to g iv e ( 150 ) .

PhaP=C R a + PhCH

PhaP = H - G = a\

(150)

phoP— c;"

TPhR

R

( 149)

—70—

However, when i s o p r o p y l id e n e t r i p h e n y l p h o s p h o r a n e was

r e a c t e d w i th h e n z o n i t r i l e , a l th o u g h a v ig o r o u s r e a c t i o n

to o k p l a c e , no c r y s t a l l i n e compounds c o u ld be i s o l a t e d .

A l k a l i n e h y d r o l y s i s o f th e r e a c t i o n m ix tu re gave

t r ip h e n y lp h o s p h in e ox id e and i s o p r o p y lp h e n y l k e to n e .

T h is k e to n e c o u ld have b e e n fo rm ed by h y d r o l y s i s o f e i t h e r

th e i n t e r m e d i a t e ( l4 9 ) o r th e r e a r r a n g e d p r o d u c t ( 150 ) .

-7 1 -

E x p e r im e n ta l

A l l e x p e r im e n ts u s in g p h o s p h o ra n e s , and s i m i l a r

u n s t a b l e compounds, were c a r r i e d o u t u n d e r an o x y g e n - f r e e

n i t r o g e n a tm o s p h e re . A l l s o l v e n t s were d r i e d b e f o r e u s e .

M e l t in g p o i n t s were c o r r e c t e d .

A t te m p te d p r e p a r a t i o n o f g - M e th o x y c a rb o n y le th y l id e n e -

t r i p h e n y lp h o s p h o r a n e . - a - M e t h o x y c a r b o n y l e t h y l t r i p h e n y l -143

phosphonium i o d i d e ( 9 .5 g . ) was d i s s o l v e d i n e t h a n o l -

w a te r ( 1 :1 ) (80 m l . ) and one e q u i v a l e n t o f sodium h y d ro x id e

( IE ; 20 m l . ) added s lo w ly w i th s t i r r i n g . The s o l u t i o n

rem ained c l e a r and v/as e x t r a c t e d w i th c h lo r o fo r m . The

c h lo ro fo rm s o l u t i o n was d r i e d and e v a p o r a te d to g iv e

e th y l t r ip h e n y lp h o s p h o n iu m io d id e (5*8 g . ) , m .p . and m ixed

m .p . (from c h lo r o f o r m - e t h y l a c e t a t e ) l 6 6 - l 6 7 ° .

89P r e p a r a t i o n o f C y a n o m e th y le n e t r ip h e n y lp h o s p h o ra n e . - The

89phosphonium s a l t (15»7 g . ) v/as d i s s o l v e d i n w a te r (300 m l . )

and one e q u i v a l e n t o f aqueous sodium h y d ro x id e (IN ; 47 m l . )

v/as added s lo w ly a t 0° w i th s t i r r i n g . The s o l i d p r e c i p i t a t e

was f i l t e r e d and w ashed w i th w a te r u n t i l th e w a sh in g s were

n e u t r a l . Thorough d r y in g and r e c r y s t a l l i s a t i o n from e t h y l

-7 2 -

a c e t a t e gave th e p h o sp h o ra n e ( 1 0 .4 g . ) , m .p . (from89

e t h y l a c e t a t e ) 195-196° ( l i t . 1 9 5 -1 9 6 ° ) .

P r e p a r a t i o n o f a -C y a n o e th y l t r ip h e n y lp h o s p h o n iu m I o d i d e . -

C y a n o m e th y le n e t r ip h e n y lp h o s p h o ra n e ( 1 2 g . ) and m e th y l

i o d i d e (25 g . ) were h e a t e d t o g e t h e r , w i th o u t s o l v e n t , a t

1 0 0 ° f o r l6 h o u r s . The r e a c t i o n m ix tu r e was t r i t u r a t e d

w i th benzen e (5 x 50 m l . ) . The b e n z e n e - i n s o l u b l e o i l

c r y s t a l l i s e d from e t h a n o l - w a t e r (1 2 g . ) , m .p . (from

e t h a n o l - w a t e r ) 1 2 0 - 1 2 2 ° . [Pound: G, 5 4 .5 ; H , 4 . 3 ; G a le ,

f o r Ggj^HigNPI: C, 5 6 .8 0 ; H , 4 . 3 , G a le , f o r G g iH ig N P I . HgO:

G, 5 4 .6 ; H, 4 . 5 ^ ] .

P r e p a r a t i o n o f a - G y a n o e th y l id e n e t r ip h e n y lp h o s p h o r a n e . - The

phosphonium i o d i d e (7 g . ) was d i s s o l v e d i n c h lo ro fo rm (60 m l . )

and c o o le d to 0 ° . T h is s o l u t i o n was sh ak en i n a s e p a r a t o r y

f u n n e l w i th an i c e - c o l d s o l u t i o n o f sodium h y d ro x id e ( 0 . 2 5 g . )

i n w q te r (50 m l . ) f o r one m in u te . The c h lo ro fo rm l a y e r was

s e p a r a t e d , w ashed w i th w a te r ( 4 x 3 0 m l . ) , d r i e d and

e v a p o r a t e d t o g i v e th e p h o sp h o ra n e ( 4 . 1 g . ) , m .p . ( f ro m

e t h y l a c e t a t e - p e t r o l ) 173-174® [P ound : G, 7 6 . 6 , H, 5 .7 ;

N , 3 . 5 ^ , G a le , f o r GgiHigNP: C, 8 0 .0 ; H, 5 .7 6 ; N, 4 .45 /S ].

-7 3 -

P r e p a r a t i o n o f a -E th o x y c a r 'b o n y le th y l t r lp h e n y lp h o sp h .o n i 'u m69

Brom ide . - E t h y l a -h r o m o p r o p i o n a t e (5 2 g , ) and t r i p h e n y l

p h o sp h in e (75 g . ) were d i s s o l v e d i n benze n e (400 m l . ) and

r e f l u x e d t o g e t h e r f o r 7 h o u r s . The o i l which s e p a r a t e d

was d e c a n t e d o f f and t r i t u r a t e d w i t h e t h y l a c e t a t e t o g i v e

t h e phosphonium s a l t (89 g . ) m .p . ( f rom c h l o r o f o r m - e t h y l

a c e t a t e ) 199-201° ( l i t . 1 9 9 - 2 0 0 ° ) .

P r e p a r a t i o n o f a - E t h o x y c a r b o n y l e t h y l i d e n e t r i p h e n y l p h o s -69

p h o r a n e . — The phosphonium s a l t (22 g . ) was d i s s o l v e d i n

e t h a n o l - w a t e r ( 1 :1 , . 200 m l . ) and c o o l e d t o 0 ° . One

e q u i v a l e n t o f aqueous sodium h y d r o x id e ( IN ; 50 m l . ) v/as

s l o w l y added w i th s t i r r i n g . The o i l w h ich s e p a r a t e d

c r y s t a l l i s e d on t r i t u r a t i o n (13 g . ) , m .p . ( f ro m e t h y l

a c e t a t e ) 157-159° ( l i t . 1 5 6 - 1 5 7 ° ) .

P r e p a r a t i o n o f a - M e t h y l p h e n a c y l t r i p h e n y lp h o s p h o n i u m43

Brom ide . - a -B rom oprop iophenone (32 g . ) and t r i p h e n y l

p h o s p h in e (40 g . ) were r e f l u x e d t o g e t h e r i n b en zen e (200 m l . )

f o r l 6 h o u r s . The o i l which s e p a r a t e d c r y s t a l l i s e d (6 2 g . )

on t r i t u r a t i o n w i t h e t h y l a c e t a t e , m .p . and m ixed m .p .

( f rom c h l o r o f o r m - e t h y l a c e t a t e ) 2 4 2 -2 4 3 ° .

-7 4 -

43P r e p a r a t i o n of g - M e t h y l p h e n a c y l i d e n e t r i p h e n y l p h o s p h o r a n e . -

The phosphonium s a l t (25 g . ) was d i s s o l v e d i n e t h a n o l - w a t e r

( 1 : 1 ; 300 m l . ) . One e q u i v a l e n t o f aqueous sodium h y d r o x id e

( IN ; 53 m l . ) was ad ded s l o w l y w i t h s t i r r i n g . The p r e c i p i t a t e

v/as f i l t e r e d , washed w i t h w a te r and d r i e d (20 g . ) , m .p . and

m ixed m .p . ( f rom e t h y l a c e t a t e ) l 6 l - l 6 3 ° .

R e a c t i o n o f D i m e t h y l A c e t y l e n e d i c a r b o x y l a t e w i t h

< x - E t h o x y c a r b o n y l e t h y l i d e n e t r i p h e n y l p h o s p h o r a n e . - T h e

pho sp h o ran e (12 g . ) , i n e t h y l a c e t a t e (150 m l . ) , was added

t o a s o l u t i o n of t h e d i e s t e r (5 g . ) i n e t h y l a c e t a t e (50 m l . ) .

The deep r e d r e a c t i o n m ix t u r e was r e f l u x e d f o r 3 h o u r s .

E v a p o r a t i o n and c h ro m a to g ra p h y on Woelmu n e u t r a l a lu m in a

u s i n g benzene a s t h e e l u e n t , gave y e l l o w c r y s t a l s (5 g . )

m .p . [ f rom l i g h t p e t r o l e u m ( b . p . 1 0 0 -1 2 0 ° ) ] 137-138° (Pound:

G, 6 8 .9 0 ; H, 5*90; P , 6 . 3 0 ; C a l c , f o r a 1 : 1 a d d u c t

GggHsgPOg: G, 6 9 .0 ; H, 5*75; P , 6 . 1 5 ^ ) .

P r e p a r a t i o n o f th e P e r c h l o r a t e o f t h i s A d d u c t . - The a d d u c t

( 1 . 2 g . ) was d i s s o l v e d i n m e th a n o l (10 m l . ) and an aqueous

s o l u t i o n of p e r c h l o r i c a c i d {lOfo) added d ro p w ise u n t i l t h e

o r i g i n a l y e l lo w c o l o u r o f th e s o l u t i o n was d i s c h a r g e d .

-7 5 -

A d d i t i o n of w a t e r t o t u r b i d i t y gave c r y s t a l s ( 0 . 9 g # ) ,

m .p . ( m e th a n e 1 -w a te r ) 179-181° (Pound: 0 , 5 6 .0 ; H, 5*00; P ,

5 . 5 9 ; C a lc , f o r OggHgoClPOio: 0 , 57*60; H, 4*97; P , 5 * 1 5 ^ ) .

R e a c t i o n o f a - C y a n o e t h y l i d e n e t r i p h e n y l p h o s p h o r a n e w i t h

D im e th y l A c e t y l e n e d i c a r b o x y l a t e . - The p h o sp h o ra n e ( l l g . ) , i n

c h lo r o f o r m (120 m l . ) , was added t o a s o l u t i o n of t h e d i e s t e r

(5 g . ) i n c h lo r o f o r m (20 m l . ) . The r e a c t i o n m i x t u r e was

r e f l u x e d f o r 3 h o u r s . E v a p o r a t i o n and c h ro m a to g ra p h y on

V/oelm n e u t r a l a lu m i n a , u s i n g benzen e a s t h e e l u e n t , gave

y e l lo w c r y s t a l s (4 g . ) m .p . [ f rom c a r b o n t e t r a c h l o r i d e - l i g h t

p e t r o l e u m ( b . p . 6 0 - 8 0 ° ) ] 149-151° (Pound: C, 7 0 .8 0 ; H, 5*22;

P , 7 . 0 1 ; C a lc , f o r a 1 : 1 a d d u c t G27H24PNO4 : C, 7 0 . 9 ;

H, 5 .2 5 ; P , 6 . 7 8 ^ ) .

P r e p a r a t i o n o f th e P e r c h l o r a t e o f t h i s A d d u c t . - The a d d u c t

(2 g . ) was d i s s o l v e d i n m e th a n o l (10 m l . ) and an aqu eo us

s o l u t i o n o f p e r c h l o r i c a c i d (70^) was ad d ed dropv/ise u n t i l

t h e o r i g i n a l y e l lo w c o l o u r o f th e s o l u t i o n v/as d i s c h a r g e d .

A d d i t i o n o f w a te r t o t u r b i d i t y gave c r y s t a l s (,1.7 g . ) , m .p .

( f rom m e t h a n o l - w a t e r ) 184—185° (Pound: C, 5 7 .5 ; H, 4*39;

P , 5 *5 6 ; C a lc , f o r C2.7H25 CINPO8 : C, 58.1;: H, 4 . 4 8 ; P , 5 * 5 5 ^ ) .

R e a c t i o n o f a ’-^ M eth y lp h en a cy l ldene t r lph e n y lph o sp ho rane w i t h

D im e th y l A c e t y l e n e d i c a r b o x y l a t e . - The p h o sp h o ra n e (8 g . ) ,

i n e t h y l a c e t a t e (100 m l . ) , was a d d ed t o a s o l u t i o n of th e

d i e s t e r (3 g . ) i n e t h y l a c e t a t e (30 m l . ) . The r e a c t i o n

m i x t u r e was r e f l u x e d f o r 3 h o u r s . E v a p o r a t i o n and

ch ro m a to g ra p h y on Y/oelm n e u t r a l a lu m i n a , u s i n g benzene

a s t h e e l u e n t , gave y e l lo w c r y s t a l s ( 8 . 4 g . ) m .p .

(f rom c a r b o n t e t r a c h l o r i d e - p e t r o l ) 191-192° (Pound: G, 7 3 .7 9 ;

H, 5 . 0 8 ; C a lc , f o r a 1 : 1 a d d u c t CasHggOgP: C, 7 3 .8 0 ; H, 5 .4 0 /0*

P r e p a r a t i o n o f t h e P e r c h l o r a t e of t h i s A d d u c t . — The a d d u c t

(1 g . ) was d i s s o l v e d i n m e t h a n o l (8 m l . ) and an aqueous

s o l u t i o n o f p e r c h l o r i c a c i d (70^) was added d ro p w ise u n t i l

th e s o l u t i o n became c o l o u r l e s s . A d d i t i o n o f w a t e r gave

c r y s t a l s ( 0 . 6 g . ) m .p . ( f rom m e t h a n o l —w a t e r ) 2 0 2 -2 0 4 ° .

A t te m p te d M é t h y l a t i o n o f t h e A dduc t from a - C y a n o e t h y l i d e n e -

t r l p h e n y l p h o s p h o r a n e and D im e th y l A c e t y l e n e d i c a r b o x y l a t e . -

( a ) The a d d u c t ( 0 . 8 g . ) , i n b e n ze n e (10 m l . ) , an d m e t h y l

i o d i d e (5 m l . ) were r e f l u x e d t o g e t h e r f o r 20 h o u r s .

E v a p o r a t i o n gave th e a d d u c t ( 0 . 6 g . ) . (b ) The a d d u c t ( 0 . 5 g . ) ,

and m e th y l i o d i d e (4 m l . ) , were h e a t e d t o g e t h e r on a s team

b a t h f o r 2 d a y s . E v a p o r a t i o n gave th e a d d u c t ( 0 . 3 g . )

-7 7 -

S i m i l a r r e s u l t s w e r e o b t a i n e d f r o m a n a l o g o u s

e x p e r i m e n t s w i t h t h e a d d u c t s f r o m a - m e t h y l p h e n a c y l i d e n e -

t r i p h e n y l p h o s p h o r a n e a n d a - e t h o x y c a r b o n y l e t h y l i d e n e -

t r i p h e n y l p h o s p h o r a n e .

R e a c t i o n o f t h e A d d u c t f r o m a - M e t h y l p h e n a c y l i d e n e t r i p h e n y l -

p h o s p h o r a n e a n d D i n s t h y l A c e t y l e n e d i c a r b o x y l a t e w i t h

H y d r o c h l o r i c A c i d . - T h e a d d u c t ( 1 g . . ) a n d c o n c e n t r a t e d

h y d r o c h l o r i c a c i d ( 2 m l . ) w e r e h e a t e d i n a s t e a m b a t h f o r

12 h o u r s . W a t e r ( 5 m l . ) w a s a d d e d a n d t h e s o l u t i o n f i l t e r e d .

E x t r a c t i o n o f t h i s s o l u t i o n w i t h e t h y l a c e t a t e g a v e a s m a l l

a m o u n t o f o i l . A d d i t i o n o f a q u e o u s s o d i u m h y d r o x i d e s o l u t i o n

( ^ . ) t o t h e a q u e o u s e x t r a c t u n t i l a l k a l i n e g a v e t h e o r i g i n a l

a d d u c t ( O . l g . ) , m . p . a n d m i x e d m . p . 1 9 1 - 1 9 2 °

S i m i l a r e x p e r i m e n t s v / i t h o t h e r a d d u c t s g a v e

a n a l o g o u s r e s u l t s .

R e a c t i o n s o f t h e A d d u c t s w i t h B r o m i n e . — A l l t h e a d d u c t s

r e a c t e d w i t h b r o m i n e . A t y p i c a l e x p e r i m e n t w a s :

t h e a d d u c t ( 0 . 8 g . . ) , i n b e n z e n e ( 1 0 m l . ) , w a s s l o w l y a d d e d

t o a s o l u t i o n o f b r o m i n e ( 0 . 2 8 g . ) i n b e n z e n e ( 5 m l . ) a n d

t h e m i x t u r e w a r m e d f o r 5 m i n u t e s . T h e o i l w h i c h s e p a r a t e d

-7 8 -

v/as t r i t u r a t e d w i t h e t h y l a c e t a t e t o g iv e a s o l i d v/hich

c o u l d n o t he s a t i s f a c t o r i l y p u r i f i e d .

A l k a l i n e H y d r o l y s i s o f t h e A dduc t from a - M e t h y l p h e n a c y l i d e n e -

t r i p h e n y l p h o s p h o r a n e and D im e th y l A c e t y l e n e d i c a r b o x y l a t e . - The

a d d u c t (2 g . ) , i n m e th a n o l (25 m l . ) , v/as ad ded t o a s o l u t i o n

o f sodium h y d r o x i d e (2 g . ) i n w a t e r (10 m l . ) . The s o l u t i o n

was r e f l u x e d f o r 60 h o u r s , c o o l e d and w a te r (30 m l . ) add ed .

The s o l i d v/as f i l t e r e d o f f ( 0 . 8 g . ) m .p . and mixed m .p .

157- 158° , w i t h an i n f r a r e d sp ec t ru m i d e n t i c a l w i t h t h a t o f

t r i p h e n y l p h o s p h i n e o x i d e . The f i l t r a t e v/as e x t r a c t e d w i t h

e t h e r (3 x 20 m l . ) , and t h e e t h e r e x t r a c t on g . l . c . (6 m. a p ie z o n L column a t 220°) showed p ro p io p h e n o n e (H^o).

E v a p o r a t i o n of th e e t h e r e x t r a c t gave a s m a l l q u a n t i t y o f

o i l (10 mg.) which h a d A 5 * 9 8 ^ . The a l k a l i n e e x t r a c t

was t h e n made a c i d t o Congo Red and th e r e s u l t i n g s u s p e n s i o n

e x t r a c t e d w i t h e t h e r ( 4 x 30 m l . ) . The e t h e r s o l u t i o n was

d r i e d (MgSO*) and e v a p o r a t e d t o g iv e a n o i l . The o i l

c r y s t a l l i s e d from m e t h a n o l - w a t e r (38 mg.) m .p . I 4 l - 1 4 2 ° ,

Xfflax 5 . 8 8 , 5 . 9 8 , 8 . 0 , 8 . 2 5 , 13 . 2 5 , 14 . 6/ 1 . (Found : C, 7 0 .5 1 ;

H, 6 .0 2 ; C a lc , f o r CisHigOg: C, 7 0 .6 0 ; H, 5 . 8 8 ^ ) .

-7 9 -

H y d r o g e n a t io n o f A c id from H y d r o l y s i s o f P h e n a c y l A d d u c t . -

The a c i d (7 m g . ) , i n e t h a n o l (,3 m l . ) was h y d r o g e n a t e d u s i n g

p a l l a d i u m on c h a r c o a l (3 mg.) a s c a t a l y s t . The u p ta k e

a f t e r 10 m i n u t e s was 1 . 2 m l . o f h y d ro g en . T h e o r e t i c a l

u p t a k e f o r one mole o f h y d ro g e n p e r m ole , 0 . 7 0 ml.

D e t e r m i n a t i o n o f t h e E q u i v a l e n t W eight o f th e A c i d i c

H y d r o l y s i s P r o d u c t by A l k a l i T i t r a t i o n . - The a c i d ( 5 . 9 mg.)

was d i s s o l v e d i n w a t e r (5 m l . ) and th e r e s u l t i n g s o l u t i o n

t i t r a t e d w i t h aqueous sodium h y d r o x i d e s o l u t i o n (N/lOO)

u s i n g p h e n o l p h t h a l e i n a s t h e i n d i c a t o r .

5 . 9 mg. of a c i d was e q u i v a l e n t t o 3 . 0 5 ml. o f

N / 100 sodium h y d r o x id e s o l u t i o n , g i v i n g an e q u i v a l e n t

w e ig h t o f 194. T h i s t i t r a t i o n was r e p e a t e d u s i n g s i m i l a r

c o n d i t i o n s and t a b u l a t i n g th e p .H . o f th e s o l u t io n (See

T ab le l ) .

-8 0 -

T a b l e I

t r e ( m l . ) p . H . T i t r e ( m l . ) p . H .

0 .0 7 5 . 9 8 3 .1 0 7 .4 0

0 .5 0 3 . 8 8 3 .2 0 8 .4 0

1 .0 0 4 . 3 0 3 .5 0 9 .0 0

1 .50 4 .6 0 4 . 0 0 9 .5 0

2 .0 0 4 .8 6 4 .5 0 9 .6 0

2 .5 0 5 .3 0 5 .0 0 9 .8 0

2 .90 6 .5 0 5 .5 0 9 .9 0

3 . 0 0 6 .7 0 6 .0 0 1 0 .0 5

R e a c t i o n o f I s o p r o p y l l d e n e t r i p h e n y l p h o s p h o r a n e w i t h

B e n z o n i t r l l e . - ( a ) I s o p r o p y l t r i p h e n y l p h o s p h o n i u m i o d i d e

( 15 g . ) , su sp en d e d i n e t h e r (200 m l . ) , v/as s t i r r e d and

LiBu i n e t h e r ( IN ; 35 m l . ) was a d d e d . The s o l u t i o n v/as

s t i r r e d f o r 1 h o u r a t room t e m p e r a t u r e . To t h i s s o l u t i o n

h e n z o n i t r i l e (10 m l . ) , i n e t h e r (20 m l . ) , was s l o w l y ad d ed ,

th e s o l u t i o n t u r n i n g from deep r e d t o b l a c k , and s t i r r i n g

c o n t i n u e d a t room t e m p e r a t u r e f o r I 6 h o u r s . The s o l u t i o n

v/as e v a p o r a t e d , d i s s o l v e d i n c h lo r o f o r m ( 15O m l . ) , washed

w i t h w a t e r (3 x 60 m l . ) and d r i e d . E v a p o r a t i o n gave an

o i l which c r y s t a l l i s e d on t r i t u r a t i o n w i th l i g h t p e t r o l e u m

—8 l—

( b . p . 40 - 60 °) t o g iv e t r i p h e n y l p h o s p h i n e o x ide ( 1 . 3 g . )

m .p . and mixed m .p . 1 5 7 -1 3 8 ° .

(b ) To a s o l u t i o n o f i s o p r o p y l i d e n e t r i p h e n y l p h o s p h o r a n e ,

from t h e phosphonium i o d i d e (15 g . ) and BuLi (IN; 35 m l ) ,

was s l o w l y added a s o l u t i o n o f h e n z o n i t r i l e (10 m l . ) i n

e t h e r (20 m l . ) . The r e s u l t i n g s o l u t i o n was s t i r r e d f o r

20 h o u r s a t room t e m p e r a t u r e . To t h i s s o l u t i o n m e th y l

i o d i d e (2 m l . ) , i n e t h e r (10 m l . ) , was added and th e

r e a c t i o n m i x t u r e r e f l u x e d f o r 4 h o u r s . The s o l u t i o n was

e v a p o r a t e d , d i s s o l v e d i n c h lo r o f o r m (200 m l . ) and washed

w i t h w a t e r (3 x 70 m l . ) . D ry ing (MgSO^) and e v a p o r a t i o n

gave an o i l v/hich c r y s t a l l i s e d on t r i t u r a t i o n w i t h e t h y l

a c e t a t e t o g i v e j fc -b u ty l t r ip h en y lp h o sp h o n iu m i o d i d e ( 2 . 3 g . )

m .p. and mixed m .p . ( f rom c h l o r o f o r m - e t h y l a c e t a t e )

204- 206° ( d ) .

( c ) To a s o l u t i o n of i s o p r o p y l i d e n e t r i p h e n y l p h o s p h o r a n e ,

from t h e phosphonium i o d i d e ( 8 . 6 g . ) and BuLi (IN; 20 m l . ) ,

was s l o w l y added a s o l u t i o n o f h e n z o n i t r i l e (8 m l . ) i n

e t h e r (20 m l . ) and th e r e s u l t i n g s o l u t i o n r e f l u x e d f o r

5 h o u r s . The e t h e r v/qs d i s t i l l e d o f f and sodium h y d r o x i d e

(10 g . ) i n m e t h a n o l - w a t e r ( 9 : 1 ; 100 m l . ) a d d ed . The s o l u t i o n

v/as r e f l u x e d f o r 1 h o u r , c o o l e d and e v a p o r a t e d . The

-82 -

r e s i d u e was e x t r a c t e d w i t h l i g h t p e t r o l e u m (4 0 -6 0 ° b . p . )

(5 X 50 m l . ) . The p e t r o l e x t r a c t was d r i e d (MgSO*) and

d i s t i l l e d t o g iv e t h r e e f r a c t i o n s ( a ) b . p . 1 0 0 - 1 2 0 ° ,

( b ) 122-144° and ( c ) 1 4 4 -1 8 0° . These f r a c t i o n s were

c h ro m a to g ra p h e d on p r e p a r a t i v e g . l . c . (20 f t . S i l i c o n

o i l column a t 1 8 0 ° ) . Three p u r e compounds were i s o l a t e d

( a ) d i m e t h y l - n - b u t y l c a r b i n o l ( 0 . 7 g . ) , (b ) i s o p r o p y l

p h e n y l k e to n e ( 0 . 7 g . ) and ( c ) n - b u t y l p h e n y l k e t o n e

( 1 . 4 g . ) a l l h a v in g i n f r a r e d s p e c t r a i d e n t i c a l t o t h a t

o f a u t h e n t i c s a m p le s .

-8 3 -

Some R e a c t i o n s o f P h o s p h o r u s - C o n t a i n i n g

B e t a i n e s i n W i t t i g R e a c t i o n s

T h e M e c h a n i s m o f t h e W i t t i g R e a c t i o n

A lth o u g h th e r e a c t i o n o f p h o s p h o r a n e s w i t h

a ld e h y d e s and k e to n e s v/as d i s c o v e r e d by S t a u d i n g e r and4 5 6

Meyer i n 1919, i t was n o t u n t i l 1953 t h a t W i t t i g

d e v e lo p e d i t i n t o a g e n e r a l method of o l e f i n s y n t h e s i s .

The scope and l i m i t a t i o n s o f th e s y n t h e s i s have43 ,59 ,6 0 ,91

b een d i s c u s s e d i n a l a r g e number o f p a p e r s and r e v i e w s

and r e c e n t l y more a t t e n t i o n h a s b e en d i r e c t e d t o t h e mechanism

of th e r e a c t i o n .

The s u g g e s t i o n t h a t t h e r e a c t i o n p r o c e e d e d v i a

an i n t e r m e d i a t e o f th e ty p e ( I 5 1 ) , o r i t s c o v a l e n t

e q u i v a l e n t ( 1 5 2 ) , was p u t f o r w a r d by W i t t i g i n h i s e a r l i e s t6 5 ,&44

p u b l i c a t i o n s .

PhoP— PhaP CR^r ® PhgP----- CR^R®■r\ ^ > - I or I0 = = C - r3 0 -----CR°R* 0 -----

R-0 CR®R'*

(151) (152)

He s u p p o r t e d t h i s t h e o r y w i t h t h e i s o l a t i o n of

2 - h y d r o x y -2 , 2 - d i p h e n y l e t h y 11 r iphenyIphosphon ium i o d i d e (153)

—84—

from th e r e a c t i o n m i x t u r e o f m e t h y l e n e t r i p h e n y I p h o s p h o r a n e145

and henzophenone a f t e r qu en ch in g w i t h h y d r i o d i c a c i d .

+■ + P h a P - ^ H g PhgP-----CHs PhgP----- GEg

_+ I — 10 = G P h g 0— GPhg HO— GPhg

(153)

The same typ e of b e t a i n e i n t e r m e d i a t e ( I 5 l ) was

a l s o p o s t u l a t e d i n th e r e a c t i o n o f t r i p h e n y l p h o s p h i n e w i t h6 5

s t y r e n e o x id e t o g i v e s t y r e n e and t r i p h e n y l p h o s p h i n e

o x id e .

P h a P / v c H g ^ PhaP--- G% PhaPO9 > o + 1

C H ^ " 0 ---CHPh GHg, = CHPhiPh

(151)

I f th e above f o r m u l a t i o n i s c o r r e c t we have tv/o

p o s s i b i l i t i e s f o r t h e r a t e d e t e r m i n i n g s t e p , b e t a i n e

f o r m a t i o n or b e t a i n e d e c o m p o s i t i o n .

I n b e t a i n e f o r m a t i o n , a ssum ing t h a t t h i s i n v o l v e s

n u c l e o p h i l i c a t t a c k of th e a - c a r b a n i o n o f t h e p h o sp h o ra n e on

th e c a r b o n y l g r o u p , th e r a t e w i l l depend on b o t h t h e

n u c l e o p h i l i c i t y o f th e cc-carbon and t h e r e a c t i v i t y d i s p l a y e d

—85—

to w a rd s n u c l e o p h i l e s by t h e c a r b o n y l g ro u p .

S u b s t i t u e n t s on th e a - c a r b o n which c a n d é l o c a l i s é

th e n e g a t i v e c h a rg e w i l l d e c r e a s e t h e r e a c t i v i t y o f t h e

p h o s p h o r a n e , w h i l e e l e c t r o n - d o n a t i n g s u b s t i t u e n t s on th e

p h o sp h o ru s w i l l i n c r e a s e t h e r e a c t i v i t y o f t h e p h o sp h o ra n e ,

by s t a b l i s i n g t h e d i p o l a r fo rm .

B e t a i n e d e c o m p o s i t i o n i s u s u a l l y assumed t o

p r o c e e d v i a a four-m em bered c y c l i c t r a n s i t i o n s t a t e , a l t h o u g h

t h e r e i s no r e a l e v id e n c e f o r t h i s . Any e l e c t r o n - d o n a t i n g

g ro up on th e p h o s p h o ru s w i l l d e c r e a s e i t s p o s i t i v e c h a r g e

and t h u s h i n d e r th e d e c o m p o s i t i o n , i n f a c t when th e p h o s p h o r u s

h a s t h r e e p -m e th o x y p h e n y l s u b s t i t u e n t s e l i m i n a t i o n w i l l n o t1 46

t a k e p l a c e and th e b e t a i n e i s s t a b l e . On t h e o t h e r hand

any s u b s t i t u e n t s on th e c a r b o n a toms of t h e b e t a i n e which

c an c o n j u g a t e w i t h t h e doub le bond t o be form ed w i l l h e l p t h e

e l i m i n a t i o n s t e p ; t h u s i n t e r m e d i a t e b e t a i n e s have n e v e r b e en

i s o l a t e d when s t a b l e p h o s p h o ra n e s o f t h e ty p e ( 1 5 4 ) have

b e e n u se d .

RgPz: C H - G O - R

(154)

The s t e r e o c h e m i s t r y , o f t h e o l e f i n s r e s u l t i n g from

a W i t t i g r e a c t i o n ^ i s d e te r m in e d by t h e s t e r e o c h e m i s t r y of

-8 6 -

t h e i n t e r m e d i a t e b e t a i n e s . I n t h e r e a c t i o n of t h e

p h o sp h o ra n e (155; H ) and t h e a ld e h y d e (156) v/e

have th e p o s s i b i l i t y o f tv/o s t e r e o i s o m e r i c b e t a i n e s

( 157 ) and ( 158 ) , which l e a d to c i s and t r a n s - o l e f i n s

r e s p e c t i v e l y a f t e r t h e e l i m i n a t i o n s t e p .

EsP= CHR + R GHO

( 155) (1 5 6 )

R3B

( 157)H

( 15 8 )

CIS

> = <

H

H R<t r a n s

I f th e b e t a i n e f o r m a t i o n s t e p i s s lo w , t h e n (158)

i s t h e p re d o m in a n t i so m er and th e o l e f i n fo rm ed i s m a i n l y

t r a n s , w h i l e a f a s t b e t a i n e fo rm in g s t e p p r o d u c e s a more

n e a r l y eq_ual m ix t u r e o f (157) and ( I 58 ) , and c o n s e q u e n t

amounts o f c i s and t r a n s - o l e f i n s .

-8 7 -

Th-us s t a b l e p h o s p h o r a n e s g i v e m a i n l y t r a n s

o l e f i n s when r e a c t e d w i t h a ld e h y d e s , w h i l e

p - n i t r o b e n z a l d e h y d e and p - m e t h o x y b e n z y l i d e n e t r i p h e n y l -

p h o s p h o r a n e , a r e a c t i v e a ld e h y d e and p h o s p h o r a n e , g i v e148

a m i x t u r e o f c i s and t r a n s - s t i l b e n e s . However,

a n i s a l d e h y d e and £ - n i t r o b e n z y l i d e n e t r i p h e n y I p h o s p h o r a n e

where b o t h t h e a ld e h y d e and p ho sp h o ra n e a r e d e a c t i v a t e d

by t h e s u b s t i t u e n t s , r e a c t s l o w ly t o g i v e m a i n l y th e148

t r a n s - s t i l b e n e .

R e a c t i o n s o f I n t e r m e d i a t e B e t a i n e s i n t h e W i t t i g R e a c t i o n

o t h e r t h a n O l e f i n F o r m a t i o n .

S in c e th e s u g g e s t i o n o f a b e t a i n e i n t e r m e d i a t e

l e a d i n g t o o l e f i n s i n th e W i t t i g r e a c t i o n , a number o f

o t h e r r e a c t i o n s o f t h e b e t a i n e h av e been p o s t u l a t e d .

R e s u l t s o b t a i n e d from a v a r i e t y o f W i t t i g r e a c t i o n s

h ad u s u a l l y b e e n r a t i o n a l i s e d by th e a s s u m p t io n t h a t th e

b e t a i n e - f o r m a t i o n s t e p v/as r e v e r s i b l e . However , i t was n o t

u n t i l 1963 t h a t e v id e n c e f o r t h i s was r e p o r t e d . S p e z i a l e 149

and H i s s i n g a l l o w e d e t h y l t r a n s - p h e n y I g l y c i d a t e and

t r i b u t y l p h o s p h i n e t o r e a c t , i n t h e p r e s e n c e o f m - c h l o r o b e n -

z a ld ehy d e , and o b t a i n e d b o t h e t h y l c in n a m a te and e t h y l

-88-

m -ch lo ro c in n a m a te * They assumed t h a t t h e b e t a i n e (159)

was th e i n t e r m e d i a t e , and t h a t i t c o u ld e l i m i n a t e p h o s p h in e

o x ide ( t h e no rm al W i t t i g p a t h ) t o g iv e c i n n a m a t e , o r

d i s s o c i a t e t o b e n z a ld e h y d e and p h o sp h o ran e which c o u ld t h e n

r e a c t w i t h t h e more r e a c t i v e m—chlorobenzaldehy de, B e t a in e

r e v e r s i b i l i t y h a s s i n c e b e en d e m o n s t r a t e d i n t h e c a s e o f15 0

u n s t a b l e p h o s p h o r a n e s .

BUqP 4 P h - C E - C H - C O O E t BUq P - CHGOOEt

(159)

BtioP = CHDOOEt + PhCHO

CHO

'VBUgPO

+

Ph - GH= GH~GOOEt

m - G 1 'G 6 % - GH= GH- GOOEt

+ BUgPO

The c o r r e s p o n d i n g r e a c t i o n s o f c i s and t r a n s -l 5 l

b u t - 2 - e n e e p o x id e s w i t h t r i b u t y l p h o s p h i n e do n o t a p p e a r

t o be c o m p l e t e l y s t e r e o s p e c i f i c , t h e t r a n s - e p o x i d e g i v e s

7 % c i s and 28/^ t r a n s - b u t e n e , and t h e c i s - e p o x i d e g i v e s

-8 9 -

81^ t r a n s and 19^ c i s - b u t e n e . Thus i t seems l i k e l y t h a t

b e t a i n e r e v e r s i b i l i t y i s t a k i n g p a r t t o g iv e t h e u n e x p e c t e d

s t e r e o i s o m e r .

A f u r t h e r example o f b e t a i n e r e v e r s i b i l i t y i s t o

be fo u n d i n t h e r e a c t i o n be tw een d i p h e n y I p h o s p h in e and 162

s t y r e n e o x i d e . The p r o d u c t s from t h i s r e a c t i o n a r e

e x t r e m e l y d e p e n d e n t upon t h e c o n d i t i o n s , b u t a t 140°, w i t h o u t

s o l v e n t , b e n z a ld e h y d e and m e t h y l d ip h e n y lp h o s p h i n e o x id e a r e

formed t o g e t h e r w i th o t h e r p r o d u c t s . P re su m a b ly t h e r e a c t i o n

p r o c e e d s v i a th e b e t a i n e ( l 6 o ) ( f u r t h e r e v id e n c e f o r t h i s

a s s u m p t io n i s g iv e n be low ; p .^^^ ) d i s s o c i a t i o n and

r e a r r a n g e m e n t g i v i n g b e n z a ld e h y d e and m e t h y l d i p h e n y l p h o s p h i n e ,

a- d k i - c iPhgPH + P h -C fH i-C H a -» P h a P jiC H a PhCHO

A HO^GHPhC v A,TTT1_ +

(160) PaaPjr\cHaHI

P h a P -G H q

I n t h i s c a s e i t was p o s s i b l e t o o b se rv e b e t a i n e r e v e r s i b i l i t y

b e c a u s e t h e p hosphorane fo rm ed i s r e a d i l y a b l e t o r e a r r a n g e

to th e p h o s p h i n e , t h u s rem oving any p o s s i b i l i t y o f r e f o r m i n g

th e b e t a i n e . A s i m i l a r r e a c t i o n t a k e s p l a c e i f t h e p r o d u c t

-9 0 -

from th e o p e n in g of t r a n s - s t i l b e n e o x id e w i t h sodium

d i p h e n y I p h o s p h id e , th e p h o sp h in e ( l 6 l ) , i s p r o t o n a t e d

w i t h e t h a n o l . The p r o d u c t s a r e b e n z a ld e h y d e and15 0

b e n z y l d i p h e n y l p h o s p h i n e .

A l t h o u g h i t i s p o s s i b l e t h a t t h i s r e a c t i o n p r o c e e d s

v i a an i n t e r m e d i a t e b e t a i n e s i m i l a r t o (l6o), a s t h e r e i s

an e q u i v a l e n t amount of b a se p r e s e n t , i n th e form o f

e t h o x i d e , once p r o t o n a t i o n of t h e oxygen h a s t a k e n p l a c e ,

p r o t o n a t i o n o f t h e p h o sp h o ru s would seem u n l i k e l y . An

a l t e r n a t i v e e x p l a n a t i o n i s t h a t t h e p - h y d r o x y p h o s p h in e

( 16 2 ) u n d e rg o e s a b a se c a t a l y s e d r e v e r s e a l d o l r e a c t i o n .

Phi^E. y E

P h a P P h » — iÇw 9 " " ^ P h EtOH

* L - = ^

( 1 6 1 )

P h a P - CHPh- C(OH)HPh ( 1 6 2 )

Etc

PhgPCHgPh + PhCHO

—91*”

A t h o r o u g h d i s c u s s i o n o f b e t a i n e r e v e r s i b i l i t y150

i s g i v e n i n r e f e r e n c e

A l t h o u g h r e v e r s i b l e b e t a i n e f o r m a t i o n m u s t b e

i n v o k e d i n r e a c t i o n s l i k e t h a t o f d i p h e n y l p h o s p h i n e w i t h

s t y r e n e o x i d e , w h e r e t h i s r e v e r s i b i l i t y i s u s e d t o e x p l a i n

b e t a i n e i n t e r c o n v e r s i o n t h e r e i s a p o s s i b i l i t y o f a f u r t h e r

e x p l a n a t i o n . T h e r e c o u l d b e d i r e c t i n t e r c o n v e r s i o n o f o n e

s t e r e o i s o m e r i c b e t a i n e t o t h e o t h e r w i t h o u t d i s s o c i a t i o n60

t o a l d e h y d e a n d p h o s p h o r a n e .

T h e tv/o i s o m e r i c b e t a i n e s , w h i c h c a n b e p r o d u c e d

b y t h e r e a c t i o n o f a p h o s p h o r a n e a n d a n a l d e h y d e , a r e

i n t e r e o n v e r t a b l e v i a t h e p h o s p h o r a n e ( 1 6 3 ) , f o r m e d b y t h e

r e m o v a l o f a p r o t o n f r o m t h e a —c a r b o n o f t h e i s o m e r i c

b e t a i n e s . O b v i o u s l y t h i s p r o t o n w i l l b e m o s t r e a d i l y r e m o v e d

w h e n i s a n a c t i v a t i n g g r o u p ; t h u s d i r e c t i n t e r c o n v e r s i o n

i s m o s t l i k e l y t o b e f o u n d i n W i t t i g r e a c t i o n s i n v o l v i n g

s t a b l e p h o s p h o r a n e s .

-9 2 -

RgPr: GHR^ + R®GHO

As a l l th e s t e p s shown may he o p e r a t i n g a t any g i v e n t ime

i t i s n o t u s u a l l y p o s s i b l e t o d i s t i n g u i s h be tw een them.15 0

However, T r i p p e t t h a s shown t h a t i n the sy s tem

i n c l u d i n g th e b e t a i n e ( I 6 5 ) d i r e c t i n t e r c o n v e r s i o n i s

r e l a t i v e l y u n i m p o r t a n t . When t h i s b e t a i n e was p r o d u c e d

from i t s c o r r e s p o n d i n g phosphonium i o d i d e Cl6i-|.) i n t h e

p r e s e n c e of an e x c e s s o f m - c h l o r o b e n z a l d e h y d e , 49^ o f

c i s and 9*9^ o f t r a n s - s t i l b e n e was form ed. The amount o f

t r a n s - s t i l b e n e was r e d u c e d t o hffo by f u r t h e r i n c r e a s i n g th e

e x c e s s o f m - c h l o r o b e n z a l d e h y d e .

-H

HO- Ph

(164)

-9 3 -

MePhgP. Base 0(

Ph

- n / X Ph

!H0

c i s - s t i l b e n e

c i s and t r a n s -MePhgP = GHPh m - c h l o r o s t i l b e n e

+ PhCHO (166)

Under t h e s e c o n d i t i o n s b e t a i n e i n t e r c o n v e r s i o n v i a

b e t a i n e d i s s o c i a t i o n i s i m p o s s i b l e b e c a u s e th e b e n z y l i d e n e -

p h o sp h o ra n e ( l 6 6 ) w i l l be i r r e v e r s i b l y c a p t u r e d by t h e

m -c h lo r o b e n z a ld e h y d e t o g i v e m - c h l o r o s t i l b e n e s . Thus t h e

s m a l l p e r c e n t a g e o f t r a n s - s t i l b e n e fo rm ed c an o n ly come from

d i r e c t i n t e r c o n v e r s i o n o f the b e t a i n e s v i a a p h o s p h o ra n e of

t h e t y p e ( 1 6 3 ) .

A n o t h e r r e a c t i o n o f i n t e r m e d i a t e b e t a i n e s h a s b e en163

d e s c r i b e d by Hands and M e rc e r . When p - h y d r o x y e t h y l t r i -

pheny lphosphon ium s a l t s ( 16? ) were t r e a t e d w i t h sodium

e t h o x i d e , i n e t h a n o l , p - e t h o x y e t h y l d i p h e n y l p h o s p h i n e ox ide

( 169 ) and b enzen e were fo rm ed . A s i m i l a r r e a c t i o n u s i n g

-9 4 -

aqueous p o t a s s i u m h y d r o x i d e gave p - h y d r o x y e t h y l d i p h e n y l -

p h o s p h in e o x i d e . Hands s u g g e s t e d t h a t t h e s e r e a c t i o n s i n v o l v e

a t t a c k by a l k o x i d e on t h e p - c a r b o n of th e b e t a i n e ( l 6 8 ) , t h e

f o r m a t i o n of a p h osp h o ru s oxygen bond and the e x p u l s i o n o f a

p h e n y l g ro u p a s i t s a n i o n , which t a k e s up a p r o t o n from t h e

s o l v e n t .

+ X“ ^ P h0

EtO~ V CHa V + Pit"

HOOEt CHs.

^OEt(167) ( 168 ) (169)

However, c o n s i d e r a t i o n o f th e a l c o h o l y s i s of164

phosphonium s a l t s makes t h i s mechanism a p p e a r u n l i k e l y .

Under c o n d i t i o n s o f a l c o h o l y s i s i t i s s u g g e s t e d t h a t th e

f i v e v a l e n t p h o s p h o r u s i n t e r m e d i a t e (170) i s fo rm ed

i n i t i a l l y , by a t t a c k o f a l k o x i d e on p h o s p h o r u s . F u r t h e r

a t t a c k o f a l k o x i d e on t h i s l e a d s t o th e f o r m a t i o n o f an

e t h e r and p h o s p h in e o x id e by d i s p l a c e m e n t o f t h e a n i o n (R^)~ .

-9 5 -

R2R^

^ R

(170)

A l c o h o l y s i s , how ever , w i l l o n ly t a k e p l a c e when R = b e n z y l

o r s u b s t i t u t e d b e n z y l , n o t when R^ = p h e n y l . I f we w r i t e

( l 6 8 ) a s (171) i t i s r e a d i l y s e e n t h a t th e mechanism

s u g g e s t e d by Hands i s a n a lo g o u s t o a l c o h o l y s i s *

?>Ph

PiLjP CHja

— CHcfla 1. OEt

(171)

There a p p e a r s t o be no v a l i d r e a s o n why a p h e n y l

g ro u p s h o u ld l e a v e i n t h i s c a s e when i t w i l l n o t i n n o fm a l

a l c o h o l y s i s .

A p o s s i b l e a l t e r n a t i v e t o t h i s mechanism i s t h e

r em o v a l o f a p r o t o n from th e a - c a r b o n atom i n th e b e t a i n e

(168) by a l k o x i d e , f o l l o w e d by t h e e l e c t r o n s h i f t s shown

-9 6 -

( 1 7 2 ) t o g i v e a v i n y l p h o s p h i n e o x i d e , w h i c h c a n r e a d i l y

a d d e t h a n o l t o g i v e H a n d s ’ p r o d u c t *

J^PhM 0-P h g R \ O E t

+ P h

( 172 )

2

EtOHV

P h . "

2

CHgOEt

I n t h e r e a c t i o n w i t h a q u e o u s p o t a s s i u m h y d r o x i d e i t i s

p o s s i b l e t h a t s i m p l e h y d r o l y s i s o f t h e p h o s p h o n i u m s a l t

i s t a k i n g p l a c e .

A f u r t h e r e x a m p l e o f t h i s t y p e c a n b e f o u n d i n t h e

r e a c t i o n o f d i p h e n y l p h o s p h i n e w i t h s t y r e n e o x i d e . T h e

d i p h o s p h i n e d i o x i d e (175) i s one o f s e v e r a l p r o d u c t s

i s o l a t e d a n d c o u l d b e f o r m e d b y t h e a d d i t i o n o f157 ,16 8

d i p h e n y l p h o s p h i n e o x i d e , o r i t s a n i o n , t o t h e

v i n y l p h o s p h i n e ( 1 7 4 ) , w h i c h i n t u r n may b e f o r m e d b y

—97—

p r o t o n a t i o n on oxygen o f t h e b e t a i n e (173) and s u b s e q u e n t

l o s s o f w a t e r , w i th o r w i t h o u t l o s s o f a p r o t o n from t h e

p h o s p h o r u s . S u b s e q u e n t a i r o x i d a t i o n g i v e s t h e p r o d u c t

( 1 7 5 ) .

PhaPH+

P l i - c m - CHa,

0II

PhaP^CHa

H.CH^ P h g P / ^ P h

(175)

9PhgP^

(1 7 3 )

PhgP,0II

: ’V al / C H

P h a P ^ ^Ph

Pha,P^CHaŒI

HO^ Ph

PhgP,'CH

IIOHN Ph

(174)

-9 8 -

Abnormal R e a c t i o n s o f t h e B e t a i n e s R3 P —CH^ GH(0)R

165W i t t i g h a s shown t h a t h e n z y l i d e n e t r i p h e n y l -

p h o sp h o ran e w i t h b e n z a ld e h y d e i n e t h e r g i v e s > 80^ o f

s t i l b e n e . The e q u i v a l e n t r e a c t i o n u s i n g sodium e t h o x i d e

i n e t h a n o l a s t h e b a se to p ro d u c e t h e p h o sp h o ra n e g i v e s

>96^ y i e l d o f s t i l b e n e s . However, m e t h y l t r i p h e n y l p h o s -

phonium h a l i d e s i n a l c o h o l i c - a l k o x i d e g iv e o n l y p o o r y i e l d s

o f o l e f i n s a n d , u n l i k e t h e b e n z y l s a l t s , do n o t u n d e rg o164

a l c o h o l y s i s . O b v io u s ly r e a c t i o n s o t h e r t h a n a l c o h o l y s i s

must be s u c c e s s f u l l y com pe t ing w i t h o l e f i n f o r m a t i o n i n

t h i s c a s e .

M e th y l t r ip h e n y lp h o s p h o n iu m b ro m id e , o r i o d i d e ,

on s t a n d i n g a t room t e m p e r a t u r e , w i t h b e n z a ld e h y d e i n

e t h a n o l i c sodium e t h o x i d e , formed s t y r e n e (l]yb) and a

h i g h l y c r y s t a l l i n e , i n s o l u b l e compound. T h i s v/as shown

t o be 1 , 2 - d i p h e n y l e t h y l d i p h e n y l p h o s p h i n e o x id e ( 1 7 6 ; R = P h ) .

F u s i o n o f t h i s compound w i t h a l k a l i gave a h i g h y i e l d o f166

s t i l b e n e and n o t 1 , 2 - d i p h e n y l e th a n e a s p r e v i o u s l y r e p o r t e d .

Compound (176), i s p r e s u m a b ly formed from t h e b e t a i n e (177)

by s i m u l t a n e o u s m i g r a t i o n of a p h e n y l g rou p from p h o s p h o r u s

to a - c a r b o n and of h y d r o g e n from gl t o t h e 0 - c a r b o n .

-9 9 -

4- OEtPhaP-C H a , Phg.P = CHg ^ Ph%P-GHj-H

O^CHR (177)

0 \kP h g P - CliPli.CHgR (176)

R ep lacem en t o f b e n z a ld e h y d e by s u b s t i t u t e d

b e n z a ld e h y d e s gave th e c o r r e s p o n d i n g p h o s p h in e o x id e s

( 176 ; R = m - c h l o r o p h e n y l , ^ - t o l y l , p i p e r o n y l , m - n i t r o p h e n y l )

whose s t r u c t u r e s were d e t e r m i n e d b o th by f u s i o n w i t h a l k a l i ,

and i d e n t i f i c a t i o n of th e r e s u l t i n g s t i l b e n e s , and by

s y n t h e s i s from b e n z y l h a l i d e s and m e t a l l a t e d b e n z y l d i p h e n y l -

p h o sp h in e o x id e .

As th e b e t a i n e (177; R = Ph) i s t h e e x p e c t e d

i n t e r m e d i a t e i n t h e r e a c t i o n o f t r i p h e n y l p h o s p l i i n e w i t h

s t y r e n e ox ide i t would seem r e a s o n a b l e t h a t th e p h o s p h i n e

o x id e ( 176 ; R= Ph) would be th e m a jo r p r o d u c t , a l t h o u g h6 5

W i t t i g and Haag have r e p o r t e d t h a t t h i s r e a c t i o n i n t h e

a b s e n c e o f s o l v e n t g i v e s s t y r e n e (50^) and t r i p h e n y l p h o s p h i n e

o x id e (86$^). However, when th e r e a c t i o n was c a r r i e d o u t

i n r e f l u x i n g e t h a n o l t h e r e a r r a n g e d o x id e (176; R = Ph) was

-1 0 0 -

forraed i n h i g h y i e l d .

T h i s l e d u s to b e l i e v e t h a t t h e r e a c t i o n was

h i g h l y d ep en d e n t on s o l v e n t , and f u r t h e r work showed t h i s

t o be t r u e . A l th o u g h r e a c t i o n i n d i - n - b u t y l e t h e r gave

t h e r e a r r a n g e d o x id e (176; R = B h ) i n somewhat r e d u c e d

y i e l d , r e a c t i o n i n benzene was e x t r e m e l y slow t o g i v e

s t y r e n e ( 36^ ) and t r i p h e n y l p h o s p h i n e o x id e ( 4 0 ^ ) , a f t e r

a w eek ,an d no t r a c e o f t h e r e a r r a n g e d o x id e ( 1 7 6 ) . Even

i n m e th a n o l t h e y i e l d o f th e o x id e (176) v/as r e d u c e d and

t h a t o f s t y r e n e c o n s e q u e n t l y i n c r e a s e d .

The m i g r a t o r y a p t i t u d e s of s u b s t i t u t e d p h e n y l

g ro u p s i n t h e above r e a r r a n g e m e n t were i n v e s t i g a t e d u s i n g+ —

b o th t h e r e a c t i o n s of t h e i o d i d e s MePhgPG6H.g3C.. I w i t h

b e n z a ld e h y d e s i n e t h a n o l i c sodium e t h o x i d e , and t h e r e a c t i o n s

o f th e p h o s p h i n e s P h g P G ^ w i t h s t y r e n e o x id e i n r e f l u x i n g

e t h a n o l . I n a l l r e a c t i o n s t h e o r d e r o f m i g r a t i o n was

m - c h l o r o p h e n y l ^ p h e n y l ^ p - a n i s y l , t h a t g ro u p m i g r a t i n g w h ich

i s t h e more s t a b l e a s t h e a n i o n . T h e r e f o r e , i t a p p e a r s

t h a t th e m i g r a t i n g g r o u p , w i t h i t s b o n d in g e l e c t r o n s , i s

b e in g ’’p u s h e d ” from t h e p h o s p h o r u s , t h e e l e c t r o n s h i f t

( I ; fo r m u la 177) b e in g i n advance o f t h e o t h e r s and th e

d r i v i n g f o r c e f o r t h e r e a c t i o n b e in g th e f o r m a t i o n o f t h e

ÿ — 0 bond. T h i s i s a n a lo g o u s t o th e b e n z i l - b e n z i l i c a c i d

-101-

r e a r r a n g e m e n t , which i n v o l v e s a t t a c k o f h y d r o x i d e a n i o n

on one c a r b o n y l o f b e n z i l , f o l lo w e d by m i g r a t i o n o f a

p h e n y l a s an a n io n from t h i s c a rb o n t o t h e o t h e r

c a r b o n y l c a r b o n .

OH ^ C - C0 - ? 0 0—

■ - H O - C - C ^ -» H O - G - G ,

The s e a r c h f o r r e a r r a n g e m e n t s of t h i s ty p e i n s l i g h t l y

d i f f e r e n t sy s te m s was g r e e t e d w i t h v a r y i n g s u c c e s s . When

p r o p i o n a l d é h y d e was t r e a t e d w i t h m e t h y l t r i p h e n y l p h o s p h o n i u m

i o d i d e i n e t h a n o l i c sodium e t h o x i d e , no o l e f i n o r r e a r r a n g e d

o x id e was fo rm ed . T h i s i s p re s u m a b ly due t o n e i t h e r o f

t h e s e r e a c t i o n s b e in g a b l e t o compete w i t h b a se c a t a l y s e d

p o l y m e r i s a t i o n o f th e a ld e h y d e . E t h y l t r i p h e n y l p h o s p h o n i u m

i o d i d e w i th b e n z a ld e h y d e i n e t h a n o l i c sodium e t h o x i d e gave

h i g h y i e l d s o f 0 - m e t h y l s t y r e n e , and e v en h i g h e r y i e l d s i n

m e t h a n o l i c sodium m e th o x id e , no r e a r r a n g e d o x id e b e i n g

d e t e c t e d .

The r e a c t i o n of d i p h e n y l p h o s p h i n e w i t h s t y r e n e o x id e

was f a r more p r o f i t a b l e . Here i t was p o s s i b l e t o o b s e r v e ,

d e p e n d in g upon t h e c o n d i t i o n s u s e d , t h e m a j o r i t y o f t h e

—102—

r e a c t i o n o f b e t a i n e s . W i th o u t s o l v e n t a t 120° th e p r o d u c t s

were ( 3 - p h e n y le th y ld ip h e n y lp h o s p h in e o x id e (178) ( 2 5 ^ ) ,

p r e s u m a b ly form ed by a r e a r r a n g e m e n t ( a ) , a n a lo g o u s t o

t h a t o f th e b e t a i n e (177) to g i v e t h e o x id e ( 1 7 6 ) , b u t

i n v o l v i n g th e m i g r a t i o n o f h y d r i d e r a t h e r t h a n p h e n y l

a n i o n , t o g e t h e r w i t h b e n z a ld e h y d e (2lj^o) and m e t h y l d i p h e n y l -

p h o s p h in e ( i s o l a t e d a s t h e o x id e ) (3 i#^) , t h e s e l a s t two

p r e s u m a b ly b e in g fo rm ed by d i s s o c i a t i o n (b ) o f t h e

i n t e r m e d i a t e b e t a i n e ( 1 7 9 ) . V/hen th e r e a c t i o n was c a r r i e d

o u t i n r e f l u x i n g e t h a n o l t h e p r o d u c t s were s t y r e n e (6CÇo),

p r o b a b l y r e s u l t i n g from a c o n v e n t i o n a l W i t t i g e l i m i n a t i o n

( c ) from t h e b e t a i n e ( 1 7 9 ) , b e n z a ld e h y d e and m e t h y l d ip h e n y l -

p h o s p h in e (f rom b e t a i n e d i s s o c i a t i o n ) and t h e d i p h o s p h i n e

d i o x i d e ( l 8 0 ) , t h e p o s s i b l e mode o f f o r m a t i o n o f which h a s

a l r e a d y b e en d i s c u s s e d ( p . 9 7 ) .

0I I

PhgP -G H g-G H gPh

HPhg P = CHs -> PhgPGHg

PhgPH + Ph-GH-GHa

(178)

(a

(179) ^ PhGH= GHs

\PhsP—CiHs— carphPhgP = 0 (1 8 0 )

—103—

A u t h e n t i c d i o x i d e ( l 8 0 ) was s y n t h e s i s e d by

t h e t h e r m a l r e a r r a n g e m e n t o f t h e p h o s p h i n i t e ( l 8 l ) o b t a i n e d

from c h l o r o d i p h e n y l p h o s p h i n e an d 2 - h y d r o x y - 2 - p h e n y l e t h y l -

d i p h e n y l p h o s p h i n e o x id e ( l 8 2 ) .

0 0 II , , p y ^ I)

PhgPCl + PhaP-CH s-CH CO H )Ph ----- » P h g P ^

(1S2) (181)CHPh

P h g P - 0 ^

H e a t 120°

° »Ph^P

^GHs0 I (180)

CHPhPhgP-^

A number o f o t h e r e p o x id e s were r e a c t e d w i t h

t r i - and d i p h e n y l p h o s p h i n e . I t was found t h a t a l l t h e

r e a c t i o n s r e q u i r e d f a r more v i g o r o u s c o n d i t i o n s t h a n th o s e

o f s t y r e n e o x id e and p h o s p h i n e s , m a in ly s e a l e d t u b e s and

h i g h t e m p e r a t u r e s . T h i s i s a l i t t l e s u r p r i s i n g a s a s e a r c h

o f t h e l i t e r a t u r e showed no e v id e n c e of e x t r a r e a c t i v i t y

to w a rd s n u c l e o p h i l e s i n t h e c a s e o f s t y r e n e o x id e when

compared w i th o t h e r e p o x i d e s . 1 ,2 -E poxyhexane gave

h e x - l - e n e a s t h e m a jo r p r o d u c t on r e a c t i o n w i t h e i t h e r

-104-

d i - o r t r i p h e n y l p h o s p h i n e , p re su m ab ly by a no rm al W i t t i g

e l i m i n a t i o n . No b e t a i n e d i s s o c i a t i o n p r o d u c t s c o u ld be

d e t e c t e d i n e i t h e r c a s e . However, w i t h d i p h e n y l p h o s p h i n e ,

1 , 2 - epoxyhexane d i d g i v e a sm a l l y i e l d (ii/0 o f

h e x y ld i p h e n y l p h o s p h i n e o x id e ( l 8 3 ) p re s u m a b ly by a

mechanism s i m i l a r t o ( a ) above .

PhgPH + CHg - a i - ( CHa )s - CHg -» P h ^ ^C H jH

/ N gH - (CHg )a - CHa

I -1

P h g P - (CHg ) a - C H a

(183)

t r a n s - S t i l b e n e o x ide gave on ly p o o r y i e l d s of

s t i l b e n e , and p h o sp h in e o x i d e , when r e a c t e d v / i th o u t s o l v e n t

w i t h t r i p h e n y l p h o s p h i n e a t 180° f o r f o u r days and no o t h e r

i s o l a t a b l e p r o d u c t . T h i s was e q u a l l y t r u e o f c i s - s t i l b e n e156

o x id e .

The r e a c t i o n of 1 ,2 - e p o x y c y c lo h e x a n e w i t h

d ip h e n y l p h o s p h i n e gave c y c lo h e x e n e {6%) and c y c l o h e x y l -

d ip h e n y l p h o s p h i n e o x id e (30) a s t h e o n ly i s o l a t a b l e p r o d u c t s .

However, w i t h t r i p h e n y l p h o s p h i n e , o r m e t h y l d i p h e n y l p h o s p h i n e ,

—105""

a l t h o u g h th e y i e l d of o l e f i n was n o t im proved , th e

c o r r e s p o n d i n g c y c lo h ex e n y lp h p sp h o n iu m s a l t (185) was

fo rm ed . T h i s i s p r o b a b l y p r o d u c e d by e l i m i n a t i o n o f ”’0H

from th e i n t e r m e d i a t e b e t a i n e ( 1 8 4 ) .

R = Ph o r Me

OH

RPh.

PhgRP

(184)

T h i s may be a co n seq u e n ce of t h e h i g h e n e rg y

o f a t r a n s i t i o n s t a t e f o r o l e f i n f o r m a t i o n , i n v o l v i n g a

four -m em bered r i n g f u s e d d i e q u a t o r i a l l y t o a s i x membered

r i n g . Benzene (20 /0 was a l s o form ed i n t h e s e r e a c t i o n s ,

p r o b a b l y by d e c o m p o s i t i o n o f th e phosphonium h y d r o x id e

( 1 8 5 ) .

I n an a t t e m p t t o r a t i o n a l i s e t h e s e r e s u l t s

c y c l o o c t e n e ox ide was r e a c t e d w i t h t r i p h e n y l p h o s p h i n e .

The p ro b le m s o f a h i g h - e n e r g y t r a n s i t i o n s t a t e f o r o l e f i n

f o r m a t i o n sh o u ld n o t a r i s e i n t h i s c a s e b e c a u se t h e sys tem

w i l l c o n s i s t of a four -m em bered r i n g f u s e d t o an e i g h t -

membered. A l th o u g h th e r e a c t i o n r e q u i r e d even more

—106—

v i g o r o u s c o n d i t i o n s t h a n th e c y c lo h e x a n e c a s e , th e on ly

p r o d u c t s were p h o sp h in e o x id e and c y c l o o c t e n e (38/&), no

phosphonium s a l t b e in g fo rm ed .

I t c an be s e e n from t h i s d i s c u s s i o n t h a t i n t e r

m e d i a t e b e t a i n e s i n W i t t i g r e a c t i o n s can undergo a number of

r e a c t i o n s o t h e r t h a n e l i m i n a t i o n o f p h o sp h in e o x ide t o g iv e

o l e f i n s ; They may;

( a ) d i s s o c i a t e t o p h o sp h o ra n e and c a r b o n y l compound,

(b ) r e a r r a n g e t o p h o s p h in e o x ide by m i g r a t i o n of

p h e n y l from p h o s p h o ru s t o a - c a r b o n ,

( c ) s u f f e r f u r t h e r a t t a c k by n u c l e o p h i l e s t o g i v e

^ - s u b s t i t u t e d p h o s p h in e o x i d e s , and

(d ) e l i m i n a t e h y d r o x i d e t o g i v e v i n y l phosphonium

s a l t s .

E x p e r i m e n t a l

A l l e x p e r i m e n t s i n v o l v i n g p h o s p h o r a n e s and s i m i l a r

u n s t a b l e compounds were c o n d u c te d u n d e r a n o x y g e n - f r e e n i t r o g e n

a tm o sp h e re . A l l a r o m a t i c a ld e h y d e s were f r e s h l y d i s t i l l e d

u n d e r an o x y g e n - f r e e n i t r o g e n a tm o s p h e r e . A l l s o l v e n t s were

d r i e d b e f o r e u s e . M e l t i n g p o i n t s were c o r r e c t e d .

R e a c t i o n of M e th y l t r i p h e n y lp h o s p h o n iu m I o d i d e w i t h

B e n za ld eh yd e i n E t h a n o l i c Sodium E t h o x i d e . - A s o l u t i o n of

-107-

m e t h y l t r i p h e n y l p h o s p h o n i u m i o d i d e ( l 6 . 2 g . ) and b e n z a ld e h y d e

(4 .2 5 g . ) , i n e t h a n o l (60 m l . } , c o n t a i n i n g sodium (0*97 g * ) ,

v/as s e t a s i d e a t room t e m p e r a t u r e u n d e r o x y g e n - f r e e n i t r o g e n .

A f t e r 48 h r . , g . l . c . (2m. A p ie zo n column a t 130®) showed th e

p r e s e n c e o f s t y r e n e (1 0 ^ ) and b e n z a ld e h y d e (<5^0 , a n d f i l t r a

t i o n gave 1 , 2 - d i p h e n y l e t h y l d i p h e n y l p h o s p h i n e o x id e ( 6 8 ^ ) , m .p .

and m ixed m .p . ( f rom e t h a n o l ) 232-233® (Pound: G, 8 1 .3 ; H , 3 . 9 ;

P , 8 . 0 7 . C a l c , f o r CseHaaOP: G, 8 1 .6 ; H, 6 .0 2 ; P , 8 . 1 2 ^ ) .

The same e x p e r im e n t i n m e th a n o l gave s t y r e n e (26^) and o x id e

( 34^ ) . The ox ide (8 g . ) was f u s e d w i t h sodium h y d r o x i d e

(15 g . ) , t o which w a t e r (1 m l . ) h a d b e en ad d ed , f o r 2 h r . and

t h e c o o l e d m ix t u r e d i s s o l v e d i n w a t e r (200 m l . ) . E x t r a c t i o n

w i t h c h lo r o f o r m gave a s o l u t i o n which g . l . c . (2m. A p ie z o n

column a t 25O®) showed t o c o n t a i n c i s (40 ^ ) and t r a n s (8 ^ )

s t i l b e n e s . The aqu eo u s l a y e r g a v e , on a c i d i f i c a t i o n ,

d i p h e n y l p h o s p h i n i c a c i d ( 8 1 ^ ) , m .p . and mixed m .p . 192.-193°.

S i m i l a r e x p e r i m e n t s i n e t h a n o l u s i n g s u b s t i t u t e d

b e n z a ld e h y d e s gave th e f o l l o w i n g p h o sp h in e o x i d e s .

1 - P h e n y l - 2 - m - c h l o r o p h e n y l e t h y l d i p h e n y l p h o s p h i n e o x i d e , ( 4 8 ^ ) ,

m .p . and mixed m .p . ( f rom e t h a n o l ) 212-213®.

1 - P h e n y l - 2- 2 - t o l y l e t h y l d i p h e n y l p h o s p h i n e o x id e ( 4 C # ) , m .p .

an d mixed m .p . ( f ro m e t h a n o l ) 240-241®.

-108 -

l - P h e n y l - 2 - ( 3 * ,4 * - m e t l iy l e n e d lo x y p h e n y l ) e t h y l d i p h e n y l p h o s p h i n e

o x id e ( 38%), m .p . ( f rom e t h a n o l ) 204-203® (Pound: C, 7 6 . 6 ;

H, 3 . 8 ; P , 7 *1 3 . C27H23O3 P r e q u i r e s C, 7 6 . 2 ; H, 3 . 4 ; P , 7 . 3 ^ ) .

1 - P h e n y l - 2 -m -n i t r o p h e n y l e t h y l d i p h e n y l p h o s p h i n e o x ide ( lO o ) ,

m .p . ( f rom e t h a n o l ) 203-204® (Pound: C, 7 2 . 3 ; H, 3 . 2 ; P , 7 . 2 ;

N , 3 . 4 . C26H22NO3P r e q u i r e s C, 7 3 .0 ; H, 3 . 2 ; P , 7 .2 3 ;

N , 3 .3% ).

1 - P h e n y l - 2 -m- c h l o r o p h e n y l e t h y l d i p h e n y l p h o s p h i n e O x ide . -

E t h e r e a l b u t y l - l i t h i u m (13 m l . ) was added t o a s o l u t i o n

o f b e n z y l d ip h e n y l p h o s p h i n e o x id e ( 4 . 2 g . ) i n e t h e r (100 m l . )

and th e s o l u t i o n h e a t e d u n d e r r e f l u x f o r % h r . m -C h lo ro -

b e n z y l b romide (4 g . ) , i n e t h e r (40 m l . ) , was t h e n added and

t h e s o l u t i o n h e a t e d u n d e r r e f l u x f o r a f u r t h e r 2 h r . I t was

t h e n v/ashed w i t h w a t e r , d r i e d an d e v a p o r a t e d and th e r e s i d u e

c r y s t a l l i s e d from e t h a n o l t o g i v e th e p h o s p h in e o x id e ( 67%),

m .p . 212- 213®, (Pound: G, 7 4 . 3 ; H, 3 . 0 ; G l , 7 . 6 ; ? , 8 . 6 3 .

G26H22GIOP r e q u i r e s G, 7 4 . 7 ; H, 3 . 3 ; G l , 7 . 4 ; P , 8 . 3%),

P u s i o n w i t h sodium h y d r o x id e gave ( g . l . c . ) c i s ( 3 ^ ) and

t r a n s - 3 - c h l o r o s t i l b e n e (12%), and d i p h e n y l p h o s p h i n i c a c i d ( 7 ^ 0 <

A s i m i l a r e x p e r im e n t u s i n g 4 - m e t h y l b e n z y l b rom ide

gave 1—p h e n y l - 2 - p - to l y l e t h y l d i p h e n y l p h o s p h i n e o x ide ( 6 2 / 0 ,

m.p* ( f rom e t h a n o l ) 240-241® (Pound: G, 8 1 . 7 ; H, 6 . 3 ; P , 7 . 8 .

—109—

02 7^ 35GP r e q u i r e s C, 8 1 . 6 ; H, 6 . 3 ; P , 8 .0% ) . F u s i o n w i t h

sodium h y d r o x id e gave ( g . l . c . ) c i s (36%) and t r a n s - 4 - m e t h y l -

s t i l b e n e (7%), and d i p h e n y l p h o s p h i n i c a c i d (77%).

E x p e r im e n t s u s i n g m-C h l o r o p h e n y l d i p h e n y l p h o s p h i n e .

A s o l u t i o n o f c h l o r o d i p h e n y l p h o s p h i n e (35 g . ) i n e t h e r

(150 m l . ) was added s l o w l y t o t h e G r i g n a r d r e a g e n t from

m -c h lo r o io d o b e n z e n e (45 g . ) and magnesium (4*6 g. ) i n e t h e r

(200 m l . ) c o o le d t o 0®, and th e s o l u t i o n s t i r r e d a t room

t e m p e r a t u r e f o r 2 h r . 2 N - ^ y d r o c h l o r i c a c i d (250 m l . ) was

t h e n s l o w l y added f o l l o w e d by c h lo r o f o r m (200 m l . ) . The

o r g a n i c l a y e r was washed w i th w a t e r , d r i e d , and e v a p o r a t e d .

D i s t i l l a t i o n gave m - c h lo r o p h e n y l d i p h e n y l p h o s p h i n e (37 g . ) ,

b . p . 208-212®/2mm., which d i d n o t c r y s t a l l i s e and was

c h a r a c t e r i s e d a s th e m e t h i o d i d e . m .p . ( f rom c h l o r o f o r m - e t h y l

a c e t a t e ) 170-173® (Found: C, 5 2 . 0 ; H, 4 . 0 ; 0 1 , 7 . 9 5 ; P , 6 . 9 .

G igH i^C lIP r e q u i r e s G, 5 2 . 0 ; H, 3 . 9 ; 0 1 , 8 . 1 ; P , 7 .05% ).

m -G h lo ro p h en y lm e th y ld ip h en y lp h o sp h o n iu m i o d i d e

( 4 . 4 g . ) and b e n z a ld e h y d e ( 1 . 2 g . ) were added t o e t h a n o l

(50 m l . ) c o n t a i n i n g sodium ( 0 .2 5 g . ) and t h e s o l u t i o n s e t

a s i d e a t room t e m p e r a t u r e f o r 5 d a y s . W ater was t h e n added

t o t u r b i d i t y . G r y s t a l l i s a t i o n t h e n gave 1 - m - c h l o r o p h e n y l -

2 - p h e n y l e t h y l d i p h e n y l p h o s p h i n e o x id e ( 1 . 6 g . ) , m .p . and

-n o -

m ixed m .p . ( f rom aqueous e t h a n o l ) 193-194®. A s i m i l a r

e x p e r im e n t u s i n g m - c h lo r o b e n z a ld e h y d e ( 1 . 4 g . ) gave

1 , 2 - d i - m - c h l o r o p h e n y l e t h y l d i p h e n y l p h o s p h i n e o x id e ( 1 . 8 g . ) ,

m .p . and mixed m .p . ( f rom aqueous e t h a n o l ) 194-193®.

A s o l u t i o n o f m - c h l o r o p h e n y l d i p h e n y l p h o s p h i n e

( 2 .9 6 g . ) and s t y r e n e o x ide ( 1 . 2 g . ) i n e t h a n o l (25 m l . )

v/as h e a t e d u n d e r r e f l u x f o r 24 h r . , and w a t e r t h e n added t o

t u r b i d i t y . C r y s t a l l i s a t i o n gave l - m - c h l o r o p h e n y l - 2 - p h e n y l -

e t h y l d i p h e n y l p h o s p h i n e o x id e ( 3 . 1 g . ) , m .p . and m ixed m .p .

( f rom aqueous e t h a n o l ) 192-194®.

1 , 2 - D i -m -c h l o r o p h e n y l e t h y l d i p h e n y l p h o s p h i n e O x id e . -

A s o l u t i o n of m - c h l o r o b e n z y l b romide (8 g . ) i n benze n e (20 m l . )

was add ed s lo w ly t o a c o o l e d s o l u t i o n o f m e th y l d i p h e n y l -

p h o s p h i n i t e ( 7 . 8 g . ) i n benzene (20 m l . ) and th e r e s u l t i n g

s o l u t i o n h e a t e d u n d e r r e f l u x f o r 1 h r . A d d i t i o n of l i g h t

p e t r o l e u m ( b . p . 40 - 6O®) t h e n gave m-c h l o r o b e n z y l d i p h e n y l p h o s p h i n e

o x id e ( 7 .5 g . ) , m .p . 162 .5 -163 .3® (Found: G, 6 9 .6 2 ; H, 4*7 9 ;

P , 9 . 3 0 . GigHigClOP r e q u i r e s G, 6 9 . 8 0 ; H, 4 . 9 0 ; P , 9 .49% ).

E t h e r e a l I N - b u t y 1 - l i t h i u m (8 m l . ) was added to

m - c h l o r o b e n z y ld i p h e n y lp h o s p h in e o x id e ( 2 . 2 g . ) i n benzene

(100 m l . ) and th e s o l u t i o n h e a t e d u n d e r r e f l u x f o r 1 h r . and

t h e n c o o le d d u r i n g t h e a d d i t i o n o f m - c h l o r o b e n z y l bromide

-111-

(4 g . ) i n benzene (20 m l . ) . The r e s u l t i n g s o l u t i o n was

h e a t e d u n d e r r e f l u x f o r 1 h r . and t h e s o l v e n t t h e n removed

u n d e r r e d u c e d p r e s s u r e . A s o l u t i o n o f th e r e s i d u e i n

c h lo r o f o r m was washed w i t h w a t e r , d r i e d , and e v a p o r a t e d .

T h e r e s i d u e c r y s t a l l i s e d o n t r i t u r a t i o n w i t h l i g h t p e t r o l e u m

t o g i v e 1 , 2 - d i - m - c h l o r o p h e n y l e t h y l d i p h e n y l p h o s p h i n e o x i d e

( 2 . 3 g . ) , m . p . ( f r o m a q u e o u s e t h a n o l ) 194-193® ( F o u n d :

G, 6 9 .0 3 ; H, 4 . 6 ; G l , 1 5 .6 5 ; p , 7 . 0 . GggHgiGlgOP r e q u i r e s

G, 6 9 . 2 ; H, 4 . 6 5 ; G l , 1 5 .7 5 ; P , 6 .9 % ) . F u s i o n w i th s so d iu m

h y d r o x i d e gave ( g . l . c . ) c i s - 3 . 3 ^ - d i - c h l o r o s t i l b e n e ( 69%).

A s i m i l a r e x p e r i m e n t u s i n g b e n z y l b r o m i d e g a v e

l- f f l -c h l o r o p h e n y l - 2 - p h e n y l e t h y l d i p h e n y l p h o s p h i n e o x i d e ( 65%),

m . p . ( f r o m a q u e o u s e t h a n o l ) 192-193® ( F o u n d : G, 7 4 .8 5 ;

H, 5 .4 2 ; G l , 8 .4 5 ; P , 7 . 2 2 . GgsHggGlOP r e q u i r e s G , 7 4 .9 5 ;

H, 5 .2 8 ; G l , 8 . 5 ; P , 7 .22% ) . F u s i o n w i t h sodium h y d r o x id e

gave ( g . l . c . ) c i s - 3 - c h l o r o s t i l b e n e (73%).

E x p e r im e n t s w i t h p - M e t h o x y p h e n y ld ip h e n y lp h o s p h in e .

p -M e th o x y p h en y lm e th y ld ip h en y lp h o sp h o n iu m i o d i d e ( 4 . 3 4 g . )

and b e n z a ld é h y d e ( 1 . 2 g . ) were added t o e t h a n o l (20 m l . )

c o n t a i n i n g sodium ( 0 .2 5 g . ) and th e s o l u t i o n s e t a s i d e a t

room t e m p e r a t u r e f o r 4 d a y s . F i l t r a t i o n t h e n gave

I , 2 - d i p h e n y l e t h y l - p - m e t h o x y p h e n y l p h e n y l p h o s p h i n e o x i d e

( 1 .7 g . ) , m . p . ( f r o m e t h a n o l ) 185-186° ( F o u n d : Û, 7 8 .4 5 ;

-112-

H, 5 . 9 ; P , 7 . 5 . G27H25 O2P r e q u i r e s C , 7 8 .8 ; H, 6 . 1 ; P , 7 .5%).

P u s i o n w i t h sodium h y d r o x i d e gave ( g . l . c . ) c i s (40%) and

t r a n s - s t i l b e n e ( 8%) w i t h no t r a c e o f 4 - i n e t h o x y s t i l b e n e s .

A s i m i l a r e x p e r im e n t w i t h m - c h l o r o b e n z a ld e h y d e

( 1 .5 g . ) gave l - p h e n .v l - 2 -m -c h l o r o p h e n y le th y l - p - m e t h o x y p h e n y l

p h e n y lp h o s p h in e o x ide ( 1 .9 g . ) , m .p . ( f ro m aqueou s e t h a n o l )

165- 167® (Found: C, 72*7; H, 5*5; C l , 7*85; P , 6 . 9 .

C27H24CIO&P r e q u i r e s C , 7 2 . 5 ; H, 5*4; C l , 7*9; P , 6 .95% ).

F u s i o n w i th sodium h y d r o x i d e gave ( g . l . c . ) c i s (49^0 and a

t r a c e o f t r a n s - 5 - c h l o r o s t i l b e n e .

A s o l u t i o n o f p - m e th o x y p h e n y ld ip h e n y lp h o s p h in e ( 5 g . )

and s t y r e n e ox ide ( 2 . 1 m l . ) i n e t h a n o l (25 m l . ) was h e a t e d

u n d e r r e f l u x f o r 24 h r . and w a te r t h e n added t o t u r b i d i t y .

C r y s t a l l i s a t i o n gave 1 , 2 - d i p h e n y l e t h y l - £ - m e t h o x y p h e n y l p h e n y l

p h o s p h in e ox ide (3 g . ) , m .p . and m ixed m .p . ( f rom e t h a n o l )

185- 186*.

R e a c t i o n b e tw ee n T r i p h e n y l p h o s p h i n e and S t y r e n e

O xide . - A s o l u t i o n o f t r i p h e n y l p h o s p h i n e ( 7 . 5 g. ) and

s t y r e n e o x id e ( 3 . 5 g . ) i n e t h a n o l (50 m l . ) was h e a t e d u n d e r

r e f l u x f o r 24 h r . C r y s t a l l i s a t i o n t h e n gave 1 , 2 - d i p h e n y l -

e t h y l d i p h e n y l p h o s p h i n e o x id e ( 6 .3 g . ) m .p . and mixed m .p .

232- 233®. S t y r e n e (8%) was a l s o fo rm ed ( g . l . c . ) .

-113-

A s i m i l a r r e a c t i o n i n d i b u t y l e t h e r a t 120° f o r 20

h r . gave 1 , 2 - d i p h e n y l e t h y l d i p h e n y l p h o s p h i n e o x ide (40%) and

s t y r e n e (20%).

A s o l u t i o n o f t r i p h e n y l p h o s p h i n e (13 g . ) and

s t y r e n e o x id e (6 g . ) i n benzene (80 m l . ) was h e a t e d u n d e r

r e f l u x f o r 6 d a y s . S t y r e n e (32%) and unchanged s t y r e n e

o x id e (20%) were t h e n p r e s e n t ( g . l . c . ) . M ethyl i o d i d e

(10 m l . ) was t h e n ad d ed and th e s o l u t i o n h e a t e d u n d e r r e f l u x

f o r 1 h r . The s y r u p which s e p a r a t e d g a v e , on t r i t u r a t i o n

w i t h e t h y l a c e t a t e , m e th y l t r i p h e n y l p h o s p h o n i u m i o d i d e ( 7 . 7 g . ) ,

m .p . and mixed m .p . 1 8 9 -1 9 0 ° . The m o th e r l i q u o r s were

e v a p o r a t e d and th e r e s i d u e c h ro m a to g ra p h e d on a lu m in a .

E l u t i o n w i th benzen e gave t r i p h e n y l p h o s p h i n e o x id e (7 g . ) ,

m .p . and mixed m .p . 1 5 7 -1 5 8 ° .

R e a c t i o n o f E t h y l t r i p h e n y l p h o s p h o n i u m I o d i d e w i t h

B enza ldehy d e i n E t h a n o l i c Sodium E t h o x i d e . - A s o l u t i o n of

e t h y l t r i p h e n y l p h o s p h o n i u m i o d i d e ( 1 0 . 5 g . ) and b e n z a ld e h y d e

( 2 . 6 g . ) i n e t h a n o l (100 m l . ) c o n t a i n i n g sodium ( 0 . 5 1 g . )

was s e t a s i d e a t room t e m p e r a t u r e f o r 4 d ays ,w hen g . l . c .

showed t h e p r e s e n c e o f c i s (l6%) and t r a n s - 3 - m e t h y l s t y r e n e

(46%). The s o l u t i o n was e v a p o r a t e d and th e r e s i d u e , i n

c h lo r o f o r m , washed w i t h w a t e r , d r i e d , and th e s o l v e n t removed

u n d e r r e d u c e d p r e s s u r e . The r e s i d u e was e x t r a c t e d w i t h benzene

-1 1 4 -

l é a v i n g u n d i s s o l v e d e th y l t r i p h e n y l p h o s p h o n i u m i o d i d e ( 1 . 9 g . ) ,

m .p . and mixed m .p . 164-165®, and t h e e x t r a c t ch ro m a to g ra p h ed

on a lu m in a t o g i v e t r i p h e n y l p h o s p h i n e o x ide ( 2 . 4 9 g . ) , m.p .

and mixed m .p . 157-158®.

A s i m i l a r r e a c t i o n i n m e th a n o l gave c i s (26%) and

t r a n s - 3 - m e t h y l s t y r e n e (54%).

R e a c t i o n o f D ip h e n y lp h o s p h in e m t h S t y r e n e O x id e . -

( a ) w i t h o u t s o l v e n t . - D ip h e n y lp h o s p h in e ( 6 . 5 g . ) and

s t y r e n e ox ide ( 4 . 5 g . ) were h e a t e d t o g e t h e r u n d e r o x y g e n - f r e e

n i t r o g e n a t 140° f o r 12 h r . when g . l . c . showed th e p r e s e n c e

o f b e n z a ld e h y d e ( 2l{%) and s t y r e n e o x id e ( 20^b) . The r e a c t i o n

m i x t u r e , i n b e n z e n e , was c h ro m a to g ra p h e d on a lu m in a . E l u t i o n

w i t h b en zene gave 3 - p h e n y l e t h y l d i p h e n y l p h o s p h i n e o x id e ( 2 . 6 g . ) ,

m .p . an d mixed m .p . ( f rom l i g h t p e t r o l e u m ; b . p . 1 0 0 -1 2 0 ° )

103-105®; e l u t i o n w i t h b e n z e n e - e t h e r ( 1 : 1 ) gave m e t h y l d i p h e n y l

p h o s p h in e ox ide ( 2 . 4 g . ) , m .p . and m ix ed m.p. ( f rom l i g h t

p e t r o l e u m , b . p . 8 0 -1 0 0 ° ) 1 0 9 -1 10 ° .

(b ) i n e t h a n o l . - A s o l u t i o n o f d ip h e n y l p h o s p h i n e ( 8 . 1 g . )

and s t y r e n e o x id e (8 g . ) i n e t h a n o l (80 m l . ) was h e a t e d

u n d e r r e f l u x f o r 40 h r . when g . l . c . showed the p r e s e n c e o f

s t y r e n e (60%) and b e n z a ld e h y d e (13%). The s o l v e n t was

e v a p o r a t e d and th e r e s i d u e , i n b e n z e n e , c h ro m a to g ra p h e d on

a lu m in a . E l u t i o n w i t h benzen e gave l , 2 - d i ( d i p h e n y l p h o s p h i n y l ) -

1 -p h e n y l e th a n e (3 g . ) , m .p . and m ixed m .p . ( f rom e t h a n o l )

-115 -

283-2 84 ° ; e l u t i o n w i t h b e n z e n e - e t h e r ( l : l ) gave

m e t h y l d ip h e n y lp h o s p h i n e o x id e (2 g . ) , m .p . and mixed

m .p . 1 0 9 -1 1 0° .

1 ? 2 - D i ( d i p h e n y l p h o s p h i n y l ) - l - p h e n y l e t h a n e . -

C h lo r o d ip h e n y l p h o s p h i n e ( 2 . 2 g . ) was added t o a s o l u t i o n

o f 3 - h y d r o x y - 3 - p h e n y l e t h y l d i p h e n y l p h o s p h i n e o x id e ( 3 . 2 g . )

i n p y r i d i n e (10 m l . ) and th e s o l u t i o n h e a t e d u n d e r r e f l u x

f o r 3 hr* , , t h e n c o o l e d and p o u r e d i n t o w a t e r . The

p r e c i p i t a t e d s y r u p c r y s t a l l i s e d from aqueous e t h a n o l t o

g i v e 1 . 2 - d i ( d i p h e n y l p h o s p h i n y l ) - l - p h e n y l e t h a n e ( 3 . 4 g . )

m .p . 283-284° (P o u nd îC , 7 5 . 8 ; H, 5 . 4 ; P , 1 2 .0 .

r e q u i r e s C, 7 5 . 9 ; H, 5 . 5 ; P , 12 .2% ).

3 - P h e n y l e t h y l d i p h e n y l p h o s p h i n e O x id e . - A s o l u t i o n

o f d ip h e n y l p h o s p h i n e ( 3 . 4 g . ) i n t e t r a h y d r o f u r a n (30 m l . )

was h e a t e d u n d e r r e f l u x w i t h sodium w ire (6 g . ) f o r 2 h r .

The e x c e s s o f sodium was t h e n removed and 3 - b ro m o e th y lb e n z e n e

( 3 . 4 9 g . ) i n t e t r a h y d r o f u r a n (6 m l . ) ad d ed . The m ix t u r e was

h e a t e d u n d e r r e f l u x f o r 1 h r . , t h e s o l v e n t t h e n removed

u n d e r r e d u c e d p r e s s u r e and th e r e s i d u e , i n c h lo r o f o r m , washed

w i t h w a t e r and t h e n s t i r r e d a t room t e m p e r a t u r e f o r 10 m in u t e s

w i t h h y d ro g e n p e r o x i d e (6%). The s o l u t i o n was t h e n washed

w i t h w a t e r , d r i e d , and e v a p o r a t e d . The r e s i d u e c r y s t a l l i s e d

-116-

from l i g h t p e t r o l e u m t o g i v e P -ph en y l e t h y l d i p h e n y l p h o s p h i n e

o x id e (4 g . ) , m .p . 104-106° (Pound: 0 , 7 8 .3 ; H, 6 . 2 ; P , 1 0 .1 .

G20H1 9 OP r e q u i r e s G, 7 8 . 4 ; H, 6 . 2 ; P , 10. IJo).

R e a c t i o n s of 1 , 2 -Spoxyhexane w i t h P h o s p h i n e s . -

T r i p h e n y l p h o s p h i n e ( 3 . 2 4 g . ) and 1 ,2 -e p o x y h e x a n e ( 1 . 2 g . )

were h e a t e d t o g e t h e r i n a s e a l e d tub e a t 220° f o r 7 days

and th e p r o d u c t d i s s o l v e d i n e t h a n o l (23 m l . ) g . l . c . ( 50m.

c a p i l l a r y column c o a t e d w i t h p o l y p r o p y le n e g l y c o l , a t 4 0 °)

showed th e p r e s e n c e o f h e x - l - e n e ( 6 l%). The e t h a n o l was

e v a p o r a t e d and th e r e s i d u e c r y s t a l l i s e d from e t h y l a c e t a t e

t o g iv e t r i p h e n y l p h o s p h i n e o x id e ( 2 .4 g . ) , m .p . an d mixed

m .p . 157- 158° .

A s i m i l a r r e a c t i o n w i t h d ip h e n y l p h o s p h i n e gave

h e x - l - e n e (38%) and h e x y l d i p h e n y l p h o s p h i n e o x id e (4^o) h a v in g

an i n f r a r e d sp e c t ru m i d e n t i c a l w i t h t h a t o f an a u t h e n t i c

sam p le .

R e a c t i o n o f 1 , 2 -E pox y cyc loh ex an e w i t h P h o s p h i n e s . -

M e t h y ld ip h e n y lp h o s p h in e ( 4 g . ) and 1 ,2 - e p o x y c y c lo h e x a n e (2 g . )

were h e a t e d t o g e t h e r a t 120° f o r 30 h r . , c o o l e d , and t h e

p r o d u c t e x t r a c t e d v / i th e t h y l a c e t a t e (3 x 50 m l . ) . The

e x t r q c t was t r e a t e d w i t h m e th y l i o d i d e (5 m l . ) and s e t a s i d e

a t room t e m p e r a t u r e f o r I 6 h r . F i l t r a t i o n t h e n gave

d im e th y 1 d iphenyIphosphoniurn i o d i d e ( 2 . 3 g . ) , m .p . and m ixed

-117-

m .p. 256- 257° . The m o th e r l i q u o r v/as e v a p o r a t e d and t h e

r e s i d u e c r y s t a l l i s e d from l i g h t p e t r o l e u m t o g iv e

m e th y l d ip h e n y lp h o s p h i n e o x id e ( 1 . 3 g . ) , m .p . and mixed

m .p . 109- 110° .

The r e s i d u e from th e e x t r a c t i o n w i t h e t h y l a c e t a t e

was d i s s o l v e d i n c h lo r o f o r m and t h e s o l u t i o n washed (i+x)

w i t h s a t u r a t e d aqu eo u s p o t a s s iu m i o d i d e , d r i e d , and

e v a p o r a t e d . C r y s t a l l i s a t i o n of t h e r e s i d u e from c h l o r o f o r m /

e t h y l a c e t a t e gave c y c l o h e x - l - e n y l m e t h y l d ip h e n y lp h o s p h o n i u m

i o d i d e (.1 g . ) , m .p . and mixed m .p . 2 2 5 -2 2 6 ° , h a v in g an

i n f r a r e d spec t rum i d e n t i c a l w i th t h a t o f an a u t h e n t i c sam p le .

A s o l u t i o n o f t r i p h e n y l p h o s p h i n e ( 6 . 6 g . ) and

c y c lo h e x e n e ox ide ( 3 . 3 g . ) i n e t h a n o l (40 m l . ) was h e a t e d

u n d e r r e f l u x f o r 60 h r . G . l . c . (50 m. c a p i l l a r y column

c o a t e d w i t h p o l y p r o p y l e n e g l y c o l , a t 4 0 ° ) showed th e

p r e s e n c e o f c y c lo h e x e n e (50 ) and b en zene ( 2 ^ 6 ) . The

s o l u t i o n was e v a p o r a t e d an d th e r e s i d u e e x t r a c t e d w i th e t h y l

a c e t a t e (2 x 50 m l . ) . The e x t r a c t was h e a t e d u n d e r r e f l u x

vd t h m e th y l i o d i d e f o r % h r . t o g iv e m e t h y l t r i p h e n y l p h o s -

phonium i o d i d e ( l . 1 g . ) , m .p . and mixed m .p . 188- 189° .

- 1 1 8 -

The m o th e r l i q u o r , on e v a p o r a t i o n , g a v e t r i p h e n y l p h o s p h i n e

o x ide (3 g . ) , m .p . and m ixed m .p . ( f rom c h l o r o f o r m / l i g h t

p e t r o l e u m ) 13 7 -1 3 8° .

The r e s i d u e from th e e x t r a c t i o n w i t h e t h y l a c e t a t e

v/as d i s s o l v e d i n c h lo r o f o r m and t h e s o l u t i o n washed (4x)

w i t h s a t u r a t e d aqueous p o t a s s iu m i o d i d e , d r i e d , and

e v a p o r a t e d . The r e s i d u e c r y s t a l l i s e d from c h l o r o f o r m / e t h y l

a c e t a t e t o g iv e what i s p r o b a b l y c y c l o h e x - l - e n y l t r i p h e n y l -

phosphonium i o d i d e ( 0 . 4 g . ) , m .p . 2 2 8 - 2 3 3 ° . The compound

c o u ld n o t be s a t i s f a c t o r i l y p u r i f i e d . I t s n . m . r . sp e c t ru m

showed a d o u b l e t a t 3 .3 T ( J p g 22 c / s e c . ) e q u i v a l e n t t o one

p r o t o n .

C y c lo h e x - l - e n y l m e th y l d i p h e n y l p h o s p h o n i u m I o d i d e . -

G h l o r o d ip h e n y lp h o s p h in e (22 g . ) i n e t h e r (50 m l . ) v/as

s lo w ly added t o a s t i r r e d , c o o l e d , s o l u t i o n o f

e y e l o h e x - l - e n y 1 - l i t h i u m , p r e p a r e d from l i t h i u m (6 g . )

and 1 - c h l o r o c y c l o h e x e n e (15 g . ) i n e t h e r (150 m l . ) and

th e s o l u t i o n h e a t e d u n d e r r e f l u x f o r 1 h r . and t h e n

c o o le d d u r i n g th e a d d i t i o n o f w a t e r (100 m l . ) . The

e t h e r e a l l a y e r was washed w i t h w a t e r , d r i e d , and h e a t e d

u nder r e f l u x f o r 2 h r . w i t h m e th y l i o d i d e (10 m l . ) . The

r e s u l t i n g s o l i d v/as r e c r y s t a l l i s e d from c h l o r o f o r m / e t h y l

a c e t a t e t o g i v e c y c l o h e x - l - e n y l m e t h y l d ip h e n y lp h o s p h o n i u m

-119-

i o d i d e ( l 6 g . ) , m .p . 2 2 5 -2 2 6 ° .

R e a c t i o n o f T r ip h e n y lp h o s p h in e w i t h C y c lo o c te n e

o x i d e . - T r i p h e n y lp h o s p h in e ( 6 . 8 g . ) and 1 , 2 - e p o x y c y c l o o c t e n e

( 5 . 2 g . ) were h e a t e d t o g e t h e r i n a s e a l e d tu be a t 210° f o r

6 d ay s and th e p r o d u c t e x t r a c t e d w i t h e t h a n o l (100 m l . ) .

G . l . c . (6 m. a p i e z o n L column, a t 140°) showed t h e p r e s e n c e

o f c y c l o o c t e n e ( 2 0 0 ) . The s o l u t i o n was e v a p o r a t e d , and t h e

r e s i d u e a d s o r b e d on b a s i c a lu m in a . E l u t i o n w i t h l i g h t

p e t r o l e u m ( b . p . 4 0 - 6 0 ° ) gave t r i p h e n y l p h o s p h i n e ( 2 . 3 g . ) ,

m .p . and mixed m .p . ( f ro m e t h y l a c e t a t e - p e t r o l ) 7 8 - 7 9 ° ;

e l u t i o n w i th e t h e r - m e t h a n o l ( 2 0 :1 ) gave t r i p h e n y l p h o s p h i n e

o x id e ( 4 . 2 g . ) , m .p . and mixed m .p . ( f rom e t h y l a c e t a t e )

157-158°C.

R e a c t i o n o f t r a n s - s t i l b e n e ox ide w i th T r i p h e n y l -

p h o s p h in e . - T r i p h e n y l p h o s p h i n e ( 6 . 8 g . ) and t r a n s - s t i l b e n e

o x ide ( 4 . 9 g . ) were h e a t e d t o g e t h e r a t 180° f o r 4 days and

the p r o d u c t e x t r a c t e d w i t h e t h a n o l (80 m l . ) . G . l . c . (6 m.

a p i e z o n column, a t 250°) showed th e p r e s e n c e of t r a n s - s t i l b e n e

(9^0 and c i s - s t i l b e n e ( ^ ) . The s o l u t i o n was e v a p o r a t e d

and t h e r e s i d u e a d s o r b e d on b a s i c a lu m in a . E l u t i o n w i t h

l i g h t p e t r o l e u m ( b . p . 4 0 - 6 0 ° ) gave t r a n s - s t i l b e n e ( O . l g . )

m .p . and mixed m .p . 1 24 -1 2 5 ° ; e l u t i o n w i th l i g h t p e t r o l e u m -

e t h e r ( 4 : 1 ) gave t r i p h e n y l p h o s p h i n e ( 1 . 4 g . ) , m .p . and mixed

- 1 2 0 -

m.p* 7 8 - 7 9 ° ; and e l u t i o n w i t h e t h e r - m e t h a n o l ( 2 0 : 1 ) gave

t r i p h e n y l p h o s p h i n e ox ide (4«5 g . ) , m .p . and m ixed m.p.

( f rom e t h y l a c e t a t e ) 1 5 7 -1 5 8 ° .

—1 2 0 a —

Abnormal Q u a t e r n i s a t i o n R e a c t i o n s o f Some A c t i v a t e d

A l k y l H a l i d e s .

( a ) R e a c t i o n s P r o c e e d i n g v i a Eno l-Phosphon ium S a l t s .

Most p r i m a r y a l k y l h a l i d e s q u a t e r n i s e n o r m a l ly

w i t h t e r t i a r y p h o s p h i n e s , n u c l e o p h i l i c a t t a c k by th e

p h o s p h in e a t c a r b o n , l e a d i n g t o d i s p l a c e m e n t o f h a l i d e

i o n and th e f o r m a t i o n o f a phosphonium s a l t .

R3P + R * - C H 2, - X R g P - C H s - R * X"

However, t h e r e a r e a number o f exam ples o f

a b n o rm a l r e a c t i o n s b e tw ee n p h o s p h i n e s and o r g a n i c h a l i d e s .

One g ro u p of t h e s e d a th e r e a c t i o n o f p h o s p h i n e s w i t h

a l k y l h a l i d e s c o n t a i n i n g a c t i v a t i n g g ro u p s a t t a c h e d t o

t h e a - c a r b o n atom.

When a l l o w e d t o r e a c t w i t h t e r t i a r y p h o s p h i n e s ,

c e r t a i n a - h a l o k e t o n e s do n o t g i v e th e e x p e c t e d p - k e t o p h o s -

phonium s a l t s , b u t i n s t e a d , p r o d u c t s , which on t r e a t m e n t

w i t h a l c o h o l s g i v e t e r t i a r y p h o sp h in e o x i d e s , d e - h a l o g e n a t e d1 6 9 ,1^0

k e t o n e s and a l k y l h a l i d e s .

0 = GRnP +

— G — H a l

- 1 2 1 -

R3P — G — GO — H al

Normal Route

C r y s t a l l i n e body. Abnormal R o u te .

R*OH

aR3 PO + — “ G*—

H4- RdHal,

Bromides show a g r e a t e r t e n d e n c y t o r e a c t

a b n o rm a l ly t h a n th e c o r r e s p o n d i n g c h l o r i d e s , a l t h o u g h

m o n o -h a lo m e th y lk e to n e s do n o t u s u a l l y show th e abnorm al16±

r e a c t i o n w h a te v e r th e h a l o g e n . The abnorm al r e a c t i o n

becomes more l i k e l y a s t h e number of h a l o g e n s u b s t i t u e n t s

on t h e a - c a r b o n i n c r e a s e s , f o r exam ple , e v e n when t h e

h a lo g e n i s c h l o r i n e , compounds l i k e c h l o r a l undergo an

abnorm al r e a c t i o n w i t h t r i p h e n y l p h o s p h i n e i n a v i o l e n t l y1 6 9

e x o th e r m ic manner.

The i n t e r m e d i a t e compound form ed i n t h e s e r e a c t i o n s

h a s b een f o r m u l a t e d a s th e en o l-p ho sp ho n ium s a l t . (186)1 6 9 ,16 0

-122-

+

R»” R.»R'» ^R»** .i0

(186) R " - G - HR t t l

162S p e z i a l e a n d P a n t o s f i n a l l y e s t a b l i s h e d t h e

s t r u c t u r e o f t h e i n t e r m e d i a t e ( 1 8 8 ) i n t h e r e a c t i o n o f

t h e c h l o r o k e t o n e ( 1 8 7 ) w i t h t r i p h e n y l p h o s p h i n e , b y e l e m e n t a l

a n a l y s i s , t h e a b s e n c e o f a c a r b o n y l s t r e t c h i n g f r e q u e n c y

i n i t s i n f r a r e d s p e c t r u m a n d t h e p r e s e n c e o f a p h o s p h o n i u m

s a l t l i k e r e s o n a n c e i n i t s P®^ N . M . R . s p e c t r u m .

PhgP + P h j a G - G - P h P h 2 G = G - P hs(187) (1 88 )

I +G1 Ù O - P P h a G1

I t s e e m s l i k e l y t h a t i n t e r m e d i a t e s o f t h e t y p e

( 1 8 6 ) d o n o t d e c o m p o s e b e c a u s e t h e l i k e l y h o o d o f n u c l e o p h i l i c

a t t a c k b y h a l o g e n a t a v i n y l i c c a r b o n a t o m i s s m a l l . T h i s1 5 9 ,163 ,16

c a n b e c o m p a r e d w i t h t h e I l i c h a e l i s - A r b u s o v r e a c t i o n .

-123-

The eno l-ph o sph o n iu m s a l t (188) i s a M i c h a e l i s - Arbusov

r e a c t i o n i n t e r m e d i a t e and t h e s e w i l l n o t decompose when

h a l i d e a t t a c k i s r e q u i r e d on an a r o m a t i c n u c l e u s , a n a lo g o u s

to t h e v i n y l i c sys tem ( 1 8 8 ) . The r e a c t i o n of t h e s e sy s te m s

w i t h a l c o h o l s may be e x p l a i n e d by t r a n s e s t é r i f i c a t i o n to g i v e

a n a Iko x y—phosphonium s a l t ( 1 8 9 ) , which can t h e n undergo

t h e seco n d s t a g e o f t h e M i c h a e l i s - A r b u s o v r e a c t i o n .

ROH ^ 0 = // II H a l" I

{ 1 8 9 )A H

\— PC + RHal. /

E nol-phosphon ium s a l t s have n o t o n ly been i s o l a t e d

from t h e r e a c t i o n o f a —h a l o k e t o n e s w i t h t e r t i a r y p h o s p h i n e s ,

e t h y l t r i c h l o r o a c e t a t e , c h l o r o a c e t y l c h l o r i d e , and

bromomalonic e s t e r have a l l been shown t o g i v e en o l-p h o sp h o n iu m159

s a l t s w i t h t e r t i a r y p h o s p h i n e s .

Many o t h e r r e a c t i o n s o f t e r t i a r y p h o s p h i n e s w i t h

h a lo g e n compounds, t o g i v e p r o d u c t s o t h e r t h a n t l ioseexpec ted

by no rm al q u a t e r n i s a t i o n , c a n be e x p l a i n e d by th e p o s t u l a t i o n

o f e n o l -p ho sp ho n ium s a l t i n t e r m e d i a t e s .

— 124—

D esy l c h l o r i d e and t r i p h e n y l p h o s p h i n e r e a c t t o

g iv e d i p h e n y l a c e t y l e n e , t r i p h e n y l p h o s p h i n e o x ide and h y d ro g e n170

c h l o r i d e .

PhnP + P h - G O - G H O l - P hP h ^

P h a r

r \ ■E•g z z i g :

G1^ P h

( 190)

PhaPO -F P h - G = G - P h + HGl

T h is may be e x p l a i n e d by i n i t i a l f o r m a t i o n o f t h e

e n o l-p h osp h on iu m s a l t ( 1 9 0 ) , f o l l o w e d by d e c o m p o s i t i o n a s

shown.

E nol-phosphon ium s a l t s may be p o s t u l a t e d a s

i n t e r m e d i a t e s i n th e r e a c t i o n of N-bromo-amides ( l 9 l ) w i th

t r i p h e n y l p h o s p h i n e , which l e a d t o n i t r i l e , p h o s p h in e ox ide170

and h yd ro g en b ro m id e .

RGONHBr + PhaP

(191 )

> P \

PhaPBr

PhaPO + RGN

+■ HBr

-125-

166S p e z i a l e and Sm ith have s t u d i e d t h e r e a c t i o n

o f t r i p h e n y l p h o s p h i n e w i t h N - d h l o r o - N - e th y l b e n z a m i d e ( 1 9 2 ) ,

where any e n o l -ph o sph o n iu m s a l t fo rm ed w i l l n o t be a b l e t o

d e p r o t o n a t e . They fo u n d t h a t th e p r o d u c t s were t r i p h e n y l

p h o s p h i n e ox ide and N - e t h y l b e n z l m i d o y l c h l o r i d e ( 1 9 4 ) . I t

i s s u g g e s t e d t h a t th e eno l-p h o sp h o n iu m s a l t (193) i s

i n i t i a l l y formed and t h e n a t t a c k o f h a l i d e i o n on t h i s

l e a d s t o th e p r o d u c t s .

Ph-CON.\

G1 PhaP

E t

(1 9 2 )

P h - C = N E t

PPho

i(193)

P h aP O + P h - C = H S t

C l(194)

H a l i d e a t t a c k i n t h i s w a y o f f e r s a n a l t e r n a t i v e e x p l a n a t i o n

t o d e p r o t o n a t i o n i n t h e d e c o m p o s i t i o n o f t h e e n o l - p h o s p h o n i u m

s a l t s d e s c r i b e d a b o v e . T h e u n s t a b l e u n s a t u r a t e d h a l o g e n

c o m p o u n d ( 1 9 3 ) s o f o r m e d , u n d e r g o i n g s p o n t a n e o u s d e h y d r o -

h a l o g e n a t i o n .

—126^

T % » ^ l A< v X = Y - P 0 + H a l - X = Y - Hf N /

+ / ° '1' (195 )P - X = Y + H H a l .

The r e a c t i o n s o f N , N - d i s u b s t i t u t e d t r i c h l o r o —

a c e ta m i d e s (196) w i t h t r i a l k y l p h o s p h i t e s and t e r t i a r y16 6

p h o s p h i n e s h ave b e e n s t u d i e d by S p e z i a l e and Freeman.

The p r o d u c t s a r e t r i c h l o r o v i n y l a m i n e s (197) and th e

c o r r e s p o n d i n g t r i a l k y l p h o s p h a t e o r t e r t i a r y p h o s p h in e

o x i d e .

C l NRg

G l a CONRa + R ' a P -» ' ^ G = G + R ’aP O

' C l ' ^ G l

(196) (197)

I t i s s u g g e s t e d t h a t th e en o l-p h o sp h o n iu m s a l t

( 198 ) i s i n i t i a l l y fo rm ed , and t h i s i s decomposed by a t t a c k

o f h a l i d e i o n a t t h e a c t i v a t e d v i n y l i c c a r b o n a tom.

0 J 7Clgj GONRg + Rg P —> Clg C izzrC—NRg p r o d u c t s

( 198)

-127-

A p o s s i b l e a l t e r n a t i v e t o t h i s mechanism h a s b e e n16 5

s u g g e s t e d . The lo n e p a i r o f e l e c t r o n s on n i t r o g e n may

h e l p t o d i s p l a c e th e p h o s p h in e o x ide d i r e c t l y .

r *3p ^ . o rr ^ C = CGlg R ’aPO + R 2 N = C = C G l3

G1" ,0= CGlg

RgN'"

(b ) The Mechanism o f E n o l —Phosphonium S a l t F o r m a t i o n .

A co m p re h en s iv e s t u d y o f t h i s h a s been c a r r i e d167

o u t . Assuming t h a t th e a t t a c k o f th e p h o sp h o ru s compound16 8

i s n u c l e o p h i l i c , which h a s been v e r i f i e d by S p e z i a l e ^ a l ,

t h e r e a r e f i v e p o s s i b l e ways i n which t h i s i n i t i a l a t t a c k

may t a k e p l a c e ,

( a ) a t t h e h a l o g e n b e a r i n g c a r b o n atom,

(b ) a t th e c a r b o n y l c a rb o n a tom ,

( c ) a t t h e c a r b o n y l oxygen a to m ,

(d ) a t th e h a lo g e n a tom, and

(e ) i n a f i v e membered c y c l i c r e a c t i o n t o g i v e a

p e n t a —c o v a l e n t p h o sp h o ru s i n t e r m e d i a t e .

-12 8 -

167P o s s i b i l i t i e s ( a ) and (b) have b e e n shown t o be u n l i k e l y .

D i s t i n c t i o n be tw een t h e r e m a in in g p o s s i b l e modes o f a t t a c k167 ,169

h a s b een th e s u b j e c t o f much d i s c u s s i o n , and no

a b s o l u t e p r o o f h a s y e t be en p u t f o r w a r d a s t o t h e t r u e mode

o f a t t a c k . However, i t h a s been shown t h a t the r e a c t i o n c an ,

i n th e a - h a l o k e t o n e c a s e a t l e a s t , p r o c e e d by e i t h e r a n a c i d

c a t a l y s e d , o r a n o n - a c i d c a t a l y s e d , m echan ism (depend ing upon167

t h e c o n d i t i o n s u s e d .

( c ) The R e a c t i o n o f T r i p h e n y l p h o s p h i n e w i t h d - B r o m o - l - N i t r o -

a l k a n e s .

I n g e n e r a l 1 - b r o m o - l - n i t r o a l k a n e s r e a c t w i t h

t r i p h e n y l p h o s p h i n e to g iv e p h o sp h in e o x i d e , n i t r i l e and

p h o sp h in e o x id e h y d ro b ro m id e . However, b ro m o n i t ro m e th a n e

and 1 -brom 0- 1—n i t r o e t h a n e have b een shown a l s o t o g iv e s a l t s ,

which were o r i g i n a l l y f o r m u l a t e d a s a - n i t r o a l k y l - p h o s p h o n i u m171

b r o m id e s , m a in ly on t h e e v id e n c e t h a t t h e s a l t from

b ro m o n i t ro m e th an e and t r i p h e n y l p h o s p h i n e gave p h o sp h in e o x id e

and f u l m i n i c a c i d when t r e a t e d w i t h aqueous a l k a l i a t 0 ° .

T h i s r e a c t i o n was th o u g h t t o p r o c e e d v i a t h e p h o s p h o b e t a i n e

( 1 9 9 ) .

-1 2 9 -

+ + NaOH + - +P h a P - C H g - F ^ B f ----------- > P h o P - C H - NA ^ 0

Phg l / HPho.RO A ç / .

^ 1+ (199)H C =H O , - / \ -

0 0

I t was hoped t o e x t e n d t h i s r e a c t i o n t o th e

p r e p a r a t i o n o f a l i p h a t i c n i t r i l e o x i d e s by t r e a t m e n t of

t h e s a l t from t r i p h e n y l p h o s p h i n e a n d 1 - b r o m o - 1 - n i t r o e t h a n e

w i t h aq ueous sodium h y d r o x i d e . However , when t h i s v/as1 7 0

c a r r i e d out , no n i t r i l e o x id e c o u l d be d e t e c t e d , even

i n t h e p r e s e n c e o f s t i l b e n e , which r e a d i l y c o n d e n se s wit&17 2

n i t r i l e o x id e s t o g iv e A ® - i s o x a z o l i n e s .

R e i n v e s t i g a t i o n of t h e s e r e a c t i o n s h a s l e d t o

d i f f e r e n t c o n c l u s i o n s . B ro m o n i t r o m e th a n e , 1 - b r o m o - 1 - n i t r o -

e th a n e and 1 - b r o m o - l - n i t r o p r o p a n e have a l l been shown t o

g iv e s a l t s w i t h t r i p h e n y l p h o s p h i n e ( a l t h o u g h t h a t from

1 - b r o m o - l - n i t r o p r o p a n e was o b t a i n e d i n v e r y s m a l l y i e l d ) .

I f t h e homologous s e r i e s i s e x te n d e d f u r t h e r t h e r e a c t i o n

g i v e s no s a l t , b u t o n ly p h o s p h in e o x id e h y d ro b ro m id e and

n i t r i l e , which a r e a l s o fo rm ed i n s m a l l y i e l d t o g e t h e r w i t h

-130-

t h e above s a l t s . The r e a c t i o n a p p e a r s t o be e x t r e m e ly

s e n s i t i v e to t e m p e r a t u r e . I f t h e a d d i t i o n o f th e bromo—

compound, t o th e p h o s p h i n e , i s n o t c a r r i e d o u t s t r i c t l y a t

3 ° , o r b e lo w , th e seco n d r e a c t i o n , t o g i v e n i t r i l e and

p h o s p h in e o x id e h y d r o b r o m id e , p r e d o m in a te s e ven i n th e

b ro m o n i t ro m e th a n e c a s e .

I t was fo u nd t h a t t h e optimum r e a c t i o n was t h a t

b e tw een two m o le s o f p h o sp h in e and one mole o f bromo-compound

t o g i v e th e s a l t and p h o sp h in e o x i d e .

2PhoP + RCHBr.NOg S a l t + PhaPO

These s a l t s were shown to be a - h y d r o x y ^ im in o p h o s -

phonium b rom ides ( 2 0 0 ) .

P h o P - G R z i F - OH B r"

( 200)

The h y d r o x y l g r o u p s o f th e s a l t s a r e a p p a r e n t

i n t h e i n f r a r e d a t < ^ 2 , 7 5 0 cm.”^ , and t h e N.M.R. sp e c t ru m

o f t h e s a l t (200; R = Me) shows th e a b se n c e o f h y d ro g e n on

th e a - c a r b o n atom ( d o u b l e t a t 7 * 8 ^ , = IC c . p . s . ) . The

s t a b i l i t y o f th e s a l t s t o a l k a l i n e h y d r o l y s i s i n c r e a s e d

m a rk e d ly from R = H t o R = E t . T h is made i t p o s s i b l e to f o l l o w

th e r e a c t i o n i n th e c a s e o f th e s a l t (200 ; R = Me) u s i n g an

-131-

N.LI.R. s p e c t r o m e t e r . I t v/as found t h a t t h e e t h y l and

p r o p y l s a l t s (200; R = Me and E t ) were s o l u b l e i n aqueous

sodium h y d r o x i d e , f r o m which s o l u t i o n t h e y c o u ld be

r e p r e c i p i t a t e d by th e a d d i t i o n o f a c i d . I f a l lo w e d to

s t a n d a t room t e m p e r a t u r e o v e r n i g h t , o r warmed to 50° f o r

f i v e m i n u t e s , t h e s e s o l u t i o n s decomposed t o p h o sp h in e o x id e

and n i t r i l e .

+ NaOHP hQ p-C R = NOH Br"--------------y PhgPO + RON

T h is r e a c t i o n was c a r r i e d o u t i n t h e sample

w e l l o f th e N.M.R. s p e c t r o m e t e r by d i s s o l v i n g t h e s a l t

(200 ; R= Me) i n NaOD/DgO and t a k i n g a s e r i e s o f s p e c t r a

a t i n t e r v a l s o f one m in u te a t 4 0 ° . The d o u b l e t a t 7 . 8 ^

due t o th e m e th y l g roup s t e a d i l y d e c r e a s e d i n i n t e n s i t y

and was r e p l a c e d by a s i n g l e t a t 8 . 0 5 ^ , due t o a c e t o n i t r i l e ,

The a l k a l i n e h y d r o l y s i s p re s u m a b ly i n v o l v e s th e

i n i t i a l d e p r o t o n a t i o n o f t h e h y d r o x y l g roup t o g i v e th e

i n t e r m e d i a t e ( 2 0 l ) , which th e n e l i m i n a t e s p h o sp h in e o x id e t o

g iv e t h e n i t r i l e .

Br- ^RC=K

H O ^( 201)

-132-

A c id h y d r o l y s i s of t h e s e compounds r e q u i r e s f a r

more v i g o r o u s c o n d i t i o n s , and t h e c o u r s e depends t o a

l a r g e e x t e n t on a c i d c o n c e n t r a t i o n . I n 2^ h y d r o c h l o r i c

a c i d r e f l u x i n g f o r two o r t h r e e h o u r s l e a d s m a in ly t o

p h o sp h in e o x id e and n i t r i l e , h o w e v e r , i n 12N h y d r o c h l o r i c

a c i d t h e m a jo r p r o d u c t s a r e t r i p h e n y l p h o s p h i n e , h y d r o x y lamine

( i s o l a t e d as b e n za ld o x im e) and c a r b o x y l i c a c i d . T h i s i s

b e s t e x p l a i n e d by t h e com p e t in g r e a c t i o n of h y d r o l y s i s by

w a t e r .

The f o r m a t i o n o f h y d ro x y lam in e and c a r b o x y l i c a c i d

p r o b a b l y goes t h r o u g h t h e i n t e r m e d i a t e (202) which f u r t h e r

h y d r o l y s e s to p h o s p h in e and c a r b o x y l i c a c i d .

Pha .P- CR = N -O H

B r"

R+ I

P h o P - C = 0

(262)

PhoP + R'COOH

The mode of f o r m a t i o n o f t h e s e s a l t s i s , a s y e t ,

o b s c u r e . The r e a c t i o n may i n f a c t p r o c e e d v i a a t r u e

n i t r o p h o s p h o n iu m s a l t ( 2 0 3 ) , which i s t h e n d e - o x y g e n a t e d by

p h o s p h in e a s shown to g iv e th e i n t e r m e d i a t e ( 2 0 4 ) .

M i g r a t i o n of a p r o t o n w i l l t h e n l e a d t o th e o b s e r v e d

p r o d u c t .

PhgP + BrCHR.NOg

PhsP

Br I IN

OH

4

-133-

P R . Î H

r ^ HBr

(203)

A:PPhs

P h g P ^ y t

-

^ 0 "

(204)

Br+- PhaPO

The f o r m a t i o n o f n i t r i l e and p h o sp h in e o x id e

c o u l d p r o c e e d v i a a n e n o l -ph o sp h o n iu m s a l t of the type

( 2 0 3 ) , which decomposes t o g i v e n i t r i l e ox ide an d p h o sp h in e

o x i d e , th e n i t r i l e o x ide b e in g d e -o x y g e n a t e d by f u r t h e r

p h o s p h i n e .

RI + /

PhaP + B r - C H ^ N ^:0

Br"

^ P P h a( 205)

R - C 3 [ + PhaPO < R - C = N - 0 + PhaPO

-134-

A n a l t e r n a t i v e m e c h a n i s m f o r t h e f o r m a t i o n o f

t h e s e s a l t s i n v o l v e s t h e i n i t i a l f o r m a t i o n o f n i t r i l e o x i d e

a n d t r i p h e n y l p h o s p h i n e o x i d e v i a t h e i n t e r m e d i a t e ( 2 0 5 ) .

A t t a c k o f t r i p h e n y l p h o s p h i n e , o r t r i p h e n y l p h o s p h i n e h y d r o -

b r o m i d e , o n t h e n i t r i l e o x i d e c a n t h e n l e a d t o ( 2 0 6 ) w h i c h

m a y p r o t o n a t e m o r e r a p i d l y t h a n i t c a n e l i m i n a t e u n d e r t h e

a c i d i c c o n d i t i o n s .

+ -^ c a - 0 Phg.p E

II (206)

H B r

+PhaP.

Br . ..^OH

T h i s i s s u p p o r t e d t o som e e s t t e n t b y t h e r a p i d d e c r e a s e i n

y i e l d o f t h e s a l t i n g o i n g f r o m R = H t o R = GgHg , t h e i n d u c t i v e

e f f e c t o f t h e a l k y l g r o u p d e c r e a s i n g t h e l i k e l y h o o d o f

n u c l e o p h i l i c a t t a c k o n t h e c a r b o n o f t h e n i t r i l e o x i d e a n d

p r e f e r e n t i a l l y a l l o w i n g d e o x y g e n a t i o n t o t a k e p l a c e *

-135 -

1.73Z b i r a l h a s c a r r i e d o u t t h e r e a c t i o n of

p h o s p h o r a n e s w i t h e t h y l n i t r i t e and shown t h a t , i n t h e c a s e

o f p h o s p h o r a n e s w i t h a h y d ro g en on th e a - c a r b o n a tom ,

n i t r i l e s and p h o sp h in e o x i d e s a r e p r o d u c e d . T h i s r e a c t i o n

p r e s u m a b ly goes t h r o u g h an i n t e r m e d i a t e s i m i l a r t o ( 2 0 3 ) .

However, t h e a n io n w i l l be e th o x i d e i n t h i s c a s e , w h ich can

remove an a - p r o t o n t o g iv e t h e p h o s p h o b e t a i n e ( 2 0 7 ) . T h i s

c an t h e n e l i m i n a t e a s shown. I n our c a s e t h i s ty p e o fth e

e l i m i n a t i o n i s h i n d e r e d byÿ^lack o f a s u f f i c i e n t l y p o w e r f u l

base*

PhaP= C H - R + EtONO P h g P ^ ^ R

PhaPO+ 4---------- * ? | | + EtOH>RON 4:

(207)

The r e a c t i o n o f a r o m a t i c n i t r o s o compounds w i t h90

p h o sp h o ra n e s i s a l s o a n a l o g o u s , t h e p r o d u c t s b e i n g

p h o sp h in e o x id e and S c h i f f s b a s e , p r o b a b l y fo rm ed v i a t h e

- 1 3 6 -

i n t e r m e d i a t e b e t a l n e ( 208 ) ,

PhaE=CHPh + PMTO -> PII3 P , P h

- FI ( 208)

PhaPO + PhCH = NPh

I n an a t t e m p t t o p r e p a r e a t r u e a - n i t r o p h o s p h o n i u m

s a l t , e t h y l n i t r a t e was a l l o w e d t o r e a c t w i t h b e n z y l i d e n e -

t r i p h e n y l p h o s p h o r a n e . \7hen t h i s r e a c t i o n was c a r r i e d ou t i n

t h e p r e s e n c e o f t r i p h e n y l p h o s p h i n e , t r i p h e n y l p h o s p h i n e o x id e

and b e n z o n i t r i l e were fo rm ed , p r e s u m a b ly by a mechanism173

s i m i l a r t o t h a t o f Z b i r a l , w i t h f i n a l d e o x y g e n a t io n o f

th e n i t r i l e ox ide by p h o s p h i n e .

Pho P = CH - Ph + E tONOg -> Phg P ^OEt

0 ^ 0

P h « K .P h PhaPO

_ P h - G = N - 0

j p h a P

PhaPO + P h - G = N

-137-

o t h e r a t t e m p t s t o p r e p a r e a - n i t r o p h o s p h o n i u m

s a l t s w e r e e q u a l l y u n s u c c e s s f u l .

T h e r e a c t i o n o f s o d i u m d i p h e n y l p h o s p h i d e w i t h

b r o m o n i t r o m e t h a n e g a v e d i p h e n y l p h o s p h i n i c a c i d a s t h e o n l y

i s o l a t a b l e p r o d u c t , a s d i d t h e r e a c t i o n b e t w e e n t h e s o d i u m

s a l t o f n i t r o m e t h a n e a n d c h l o r o d i p h e n y l p h o s p h i n e . R e a c t i o n s

o f n i t r y l c h l o r i d e (NOgCl) w i t h p h o s p h o r a n e s g a v e n o

c r y s t a l l i n e p r o d u c t s .

T h i s w o r k m e a n s t h a t , a s y e t , n o a - n i t r o a l k y l p h o s -1 6

p h o n i u m s a l t s h a v e b e e n i s o l a t e d , a l t h o u g h H o r n e r h a s

m a de a - n i t r o a r s o r a n e s b y t h e r e a c t i o n o f n i t r o p h e n y l m e t h a n e

w i t h d i c h l o r o t r i p h e n y l a r s o r a n e i n t h e p r e s e n c e o f

t r i e t h y l a m i n e .

^ P h Ph ^PhsAsClg + CHb phgAs = + 2EtaKH

^ NOg, KOg C l"

T he a n a l o g o u s r e a c t i o n w i t h d i c h l o r o t r i p h e n y l -

p h o s p h o r a n e g a v e o n l y p h o s p h i n e o x i d e a n d b e n z o n i t r i l e . T h i s

m u s t b e d u e t o t h e m u c h d e c r e a s e d o x y g e n a f f i n i t y o f a r s e n i c

w h e n c o m p a r e d w i t h p h o s p h o r u s . T h i s i s b o r n e o u t b y t h e

f o r m a t i o n o f e p o x i d e s f r o m m any a r s e n i c b e t a i n e s , w h e r e t h e

a n a l o g o u s p h o s p h o r u s b e t a i n e s g i v e o l e f i n s . T h u s a t t a c k o f

- 1 3 8 -

oxygen i s on c a r b o n r a t h e r t h a n th e p o s i t i v e l y c h a r g e d

a r s e n i c atom, a l t h o u g h c e r t a i n a r s e n i c b e t a i n e s have b e en174:

shown t o g i v e q u i t e h i g h y i e l d s o f o l e f i n s .

^GRgI P h a A s + 0 ^ [CRa \ ^ C R a

' ^ 0

PhaP, _CRa P haP O

"0^

4r GRg — GRg

-139 -

E x p e r i m e n t a l

A l l e x p e r i m e n t s u s i n g p h o s p h o r a n e s , and s i m i l a r

u n s t a b l e compounds, were c a r r i e d ou t u n d e r an o x y g e n - f r e e

n i t r o g e n a tm o sp h e re . A l l s o l v e n t s were d r i e d b e f o r e u s e .

M e l t i n g p o i n t s were c o r r e c t e d .

175P r e p a r a t i o n o f B ro m o n i t ro m e th a n e . - To a s o l u t i o n o f

sodium (.3*3 g. ) i n e t h a n o l (70 g . ) was added a s o l u t i o n of

n i t r o m e t h a n e (10 g . ) i n e t h a n o l (30 g . ) v / i th s t i r r i n g . The

s o l i d sodium s a l t o f n i t r o m e t h a n e was f i l t e r e d and washed

v / i th e t h e r (3 x 30 m l . ) . (The sodium s a l t s h o u l d be u se d

d i r e c t l y , a s an e x p l o s i o n o c c u r r e d on d r y i n g and s t o r a g e ) .

To th e s o l i d sodium s a l t p r e p a r e d i n t h i s v/ay v/as s lo w ly

added , w i t h i c e c o o l i n g , a s o l u t i o n of b rom ine (22 g . ) i n

c a rb o n d i s u l p h i d e (100 g . ) w h i l e t h e r e a c t i o n m i x t u r e was

v i g o r o u s l y s t i r r e d . The c a r b o n d i s u l p h i d e s o l u t i o n was

f i l t e r e d and washed w i t h w a t e r (3 x 40 m l . ) . D ry in g

(NagSOa), e v a p o r a t i o n and d i s t i l l a t i o n gave b r o m o n i t r o

m ethane (7 g . ) b . p . 146- 130 ° ( l i t . b , p . 149 ° ) .

S i m i l a r l y p r e p a r e d were 1 - b r o m o - 1 - n i t r o e t h a n e177/

b .p * 143° ( l i t . 1 4 6 -7 3 and 1 - b r o m o - l - n i t r o - p r o p a n e b . p .

163- 166° ( l i t . ^ ^ ^ ^ 160- 163° ) .

—i4o—

R e a c t i o n o f B rom onit rom ethgne w i t h T r i p h e n y l p h o s p h i n e . -

A s o l u t i o n o f b ro m o n i t ro m e th a n e (7 g . ) i n benzene (13 m l . )

was added s lo w ly t o a s o l u t i o n o f t r i p h e n y l p h o s p h i n e (26 g . )

i n benzen e (30 m l . ) so t h a t th e t e m p e r a t u r e d i d n o t r i s e

above 3 ° , and t h e r e s u l t i n g s u s p e n s i o n s e t a s i d e a t < 3 ° f o r

1 h o u r . F i l t r a t i o n gave h y d r o x y i m i n o m e t h y l t r i p h e n y l p h o s -

phonium bromide (13 g . ) , m .p . ( f rom n i t r o m e t h a n e - e t h y l

a c e t a t e ) l66°C (decom p.) (Found: C, 39*0; H, 4 . 3 ; N, 3 . 6 .

OigHiYBrNOP r e q u i r e s C, 3 9 .0 3 ; H, 4 . 4 ; N, 3 . 6 0 ) . E v a p o r a t i o n

o f t h e f i l t r a t e and r e c r y s t a l l i s a t i o n from e t h y l a c e t a t e

gave t r i p h e n y l p h o s p h i n e o x id e ( 1 2 . 3 g . ) , m .p . and m ixed

m .p . 1 3 7 -13 8 ° .

I n a s i m i l a r way, 1 - b r o m o - l - n i t r o e t h a n e gave

a - h y d r o x y i m in o e t h y l t r i p h e n y l p h o s p h o n i u m brom ide ( 6 ^ ) , m .p .

( f rom c h l o r o f o r m - e t h y l a c e t a t e ) 133-134° (Found: G, 3 9 .8 3 ;

H, 4 . 9 ; N, 3 . 3 . GgoHigBrNOP r e q u i r e s C, 3 9 .9 ; H, 4 . 7 3 ;

N, 3 . 3 0 ) * and t r i p h e n y l p h o s p h i n e o x ide ( 80^5) ;

-141 -

l - b r o m o - l - n i t r o p r o p a n e ggve g - h y d r o x y i m i n o p r o p y l t r i p h e n y l -

phosphonium bromide ( l6^o) , m .p . 152-154® (Pound: G, 6 0 .7 6 ;

H, 5 . 2 ; N, 3 . 3 ; 7*4 . CsiHgiBrNOP r e q u i r e s C, 6 0 .8 ;

H, 5 . 1 ; N, 3 . 4 ; p , 7 . 5 ^ ) . The f i l t r a t e from t h e l a s t

r e a c t i o n was shown by g . l . c . [ C a p i l l a r y column (50 m. x

0 . 5 mm.) c o a t e d w i t h p o l y p r o p y l e n e g l y c o l ] t o c o n t a i n

p r o p i o n i t r i l e ( /^ 6O0).

A l k a l i n e H y d r o l y s i s o f These S a l t s . - H y d ro x y im in o m e th y l -

t r ip h e n y lp h o s p h o n iu m brom ide ( 4 . 9 2 g . ) was d i s s o l v e d i n

w a te r (30 m l . ) and e t h a n o l (30 m l . ) , aqueous sodium

h y d r o x i d e ( IN; 13 m l . ) a d d e d , and t h e s u s p e n s i o n s e t a s i d e

a t room t e m p e r a t u r e f o r 15 m in . F i l t r a t i o n gave t r i p h e n y l -

p h o sp h in e o x id e ( 3 . 4 g . ) , m .p . and m ixed m.p* 1 5 7 -158° .

T i t r a t i o n o f t h e f i l t r a t e w i t h s i l v e r n i t r a t e showed t h e

p r e s e n c e o f c y a n i d e i o n ( 2 8 ^ ) .

a - H y d r o x y im i n o e t h y l t r i p h e n y l p h o s p h o n i u m brom ide

and a - h y d r o x y i m in o p r o p y l t r i p h e n y lp h o s p h o n i u m b rom ide b o t h

d i s s o l v e d i n d i l u t e a l k a l i a t room t e m p e r a t u r e to g iv e

s t a b l e s o l u t i o n s from w h ich t h e y c o u l d be r e c o v e r e d on

a c i d i f i c a t i o n . R e f l u x i n g a s o l u t i o n o f g - h y d r o x y i m i n o e t h y l -

t r ip h e n y lp h o s p h o n iu m b ro m id e i n aqueous sodium h y d r o x i d e

s o l u t i o n ( 0 . 5N) f o r 10 m in . g a v e , on c o o l i n g and f i l t r a t i o n .

—1 4 2 —

t r i p h e n y l p h o s p h i n e o x i d e ( Q8%) , m . p . a n d m i x e d m . p .

1 3 7 - 1 5 8 ° . A n a l y s i s o f t h e f i l t r a t e b y g . l . c . [ c a p i l l a r y

c o l u m n ( 5 0 m. x 0 .5 m m .) c o a t e d w i t h p o l y p r o p y l e n e g l y c o l ]

s h o w e d t h e p r e s e n c e o f a c e t o n i t r i l e ( 50^ ) # S i m i l a r l y

g - h y d r o x y i m i n o p r o p y l t r i p h e n y l p h o s p h o n i u m b r o m i d e g a v e

t r i p h e n y l p h o s p h i n e o x i d e ( 91^ ) a n d p r o p i o n i t r i l e (6CÇ0).

A c i d i c H y d r o l y s i s o f T h e s e S a l t s . - A s o l u t i o n o f t h e s a l t

( 1 -2 g . ) i n h y d r o c h l o r i c a c i d (30 m l . ) w a s r e f l u x e d f o r

2 -3 h r . , , t h e r e s u l t i n g s o l u t i o n a n a l y s e d d i r e c t l y f o r

n i t r i l e b y g . l . c . [ c a p i l l a r y c o l u m n ( 5 0 m. x 0 .5 mm.) c o a t e d

w i t h p o l y p r o p y l e n e g l y c o l ] a n d t h e n e x t r a c t e d w i t h c h l o r o f o r m .

T h e e x t r a c t w a s w a s h e d w i t h w a t e r , d r i e d a n d e v a p o r a t e d , a n d

t h e r e s i d u e s e t a s i d e a t r o o m t e m p e r a t u r e o v e r n i g h t i n

b e n z e n e (10 m l . ) c o n t a i n i n g m e t h y l i o d i d e (2 m l . ) . F i l t r a t i o n

g a v e m e t h y l t r i p h e n y l p h o s p h o n i u m i o d i d e , m . p . a n d m i x e d m . p .

1 9 0 - 1 9 2 ° ( f r o m c h l o r o f o r m - e t h y l a c e t a t e ) . E v a p o r a t i o n o f

t h e f i l t r a t e g a v e t r i p h e n y l p h o s p h i n e o x i d e , m . p . a n d m i x e d

m . p . 1 5 7 - 1 3 8 ° ( f r o m e t h y l a c e t a t e ) . T h e y i e l d s a r e g i v e n

i n t h e T a b l e .

-143-

S a l t H y d ro im in o m e th y l -phosphonium

g-H y dro xy im ino - e thy lphosphon ium

g -H y d ro x y im in o -p rop y lph o sp h on iu m

2IT-HC1 12N-HC1 2N-HC1 2N-HC1 12N-HC1

Phg PO 33 12 55 71 T ra c e

Pha,P 57 74 18 T r a c e 67

RON ' 30 60

A s o l u t i o n of h y droxy im inom ethy lphosphon ium brom ide

( 6 , 3 g . ) i n 1 2 N - h y d r o c h lo r i c a c i d (15 m l . ) was r e f l u x e d f o r

3 h r . , c o o l e d , f i l t e r e d , and made a l k a l i n e a t 0° by th e

a d d i t i o n o f 3N-sodium h y d r o x id e * B enza ld eh yd e (2 g . ) was

t h e n a d d e d , th e s o l u t i o n s e t a s i d e a t room t e m p e r a t u r e f o r

1 h r . , and t h e n a c i d i f i e d by th e a d d i t i o n of s o l i d c a r b o n

d i o x i d e . E t h e r e x t r a c t i o n and d i s t i l l a t i o n o f th e e x t r a c t

a t 1 1 0 - 1 2 0 ° /3 mm. gave a l i q u i d ( 1 . 2 g . ) whose i n f r a r e d

sp ec t ru m was a co m p os i te o f e q u a l p a r t s o f benz.aldoxime

and b e n z a ld e h y d e . T h is was r e f l u x e d i n a c e t i c a n h y d r id e

(2 m l . ) f o r 15 min. A n a l y s i s by g . l . c . (6 m. a p i e z o n L

column) showed th e p r e s e n c e o f a p p r o x i m a t e l y e q u a l q u a n t i t i e s

of b e n z a ld e h y d e and b e n z o n i t r i l e .

-144-

R e a c t l o n o f B e n z y l l d e n e t r i p h e n y l p h o s p h o r a n e w i th E t h y l

N i t r a t e . - To a s o l u t i o n o f h e n z y l i d e n e t r i p h e n y l p h o s p h o r a n e ,

from th e phosphonium brom ide (12 g . ) and BuLi (IN; 29 m l . ) ,

i n e t h e r , was added t r i p h e n y l p h o s p h i n e (7 g . ) and th e

s o l u t i o n s t i r r e d u n t i l t h e p h o s p h in e had d i s s o l v e d . To t h i s

s o l u t i o n e t h y l n i t r a t e ( 2 . 6 g . ) , i n e t h e r (10 m l . ) was s l o w l y

added . The r e a c t i o n m i x t u r e v/as t h e n s t i r r e d f o r 2 h o u r s ,

when g . l . c . ( 6 m . a p i e z o n L column a t 180°) on t h e r e a c t i o n

m i x t u r e showed th e p r e s e n c e o f b e n z o n i t r i l e ( 2 8 ^ ) . The

r e a c t i o n m i x t u r e was e v a p o r a t e d , d i s s o l v e d i n c h lo r o f o r m ,

washed w i t h w a t e r and d r i e d . E v a p o r a t i o n gave t r i p h e n y l

p h o sp h in e o x id e ( 3 . 9 g . ) , m .p . and mixed m .p . 1 57 -158° .

R e a c t i o n o f Sodium D ip h e n y lp h o s p h id e w i t h B ro m o n i t ro m e th a n e .

Sodium d ip h e n y l p h o s p h i d e was p r e p a r e d from d i p h e n y l p h o s p h i n e

( l 8 . 6 g . ) and sodium i n t e t r a h y d r o f u r a n (100 m l . ) . To t h i s

s o l u t i o n was added b r o m o n i t ro m e th a n e (13 g . ) i n t e t r a h y d r o

f u r a n (13 m l . ) and th e s o l u t i o n s t i r r e d f o r 1 h r . a t room

t e m p e r a t u r e . The r e s u l t i n g s o l u t i o n was e v a p o r a t e d ,

d i s s o l v e d i n benzen e washed w i t h w a t e r and d r i e d . M ethy l

i o d i d e (13 g . ) was a d d ed , and t h i s s o l u t i o n a l l o w e d t o s t a n d

a t room t e m p e r a t u r e o v e r n i g h t . F i l t r a t i o n gave d i m e t h y l -

d iph en y lph o sp h on iu m i o d i d e (5 g . ) , m .p . and mixed m .p .

-145-

248 - 249° . E v a p o r a t i o n o f t h e f i l t r a t e g a v e , o n t r i t u r a t i o n

w i t h p e t r o l , d i p h e n y l p h o s p h i n i c a c i d ( 1 2 .8 g . ) , m . p . a n d

m i x e d m . p . 191 - 192° .

-I4 5 a -

T h e R e a c t i o n o f A l d e h y d e s a n d K e t o n e s w i t h . T r i v a l e n t

P h o s p h o r u s C o m p o u n d s . - C o n s i d e r a b l e w o r k h a s b e e n

c a r r i e d o u t o n t h e r e a c t i o n s o f c a r b o n y l c o m p o u n d s

w i t h t r i v a l e n t p h o s p h o r u s c o m p o u n d s c o n t a i n i n g a

s u b s t i t u e n t c a p a b l e o f f o r m i n g a s t a b l e a n i o n .

C h l o r o p h o s p h i n e s h a v e b e e n s h o w n t o r e a c t178 ,179 178

r e a d i l y w i t h a l d e h y d e s . C o n a n t f o u n d t h a t

c h l o r o d i p h e n y l p h o s p h i n e a n d b e n z a l d e h y d e r e a c t e d a t

ro o m t e m p e r a t u r e t o g i v e a p r o d u c t w h i c h o n t r e a t m e n t

w i t h w a t e r g a v e a - h y d r o x y b e n z y l d i p h e n y l p h o s p h i n e o x i d e

( 2 0 9 ) .

R .T . HgO phgPOPhCHO + PhgPCl ----------- ^ [X] > I

P h - C H - O H

(209)

S i m i l a r r e a c t i o n s w i t h c h l o r o a c e t a l d e h y d e s

g a v e a n a l o g o u s p r o d u c t s . C h l o r o d i e t h y l p h o s p h i n e a n d

c h l o r a l a t 0 ° g a v e a p r o d u c t w h i c h o n t r e a t m e n t w i t h179

w a t e r g a v e ( 210 ) .

- 1 4 6 -

Q OHE tg P C l + CI3C.CHO - 2^ [X] E t B P - C H - C G l i

( 210)

I f h y d r o g e n s u l p h i d e w as u s e d i n p l a c e o f w a t e r

i n t h e w o r k u p o f t h e s e r e a c t i o n s t h e p h o s p h i n e s u l p h i d e

( 2 1 1 ) a n a l o g o u s t o ( 210 ) w a s o b t a i n e d .

S OH

R g P - C H - C C l e ( 211 )

P h o s p h o r u s t r i h a l i d e s h a v e a l s o b e e n s h o w n t o r e a c t18 0, 181, 182, 18 3, 18 4:, 185

w i t h a l d e h y d e s a n d k e t o n e s . T h e

p r o d u c t s f r o m t h e s e r e a c t i o n s d e p e n d u p o n t h e r e a c t i o n

c o n d i t i o n s . When a n a l d e h y d e a n d p h o s p h o r u s t r i c h l o r i d e a r e

a l l o w e d t o r e a c t a t R . T . , a n d t h e r e a c t i o n m i x t u r e t r e a t e d

w i t h w a t e r , t h e p r o d u c t i s t h e a - h y d r o x y p h o s p h o n i c a c i d, 18 2

( 2 1 2 ) .

OH OHPCI3 + RCHO -► [X] H0 - & - C H - R

( 212)

T h e r e a c t i o n o f p h o s p h o r u s t r i c h l o r i d e w i t h k e t o n e s

i s s i m i l a r t o g i v e , a f t e r t r e a t m e n t w i t h w a t e r , t h e p h o s p h o n i c

—147—

X 185a c i d ( 2 1 3 ) .

OH ^HPCI3 + RCOMe ^ [X] H O - P - Ç - Me

( 213 )

However, when t h e s e r e a c t i o n s a r e c a r r i e d ou t a t

e l e v a t e d t e m p e r a t u r e s t h e p r o d u c t s a r e d i f f e r e n t . I f a

m i x t u r e o f b e n z a ld e h y d e and p h o s p h o ru s t r i c h l o r i d e i s180

h e a t e d , t h e p h o sp h in e o x id e (214) i s p ro d u c e d .

H ea tPhCHO + PC ^j > P h - C H C l - P C l g (214)

The r e a c t i o n b e tw ee n k e t o n e s and p h o sp h o ru s

t r i c h l o r i d e i s a n a l o g o u s , h e a t i n g i n a s e a l e d tu b e a t

200° g i v i n g ( 215 ) .

200° ®RgCO + PCI3 --------------- ^ RgÙ - PClg (^ ^ 5 )

s e a l e dtube

These r e s u l t s may be r a t i o n a l i s e d i n t h e f o l l o w i n g

m anner . The i n i t i a l s t e p i n a l l t h e r e a c t i o n s c o u ld be

n u c l e o p h i l i c a t t a c k o f p h o sp h o ru s on the c a rb o n of th e

c a r b o n y l group i n th e k e t o n e , o r a l d e h y d e , t o g i v e a b e t a i n e

o f t h e typ e ( 216 ) .

—148—

R _ R•f

G O o P :^ C l g P - à - R (216)0 = 0 -► CI3P— ck “6

I f the r e a c t i o n m i x t u r e i s t r e a t e d w i t h w a t e r a t

t h i s s t a g e p r o t o n a t i o n and h y d r o l y s i s w i l l g iv e th e

p h o s p h o n ic a c i d (213 ; Me = R ) . However, i f t h e b e t a i n e

( 216 ) i s h e a t e d i t may r e a r r a n g e , e i t h e r by an i n t r a m o l e c u l a r

mechanism ( 217 ) , o r by an i n t e r m o l e c u l a r mechanism ( 21 8 ) , to

g i v e t h e p h o sp h in e o x id e ( 219 ) .

ClgP^0 01

IC lg P -G R g

(217)

CI2P— c — R

( 219 )

R— G ' PC Ig

(218)

-149-

H o v / e v e r , i t i s p e r h a p s s u r p r i s i n g t h a t c h l o r o p h o s p h i n e s

a r e s u f f i c i e n t l y n u c l e o p h i l i c t o a t t a c k u n a c t i v a t e d k e t o n e s

a n d a l d e h y d e s a t r o o m t e m p e r a t u r e , a l t h o u g h q u i t e p o s s i b l e

t h a t t h e y w i l l a t t a c k a l d e h y d e s l i k e c h l o r a l w h e r e t h e

c a r b o n y l g r o u p i s h i g h l y s u s c e p t i b l e t o n u c l e o p h i l i c a t t a c k .

I n t h e c a s e s o f r o o m t e m p e r a t u r e r e a c t i o n s w i t h u n a c t i v a t e d

a l d e h y d e s a n d k e t o n e s a c e t i c a c i d h a s i n v a r i a b l y b e e n u s e d

a s a s o l v e n t , a n d t h i s may w e l l t a k e p a r t i n t h e r e a c t i o n .

T h e i n i t i a l s t e p m ay b e a t t a c k o f t h e c h l o r o p h o s p h i n e o n t h e

a c e t i c a c i d t o g i v e t h e a c e t o x y p h o s p h i n e a n d h y d r o g e n c h l o r i d e ,

w h i c h w i l l r a p i d l y g i v e s e c o n d a r y p h o s p h i n e o x i d e a n d a c i d

c h l o r i d e . S e c o n d a r y p h o s p h i n e o x i d e s a r e k n o w n t o a d d

r e a d i l y t o a l d e h y d e s a n d k e t o n e s t o g i v e h y d r o x y p h o s p h i n e178 ,186

o x i d e s . C o n a n t h a s i n f a c t i s o l a t e d a c e t y l c h l o r i d e

f r o m t h e s e r e a c t i o n s .

HR g P C l + CHaCOOH E g P - O - C - C H a + H C l

Q 0+ r \ «

CHa Rg P 'n I

RjCO

-» R3 P - O - 1 Ü - C H 3 R g P - H + CH3 COGI

^ - G l

R g P - C R 'g

T h e r e a c t i o n w i t h p h o s p h o r u s t r i c h l o r i d e m a y b e s i m i l a r t o

g i v e t h e a c e t o x y p h o s p h i n e i n i t i a l l y , w h i c h g i v e s t h e s e c o n d a r y

- 1 5 0 -

phosphine. o x id e (220) w i t h h y d ro g e n c h l o r i d e . A t t a c k of

t h i s on th e c a r b o n y l compound and f i n a l l y h y d r o l y s i s w i t h

w a t e r g i v i n g t h e p h o s p h i n i c a c i d ( 2 2 1 ) .

CH3COOH ({P G la ---------------- ) C I3 P - 0 - C - CH3 + HCl

Ç)ClgPH + CH3COCI

i ( 220 )RgCOÇ ÇH HgO H O ^ f i r

C l g P - CRg — 7 ^ P - GRjHcr

( 221)

T e r t i a r y p h o s p h i t e s a l s o r e a c t w i th a ld e h y d e s and

k e t o n e s . T r i a l k y l p h o s p h i t e s r e a c t w i t h p - n i t r o b e n z a l d e h y d e186

t o g i v e p h o s p h o r a t e s ( 2 2 3 ) . P re su m a b ly th e i n i t i a l a t t a c k

i s a t t h e c a r b o n y l c a r b o n to g iv e t h e b e t a i n e ( 2 2 2 ) , which

t h e n u n d e rg o e s an i n t e r n a l A r b u s o v - ty p e r e a c t i o n to g i v e th e

p r o d u c t .

l O - R y O(R 0)3? + O g H - f ^ C H O ^ (RO)gP-----C H - / ' ^ N O

'4 I ~ ( 222)

(RO)

( 223 )

-151-

S i m i l a r r e a c t i o n s t a k e p l a c e w i th a l i p h a t i c187

a l d e h y d e s u n d e r v i g o r o u s c o n d i t i o n s .

A m in o p h o sp h o n i te s have been shown to r e a c t w i t h

a ld e h y d e s a t 100° to g iv e r e a r r a n g e d p r o d u c t s a n a lo g o u s t o

( 219 ) , t h e amino g roup m i g r a t i n g i n p r e f e r e n c e t o t h e 188

a lk o x y .

0 R *20 m in s . |( ((R0)2PNEtg + R'CHO j_QQo > ( R 0 ) 2 P - C H - N E t 3

T h is r e a c t i o n p re s u m a b ly t a k e s p l a c e by a mechanism

a n a l o g o u s t o (217) o r ( 2 1 8 ) .

A m inophosphines have been shown t o u n d e rg o a

s i m i l a r r e a c t i o n w i th a ld e h y d e s . When d i m e t h y la m i n o d i p h e n y l -

p h o s p h in e and b e n z a ld e h y d e a r e h e a t e d t o 120°, a v i g o r o u s r e a c t i o ]

t a k e s p l a c e t o g iv e a h i g h l y c r y s t a l l i n e compound vdiich

c o n t a i n s n i t r o g e n and p h o s p h o ru s and a n a l y s e s f o r GgiHggNOP.

Prom i t s N.M.R. s p e c t r u m , which shows a s i n g l e t i n t e g r a t i n g

f o r s i x p r o t o n s a t 7 .6 5 T (-HMOg) and a d o u b l e t (one p r o t o n ;

J p g = 10 c . p . s . ) a t 5 . 7 ^ ( P —OH— ) , and mass s p e c t r u m , which

shows a mass p eak a t m/e =; 335 , and peak s a t m/e = 2 0 l ( P h g § ) ,

m/e = 1 3 4 (P h — CH— NMeg) t h i s compound a p p e a r s t o be

a - d i m e t h y l a m i n o b e n z y ld i p h e n y lp h o s p h in e o x id e ( 2 2 4 ) .

-152-

Pi f "PhsENMeg + PhCHO -> P hgP -C H -H M ea

(224)

T h is r e a c t i o n p r o b a b ly goes th ro u g h th e

i n t e r m e d i a t e b e t a i n e ( 225 ) , which c a n r e a r r a n g e by an

i n t r a m o l e c u l a r m echanism ( 2 2 6 ) , a n a lo g o u s to ( 2 1 7 ) , o r an

i n t e r m o l e c u l a r mechanism ( 2 2 7 ) , a n a lo g o u s to ( 2 1 8 ) , t o g iv e

th e p r o d u c t .

NIvieg Ph _ NMegA T XPhgP: Ç = 0 PhgP-— CHPh

" 0H

//

k- (225)

Phg _ INMOgMegN-r i - O-r—CHPh PhgP------ CHPh

V . n (2 2 6 ) “7PhHC y 0 A-h P — NMOg

( 2 2 7 ) ^ ^ f\ V

\

0 NMegPhgP-C H Ph

A s i m i l a r r e a c t i o n w i th p a ra fo rm a ld e h y d e gave th e p h o sp h in e

o x id e ( 2 2 8 ) , an a u t h e n t i c sam ple o f w hich was p r e p a r e d by

a iM ann ich type c o n d e n s a t io n be tw een fo rm a ld e h y d e .

-153-

dime th y lam ine and d ip h e n y lp h o s p h in e , and su b s e q u e n t

o x i d a t i o n .

/G H g hPhsENMea + 0"^ ^ 0 -► P h g P - C H g - N M e g

CHg GHg^ 0 '— ( 228)

PhgPH + HCHO + Megim Phg P - CHg “ NMeg

-Ng OgI

8PhgP-C H g-N M eg

An a t te m p t t o e x te n d t h i s r e a c t i o n to

a c r a ld e h y d e gave o n ly p o ly m e r ic s u b s t a n c e s .

D im e th y la m in o d ip h e n y lp h o sp h in e a l s o r e a c t s w i th

ac e to p h e n o n e t o g i v e th e p h o sp h in e o x id e (229) and t e t r a -189

p h e n y lb ip h o s p h in e m onoxide , p re su m ab ly by a b a se

c a t a l y s e d a l d o l c o n d e n s a t io n o f two m o le c u le s o f a ce to p h en o n e

t o g iv e dypnonCy v;hich th e n adds d ip h e n y lp h o s

p h in e o x id e , p ro d u c e d by th e a c t i o n o f w a te r on d im e th y la m in o

d ip h e n y lp h o s p h in e .

8 fPhg PNMeg 4r 2PhC0GH3 Ph - C - GH = G - Ph

0Û

P h g p - t p h g ^ fi ,P h — c — GH— GHPh

Phg PH Me

PhgP= 0 (229)

-154-

W ith c y c lo h e x a n o n e , d im e th y la m in o d ip h e n y lp h o sp h in e

g i v e s t e t r a p h e n y l b ip h o s p h in e m onoxide a s th e o n ly i s o l a t a b l e

p r o d u c t .

B e n z o y ld ip h e n y lp h o sp h in e a l s o r e a c t s w i th a ro m a t i c

a ld e h y d e s , a l th o u g h v ig o r o u s r e a c t i o n c o n d i t i o n s a r e

r e q u i r e d . B en za ldeh yde an d b e n z o y ld ip h e n y lp h o s p h in e gave

b e n z y ld ip h e n y lp h o s p h in e o x id e , w h i le m -c h lo ro b e n z a ld e h y d e

gave m -c h lo ro b e n z y ld ip h e n y lp h o s p h in e o x id e . As y e t th e

mechanism o f t h i s r e a c t i o n h a s n o t been e s t a b l i s h e d .

E x p e r im e n ta l

A l l e x p e r im e n ts u s in g p h o s p h in e s , and s i m i l a r

u n s t a b l e compounds, were c a r r i e d ou t u n d e r an o x y g e n - f r e e

n i t r o g e n a tm o sp h e re . A l l s o l v e n t s were d r i e d b e f o r e u s e .

M e l t in g p o i n t s were u n c o r r e c t e d .

190P r e p a r a t i o n o f D im e th y la m in o d ip h e n y lp h o s p h in e . - A s o l u t i o n

o f dime t h y lam ine (50 g . ) i n e t h e r (250 m l . ) was s t i r r e d and

c o o le d i n an i c e b a th w h i le a s o l u t i o n o f c h lo r o d i p h e n y l

p h o sp h in e (100 g . ) i n e t h e r (150 m l . ) was added d ro p w is e .

A f t e r th e a d d i t i o n th e r e a c t i o n m ix tu r e was a l lo w e d to warm

up to room te m p e r a tu re and s t i r r e d f o r 1 h r . The amine

-155-

h y d r o c h l o r i d e was f i l t e r e d o f f , th e s o l u t i o n e v a p o r a te d

and th e r e s i d u e d i s t i l l e d ( 1 3 0 -1 3 2 ° /0 .9 mm.) to g iv e

d im e th y la m in o d ip h e n y lp h o sp h in e (80 g . ) .

R e a c t i o n o f D im e th y la m in o d ip h e n y lp h o sp h in e w i th B e n z a ld e h y d e . -

The p h o sp h in e ( 9 .5 g . ) and b e n z a ld e h y d e ( 4 . 5 g . ) were h e a t e d

t o g e t h e r a t 140° f o r 3 h r s . The r e a c t i o n m ix tu r e was c o o le d

to g iv e a s o l i d w h ich was shown to be a -d im e th y la m in o b e n z y l -

d ip h e n y lp h o s p h in e o x id e (10 g . ) m .p . ( e t h y l a c e t a t e ) 195-196°

(Found: C, 7 5 .3 5 ; H, 6 .5 5 ; F , 4 .0 4 ; C a lc , f o r CgiHggNOP:

0 , 7 5 .6 ; 6 .5 7 ; P , 4 . 1 8 ) .

R e a c t i o n o f D im e th y la m in o d ip h e n y lp h o s p h in e w i th P a ra fo rm

a ld e h y d e . - The p h o sp h in e ( 7 .3 g . ) and p a ra fo rm a ld e h y d e (,1.2 g .

were h e a t e d t o g e t h e r a t 120° f o r 2 h o u r s , a f t e r w hich th e

r e a c t i o n m ix tu re was s o l i d . R e c r y s t a l l i s a t i o n gave

dime thyaminome th y ld ip h e n y Ip h o s p h in e o x i de ( 4 .9 g . ) , m .p .

( e t h y l a c e t a t e ) 184-185° (Found: C, 6 9 .4 1 ; H, 6 .7 9 ; P , 5 .6 4 ;

C a lc , f o r CiaRj^sNOP: C, 6 9 .5 ; H, 6 .9 5 ; P , 5 . 4 0 ) .

P r e p a r a t i o n o f D im e th y la m in o m e th y ld ip h e n y Ip h o sp h in e o x i d e . -

A m ix tu r e o f d im e th y la m in e (30 g . ) and aq u eo u s fo rm a ld e h y d e

—156-

s o l u t i o n (37%l 60 g . ) w a s s t i r r e d f o r 2 m i n s * D i p h e n y l

p h o s p h i n e ( 1 5 g . ) w a s a d d e d d r o p w i s e a n d t h e m i x t u r e

s t i r r e d a t r o o m t e m p e r a t u r e o v e r n i g h t . H y d r o g e n p e r o x i d e

(15 m l ; 20 v o l . ) w a s a d d e d s l o w l y . T h e s o l i d w a s f i l t e r e d

o f f t o g i v e d i m e t h y l a m i n o m e t h y l d i p h e n y I p h o s p h i n e o x i d e

( 1 5 .5 g . ) m . p . a n d m i x e d m . p . ( e t h y l a c e t a t e ) 1 8 4 - 1 8 5 ° .

R e a c t i o n o f D i m e t h y l a m i n o d i p h e n y l p h o s p h i n e w i t h

C y c l o h e x a n o n e . - T h e p h o s p h i n e ( 4 .3 g . ) a n d c y c l o h e x a n o n e

( 1 .2 5 g . ) w e r e h e a t e d t o g e t h e r a t 140° f o r 12 h r s . T r i t u r a t i o n

o f t h e r e a c t i o n m i x t u r e w i t h l i g h t p e t r o l e u m ( 6 0 - 8 0 ° b . p . )

g a v e t e t r a p h e n y l b i p h o s p h i n e m o n o x i d e ( 2 . 4 g . ) m . p . ( a c e t o n e -

e t h e r ) l 6 6 - l6 7 ° ( l i t . ^ ^ ^ 1 6 7 ° ) .

19 2R e a c t i o n o f B e n z o y l d i p h e n y l p h o s p h i n e w i t h B e n z a l d e h y d e . -

B e n z o y l d i p h e n y l p h o s p h i n e ( 1 .7 g . ) a n d b e n z a l d e h y d e ( 1 . 2 g . )

w e r e h e a t e d t o g e t h e r a t 190° f o r 14 h r s . On c o o l i n g t h e

r e a c t i o n m i x t u r e c r y s t a l l i s e d t o g i v e b e n z y l d i p h e n y l p h o s p h i n e

o x i d e ( 0 .8 5 g . ) , m . p . a n d m i x e d m . p . ( e t h y l a c e t a t e ) 1 9 5 -1 9 6 ° .

A s i m i l a r r e a c t i o n w i t h b e n z o y l d i p h e n y l p h o s p h i n e

a n d m - c h l o r o b e n z a l d e h y d e g a v e m - c h l o r o b e n z y l d i p h e n y I p h o s p h i n e

o x i d e ( 42^ ) m . p . a n d m i x e d m . p . ( e t h y l a c e t a t e ) l 6 2 - l 6 3 ° .

-157 -

1.

2

3

*

5

6

7

8

g

10

R e f e r e n c e s

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16 ^

H o rn e r and O e d ig e r , Chem. B e r . , 1958 , £ 1 , 437

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20B estm ann , Angew. Chem. I . E . , 1962, 270

-159 -

21 .

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620

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H offm ann, Chem. B e r . , I 96 I , £4> 1531

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866

—l 6 l —

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43Gough, T h e s i s , L e e d s , 1963

44V / i t t i g , F e s t s c h r i f t B i r k h a u s e r , B a s l e , 1954 , 48

45

46

47

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49

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