Indi an Journal or Chemist ry Vol. 43B, April 200 .. k pp. 8.+6 .. 85 1
Utility of Vil smeier Haack reagent in the synthesis of 3-amino-12-chloroquino[3 ,2-eJ [1 ,3 ]diazocines
R Nandha Kumar, T Su rcsh, T Dhanabal & P S Mohan*
Departilleni or Chemi stry. Bharathiar Uni versity. CoimbalOre 64 1 046, India
l?eU' i l'ed .J Fe/JrI {({r.l' 200J: ([cCl'/J/ed ( rel'is('(/) 24 Sepll'lIIber 200J
App licatiun of Vi l ~ l1l e icr condition on .+-hydroxyquinaldines gives a potential interillediate 4-chl oro-3- formyl -2-(2-hydroxy-ethene- I .. yl)quinolines which is utili ;:cd to prepare quinoI3.2-1' 111 .3 Id ia7.0cines ontreatillent wi th guanidine nitrate. A ll the synthes ized compounds are characteri zed by the anal y ti cal and spectroscopic data.
IPC: InLCI.7 C 07 0255/00
In recent years therc has been a growing interest on the application of Vilsmeier Haack reagent in organic synthcsis due to its remarkable advantages such as easier work-up and better yields. Earlier reports reveal about the reagent to be a mi Id and efficient one for the formylation of reacti ve aromatic and heteroaroll1<ltic substrates.I
.) The versati l ity of the reaction has becn further cxtended as an acti vating agent for acy lhalo addition4
and ring annulation. :i-7 Moreover, a wide variety of alkene deri vatives,R carbony l compounds,') acti vated methyl and methylene groupslO as well as oxygen and nitrogen ncucleophiles" efficiently react with V ilsmeier Haack reagent to yield the correspond ing iminium salts. The intramolecular cyclisation potential of halomethyleniminium salts formed under Vi lsmeier condition and microwave induced V ilsmeier cond iti o n~ were reported. ' 2.
18 The classica l V ilsmeier Haack reaction involves electrophilic substitution of an act ivated aromatic ring with a halomethyleniminium salt to yield the corresponding iminium species, which fac ili tates easy entry into large number of novel heterocyclic systems.
The capab ility of the reagent to generate a broad spectrum of iminium spec ies has been explored further for the construct ion of [c] anne lated nitrogen and oxygen heterocycles via 4-chloro-3-formy lquinaldines obtainab le from 4-hydroxyquinaldines l9
by V il smeier Haack reaction. It was presumed that the Vilsmeier Haack reaction
on 4-hydroxyquinaldines 1, (prev iously prepared from corresponding aniline and ethy l acetoacetate followed by subsequent cycli zation of the B-anilinocrotonates) could provide an utility intermediate for the preparation of several substituted k] annelated heterocyclic como. pounds. 2o
.2 1 The reaction was carricd out at 100°C for
15-20 hr, using the V ilsmeier Haac reagent deri ved from phosphorus ox ych loridc-d i methy I formamide in si/II. But, the reaction yielded a mixture of products. These were isolated usi ng sili ca gel column chromatography. The analyti ca l and spectroscopic data confirmed the products as 4-chloro-3-formyl-2-(2 .. hydroxyethene- I-y l)quinoline 2, 4-hydroxy-3-formy lquinaldine 3 and 4-chloroquinaldine 4 in good yields (Scheme I) .
Thu s, the trea tment of Vil smeier reagent on 4-hydroxy quinaldines 1 at 100°C resu lted in an effi c ient and fac il e meth od fo r the generati on of 4-chl oro-3-formy l -2-(2- hydroxy-e thene- I -y l ) quinolines 2a-e, whi ch could be fu rther utili zed for the constructi on of several nove l nitrogen and oxygen heterocyc li c rin g systems.
The Vilsmeier Haack reagents are usuall y employed for the formylation of aromatic and heteroaromatic compounds. These chloromethy leniminium species are responsible for the formylation (Sch'eme II). As in reaction, the chloromcthyleniminium s ec ies o' tained in si III from phosphorus ox ych loride-di meth y I formam ide reacts with the active methy l group of 4-hydroxyquinaldine 1 to y ield 6. Anoth er formy lati on occurs at the aromatic C3 of the quinaldine leading to the iminium compound 8. Since these iminium salts hav ing the special capability to rep lace the hydroxy l group at aromatic C4 by the nucleophiles like chlorine, bromine etc., have led to the formation of 4-chloroquinaldine 4 in minor yie lds and also in the conversion of hydroxy moiety to the chloro moiety in case of 4-chloro-3-formyl-2-(2-hydroxy-ethene-l -y l)quinoline 2. In the case of 4-hydroxyquinaldine la and 8-mcthy l-4-hydroxyquinaldine Ib the react ion was completed within 15 hours and with 5,8-dime
KUMAR I!! 0/.: SYNTHESIS OF QU INODIAZOCI ES USING VILSMEIER HAAC K REAGENT 847
R wR4
OH R wR4
CI CHO 3 I -....::::: -....::::: DMF·POCI3, 100 O.C 3 I -....::::: -....:::::
// /: // /: R2 N CH3 R2 N CH=CH·OH
R1 R1 2
+
4
1-4: a) R1=R2=R3=R4=H b) R1=CH3, R2=R3=R4=H c) R2=CH3, R1=R3=R4=H d) R3=CI , R1 =R2= R4=H e) R1=R4=CH3, R2=R3=H
Scheme I
The Mechanism
CI
ro~ CHO
I ..-': h N CH=CH.OH
2
Scheme II
848 INl' lAN 1. CH EM .. SEC 13 . APR IL 2004
Anhy. EtOHI PY reflux,3h ..
10
2,1 1,12 :a) R 1=R2=R3=R4=H b) R 1=CH3, R2=R3=R4=H c) R 2=CH3, R 1 =R3= R4=H d) R 3=CI , R1=R2=R4=H e) R 1=R4=CH3, R2=R3=H
Scheme III
Table 1- Vil sl11cicr Haack Rcac lion or 4-hydroxyquinaldincs Ja-e and synthesis or quinoI 3,2-eH I ,3ldiazocincs 12a-e
Enlry Substrales RI R2 R,
la H H H 2 Ib CH 1 H H 3 Ie H CH, H 4 Id II II CI 5 Ie CHl H H 6 2a H H H 7 21> CH, H H 8 2e H CH, H 9 2d H H CI 10 2e CH, H H
thy l-4 -h ydroxyq uin aldine I e, in 20 hours as monIto red by the TLC.
Hav ing prepared the new inte rmediates 2a-e, we were abl e to sta rt the intended synthes is o r so me annul ated quino lines. The corresponding vin yl derivative was treated w ith g uanidin e nitra te in anhydrous e thanol and pyridine at refl ux te mpe ra ture for three hou rs. After the so lve nt remova l, unde r reduced pressu re , th e res iuu e was ext rac ted with e th y l acetate. Th e s ili ca ge l co lumn c hro matog raphy affo rd ed th e desired co mpou nd s I2a-e us ing pe tro le um e the r-e th y l acetate (80:20) as the e luents (Scheme III).
The reac ti o n proceeded via the corresponding Schifr base and the subsequ ent aromat ization has y ie lded the diazocine. The y ie lds, reac ti on time and
R4
II H H H
CHl H H H H
CH,
Reaction Perccnlage y iclds timc (hr) 2 3 4 12
15 70 15 10 12.5 73.5 18 5 16 55 12 17
17.5 78 12 5 20 65 10 IS 3 82 3 85
2.5 78 :1 75.3 2 87.5
the temperature at wh ich the reacti on were carri ed out are shown in Table I.
Experimental Section T hin layer chromatography was u s~d to assess the
reactio ns and the purity of produc:s. Melting points were dete rmined o n a Boet ius Microheati ng Table (Japan) and are uncorrec ted. IR spec tra were recorded with a Shimadzu - 8201 FT in strument (J apan) in KBr discs and o nly characteristic absorptio n in rec iprocal centimeter are li sted. IH NMR spectra were recorded with a Bruker .. AMX-400 MHz spectrometer (U S) in CDCI 3 soluti on; chemical shifts are expressed in ppm
(8) re lati ve to TMS . 13C NMR spectra were recorded on a Bruker - AMX-400 MHz spectromete r (US) in C DCh with TMS as internal standa rd . Mass spec tra
KUMAR ef al. : SYNTHESIS OF QUINODIAZOCINES USING VILSMEIER HAACK REAGENT 849
were recorded using a Jeol-D-300 mass spectrometer (70 eV) (Japan). C,H,N analyses were carried out on a Perkin-Elmer Mode l 240 ana lysers (UK).
General Procedure Vilsmeier Haack reaction on 4-hydroxyquinal
dine. The Vilsmeier reagent was prepared by N,Ndimethylformamide (3 .86 mL, 0 .05 mole) taken in a round bottom flask . It was coo led in ice bath (0- 5°C) with constant stirring. To thi s , phosphorus oxychloride (13.04 mL, 0.014 mole) was added dropwise over a period of 30 min and the resultant mixture was stirred fo r further one hour. T he appropriate 4-hydroxyquinaldines la-e were added to the Vilsmeier reagent and st irred aga in for 30 min and the reaction mixture was kept on a water bath at 100°C for the period of time indi cated in Table I. After the completion of reaction (fo llowed by TLC), the reaction mixture was poured onto 500 g of crushed ice with constant stirring and left overni ght. After neutrali zation with 4N NaOH , the precipitate obtained was ex tracted using ethyl acetate and washed well with water. The combined organic layers were collected and dried over anhyd. Na2S04. The res idue obtained after removal of solven t was subj ected to chromatography using pet. ether and ethyl acetate as eluent on sili ga gel coloumn. Three products 4, 3 and 2 were obtained using petroleum ether (100), petroleum ether-ethyl acetate (94: 6) and petroleum ether-ethy l acetate (85: 15) respectively . The products were recrysta lli zed with methanol. The products were identified by the analytica l and spectroscopic data.
Preparation of 3-amino-12-chloroquino[3,2-e][1, 3]diazocines. Guanidine nitrate 10 (0.002 mole) and the appropriate 4-chloro-3- formyl-2-(2-hydroxyethene-I-yl)quinoline 2 (0.002 mole) were dissolved in 50 mL of anhydrou s ethanol along with 2 mL of pyridine. They were kept at the refluxing temperature for 3 hr. After the completion of the reaction inferred through the TLC monitoring, the ethanol was removed undcr red uced pressure. The res idua l mass was washed with dil. HCI ( 1:1) for four to five times and ex tracted with ethyl acetate. The combined organic layers werc then dried over an hyd . Na2S0~ and purified by silica gel column chromatography (pet. etherEtOAc).
4-Chloro-3-formyl-2-(2-hydl'Oxy-ethene-l-yl)quinoline 2a: IH NMR (CDCI3, 400 MHz): 87.7 (d, I H, Cs-H, 1= 8. 1 Hz), 7.6 (t, IH , CrH, 1= 8.3 Hz), 7.9 (t, I H, C6-H, 1= 7.3 Hz), 8.2 (d, I H, Cs-H, 1= 8.3 Hz), 9.2 (s, I H, Cr CHO), 9.4 and 9.6 (2s, 2H, vinylic protons),
16.5 (bs, vinylic-OH, D20 exchangeable); 13C NMR
(CDCh, 400 MHz): 8 192.419, 189.332, i89.08, 146.24, 137.30, 135.90, 133.32, 126.93, 125.21 , 122.61 , 119.32, 118,99; MS (70 eV, mlz, M+): 233 , (M+2): 235; IR cm' l: 3438, 1664, :595. Anal. Found: C, 61.62; H, 3.38; N, 5.92. Calcd for C I2Hg0 2NCI: C, 6 1.69; H, 3.45; N, 5.99%; mp ISS-56°C.
3-Formyl-4-hydroxyquinaldine 3a: I H NMR
(COCI3, 400 MHz): 82.4 (s, 3H, CH3), 7.3 (d, I H, Cg-
H, 1= 7.84 Hz), 7.5 (t, I H, CrH, 1= 7.58 Hz), 7.7 (t, I H, C6-H, 1= 7.6 Hz), 8.2 (d, I H, Cs-H, 1= 8.28 Hz), 9.4 (s, I H, CHO), 14.1 (bs, 1 H, OH); MS (70 eV, mlz, M+): 187; IR cm' l: 3520, 1695, 1610. Anal. Found: C, 70.54; H, 4.81 ; N, 7.43 . Calcd forC II H90 2N: C, 70.58 ; H, 4 .85; N, 7.48%; mp 140-41 °C.
4-Chloroquinaldine 4a: 'H NMR (CDCI3, 400 MHz): 8 2.5 (s, 3H, CH3), 7.3 (s, I H, Cr H), 8. 1 (d , I H, Cs-H, 1= 8.2 Hz), 7.7 (t, I H, C6-H, 1= 7.54 Hz), 7 .9 (t, IH, Cr H, 1=7.82 Hz), 7.5 (d, IH, Cx-H, 1= 8.14 Hz); IR cm' l: 1590, mp 65-66°C.
3-Amino-12-chloroquino[3,2-e][1,3]diazocine 12a: IH NMR (CDCI3, 400 MH z): 8 4.5 (bs, 2H, NH2) ,
6 .9-7 .8 (m, 7H, Ar-H); MS (70 eV, mlz, M+) : 256 (M+2) : 258; IR cm' l: 3300, 1595, 1580. Anal. Found: C, 60.75; H, 3.48; N, 21.76. Calcd for C I3H9N4C I: C, 60.83; H, 3.53; N, 2 1.83%; mp 14041 °C.
4-Chloro-3-formyl-8-methyl-2-(2-hydroxy-ethene-l-yl)quinoline 2b: IH NMR (COCI3, 400 MH z) :
82.8 (s, 3H, CH3), 7 .5 (t, I H, C6-H, 1= 7.92 Hz), 7.7 (d, IH , Cr H, 1= 7 .16 Hz), 8,1 (d, IH , Cs-H, 1= 8.24 Hz), 9.2 (s, I H, C3-CHO), 9.4 and 9.5 (2s, 2H, vinylic protons), 16.5 (bs, vinylic- OH, D20 exchangeable); I3C NMR (COCb, 400 MHz): 8 192.359, 189.451 , 189.0 14, 147.224, 136,948, 133.953 , 130.233, 126.611, 126.390, 122.993, 121 .964, 11 8.594, 18.459; MS (70 eV, mlz, M+): 247 (16.5 %) (M+2): 249 (5.2%), 220 (66.7%), 203 (100%), 178 (36.5%); IR cm' l: 3450, 1660, 1595 . Anal. Found: C, 62.02; H, 3.98; N, 5.63. Calcd for C 13HI00 2NCI : C, 63.04; H, 4.07; N, 5.66%; mp 132-33°C.
3-Formyl-4-hydroxy-8-methylquinaldine 3b: I H NMR (CDCb, 400 MHz): 8 2.6 (s, 6H, 2xCH3), 7.4 (t, I H, C6-H, 1= 7.6 Hz), 7.6 (d, IH, Cr H, 1= 7.28 Hz), 8.0 (d, 1 H, Cs-H, 1= 8.24 Hz), 9.3 (s, I H, CHO), 15.3 (bs, IH , OH); MS (70 eV, mlz, M+): 201 ; IR cm' l: 3500, 1710, 1590. Anal. Found: C, 71.58; H, 5.44; N, 6.98. Calcd for C1 2H1102N: C, 71.63 ; H, 5,51; N, 6.96%; mp 195-96°C.
4-Chloro-8-methylquinaldine 4b: 'H NMR (COCl3, 400 MH z): 8, 2.7 (s, 3H, CT CH3), 2.8 (s, 3H, Cs
850 INDI AN J. CHEM. , SEC 13, APR IL 2004
-CH3), 7.4 (s, IH , Cr H), 8. 1 (d, IH, C5-H, 1= 7.92 Hz), 7.4 (t, IH , C6-H, 1= 7.2 Hz), 7.6 (d, IH, Cr H, 1=6.28 Hz); IR cm-I: 1570; mp 47-48°e.
3-Amino-12-chloro-8-methylquino[3,2-e ][1 ,3]diazocine 12b: IH NMR (C OCl3, 400 MHz): 82.4 (s, 3H, CH3), 4.6 (bs, 2H, NH2), 7.2-8. 1 (m, 6H, Ar-H); MS (70 eV, mlz, M+): 270 (M+2) : 272; lR cm-I: 3320, 1602, 1585. Anal. Found: C, 62.19; H, 4.01 ; N, 20.83. Calcd for C j4 HI IN4C1: C, 62. 11 ; H, 4.09; N, 20.70%; mp I 75-76°e.
4-Chloro-3-formy 1-7 -mcthyl-2-(2-hydroxy-ethene-l-yl)quinoline 2c: IH NMR (COCl), 400 MHz): 82.6 (s, 3H, CH3), 7.6 (d, 1 H, C6-H, 1= 7.56 Hz), 7.8 (s, I H, Cx-H), 8. 1 (d, I H, Cs- H, 1= 8. 16 Hz), 9.2 (s, I H, -CHO), 9.3 and 9.5 (2s, 2H, viny lic protons), 16.5 (bs, viny lic- OH, 0 20 exchangeable); 13C NMR (COCb, 400 MH z): 8 192.28, 189.4 1, 189.09, 145.26, 135.68, 134.06, 13 1.22, 126.28, 126.05, 122.75 , 122.34, 119.70, 19.52; MS (70 eV, mlz, M+): 247 (1'.1+2): 249; IR cm-I: 3480, 1670, 1590. Anal. Found: C, 62.98; H, 4.01; N, 5.59. Ca lcd for C I}H I00 2NCI: C, 63.04; H, 4.07; N, 5.66%; mpI 48-49°e.
3-Formyl-4-hydroxy-7 -mcthylquinald inc 3c: IH NMR (COCI3, 400 MHz): 8 2.5 (s, 6H, 2xCH)), 7.6 (d, I H, C6-H, 1= 7. 14 Hz), 7.8 (s, I H, Cx- H), 8.0 (d, I H, C5-H, 1= 8.20 Hz), 9.4 (s, I H, CHO), 15. 1 (bs, I H, OH); MS (70 eV, mlz, M+): 201; IR cm-I: 3350, 1700, 1600. Anal. Found : C, 71.61 ; H, 5.46; N, 6.94. Calcd for C I2H I 102N: C, 7 1.63; H, 5.5 1; N, 6.96%; mp 2 15- 16°e.
4-Chloro-7-methylq ~.linaldinc 4c: IH NMR (COCl), 400 MH z) : 8 2.6 (s, 6H, 2xCH)), 7.3 (s, I H, C}-H), 7.5 (s, I H, Cx-H), 7 .8 (d, I H, C6-H, 1= 7.24 Hz), 8. 1 (d, I H, C5-H, J= 8.06 Hz); IR cm-I: 1585 ; mp 92-93°e.
3-Amino-12-chloro-9-methylquino[3,2-e][I,3]diazocine 12c: IH NMR (COCl), 400 MH z) : 82.5 (s , 3H, CH 3), 4.5 (bs, 2H, NH2), 7. 1-7.9 (m, 6H, Ar- H); MS (70 eV, m/z, M+): 270 (M+2): 272; IR cm-I: 3345, 16 10, 1592. Anal. Found: C, 62.0 I; H, 4.2 1; N, 20.58. Calcd for CI4HIIN4CI: C, 62. 11 ; H, 4.09; N, 20.70%; mp 209-10°e.
4,6-Dichloro-3-formyl-2-(2-hyd roxy-cthene-l-yl)quinoline 2d : IH NMR (COCI), 400MHz): 8 7.3 (d, I H, Cr H, J= 7.68 Hz), 7.5 (d, 1 H, Cx- H, J= 7.96 Hz), 8. 1 (s, I H, C5-H), 9.2 (s , I H, C)-CHO), 9.3 and 9.5 (2s, 2H, vinylic protons), 16.5 (bs, vinylic- OH , 0 20 exchangeable); 13C NMR (COCI3, 400 MH7.): 8 192.27, 189.26, 189.08, 133 .90, 133.2 1, 129.80, 129.04, 124.4 1, 121.13, 120.86, 11 9.87, 118.34; MS
(70 eV, mlz, M+): 267, (M+2): 269, (M+4) : 27 1; IR cm-I: 3470, 1670, 1590. Ana l. Found: C, 53.71; H, 2.65; N, 5.22. Calcd for C I2H70 2 C12: C, 53.76; H, 2.63; N, 5.26%; mp 180-8 1°e.
6-Chloro-3-formyl-4-hydroxyquinaldine 3d : 11-1 NMR (COCl3, 400 MH z): 8 2.5 (s, 3H, CI-h), 7.4 (d, J H, Cr H, J= 8.76 Hz), 7.7 (d, IB, Cs-H , J= 7.64 Hz), 8.2 (s, I H, C5-H), 9.4 (s, I H, CHO), 14.2 (bs, IH , OH); MS (70 eV, mlz, M+): 22 1, (M+2): 223; IR cm· l
: 3480, 171 5, 1595. Anal. Found: C, 59.52; H, 3.57; N, 6.27. Ca lcd fo r CIIHxO:: NCI: C, 59.61; H, 3.64; N, 6.32%; mp 230-3 1 0e.
4,6-Dichloroquinaldine 4d : I H NMR (COCl 3, 400 MHz): 8 2.4 (s, 3H, CH3), 7.4 (s, I H, Cr H), 7.7-8.0 (m, 3H, Ar-I-I); lR cm-I: 1575; mp 74-75°e.
3-Amino-l0,12-dichloroquino[3,2-e ][1,3]diazocine 12d: IH NMR (COCl), 400 MH z): 8 4.8 (bs, 2H, NH2), 7.3-8.2 (m, 6H, Ar-H); MS (70 eV, mlz, M+) : 290 (M+2): 292: (M+4): 294; IR cm-I: 3372, 1620, 1605 . Anal. Found: C, 53.58; H, 2.6:3; N, 19.18. Calcd for CI 3HRN4CI2: C, 53.63; H, 2.77; N, 19.24%; mp 11 5- 16°e.
5,8-Dimethyl-4-chloro-3-formyl-2-(2-hydroxy-ethcne-I-yl)quinoline 2e: IH NMR (COCl), 400 MHz): 82.6 (s, 6H, 2xCH3), 7.6 (d, 1 H, Cn-H, J= 7.46 Hz), 7.9 (d, IH , Cr H, J= 7.96 Hz), 9.3 (s, IH , -CHO), 9.4 and 9.5 (2s, 2H, vinylic protons) , 16.5 (bs, vinyli cOH , 0 20 exchangeab le); I)C NrvtR (COCh, 400
MH z): 8 192.34, 189.38, 189.07 , 144.34, 136.38, 133.86, 130.95, 127.54, 126.01, 123. 11 , 122.45 , 11 8.60, 19.80, 18.95; MS (70 eV, mlz, M+): 26 1 (M+2): 263; IR cm-I: 3525, 1680, 1595. Anal. Found : C, 64.21; 1-1 , 4.5 7; N, S.28. Calcd for C 14H1 20 2NCI: C, 64 .25 ; H, 4.62: N, 5.35 %; mp 170-7 J 0e.
3-Formyl-4-hydroxy-5,8-dimethylquinaldine 3e: IH NMR (CDCI3, 400 MHz): 8 2.7 (s, 9H, 3xCH 3),
7.5 (d, I H, C6-H, J= 7.84 Hz), 7.7 (d, IH , Cr H, J= 7.68 Hz), 9.2 (s, 1 H, CHO), 14.5 Cbs, I H, OH); MS (70 eV, mlz, M+): 2 15; IR cm- I: 35 10, n02, 1610. Ana l. Found: C, 72.47 ; H, 6.0 I; N, 6.42. Calcd fo r C1 3H1 30 zN: C, 72.54; H, 6.09; N,6.5 1%; mp 155-56°e.
4-Chloro-5,8-dimethylquinaldine 4e: IH NMR (COCI), 400 MH z): 8 2.6 (s, 9H, 3xCH)), 7.4 (s, 1 H, Cr H), 7.6-7.8 (m, 2H, Ar-H); IR cm-I: 1580; mp 80-81°e.
3-Amino-12-chloro-8, ll-dimethylquino[3, 2-e] [1,3] diazocine 12e: IH NMR (COCl3, 400 MHz): 8 2.7 (s, 6 H, 2xCH3), 4.6 (bs, 2H, NH::), 6.9-7.8 (m, 5H , Ar- I-I) ; MS (70 eV, mlz, M+): 284 (M+2): 286; IR cn'-
KUMAR et al.: S YNTH ES IS OF QUINODIAZOC IN ES US ING VILSM EIER I-IAAC K REAG ENT 85 1
I: 3295 1589, 1568. Anal. Found: C, 63.1 8; H, 4.51 ; N, 19.76. Cal cd for C ,sHI 3N4CI : C, 63.27; H, 4.60; N, 19.68%: I11p 235-36°C.
Acknowledgement Authors (R.N.K. & T.S. ) thank CSIR, New Delhi
fo r the award of Senior Research Fellowship. The spectra were recorded at SIF, lISe, Bangalore and CDRI , Lucknow.
References I Melh -Cohn 0 & Bramha Narine A, Tetrahedroll Lell , 23, 1978,
2045 . 2 Khan A K & Shoeb A, Illdiall J Chelll , 24 13 , 1985, 62. 3 Bell H L, McG uire M & Free man G A, J Heterocyclic Chelll ,
20, 1983,4 1. 4 Fujisawa T, licla S & Salo T. Chelll Lell, 2713, 1984, 11 73. 5 Venugopal M & Peru mal P T , SYllth COIIIIIIIIII, 2 1, 1991 , 5 15. 6 Adams D R, Dominguez J N & Perez J A, Tetrahedroll Lell, 24,
1983, 5 17. 7 Chancier Rao M S & Kri shna Rao G S, Illdiall J Chelll , 27 13 ,
1998, 2 13.
8 Se lvi S & Peru mal P T , Indian J Chell1, 39B, 2000, 163. 9 Dinakaran K & Pe ruma l P T , Illdian J Chelll , 39 13 , 20CO, 135.
10 Parameswara Reclcly M & Krishn a Rao G S, J Org Chelll, 46 , 1981 , 537 1.
II Alan Kalritzky R, Charles M & Marson M, J Am Chel1l Soc, 105, 1983, 3279.
12 Barnela S 13 & Seshaclri S , fndia ll .I Chem. 25 B, 1986, 709 . 13 HOlvath A, HenTlCCZ I, Podanyi 13 & Meszaros Z, J HeterrxJclic
G elll. 22, 1985, 593. 14 Nohara A, Umetani T & Sanno A, Tetrahed ron. 30, 1974,
3553. 15 Ram Singh R S & Singh M R, fll d iall J Chelll. 39 13 , 2000,
688. 16 Ali Tasneem M M, Rajanna K C & Sai Prakash P K, SYll lell ,
2, 2001 ,251 . 17 Majo V J & Peru mal P T , .I Org Chelll. 63, 1998, 7 136. 18 Akil a S, Majo V J & Balasubramanian K, flldiall J Chelll .
4 113 , 2002, 647. 19 Thamarai Se lvi S & Mohan P S, Z NalLlrfo rsch. 54b, J 999,
1337. 20 Nanclha Kumar R, Suresh T & Mohan P S, Spec Lell. 5, 35.
2002, 74 1. 2 1 Nanclha Kumar R, Suresh T & Mohan P S, A cta Pharlll , 53,
20()3, I .
Top Related