Convergent synthesis and antibacterial activity of pyrazole and pyrazoline derivatives of diazepam

Article abstract of DOI:10.1016/S0928-0987(03)00162-3

Polysubstituted pyrazoles (5)_a-l, pyrazolines (7) _a-c, (8)_a-c and pyrazolotriazine (10) derivatives of diazepam were synthesized. The structures of hitherto unknown compounds were established by analytical and spectral methods. Some of these compounds were screened to test their antibacterial activity against gram-positive (B. subtilis) and gram-negative (P. aeruginosa). All compounds showed potent activity against these bacteria.

Full text of DOI:10.1016/S0928-0987(03)00162-3

European Journal of Pharmaceutical Sciences 20 (2003) 173–179
Convergent synthesis and antibacterial activity of pyrazole and pyrazoline
derivatives of diazepam
Moged A. Berghot∗, Evelin B. Moawad
Chemistry Department, Faculty of Science, Mansoura University, 35516 Mansoura, Egypt
Received 31 December 2002; received in revised form 22 May 2003; accepted 5 June 2003
Abstract
Polysubstituted pyrazoles (5)a–l, pyrazolines (7)a–c, (8)a–c and pyrazolotriazine (10) derivatives of diazepam were synthesized. The structures
of hitherto unknown compounds were established by analytical and spectral methods. Some of these compounds were screened to test their
antibacterial activity against gram-positive (B. subtilis) and gram-negative (P. aeruginosa). All compounds showed potent activity against
these bacteria.
© 2003 Elsevier B.V. All rights reserved.
Keywords: Diazepam; Pyrazoles; Pyrazolines
1. Introduction
2. Experimental
1,4-Benzodiazepines are therapeutically used drugs acting
on the central nervous system (CNS) (Sternbach, 1978). Di-
azepam [7-chloro-1,3-dihydro-1-methyl-5-phenyl-2H-1,4-
benzodiazepin-2-one] (1) is one of these drugs which
is used as an important tranquilizer with a broad spec-
trum (Hoffmann, 1980). Derivatives having heterocyclic
groups incorporated into 1 have become of interest for
their physical (Hara et al., 1978), chemical (Sternbach,
1979) and biological (Stefanovich and Cerprini, 1971)
properties. On the other hand, pyrazoles and pyrazolines
have emerged as analgesic and antiinflammatory drugs
(Teruhisa and Hideo, 1956; Subbanwad and Vibhute,
1992). In view of these observations and in continuation
(Berghot, 1992, 2001) of our work on 1, we therefore
considered it attractive to synthesize some pyrazoles and
pyrazolines incorporated into 1. Hitherto unrecorded 3-[7ꢀ-
chloro-1ꢀ,3ꢀ-dihydro-1ꢀ-methyl-5ꢀ-phenyl-2ꢀH-1ꢀ,4ꢀ-bezodi-
azepin-2ꢀ-one-3ꢀ-yl]-3-oxo-propanenitrile (2) was prepared,
and used as a building block for the synthesis of the title
compounds.
Melting points were measured on a Gallen–Kamp melt-
ing points apparatus. The infrared spectra were recorded in
potassium bromide on a Pye-Unicam SP 3-300 infrared spec-
trophotometer. The 1H and 13C NMR spectra were recorded
in CDCl3 or DMSO-d6 on a Varian Gemini 200 NMR spec-
trometer using TMS as an internal reference. Mass spectra
were recorded on a GCMS-QP 1000 EX mass spectrometer
at 70 eV. Microanalyses were carried out at the Microanalyti-
cal Center, University of Cairo, Egypt. C, H and N analysis
were carried out for all compounds and the results were all
within +0.4% of the theoretical values.
2.1. 3-[7ꢀ-Chloro-1ꢀ,3ꢀ-dihydro-1ꢀ-methyl-5ꢀ-phenyl-2ꢀH-
1ꢀ,4ꢀ-benzodiazepin-2ꢀ-one-3ꢀ-yl]-3-oxopropanenitrile (2)
To a mixture of 1 (0.01 mol) and acetonitrile (0.01 mol)
in dry benzene (200 ml), was added sodium hydride (1.2 g).
The reaction mixture was refluxed for 8 h, then allowed to
cool. The solid that precipitated was collected, washed with
ether and dried. The product was dissolved in water and the
resulting solution was treated with concentrated hydrochlo-
ric acid until it become neutral. The precipitated product was
collected, washed with water, dried and recrystallized from
petroleum ether (60/80 ◦C) to afford 2. Yield, 2.8 g (80%).
m.p. 225–227 ◦C. IR(KBr) ␯: 2240 (C≡N), 1710 (COCH2),
∗
Corresponding author.
E-mail address: dal mag@hotmail.com (M.A. Berghot).
0928-0987/$ – see front matter © 2003 Elsevier B.V. All rights reserved.
doi:10.1016/S0928-0987(03)00162-3

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M.A. Berghot, E.B. Moawad / European Journal of Pharmaceutical Sciences 20 (2003) 173–179
3c: Yield 3.48 g (71%), m.p. 223–224 ◦C, IR(KBr)␯:
3271 (NH), 2218 (C≡N), 1693, 1682 (2C=O), 1640, 1628
(2C=N). 1H NMR (CDCl3): ␦ 2.37 (s, 3H, NCH3), 3.44 (s,
1H, methine-H), 7.00–8.26 (m, 12H, aromatic-H), 12.22 (s,
1H, NH).
1690 (CONCH3), 1640 (C=N) cm−1. 1H NMR (CDCl3): ␦
2.39 (s, 3H, NCH3), 3.21 (s, 1H, methine-H), 4.43 (s, 2H,
CH2), 7.28–8.31 (m, 8H, aromatic-H). MS, m/z (%) 352
(M+, 78.5).
2.2. 5-Amino-3-[7ꢀ-chloro-1ꢀ,3ꢀ-dihydro-1ꢀ-methyl-5ꢀ-
phenyl-2ꢀH-1ꢀ,4ꢀ-benzodiaze-pin-2ꢀ-one-3ꢀ-yl]-1H-
pyrazole (5a) and 5-Amino-3-[7ꢀ-chloro-1ꢀ,3ꢀ-dihydro-
1ꢀ-methyl-5ꢀ-phenyl-2ꢀH-1ꢀ,4ꢀ-benzodiazepin-2ꢀ-one-3ꢀ-
yl]-1-phenylpyrazole (5b)
2.4. 5-Amino-4-arylazo-3-[7ꢀ-chloro-1ꢀ,3ꢀ-dihydro-1ꢀ-
methyl-5ꢀ-phenyl-2ꢀH-1ꢀ,4ꢀ-benzodiazepin-2ꢀ-one-3ꢀ-yl]-
1H-pyrazole (5c–e) and 5-amino-4-aryl-azo-3-[7ꢀ-chloro-
1ꢀ,3ꢀ-dihydro-1ꢀ-methyl-5ꢀ-phenyl-2ꢀH-1ꢀ,4ꢀ-
benzodiazepin-2ꢀ-one-3ꢀ-yl]-1-phenyl pyrazole (5f –h
)
A mixture of the 3-oxopropanenitrile 2 (0.02 mol) and
hydrazine hydrate (1 ml, 80%) or phenylhydrazine (2 ml) in
absolute ethanol (20 ml) was refluxed for 4–5 h. The reaction
mixture was allowed to cool and then diluted with water.
The precipitated solid was collected, washed with water and
dried. Recrystallization from ethanol afforded the pyrazoles
5a and 5b, respectively.
To a solution of the appropriate hydrazone 3a–c (0.01 mol)
in ethanol (20 ml) was added hydrazine hydrate or phenyl
hydrazine (0.01 mol). The reaction mixture was refluxed for
2 h, then cooled. The solid formed was collected, washed
with ethanol, dried and recrystallized from DMF to afford
the corresponding 5c–e and 5f–h, respectively.
5c: Yield 2.91 g (62%), m.p. 281–282 ◦C, IR(KBr)␯: 3360,
3210, 3162 (NH, NH2), 1685 (C=O), 1620, 1610 (2C=N),
1585 (N=N). 1H NMR (CDCl3): ␦ 2.37 (s, 3H, NCH3), 3.45
(s, 1H, methine-H), 7.03–7.98 (m, 13H, aromatic-H), 11.38
(s, 2H, NH2), 12.19 (s, 1H, NH). 13C NMR: ␦ 21.3 (NCH3),
42.6 (C-3 of Diazepam), 106.3 (C-4 of pyrazole), 123–129.2
(aromatic carbons), 132.3 (C-5 of pyrazole), 154.3 (C-3 of
pyrazole), 155.2 (C=N), 162.3 (C=O).
5a: Yield, 2.8 g (78%), m.p. 167–169 ◦C, IR(KBr)␯:
3385, 3210, 3048 (NH2, NH), 1693 (CONCH3), 1638, 1610
(2C=N) cm−1
.
13C NMR (CDCl3): ␦ 20.9 (N–CH3), 41.8
(C3-Diazepam), 105.8 (C4-pyrazole), 124.8–129.7 (aro-
matic carbons, 131.3 (C5-pyrazole), 153.6 (C3-pyrazole),
155.6 (C=N), 161.2 (C=O).
5b: Yield, 3.0 g (69%), m.p. 157–158 ◦C, IR(KBr)␯:
3352, 3110 (NH2, 1695 (C=O), 1635, 1618 (2C=N)
5d: Yield 3.29 g (68%), m.p. 263–266 ◦C, IR(KBr)␯:
3365, 3200, 3150 (NH, NH2), 1690 (C=O), 1625, 1618
(2C=N), 1592 (N=N).
cm−1 1H NMR (CDCl3): ␦ 2.31 (s, 3H, NCH3), 3.26
.
(s, 1H, methine-H), 6.62 (s, 1H, pyrazole H–4), 11.51
(s, 2H, NH2), 7.11–8.58 (m, 13H, aromatic-H). MS,
m/z (%) 442 [M+, 83.3], 401 [M+–(CH=CNH2), 21.5],
365 [M+–(C6H5), 10.2], 351 [M+–(NC6H5), 18.5],
322[M+–(CH=C(NH2)NC6H5), 5.8], 283 [M+–(N-phenyl-
5-amino-pyrazole), 91.3.
5e: Yield 3.63 g (72%), m.p. 281–282 ◦C, IR(KBr)␯: 3358,
3260, 3178 (NH, NH2), 1695 (C=O), 1632, 1622 (2C=N),
1595 (N=N).
5f : Yield 4.42 g (81%), m.p. 315–317 ◦C, IR(KBr)␯:
3350, 3210 (NH2), 1693 (C=O), 1628, 1618 (2C=N), 1592
1
2.3. 2-Arylhydrazono-3-[7ꢀ-chloro-1ꢀ,3ꢀ-dihydro-1ꢀ-
methyl-5ꢀ-phenyl-2ꢀH-1ꢀ,4ꢀ-benzodiazepin-2ꢀ-one-3ꢀ-yl]-
(N=N). H NMR(CDCl3)␦: 2.39 (s, 3H, NCH3), 3.49 (s,
1H, methine-H), 7.21–7.73 (m, 9H, aromatic-H), 7.95–8.52
(m, 9H, aromatic-H), 10.85 (s, 2H, NH2).
3-oxopropanenitriles (3a–c
)
5g: Yield 4.42 g (79%), m.p. >360 ◦C, IR(KBr)␯: 3346,
3280 (NH2), 1685 (C=O), 1630, 1623 (2C=N), 1600
(N=N). MS: m/z (%): 560 [M+, 20%] 441 [(M+–C7H7N2),
65%], 401 [(M+–C9H9N3), 57%], 284 [(M+–C16H14N5),
78%].
To a stirred cold solution of 2 (0.02 mol) in ethanol (30
ml) and sodium acetate trihydrate (2 g), was added the ap-
propriate arene diazonium chloride (0.02 mol) portionwise
over a period of 30 min at 0–5 ◦C. After complete addition,
the reaction mixture was stirred for a further 3 h at 0–5 ◦C.
The solid that precipitated was collected, washed with wa-
ter and dried. Recrystallization from dimethylformamide af-
5h: Yield 5.28 g (91%), m.p. 322–324 ◦C. IR(KBr)␯:
3338, 3229 (NH2), 1692 (C=O), 1632, 1620 (2C=N), 1588
(N=N).
forded the corresponding hydrazones 3a–c
.
3a: Yield 3.46 g (76%), m.p. 173–174 ◦C, IR(KBr)␯:
3283 (NH), 2220 (C≡N), 1690, 1680 (2C=O), 1637, 1622
(2C=N). 1H NMR (CDCl3): ␦ 2.38 (s, 3H, NCH3), 3.34 (s,
1H, methine-H), 6.98–8.23 (m, 13H, aromatic-H), 11.83 (s,
1H, NH).
2.5. 2-Bromo-3-[7ꢀ-chloro-1ꢀ,3ꢀ-dihydro-1ꢀ-methyl-5ꢀ-
phenyl-2ꢀH-1ꢀ,4ꢀ-benzodiazepin-2ꢀ-one-3ꢀ-yl]-3-
oxopropanenitrile (4)
A solution of 2 (0.01 mol) in acetic acid (100 ml) was
treated with Br2 (0.01 mol) in acetic acid (10 ml) dropwise
with constant shaking. After 10 min the solution lightened
in colour. The mixture was poured into a large quantity
of ice-water containing a little sodium carbonate and kept
overnight. The precipitated solid was collected, washed with
3b: Yield 3.19 g (68%), m.p. 182–184 ◦C, IR(KBr)␯:
3256 (NH), 2225 (C≡N), 1695, 1682 (2C=O), 1640, 1633
1
(2C=N). H NMR (CDCl3): ␦ 2.22 (s, 3H, CH3), 2.35 (s,
3H, NCH3), 3.34 (s, 1H, methine-H), 7.18–8.19 (m, 12H,
aromatic-H), 12.10 (s, 1H, NH).

M.A. Berghot, E.B. Moawad / European Journal of Pharmaceutical Sciences 20 (2003) 173–179
175
water, dried and recrystallized from acetic acid to afford the
bromo derivative 4. Yield 3.53 g (82%), m.p. 220–222 ◦C,
IR(KBr)␯: 2225 (C≡N), 1700, 1689 (2C=O), 1635 (C=N).
1H NMR(CDCl3): ␦ 2.38 (s, 3H, NCH3), 3.41 (s, 1H,
methine-H), 6.11 (s, 1H, COCH(Br)CN), 7.23–8.09 (m, 8H,
aromatic-H).MS, m/z (%) 430 (M+, 32), 431 [(M++1), 2],
429 [(M+−1), 1].
aromatic aldehyde (0.02 mol). The reaction mixture was
refluxed for 5 h and acidified with HCl (10%, 5 ml). The solid
that precipitated was collected, washed with water and dried.
Recrystallization from dioxane afforded the corresponding
arylidenes 6a–c
.
6a: Yield 2.50 g (57%), m.p. 168–169 ◦C, IR(KBr)␯: 2200
(C≡N), 1690, 1680 (2C=O), 1640 (C=N) cm−1
.
6b: Yield 3.07 g (68%), m.p. 210–212 ◦C, IR(KBr)␯: 2210
(CN), 1686, 1680 (2C=O), 1642 (C=N). 1H NMR(CDCl3):
␦ 2.31 (s, 3H, CH3), 2.36 (s, 3H, NCH3), 3.31 (s, 1H,
methine-H), 5.21 (s, 1H, ), 7.32–8.62 (br, 12H, aromatic-H).
6c: Yield 3.25 g (69%), m.p. 232–233 ◦C, IR(KBr)␯: 2220
(CN), 1690, 1685 (2C=O), 1640 (C=N). 1H NMR(CDCl3):
␦ 2.36 (s, 3H, NCH3), 2.25 (s, 1H, methine-H), 5.11 (s, 1H,),
7.19–8.43 (m, 12 H, aromatic-H).
2.6. 5-Amino-4-bromo-3-[7ꢀ-chloro-1ꢀ,3ꢀ-dihydro-1ꢀ-
methyl-5ꢀ-phenyl-2ꢀH-1ꢀ,4ꢀ-benzodiazepin-2ꢀ-one-3ꢀ-yl]-
1H-pyrazole (5i) and 5-amino-4-bromo-3-[7ꢀ-chloro-
1ꢀ,3ꢀ-dihydro-1ꢀ-methyl-5ꢀ-phenyl-2ꢀH-1ꢀ,4ꢀ-
benzodiazepin-2ꢀ-one-3ꢀ-yl]-1-phenylpyrazole (5j )
To a solution of 4 (0.01 mol) in ethanol (50 ml) was
added hydrazine hydrate or phenylhydrazine hydrochloride
(0.01 mol). The reaction mixture was refluxed for 5 h, then
left overnight. The solid formed was collected by filtration,
washed with ethanol, dried and crystallized from dioxane to
afford 5i,j, respectively.
2.9. 5-Aryl-4-cyano-3-[7ꢀ-chloro-1ꢀ,3ꢀ-dihydro-1ꢀ-methyl-
5ꢀ- phenyl-2ꢀH-1ꢀ,4ꢀ-benzodiazepin-2ꢀ-one-3ꢀ-yl]-1H-
pyrazoline (7a–c),5-aryl-4-cyano-3-[7ꢀ-chloro-1ꢀ,3ꢀ-
dihydro-1ꢀ-methyl-5ꢀ-phenyl-2ꢀH-1ꢀ,4ꢀ-benzodiazepin-2ꢀ-
5i: Yield 3.51 g (79%), m.p. 180–182 ◦C, IR(KBr)␯:
3105, 3215, 3320 (NH, NH2), 1690 (C=O), 1640, 1637
one-3ꢀ-yl]-1-phenylpyrazoline (8a–c
)
1
(2C=N). H NMR(CDCl3)␦: 2.38 (s, 3H, NCH3), 3.49 (s,
To a solution of 6a–c (0.01 mol) in ethanol (50 ml) was
added hydrazine hydrate (0.01 mol) and drops of acetic acid
(5 ml) or phenylhydrazine hydrochloride (0.01 mol) and
drops of pyridine (5 ml). The reaction mixture was refluxed
for 6 h, then cooled. The solid formed was collected, washed
with ethanol, dried and recrystallized from acetic acid to
afford the corresponding 7a–c and 8a–c, respectively.
7a: Yield 2.39 g (48%), m.p.>360 ◦C, IR(KBr)␯: 3328
(NH2), 1693, 1688 (2C=O), 1640, 1635 (2C=N). 1H
NMR(CDCl3): ␦ 2.36 (s, 3H, NCH3), 3.38 (s, 3H, COCH3),
3.42 (s, 1H, methine-H), 4.53 (s, 2H, CH2PH), 5.24 (s, 1H,
pyrazoline C4-H), 5.62 (s, 1H, pyrazoline C5-H), 7.32–8.3
(m, 13H, aromatic-H), 9.86 (br, 2H, NH2).
1H, methine-H), 7.20–7.98 (m, 8H, aromatic-H), 10.81 (br,
2H, NH2), 11.23 (br, 1H, NH).
5j: Yield 4.27 g (82%), m.p. 196–197 ◦C, IR(KBr)␯:
3210, 3450 (NH2), 1685 (C=O), 1637, 1632 (2C=N).
1H NMR(CDCl3)␦: 2.36 (s, 3H, NCH3), 3.12 (s, 1H,
methine-H), 6.98–8.08 (m, 13H, aromatic-H), 9.78 (br, 2H,
NH2).
2.7. 5-Amino-4-anilino-3-[7ꢀ-chloro-1ꢀ,3ꢀ-dihydro-1ꢀ-
methyl-5ꢀ-phenyl-2ꢀH-1ꢀ,4ꢀ-benzodiazepin-2ꢀ-one-3ꢀ-yl]-
1H-pyrazole (5k) and 5-amino-4-anilino-3-[7ꢀ-chloro-
1ꢀ,3ꢀ-dihydro-1ꢀ-methyl-5ꢀ-phenyl-2ꢀH-1ꢀ,4ꢀ-
benzodiazepin-2ꢀ-one-3ꢀ-yl]-1-phenylpyrazole (5l)
7b: Yield 2.92 g (57%), m.p. 326–327 ◦C, IR(KBr)␯:
3320 (NH2), 1695, 1690 (2C=O), 1637, 1632 (2C=N).
13C-NMR(CDCl3): ␦ 20.3, 22.8, 23.4 (3CH3), 41.3 (di-
azepam C-3), 64.8 (CH2-Ar), 100.1, 111.6 (pyrazoline
C-4, C-5), 123.8–128.7 (aromatic carbons), 153.1, 154.6
(2C=N), 162.1, 170.4 (2C=O).
To a solution of 5i,j (0.01 mol) in dioxane (30 ml) was
added aniline (0.02 mol). The reaction mixture was refluxed
for 8 h. The solid formed was filtered, washed with ethanol,
dried and recrystallized from ethanol to give 5k,l, respec-
tively.
7c: Yield 3.31 g (62%), m.p. >360 ◦C, IR(KBr)␯: 3318
(NH2), 1689, 1680 (2C=O), 1648, 1640 (2C=N). MS,
m/z (%): 534 [(M+), 21], 491 [(M+–(COCH3), 45], 283
[M+-(substituted pyrazoline), 60].
5k: Yield 2.55 g (56%), m.p. 241–243 ◦C, IR(KBr)␯:
3405, 3383, 3210, 2305 (2NH, NH2), 1688 (C=O), 1645,
1638 (2C=N).
5l: Yield 3.19 g (60%), m.p. 283–284 ◦C, IR(KBr)␯:
3320, 3218, 3110 (NH, NH2), 1688 (C=O), 1640, 1636
8a: Yield 3.6 (68%), m.p. 278–280 ◦C, IR(KBr)␯: 2225
(C≡N), 1680 (C=O), 1643, 1646 (2C=N). 1H-NMR
(CDCl3): ␦ 2.34 (s, 3H, NCH3), 3.38 (s, 1H, methine-H),
5.96 (s, 1H, pyrazoline C4-H), 5.43 (s, 1H, pyrazoline
C5-H), 7.12–8.19 (m, 18H, aromatic-H). MS: m/z (%):
530 [(M+)46], 504 [(M+–CN) 32], 283 [M+-(substituted
pyrazoline), 61].
1
(2C=N). H NMR(CDCl3)␦: 2.38 (s, 3H, NCH3), 3.13 (s,
1H, methine-H), 5.65 (br, 1H, NHPh), 7.12–8.38 (m, 18H,
aromatic-H), 11.13 (br, 2H, NH2).
2.8. 2-Arylidene-3-[7ꢀ-chloro-1ꢀ,3ꢀ-dihydro-1ꢀ-methyl-5ꢀ-
phenyl-2ꢀH-1ꢀ,4ꢀ-benzodiazepin-2ꢀ-one-3ꢀ-yl]-3-
8b: Yield 3.2 g (59%), m.p. 263–265 ◦C, IR(KBr)␯:
2220 (C≡N), 1680 (C=O), 1640, 1633 (2C=N). 13C-NMR
(CDCl3): ␦ 20.8, 23.6 (2CH3), 40.9 (diazepam C-3), 108.6
(pyrazoline C-4), 116.2 (C≡N), 124.6–127.9 (aromatic
oxopropanenitriles (6a–c
)
To a stirred solution of 2 (0.02 mol) in ethanol (50 ml) and
potassium hydroxide (0.02 mol), was added the appropriate

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M.A. Berghot, E.B. Moawad / European Journal of Pharmaceutical Sciences 20 (2003) 173–179
carbons), 130.6 (pyrazoline C-5), 153.6, 154.8 (2C=N),
162.8 (C=O).
m.p. 309–311 ◦C, IR(KBr)␯: 3354, 3286 (NH2), 1686, 1680
(2C=O), 1618, 1605 (2C=N). 1H-NMR(DMSO-d6): ␦ 2.32
(s, 3H, NCH3), 3.11 (s, 1H, methine-H), 6.81 (pyrazole H-4),
7.20–8.32 (m, 13H, aromatic-H), 12.21 (s, 2H, NH2).
8c: Yield 3.83 g (68%), m.p. 298–300 ◦C, IR(KBr)␯: 2221
(C≡N), 1680 (C=O), 1638, 1630 (2C=N).
2.10. 3-[7ꢀ-chloro-1ꢀ,3ꢀ-dihydro-1ꢀ-methyl-5ꢀ-phenyl-
2ꢀH-1ꢀ,4ꢀ-benzodiazepin-2ꢀ-one-3ꢀ-yl]-3-oxo-2-[3-phenyl-
1H-pyrazol-5-ylhydrazono]-propanenitrile (9)
3. Results and discussion
3.1. Chemistry
To a cold solution of 2 (0.02 mol) in ethanol (50 ml)
was added 3-phenylpyrazole-5-diazonium salt (0.02 mol)
portionwise with stirring at 0–5 ◦C over a period of 30 min.
After complete addition, the reaction mixture was stirred
for a further 6 h, then kept in an ice-chest for 24 h, and
finally diluted with water. The precipitated solid was col-
lected, washed with water, dried and recrystallized from
dioxane to afford the hydrazone 9. Yield 4.48 g (86%),
m.p. 238–240 ◦C, IR(KBr)␯: 3335, 3280 (2NH), 2210
3-Ethylcarboxylate derivative 1 (Berghot, 2001) was re-
acted with acetonitrile in the presence of sodium hydride in
refluxing benzene to afford 2 in good yield (Scheme 1). Its
IR spectrum revealed two bands at 2240 and 1710 cm−1 due
1
to C≡N and C=O groups, respectively. Also, its H NMR
spectrum displayed a singlet signal at ␦ 4.43 ppm due to ac-
tive methylene protons. Moreover, the mass spectrum of 2
exhibited the molecular ion peak at m/z 352.
(C≡N), 1685, 1693 (2C=O), 1612, 1600 (2C=N) cm−1
.
Reaction of 2 with hydrazines in refluxing ethanol af-
forded the corresponding pyrazoles 5a,b. The IR spectra of
5a,brevealed the absence of C≡N group. Three bands in the
region 3385–3048 cm−1 due to NH and NH2 groups ap-
peared in the IR spectrum of 5a. Whereas, the IR spectrum
of 5b showed only two bands at 3352 and 3110 cm−1 due
1H-NMR(DMSO-d6): ␦ 2.37 (s, 3H, NCH3), 3.28 (s, 1H,
methine-H), 6.38 (s, 1H, pyrazole H4), 7.23–8.50 (m, 13H,
aromatic-H), 9.81 (s, 1H, NH), 10.93 (s, 1H, NH).
2.11. 4-Amino-3-[(7ꢀ-chloro-1ꢀ,3ꢀ-dihydro-1ꢀ-methyl-5ꢀ-
phenyl-2ꢀH-1ꢀ,4ꢀ-benzodiazepin-2ꢀ-one-3ꢀ-yl)carbonyl]-7-
phenylpyrazolo[5,1-c]-1,2,4-triazine (10)
1
to the NH2 group. H NMR spectrum of 5b displayed be-
side the absence of active methylene protons signal, two sin-
glet signals at ␦ 6.62 and 11.51 ppm due to one proton of
pyrazole H-4 and two protons of NH2 group, respectively.
Also, the 13C NMR spectrum of 5a showed three signals at
␦ 153.6, 105.8 and 131.3 ppm characteristic for C3, C4 and
C5 of the pyrazole moiety (Begtrup et al., 1993). Moreover,
A solution of 6 (0.01 mol) in pyridine (20 ml) was re-
fluxed for 5 h, then left to cool. The solid that formed was
filtered off, washed with ethanol and dried. Recrystallization
from dimethylformamide afforded 10. Yield 4.38 g (84%),
Scheme 1.

M.A. Berghot, E.B. Moawad / European Journal of Pharmaceutical Sciences 20 (2003) 173–179
177
the mass spectrum of 5b exhibited the molecular ion peak at
442, in addition to fragment ion peaks at m/z 401, 365, 351,
322 and 283 from extrusion of NH2C=CH, C6H5, NC6H5,
CH=N(NH2)C6H5 and N-phenylaminopyrazole species, re-
spectively.
In an extension to this work, reaction of 2 with aromatic
diazonium salts was investigated. Thus, treatment of 2 with
diazotized aromatic amines in cold ethanol buffered with
sodium acetate at 0–5 ◦C afforded the corresponding hy-
drazones 3a–c (Scheme 1). Its IR spectra showed, bands at
3283–3256, 2225–2218 and 1695–1680 cm−1 due to NH,
CN and CO groups, respectively. Also, its 1H NMR spectra
displayed beside the absence of active methylene protons
signal, singlet signal at ␦ 12.22–11.83 ppm due to hydrazone
NH proton.
5.65 ppm characteristic for the aminoproton of the NHPh
group.
Furthermore, reaction of 2 with aromatic aldehydes
was also investigated. Thus, compound 2 was treated with
aromatic aldehydes in refluxing ethanol and in the pres-
ence of potassium hydroxide to give the corresponding
3-oxo-2-arylidenepropanenitrile derivatives 6a–c. IR spectra
of 6a–c revealed in each case, the presence of conjugated
carbonyl and cyano bands at 1690–1680 and 2200–2210
1
cm−1, respectively. The H NMR spectra of 6b,c displayed
beside the absence of active methylene protons, singlet
signal at ␦ 5.21–5.11 ppm corresponding to methine of
arylidene proton.
Treatment of 6a–c with hydrazine hydrate in acetic acid
or with phenyl hydrazine hydrochloride in pyridine afforded
the N-acetyl-4-arylmethyl-5-amino pyrazoline derivatives
7a–c and N-phenyl-4-cyano-5-aryl pyrazoline derivative
Reaction of hydrazones 3a–c with hydrazines in reflux-
ing ethanol afforded the corresponding 4-arylazo pyrazole
derivatives 5c–h. The IR spectra of 5c–h showed, in each case,
the absence of a nitrile band, in addition to the IR spectra
of 5c–e revealed the appearance of three bands in the region
3365–3150 cm−1 due to NH and NH2 groups and the band
around 1590 cm−1 due to the azo group. Whereas, the IR
spectra of 5f–h showed only two bands at 3350–3210 cm−1
due to the NH2 group and band around 1590 cm−1 due to
8
a–c, respectively, (Scheme 2). The IR spectra of 7a–c
showed in each case, the appearance of amino bands around
3320 cm−1. While, 8a–c showed nitrile bands around 2220
1
cm–1. The H NMR spectrum of 7a displayed character-
istic signals at ␦ 3.38, 4.53, 5.24 and 5.62 ppm due to
COCH3, CH2–Ph, C4–H and C5–H of pyrazoline protons,
respectively, in addition, to a broad signal at ␦ 9.86 ppm
1
1
the azo group. The H NMR spectrum of 5c displayed sin-
due to NH2 protons. Whereas, the H NMR spectra of 8a
glet signals ␦ 12.19 and 11.38 ppm due to one proton of
displayed signals at ␦ 5.96 and 5.43 ppm characteristic
for C4–H and C5–H of pyrazoline protons, the 13C NMR
spectrum of 7b showed signals at ␦ 20.3, 22.8, 23.4, 64.8,
100.1, 111.6 and 153.1 ppm due to CH3, COCH3 N–CH3,
CH2, C-4, C-5 and C-3 of pyrazoline, whereas, 13C NMR
spectrum of 8b showed signals at ␦ 20.8, 118.2, 108.3,
116.8 and 153.6 ppm due to CH3, C≡N, C-4, C-5 and C-3
of pyrazoline, respectively. The mass spectrum of 7c exhib-
ited the molecular ion peak at m/z 534, in addition to two
major fragment ions at 491, and 283 due to [M+–COCH3]
and [M+–(substituted pyrazoline)]. The mass spectrum of
8b exhibited beside the molecular ion peak at m/z 530, the
NH and two protons of NH2 groups, respectively. Whereas,
1
the H NMR spectrum of 5f displayed a singlet signal at ␦
10.85 ppm due to two protons of NH2 group. Additionally,
the mass spectrum of 5g exhibited beside the molecular ion
peak at m/z 560, three major fragment ion peaks at m/z
441, 401 and 284 from extrusion of C7H7N2, C9H9N3 and
C16H14N5 species, respectively.
Further extension to this work, 2 was brominated in
glacial acetic acid to yield the corresponding mono-
1
bromo derivative 4. Its H NMR spectrum displayed be-
side the absence of active methylene protons signal a
singlet signal at ␦ 6.11 ppm due to methine proton of
COCH(Br)CN. Also, the mass spetrum of 4 exhibited
a molecular ion peak at m/z 430, in addition to other
fragment ion peaks at m/z 431 and 429 correspond-
ing to (M++1) and (M+−1) due to bromine isotopes,
respectively.
Refluxing of 4 with equimolar amounts of hydrazines in
ethanol yielded 4-bromopyrazoles 5i,j. The IR spectra of 5i,j
revealed, in each case, the lack of nitrile bands in addition
to the appearance of three amino bands at 3320–3105 cm−1
,
whereas, the IR spectrum of 5j showed two amino bands at
1
3450 and 3210 cm−1. Moreover, H NMR spectrum of 5i
displayed two broad signals at ␦ 10.81 and 11.23 ppm due to
NH2 and NH protons, respectively. Whereas, the only signal
at ␦ 9.78 ppm appeared in the 1H NMR spectrum of 5j due
to NH2 protons.
Reaction of 4-bromopyrazoles 5i,j with aniline in reflux-
ing dioxane yielded the corresponding 4-anilino pyrazoles
1
5
k,l. H NMR spectrum of 5l displayed a broad signal at ␦
Scheme 2.

178
M.A. Berghot, E.B. Moawad / European Journal of Pharmaceutical Sciences 20 (2003) 173–179
Table 1
Diameter of inhibition zone in mm at concentration level of 1 mg/ml as
a criterion of antibacterial activity of some synthesized compounds
Compound
B. subtilis
P. aeruginosa
5a
5b
5c
5d
5e
5f
5g
5h
5i
13.1
8.4
14.3
18.9
7.6
17.8
13.1
18.2
8.9
17.6
3.8
11.3
7.2
11.1
14.2
16.3
13.2
11.1
14.2
16.3
7.8
5j
7a
7b
8a
8c
6.2
16.4
9.7
7.3
16.6
10.8
11.3
Scheme 3.
Table 2
Minimum inhibitory concentration (MIC) of strongly active compounds
in mg/ml
Compound
B. subtilis
P. aeruginosa
fragment ion peaks at 504 and 283 due to [(M+–CN)] and
[M+–(substituted pyrazoline)].
5d
5f
5h
5j
5e
5i
7b
0.4
0.3
0.5
0.6
–
–
–
–
–
0.5
0.4
0.2
Finally, compound 2 treated with 3-phenyl pyrazole-5-
diazonium salt (Elagamey and El-Taweel, 1991) in cold
ethanol in the presence of sodium acetate furnished
3-oxo-2-(3ꢀ-phenyl-1ꢀH pyrazol-5ꢀ-ylhydrazono)propanenit-
rile derivative (9). The latter hydrazone 9 underwent in-
tramolecular cyclization when refluxed in pyridine to give
the pyrazolo[5,1-c]-1,2,4-triazine (Elghandour et al., 1992)
derivative 10 (Scheme 3). IR spectrum of 9 showed bands
at 3335, 3280, 2210, 1685, 1678, 1612 and 1608 cm−1
assignable to 2NH, CN, 2CO and 2C=N groups, respec-
–
0.3
standard compound. The minimal inhibitory concentration
(MIC) of the strongly active compounds were also measured
and listed in Table 2. The data obtained from Tables 1 and 2
shows that pyrazoline compound 7b exhibits potent activ-
ity against B. subtilis and P. aeruginosa. While, the pyra-
zole compounds 5d,f,h,j, and 5e,i shows potent activity with
certain selectivity against (B. subtilis) and (P. aeruginosa),
respectively.
1
tively. Also, H NMR spectrum of 9 displayed beside the
absence of active methylene protons three singlet signals
at ␦ 10.93, 9.81 and 6.38 ppm due to 2NH and H-4 of
pyrazole moiety, respectively. The lack of CN band in IR
spectrum of 10 and the appearance of both NH2 and CO
bands at 3354–3286 and 1650 cm−1, respectively, sup-
port the assignment of structure 10 and rule out the other
1
possible structure 11 depicted in Scheme 3. Moreover, H
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