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Synthesis Of 1,5-Benzodiazepine DerivativesJung Dai-Il a , Choi Tae-wonchoi a , Kim Yun-Younga , Kim In-Shik a , Park You-Mi a , Lee Yong-Gyun a &Jung Doo-Hee aa Department of Chemistry College of NaturalSciences, Dong-A University 840, Hadan-Dong, Saha-Gu, Pusan, Korea, 604-714Published online: 17 Sep 2007.
To cite this article: Jung Dai-Il , Choi Tae-wonchoi , Kim Yun-Young , Kim In-Shik , Park You-Mi , Lee Yong-Gyun & Jung Doo-Hee (1999): Synthesis Of 1,5-Benzodiazepine Derivatives, Synthetic Communications: An International Journal forRapid Communication of Synthetic Organic Chemistry, 29:11, 1941-1951
To link to this article: http://dx.doi.org/10.1080/00397919908086183
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SYNTHETIC COMMUNICATIONS, 29( 1 l), 1941-1951 (1999)
SYNTHESIS OF 1,s-BENZODIAZEPINE DERIVATIVES.
Dai-11, J u n i - Tae-Won, Choi - Yun-Young, Kim - In-Shik, Kim *
You-Mi, Park - Yong-Gyun, Lee * Doo-Hee, Jung
Department of Chemistry College of Natural Sciences, Dong-A University 840, Hadan-Dong, Saha-Gu, Pusan, Korea 604-7 14
Abstract : 2,4,4-Trimethyl-3H-S-hydr~.1,5-benzodiazepine was obtained by the reaction of o-phenylenediamine and acetonedicarboxylic acid (or acetone) in various methods (Method 1, 2, 3). When 0-phenylenediamine was heated with acetophenone in the presence of PPA (or SO), 2,4-diphenyl4methyl-3H-5-hydrc+1,5-benzodiazepine 5 was isolated (Method 4).
The benzodiazepines have various therapeutic applications, many being
are anticonvulsants and used for inducing sleep. Diazepam and nitrazepam
flurazepam is both an antianxiety agent and a potent hypnotic',2.
In addition to the 1 ,4-benzodiazepines, 5-aryl-l,5-benzodiazepines with
the general fomular 1 have also recently been used. They possess a
activity spectrum similar to the 5-aryl- 1,4-benz~diazepines~.
Author to whom correspondence should be addressed.
Copyright 0 1999 by Marcel Dekker, Inc.
1941
www.dekker.com
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1942 JUNG ET AL.
Merchant et a1 showed4 that the reaction of o-phenylenediamine with
acrylic acid in the presence of polyphosphoric acid (PPA) gave
benzodiazepinone 2 and pyridobenzodiazepinone 3. Recently Kalyanam et a1
reported the correct structure of pyridobenzodiazepinone 3 formed in the
reaction of o-phenylenediamine with acrylic acid catalyzed by PPASS6.
However the reaction of o-phenylenediamine with acrylic acid in the
presence of acetonedicarboxylic acid instead of PPA as catalyst only resulted
in the formation of 2,4,4-trimethyl-3H-5-hydro-1,5-benzodiazepine. In view of
this interesting result, we report the synthesis of 1,s-benzodiazepine
derivatives by using various reagents instead of PPA.
When o-phenylenediamine was treated with acrylic acid in the presence
of acetonedicarboxylic acid at room temperature for 3hrs, a yellow
crystalline solid, 4 was isolated (86%) (Method 1). It's structure was
assigned on the basis of NMR which showed a singlet at 6 1.33 and 6 2.36
for two methyl protons and one methyl protons respectively. C3-Methylene
protons show at 62.22, and N5 proton appears at 6 2.97. MS displayed a
protonated molecular ion at m/. 188 corresponding to the molecular formular
CIZHI~NZ. From these observations, this product was proposed to have the
structure of 2,4,4-trimethyl-3H-5-hydro- 1,5-benzodiazepine 4. Similar results
were obtained when PPA (isolated yield, 94%), or SiOz (isolated yield,
93%) were added to the reaction mixture.
Treatment of o-phenylenediamine with acetonedicarboxylic acid at room
temperature in the presence of PPA (or SiOz, or HC1) afforded 4 in
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1,5-BENZODIAZEPINE DERIVATIVES 1943
excellent yield (Method 2). Also, treatment of o-phenylenediamine with
acetone at room temperature in the presence of PPA (or SiOz, or
CHFCHCOOH, or CH2=CHCOOH and PPA, or CHz=CHCOOH and Si02)
afforded 4 in excellent yield (Method 3). As shown in method 1 (B)
and method 3 (D; c, d, e), these results indicate that the reactant is not
CHz=CHCOOH but acetonedicarboxylic acid (or acetone) because the product
is 2,4,4-trimethyl-3H-5-hydro-l,5-benzodiazepine 4 (Scheme 1).
A possible mechanism for the formation of 1,5-benzodiazepine is shown
Figure 1. Amine of o-phenylenediamine attacks carbonyl group of ketone,
giving the intermediate diimine A. A 1,3 shift of the hydrogen attached
methyl group then occurs to afford an isomeric enamine B which cyclizes to
produce seven-membered ring (Figure I ) .
C
1,5-Benzodiazepines
Figure 1. Possible mechanism for the formation of 1J-benzodiazepines.
However, the reaction of o-phenylenediamine with 2-ketoglutaric acid in
the presence of CHz=CHCOOH and PPA (or CHFCHCOOH and SiOz) did
not occur. When o-phenylenediamine was heated with acetophenone in the
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a a. CHz=CHCOOH Isolated Yield = 88 %
c. CH~=CHCOOH, SiOz Idated ~ ~ ~ 9 3 % b. CHz=CHCOOH. PPA Isdated Yield=w%
4
a. cnci3. PPA IdEted Yield = 91 % b. cnC13. Si02 Isolated Yield 5 89 % C. CHCIs. HCI Iddated Ysld=97%
4
'a. PPA b. SiO2 C. CHz=CHCOOH d. CHz=CHCOOH. PPA e. CH~=CHCOOH, sioz
Isolated Yield = 96 % Isolated Yiald = 95 % Isolated Yiald = 88 % lnolated Yidd = 93 % Isolatsd Yidd = 90 %
+ o=c aNHz 'CH3 D NHZ
E 40-45" C
5 'a. PPA b. Si02
ladated Yicld = 48 % Isolated Yield = 42 %
Scheme 1.
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1,5-BENZODJAZEPINE DERIVATIVES 1945
presence of PPA (or SiOz) at 4O-5O0C, a yellow crystalline solid, 2,4-di-
phenyl-4-methyl-3H-5-hydro-1,5-benzodiazepine 5 was isolated.
EXPERIMENTAL SECTION
Melting points were determined on an electrothermal capillary melting
point apparatus and uncorrected. TLC was performed on glass plates coated
with silicon oxide (silica gel 60F254) and compounds were visualized using a
uv lamp. Proton nuclear magnetic resonance and I3C NMR spectra were
obtained with Bruker AC 200 (200MHz) and Varian Gemini (200MHz)
spectrometers. Mass spectra were measured with HP 589011 GC/Mass (70eV,
EI). The organic solvents and chemicals were obtained from commercial
products and purified by the appropriate methods before use.
Reaction of o-phenylenediamine with acrylic acid in the presence of
PPA(Method 1-A-a) : o-Phenylenediamine (5.4 g, 5 x lo-* mol) and acrylic
acid (8.6 g, 12 x lo-' mol) were added to PPA (1.5 g) previously heated to
100°C. The reaction mixture was refluxed for further 3hrs, cooled to room
temperature and decomposed with ice and water. The aqueous solution was
extracted with chloroform. The chloroform extract washed with water (30
mL), then with 5% NaHC03 (100 mL) and again with water (30 mL). The
organic layer was dried (Na2S04), filtered and concentrated. The residue was
chromatographed on a silica gel (n-hexane : ethyl acetate : CHzCh = 2 : 1
: 1, v/v/v) to yield benzodiazepinone z4 (4.13 g, 51%) as a white crystalline
solid.: mp 146-147°C; IR (KBr) 3400 (s , N-H), 3100 (aromatic C-H), 2900
(aliphatic C-H), 1675 (C=O), 730 (=CH, aromatic OOP) a i l ; 'H NMR
(CDCl3) 6 2.7 (t, CH2, 2H), 3.68 (t, CH2, 2H), 3.85 ( s , NH, lH), 6.6-7.0
(m, ph, 4H), 8.11 (s, NH, 1H); I3C NMR (CDC13) 6 173.26, 138.73,
126.29, 125.20, 122.11, 120.40, 119.75, 45.39, 36.24; Mass (70eV), mlz (rel.
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1946 JUNG ET AL.
Int, %) 162 ( l lS) , 145 (5.8), 133 (3.8), 119 (loo), 107 (21.2), 92 ( l lS) ,
80 (6.7), 65 (11.5)
Reaction of o-phenylenediarnine with acrylic acid in the presence of SiOz
(Method I-A-b) : A mixture of o-phenylenediamine (5.4 g, 5 x mol) and
acrylic acid (8.6 g, 12x lo-' mol) added Si02 (1.5 x lo-' g) was stirred and
reflwed. Heating was continued for further 3hrs, the dark brown solution
cooled to room temperature, diluted with chloroform and filtered of Si02.
The filtered solution was washed with water and neutralized with NaHC03
(100 mL). The organic layer was dried (MgS04) and concentrated. The
residue was chromatographed on a silica gel (n-hexane : ethyl acetate :
CHIC12 = 2 : 1 : 1, v/v/v) to yield benzodiazepinone 2 (4.2 g, 52%) as a
white crystalline solid.
Reaction of o-phenylenediamine with acetonedicarboxylic acid in the
presence of acrylic acid (Method I-B-a) : o-Phenylenediamine (5.4 g, 5 x
lo-* mol) and acetonedicarboxylic acid (14.6 g, 10 x 10-2mol) added acrylic
acid (8.6 g, 1 2 x lo-' mol) was stirred. The reaction mixture was stirred at
room temperature for 3hrs, diluted with water and neutralized with aq.
NaOH. It was extracted with chloroform (3 x 100 mL), the extract washed
with water and dried (NazS04). Removal of chloroform gave
2,4,4-trimethyl-3H-5-hydro-1,5-benzodiazepine 47 a yellow solid (8.08 g,
86%) which crystallized from n-hexane.: m.p 147-148°C; IR (KBr) 3275 (s,
N-H), 3070 (aromatic, C-H), 2930 (aliphatic, C-H), 1660 (s, C=H); 'H NMR
(CDCl3) 6 1.35 ( s , CH3, 6H), 2.25 ( s , CH2, 2H), 2.35 ( s , CH3, 3H), 3.01
(s, NH, lH), 6.8-7.2 (m, ph, 4H); 13C NMR (CDCL) 6 172.37, 140.75,
137.85, 126.77, 125.44, 122.04, 121.69, 68.38, 45.02, 30.43, 29.83; Mass (70
eV), ndz (rel. Int, %) : 188 (35.6), 173 (loo), 158 (0.38), 132 (61.5), 117
(5.Q 92 (115), 77 (7.7), 65 (11.5). Anal. Culcd for C I ~ H M N ~ : C, 76.59; H,
8.51; N, 14.89. Found: C, 76.30; H, 8.63; N, 14.80.
Reaction of o-phenylenediamine with acetonedicarboxylic acid in the
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1.5-BENZODIAZEPINE DERIVATIVES 1947
presence of acrylic acid and PPA (Method I-B-6) : o-Phenylenediamine
(5.4 g, 5 x lo-’ mol) and acetonedicarboxylic acid (14.6 g, l o x 10’ mol)
were added to a mixture of acrylic acid (8.6 g, 12 x 10’ mol) and PPA
(1.52 g). The reaction mixture was stirred at room temperature for 3hrs,
diluted with water and neutralized with aq. NaOH. The aqueous solution
was extracted with chloroform (3 x 100 mL). The chloroform extract washed
with water and was dried (MgS04). The chloroform was removed under
aspirator pressure and the remaining sticky oil was separated by flash
column chromatography on a silica gel (n-hexane : ethyl acetate = 5 : 1,
v/v) to yield 2,4,4-trimethyl-3H-5-hydro-1,5-benzodiazepine 4 (8.83 g, 94%)
as a yellow solid.
Reaction of o-phenylenediamine with acetonedicarboxylic acid in the
presence of acrylic acid and SiOz (Method 1-B-c) : A mixture of
o-phenylenediamine (5.4 g, 5 x 10” mol) and acetonedicarboxylic acid (14.6
g, l o x lo-’ mol) added acrylic acid (8.6g, 12x 10.’ mol) and Si02 ( 1 . 5 ~
lo-’ g) was stirred at room temperature for 3hrs. The reaction mixture was
diluted with water and chloroform, then filtered off Si02. After the filterate
was separated, the chloroform extract washed with water and was dried
(MgS04). The chloroform was removed under aspirator pressure and the
remaining sticky oil was separated by flash column chromatography on a
silica gel (n-hexane : ethyl acetate = 5 : 1, v/v) to yield 2,4,4-trimethyl-3H-
5-hydro-l,5-benzodiazepine 4 (8.73 g, 93%) as a yellow solid.
Reaction of o-phenylenediamine with acetonedicarboxylic acid in the
presence of PPA (Method 2-C-a) : A solution of o-phenylenediamine (5.4 g,
5 X lo‘* mol) and acetonedicarboxylic acid (14.6 g, 10 x lo-’ mol) in chloro-
form (15 mL) added PPA (1.5 g) was stirred. The reaction mixture was
stirred at room temperature for 3hrs, diluted with water and neutralized with
5% NaHCO3 (50 A). It was extracted with chloroform (3x70 mL), the
extract washed with water and dried (NazSO4). The organic layer was
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1948 JUNG ET AL.
filtered and concentrated. The residue was chromatographed on a silica gel
(n-hexane : ethyl acetate = 5 : 1, v/v) to yield 2,4,4-trimethyl-3H-5-hydro-
1,5-benzodiazepine 4 (8.53 g, 91%) as a yellow solid.
Reaction of o-phenylenediamine with acetonedicarboxylic acid in the
presence of SiOt (Method 2-C-b) : A solution of o-phenylenediamine (5.4 g,
5 x mol) and acetonedicarboxylic acid (14.6 g, 10 x lo-’ mol) in
chloroform (15 mL) added SiO2 (0.15 g) was stirred at room temperature
for 3hrs. The reaction mixture was diluted with water and neutralized with
5% NaHCO3 (30 mL), then filtered off Si02. The aqueous solution was
extracted with chloroform (3 x 70 mL). The chloroform extract washed with
water (30 mL) and dried (MgS04). The organic layer was concentrated.
Removal of chloroform gave 2,4,4-trimethyl-3H-5-hydro-l,5-benzodiazepine 4
as a yellow solid (8.36 g, 89%) which crystallized from n-hexane.
Reaction of o-phenylenediamine with acetonedicarboxylic acid in the
presence of HCl (Method 2-C-c) : A solution of o-phenylenediamine (5.4 g,
5 x 10’ mol) and acetonedicarboxylic acid (14.6 g, 10 X loe2 mol) in
chloroform (15 mL) added 10% HCl (2 mL) was stirred. The reaction
mixture was stirred at room temperature for 8hrs. The mixture was extracted
with 10% aq. NaHCO3. The residue was chromatographed on a silica gel
(n-hexane : ethyl acetate = 5 : 1, v/v) to yield 2,4,4-trimethyl-3H-5-hydro-
1,5-benzodiazepine 4 (9.1 1 g, 97%) as a yellow solid.
Reaction of 0-phenylenediamine with acetone in the presence of PPA
(Method 3-D-a) : A solution of o-phenylenediamine (5.4 g, 5 x 10” mol)
and acetone (20 g, 3 X lo-’ mol) added PPA (0.16 g) was stirred at room
temperature for 3hrs. The reaction mixture was stirred with water and
neutralized with 5% NaHC03 (50 mL). It was extracted with chloroform (3
xlOOnL), the extract washed with water and dried (MgSO4). The organic
layer was concentrated. Removal of chloroform gave 2,4,4-trimethyl-3H-
5-hydro-l,5-benzodiazepine 4 as a yellow solid (9.02 g, 96%) which
crystallized from n-hexane.
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1,5-BENZODIAZEPINE DERIVATIVES 1949
Reaction of o-phenylenediamine with acetone in the presence of SiOz
(Method 3-D-b) : In a solution of o-phenylenediamine (5.4 g, 5 X l o 2 mol)
and acetone (20 g, 3 x 10' mol), catalyst quantity 0.15g of Si02 was added
and stirred at room temperature for 3hrs. The reaction mixture was diluted
with water and neutralized with 10% HC1 (30 mL). The aqueous solution
was extracted with chloroform (3 x 100 mL). The chloroform extract washed
with water and was dried (MgS04). The chloroform was removed under
aspirator pressure. Removal of chloroform gave 2,4,4-trimethyl-3H-5-hydro-
1,5-benzodiazepine 4 as a yellow solid (8.90 g, 95%) which crystallized
from n-hexane.
Reaction of o-phenylenediamine with acetone in the presence of acrylic
acid (Method 3-D-c) : A solution of o-phenylenediamine (5.4 g, 5 x lom2
mol) and acetone (20g, 3 x lo-' mol) added acrylic acid (5 mL) was stirred
at room temperature for 3hrs. The reaction mixture was diluted with water
and neutralized with 5% NaHCO3 (50 mL). It was extracted with chloroform
(3x100 mL), the extract washed with water and dried (MgS04). The
organic layer was concentrated. Removal of chloroform gave 2,4,4-trimethyl-
3H-5-hydro-1,S-benzodiazepine 4 as a yellow solid (8.26 g, 88%) which
crystallized from n-Hexane.
Reaction of o-phenylenediamine with acetone in the presence of acrylic
acid and PPA (Method 3-D-d) : o-Phenylenediamine (5.4 g, 5~ lo-* mol)
and acetone (20 g, 3 X 10'mol) were added to a mixture of acrylic acid ( 5
mL) and PPA (1.5 g). The reaction mixture was stirred at room temperature
for 3hrs, diluted with water and neutralized with aq. NaOH. The aqueous
solution was extracted with chloroform (3 x 100 mL). The chloroform extract
washed with water and was dried (MgS04). The chloroform was removed
under aspirator pressure and the remaining sticky oil was separated by flash
column chromatography on a silica gel (n-hexane : ethyl acetate = 5 : 1,
v/v) to yield 2,4,4-trimethyl-3H-5-hydro-1,5-benzodiazepine 4 (8.738, 93%) as
a yellow solid.
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1950 JUNG ET AL.
Reaction of o-phenylenediamine with acetone in the presence of acrylic
acid and Si02 (Method 3-D-e) : A solution of o-phenylenediamine (5.4 g, 5
x 10' mol) and acetone (20 g, 3 x lo-' mol) added acrylic acid (5 A) and
SiOz (0.15 g) was stirred at room temperature for 3hrs. The reaction mixture
was diluted with water and neutralized with 5% NaHC03 (30 mL), then
filtered off SiOz. The aqueous solution was extracted with chloroform. The
chloroform extract washed with water (30 mL) and dried (MgS04). The
organic layer was concentrated under aspirator pressure. Removal of
chloroform gave 2,4,4-trimethyl-3H-5-hydro- 1,5-benzodiazepine 4 as a yellow
solid (8.45 g, 90%), which crystallized from n-Hexane.
Reaction of o-phenylenediamine with acetophenone in the presence of PPA
(Method 4-E-a) : A solution of o-phenylenediamine (2.7 g, 2.5 x mol)
and acetophenone (8.67 g, 7 x 10-I mol) added PPA (0.63g) was stirred at
4O-5O0C for 5hrs. The reaction mixture was diluted with water and
neutralized with 5% NaHC03 (50 mL). It was extracted with chloroform (3
x 100 A), the extract washed with water and dried (MgS04). The
chloroform was removed under aspirator pressure arid the remaining sticky
oil was separated by flash column chromatography on a silica gel (n-hexane
: ethyl acetate = 8 : 1, v/v) to yield 2,4-diphenyl-4-methy1-3H-5-hydro-l,5-
benzodiazepine 5' (3.57g, 46%) as a yellow crystalline solid.: mp 151-152OC;
'H NMR (CDCh) 6 1.75 ( s , CH3, 3H), 2.93 and 3.10 (d, CHI, 2H, J =
0.17 Hz) or 2.99 and 3.16 (d, CH2, 2H, J = 0.17 Hz) 3.15 (s, NH, lH),
6.80-7.62 (m, phenyl, 14H); Mass (70eV), m/z (rel. Int, %) 312 (9.6), 310
(14.4), 295 (100). Anal, Calcd for CIZHI~NI : C, 84.60; H, 6.41; N, 8.97.
Found: C , 83.89; H, 6.83; N, 8.51.
Reaction of o-phenylenediamine with acetophenone in the presence of SiOz
(Method 4-E-b) : In a solution of o-phenylenediamine (2.70 g, 2.5 x lo-'
mol) and acetophenone (8.67 g, 7 x lo-' mol), catalyst quantity 0.08 g of
Si02 was added and stirred. The reaction mixture was stirred at 40-5O'C for
5hrs. The mixture was extracted with 10% aq. NaHCO3. The organic layer
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1,s-BENZODIAZEPINE DERIVATIVES 195 1
was dried (MgSO& filtered and concentrated. The residue was chromato-
graphed on silica gel (n-hexane : ethyl acetate = 8 : 1, v/v) to yield 2,4-di-
phenyl-4-methyl-3H-5-hydro- 1,5-benzodiazepine 5 (3.28 g, 42%) as a yellow
crystalline solid.
ACKNOWLEDGEMENT
This work was partially supported by the Korean Ministry of Education
(BSRI-97-3446) and office of Research of Dong-A University (1998).
REFERENCES
1. Randall, L. 0. and Kappell, B. "The Benzodiazepines", ed. Garattini, S.
Mussini, E. and Randall, L. 0. Raven Press, New York, 1973, pp.27 and
review articles cited therein.
2. Kyburz, E. "Medicinal Chemistry Advaces", ed. F. G. de las Heras
and Vega, S.; Pergamon, Oxford, 1981; pp. 355.
3. Roth, H. J., Eger, K. and Troschutz, R. "Drug Synthesis,
Pharmaceutical Chemisty", Ellis Honvood Limited : England, 1988.
4. Merchant, J. R., Chotia, D. S., Indian J. Chem., 1975, 8, 814.
5. Patar, S., Bentov, M., Reichmann, M. E., J. Am. Chem. SOC., 1952, 74,
845.
6. Kalyanarn, N., Manjunatha, S. G., Indian J. Chem., 1991, 9, 892.
7. Morales, H. R., Bulbarela, A. Contreras, R., Heterocycles, 1986, 24, 1,
135-139.
8. Herbert, John A. L., Suschitzky, H., J. Chem. SOC., Perkin Trans. I
1974, 23, 2657-2661.
(Received in the USA 09 November 1998)
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