Synthesis of new benzotriazepin-5(2H)-one derivatives of expected antipsychotic activity

Article abstract of DOI:10.1007/s00044-012-0102-2

A new series of 3,4-dihydro-1H-benzo[e][1,2,4]triazepin-5(2H)-one derivatives were synthesized by cyclocondensation of benzohydrazides (II, IX), derived from the reaction of N-methyl-isatoic anhydride with phenyl hydrazine and isonicotinic acid hydrazide, respectively, with formaldehyde, aromatic aldehydes in acidic medium or with carbon disulfide in alkaline medium, the last reaction was only carried out with benzohydrazide II. Benzotriazepinone derivatives IV,V _a-h,VI, and XI were subjected to ptosis test using clozapine as a reference drug to evaluate their antipsychotic activity. It was found that 2-thioxobenzotriazepinone VI had the same antipsychotic activity as reference drug clozapine but with lesser side effects whereas it showed nonsignificant CNS depressant activity upon using forced swim pool test as well as no neurotoxicity when tested in mice using rotarod or horizontal screen tests. Graphical Abstract: A new series of benzotriazepin-5(2H)-ones (IV,V _a-h, VI, and XI) were prepared starting from isatoic anhydride and their antipsychotic activity revealed that 2-thioxobenzotriazepinone VI was superior to the reference drug clozapine.[Figure not available: see fulltext.]

Full text of DOI:10.1007/s00044-012-0102-2

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res (2013) 22:1488–1496
DOI 10.1007/s00044-012-0102-2
ORIGINAL RESEARCH
Synthesis of new benzotriazepin-5(2H)-one derivatives of expected
antipsychotic activity
•
Samy M. Ibrahim Mohamed M. Baraka
•
•
Osama I. El-Sabbagh Hend Kothayer
Received: 6 February 2011 / Accepted: 22 May 2012 / Published online: 20 June 2012
Ó Springer Science+Business Media, LLC 2012
Abstract A new series of 3,4-dihydro-1H-benzo[e][1,2,4]
triazepin-5(2H)-one derivatives were synthesized by cyclo-
condensation of benzohydrazides (II, IX), derived from the
reaction of N-methyl-isatoic anhydride with phenyl hydrazine
and isonicotinic acid hydrazide, respectively, with formal-
dehyde, aromatic aldehydes in acidic medium or with carbon
disulfide in alkaline medium, the last reaction was only car-
ried out with benzohydrazide II. Benzotriazepinone deriva-
tives IV,Va–h,VI, and XI were subjected to ptosis test using
clozapine as a reference drug to evaluate their antipsychotic
activity. It was found that 2-thioxobenzotriazepinone VI had
the same antipsychotic activity as reference drug clozapine
but with lesser side effects whereas it showed nonsignificant
CNS depressant activity upon using forced swim pool test as
well as no neurotoxicity when tested in mice using rotarod or
horizontal screen tests.
Fischer et al., 1984), anticancer (Kim and Taylor, 1992), CCK2
antagonist (Spencer et al., 2008), and anti-inflammatory
´
(Fernandeza et al., 2004; Kaur and Talele, 2008) activities.
Benzotriazepine class is one of the most common clas-
ses which constitute our interest due to their CNS activity
and their use as psychoactive agents (Britton and Trepa-
nier, 1980). It was reported that compounds 1 and 2 are
useful as neuroleptic agents in the treatment of psychotic
disturbances such as schizophrenia (Fischer et al., 1984).
R2
N
O
N
H
N
N
R1
R1
R4
R4
N
N
N
H
N
Keywords Synthesis ꢀ Benzotriazepin-5(2H)-one ꢀ
Antipsychotic activity ꢀ Clozapine
R3
(1)
(2)
R1,R4=H, halogen,alkyl,alkoxy
R2=H, alkyl
Introduction
R3=H, alkyl, alkenyl or benzyl
In view of these observations, we herein report the syn-
Benzotriazepines are rarely mentioned in the literature and
found to have various pharmacological activities among of
which, central nervous system (Britton and Trepanier, 1980;
thesis of some new benzotriazepin-5(2H)-ones derivatives
hoping to be clozapine-like but with lower side effects.
S. M. Ibrahim ꢀ M. M. Baraka ꢀ H. Kothayer
Department of Medicinal Chemistry, Faculty of Pharmacy,
Zagazig University, Zagazig, Egypt
Materials and methods
Chemistry
e-mail: dr-samy2010@hotmail.com
O. I. El-Sabbagh (&)
Melting points were determined with a Gallenkamp melting
point apparatus (London, UK), and are uncorrected. IR
spectra (KBr, cm-1) were recorded on a Bruker Vector,
Department of Pharmaceutical Chemistry, Faculty of Pharmacy,
Taif University, 888 Al-Haweiah, Taif 21974, Saudi Arabia
e-mail: osamaelsabbagh@yahoo.com; o.elsabbagh@tu.edu.sa
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Med Chem Res (2013) 22:1488–1496
1489
1
22FT-IR Spectrometer (Bavaria, Germany). HNMR spec-
tra were recorded on Varian Gemini-200 (200 MHz) Spec-
trometer (CA, USA) using DMSO-d6 as a solvent and
tetramethylsilane (TMS) as an internal standard (Chemical
shift in d, ppm). Electron impact mass spectra were deter-
mined at 70 eV using a GC/MS Shimadzu QP1000EX
Spectrometer (Tokyo, Japan).Elemental analyses were
determined using Heraeus or Vario EL-III (Elemntar) (Ha-
nau, Germany) or Perkin Elmer Model 2400 (USA) CHN
analyzers at the National Research Center and Microana-
lytical Center, Faculty of Science, Cairo University, Egypt.
All the results of the elemental analyses were in an
acceptable error range. Thin layer chromatography (TLC)
was performed on silica gel G for TLC (Merck), and spots
were visualized by iodine vapors or by irradiation with
ultraviolet light (UV; 254 nm). All chemicals were pur-
chased from Sigma Chemical (St. Louis, MO, USA).
glacial acetic acid were added. The reaction mixture was
stirred at room temperature for 2 h and then poured into
water (100 ml). The separated solid was filtered, dried, and
crystallized from ethanol to give the titled compound;
yield: 43.5 %; m.p. = 198–199 °C. IR: m = 3163 (NH),
3040 (CH, aromatic), 2980 (CH, aliphatic), 1651 (CO),
1493 (C=C) cm-1; 1HNMR: d = 3.08(s, 3H, N CH3), 5.12
(s, 2H, CH2N), 6.61–7.77 (m, 9H, ArH), 10.03 (s, 1H, NH,
exch.) ppm MS m/z (rel.int.) = 255 (M? ? 2, 2.1), 254
(M??1, 2.7), 253 (M?, 8.6), 134 (14.8), 77 (100). Analysis
for C15H15N3O (253.30): Calcd: C, 71.13; H, 5.97; N,
16.59. Found: C, 70.88; H, 5.59; N, 16.27 %.
General procedure for preparation of compounds (Va–h
)
A mixture of benzohydrazide II (2.41 g, 0.01 mol) and the
appropriate aromatic aldehyde (0.01 mol) in glacial acetic
acid (20 ml) was heated under reflux for 6 h. The reaction
mixture was concentrated to half volume and poured into
cold water (100 ml). The separated solid was filtered,
dried, and crystallized from suitable solvent to give the
titled compounds.
2-(Methylamino)-N0-phenylbenzohydrazide (II)
To a mixture of N-methyl isatoic anhydride I (8.85 g,
0.05 mol) and phenyl hydrazine (6.48 g, 0.06 mol) in
ethanol (50 ml), ten drops glacial acetic acid was added.
The mixture was refluxed for 2 h, concentrated to half
volume and then cooled. The separated solid was filtered
and crystallized from aqueous ethanol to give the titled
compound; yield: 85 %; m.p. = 132–134 °C as reported
(Pestellini et al., 1978; Schuler et al., 2006).
1-Methyl-2,3-diphenyl-3,4-dihydro-1H-
benzo[e][1,2,4]triazepin-5(2H)-one (Va)
Yield: 90 %; m.p. = 190–192 °C; crystallized from etha-
1
nol; HNMR: d = 2.95 (s, 3H, NCH3), 5.88 (s, 1H, ben-
zylic H), 6.70–7.81 (m, 14H, ArH), 8.31 (br s, 1H, NH,
exch.) ppm; MS m/z (rel.int.) = 330(M? ? 1, 9.6), 329
(M?, 23.1), 194 (21.8), 134 (44.2), 77 (100). Analysis for
C21H19N3O (329.40): Calcd: C, 76.57; H, 5.81; N, 12.76.
Found: C, 76.41; H, 5.93; N, 12.63 %.
1-Methyl-3-(phenylamino)-2,3-dihydroquinazolin-
4(1H)-one (III)
To a solution of benzohydrazide II (2.41 g, 0.01 mol) in
ethanol (50 ml), 1 ml 40 % formalin and ten drops of
glacial acetic acid were added. The reaction mixture was
heated under reflux for 18 h, concentrated to half volume
and then poured into cold water (100 ml). The separated
solid was filtered, dried, and crystallized from ethanol to
give the titled compound in a yield of 87.5 %, m.p. = 163–
165 °C as reported (Legrand and Lozac’h, 1984). IR:
m = 3324 (NH), 3031 (CH, aromatic), 2994 (CH, ali-
2-(4-Chlorophenyl)1-methyl-3-phenyl-3,4-dihydro-1H-
benzo[e][1,2,4] triazepin-5(2H)-one (Vb)
Yield: 90 %; m.p. = 227–228 °C; crystallized from etha-
nol. IR: m = 3239 (NH), 3023 (CH, aromatic), 2954 (CH,
aliphatic), 1655 (CO), 1494 (C=C) cm-1
;
1HNMR:
d = 2.98 (s, 3H, NCH3), 5.99 (s, 1H, benzylic H), 6.80–
7.83 (m, 13H, ArH), 8.44 (br s, 1H, NH, exch.) ppm.
Analysis for C21H18ClN3O (363.5): Calcd: C, 69.32; H,
4.99; N, 11.55. Found: C, 69.52; H, 4.65; N, 11.37 %.
;
phatic), 1671 (CO), 1496 (C=C) cm-1 1HNMR:
d = 2.91(s, 3H, NCH3), 4.67(s, 2H, CH2N), 6.78–7.79 (m,
9H, ArH), 8.38 (s, 1H, NH, exch.) ppm; MS m/z
(rel.int.) = 253 (M?, 9.1), 161 (34.6), 92 (42.6), 77 (100).
Analysis for C15H15N3O (253.30): Calcd: C, 71.13; H,
5.97; N, 16.59. Found: C, 70.95; H, 5.85; N; 16.67 %.
2-(4-Methoxyphenyl)1-methyl-3-phenyl-3,4-dihydro-1H-
benzo[e][1,2,4] triazepin-5(2H)-one (Vc)
1-Methyl-3-phenyl-3,4-dihydro-1H-
benzo[e][1,2,4]triazepin-5(2H)-one (IV)
Yield: 93 %; m.p. = 251–253 °C; crystallized from diox-
ane/DMSO (4:1). IR: m = 3241 (NH), 3016 (CH, aro-
matic), 2959 (CH, aliphatic), 1649 (CO), 1499 (C=C)
To a solution of benzohydrazide II (2.41 g, 0.01 mol) in
ethanol (50 ml), 1 ml 40 % formalin and ten drops of
cm-1 1HNMR: d = 2.93 (s, 3H, NCH3), 3.74(s, 3H,
;
OCH3), 5.82 (s, 1H, benzylic H), 6.71–7.81 (m, 13H, ArH),
123

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Med Chem Res (2013) 22:1488–1496
8.29(brs, 1H, NH, exch.) ppm. Analysis for C22H21N3O2
(359.42): Calcd: C, 73.52; H, 5.89; N, 11.69. Found: C,
73.37; H, 6.15; N, 11.50 %.
(419.47):Calcd: C, 68.72; H, 6.01; N, 10.02. Found: C,
68.69; H, 5.88; N, 9.99 %.
1-Methyl-3-phenyl-2-thioxo-3,4-dihydro-1H-
benzo[e][1,2,4]triazepin-5(2H)-one (VI)
2-(4-Nitrophenyl)1-methyl-3-phenyl-3,4-dihydro-1H-
benzo[e][1,2,4] triazepin-5(2H)-one (Vd)
To a solution of benzohydrazide II (2.41 g, 0.01 mol) and
potassium hydroxide (0.056 g, 0.01 mol) in 95 % ethanol
(20 ml), carbon disulfide (0.08 g, 0.01 mol) was added and
the solution was heated under reflux for 18 h. The reaction
mixture was concentrated to half volume and poured into
cold water (100 ml). The separated solid was filtered, dried,
and crystallized from ethanol to give the titled compound.
Yield: 85 %; m.p. = 198–200 °C; 1HNMR: d = 4.14
(s, 3H, NCH3), 6.64–8.14 (m, 9H, ArH), 8.83 (s, 1H, NH,
exch.) ppm; MS m/z (rel.int.) = 284 (M? ? 1, 6.4), 283
(M?, 25.5), 134 (51.1), 77 (100). Analysis for C15H13N3OS
(283.35): Calcd: C, 63.58; H, 4.62; N, 14.83. Found: C,
63.73; H, 4.63; N, 15.18 %.
Yield: 78 %; m.p. = 227–229 °C; crystallized from diox-
ane; 1HNMR: d = 3.04 (s, 3H, NCH3), 6.19 (s, 1H, benzylic
H), 6.78–8.29 (m, 13H, ArH), 8.53 (brs, 1H, NH, exch.) ppm;
MS m/z (rel.int.) = 376 (M? ? 2, 1.6), 375 (M? ? 1, 3),
374 (M?, 9.8), 269 (16.6), 194 (10.2), 134 (13.4),77 (100).
Analysis for C21H18N4O3 (374.39): Calcd: C, 67.37; H, 4.85;
N, 14.96. Found: C, 67.08; H, 4.74; N, 14.71 %.
2-(4-Hydroxyphenyl)1-methyl-3-phenyl-3,4-dihydro-1H-
benzo[e][1,2,4] triazepin-5(2H)-one (Ve)
Yield: 66 %; m.p. = 222–223 °C; crystallized from etha-
1
nol; HNMR: d = 2.95 (s, 3H, NCH3), 5.81 (s, 1H, ben-
zylic H), 6.77–7.88 (m, 14H, ArH), 8.29 (brs, 1H, NH,
exch.), 9.586 (s, 1H, OH, exch.) ppm. Analysis for
C21H19N3O2 (345.39): Calcd: C, 73.03; H, 5.54; N,
12.17 %. Found: C, 72.88; H, 5.4; N, 11.88 %.
N0-[2-(Methylamino)benzoyl]nicotinohydrazide (VIII)
A mixture ofN-methyl-isatoicanhydride (I, 8.85 g, 0.05 mol)
and nicotinic acid hydrazide (6.85 g, 0.05 mol) in ethanol
(50 ml)-containing ten drops of glacial acetic acid was heated
under reflux for 8 h. The solid precipitated out after cooling
was filtered, dried, and crystallized from diox-
ane:DMSO(4:1)to give the titled compound; yield: 90.28 %,
m.p.: 229–230 °C as reported (Reddy and Reddy, 1988).
2-(2-Nitrophenyl)1-methyl-3-phenyl-3,4-dihydro-1H-
benzo[e][1,2,4] triazepin-5(2H)-one (Vf)
Yield: 79.4 %; m.p. = 216–217 °C; crystallized from
1
ethanol:dioxane (1:1); HNMR: d = 3.04 (s, 3H, NCH3),
6.56 (s, 1H, benzylic H), 6.86–7.94 (m, 14H, ArH), 8.35
(brs, 1H, NH, exch.) ppm. Analysis for C21H18N4O3-
(374.39): Calcd: C, 67.37; H, 4.85; N, 14.96. Found: C,
67.15; H, 4.78; N, 14.71 %.
N0-[2-(Methylamino)benzoyl]isonicotinohydrazide (IX)
A
mixture of N-methyl-isatoic anhydride(I, 8.85 g,
0.05 mol) and isonicotinic acid hydrazide (6.85 g,
0.05 mol) in ethanol (50 ml)-containing ten drops of glacial
acetic acid was heated under reflux for 18 h. The reaction
mixture was cooled and diluted with small amount of water
(5 ml). The separated solid was filtered, dried, and crys-
tallized from aqueous ethanol to give the titled compound.
Yield: 73 %; m.p. = 158–159 °C; 1HNMR: d = 2.84
(s, 3H, NCH3), 6.66–7.86 (m, 8H, ArH), 8.83 (brs, 1H, NH,
exch.), 10.58 (brs, 1H, NHCO), 10.64 (brs, 1H, NHCO).
Analysis for C14H14 N4O2 (270.29): Calcd: C, 62.21; H,
5.22; N, 20.73. Found: C, 61.93; H, 5.23; N, 20.72 %.
2-(4-Bromophenyl)-1-methyl-3-phenyl-3,4-dihydro-1H-
benzo[e][1,2,4] triazepin-5(2H)-one (Vg)
Yield: 93 %; m.p. = 236–238 °C; crystallized from etha-
1
nol:dioxane (1:1); H N MR: d = 3.0 (s, 3H, NCH3), 5.97
(s, 1H, benzylic H), 6.80–7.85 (m, 14H, ArH), 8.40 (brs,
1H, NH, exch.) ppm. Analysis for C21H18BrN3O (408.29):
Calcd: C, 61.78; H, 4.44; N, 10.29. Found: C, 61.47; H,
4.35; N, 10.13 %.
2-(3,4,5-Trimethoxyphenyl)1-methyl-3-phenyl-3,4-dihydro-
1H-benzo[e] [1,2,4]triazepin-5(2H)-one (Vh)
N-(1-Methyl-4-oxo-1,2-dihydroquinazolin-3(4H)-
yl)nicotinamide (X)
Yield: 86 %; m.p. = 188–190 °C; crystallized from etha-
nol:dioxane (3:1); HNMR: d = 2.97 (s, 3H, NCH3), 3.59
(s, 3H, OCH3), 3.63 (s, 3H, OCH3), 3.67 (s, 3H, OCH3),
5.81 (s, 1H, benzylic H), 6.57–7.81 (m, 11H, ArH)
8.41(brs, 1H, NH, exch.) ppm. Analysis for C24H25N3O4
To a solution of N’-(2-(methylamino)benzoyl)nicot-
1
inohydrazide (VIII, 1.77 g, 0.01 mol) in ethanol (50 ml),
40 % formalin (1 ml), and ten drops of glacial acetic acid
were added. The reaction mixture was stirred at room
temperature for 18 h and then neutralized with ammonia
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Med Chem Res (2013) 22:1488–1496
1491
solution. The formed solid was filtered, washed with
petroleum ether (60/80) and crystallized from etha-
nol:petroleum ether (1:1) to give the titled compound.
Yield: 76 %; m.p. = 165–167 °C; 1HNMR: d = 2.91
(s, 3H, NCH3), 4.78 (s, 2H, CH2N), 6.87–9.08 (m, 8H,
ArH), 11.20 (s, 1H, NH, exch.) ppm; MS m/z (rel.
int.) = 282 (M?, 25), 161 (100), 118 (50), 105 (75), 64
(40). Analysis for C15 H14N4O2 (282): Calcd: C, 63.82; H,
4.96; N, 19.85. Found: C,63.52; H, 5.23; N, 19.51 %.
closure from normal. The ptosis ratio was made 4 for
complete ptosis, 3 for 3/4, 2 for ‘, and 1 for 1/4 ptosis.
Forced swim pool test
The forced swim pool method (FSP) described by Porsolt
et al., (1978) was followed. Mice were classified into 13
groups, each of six and then injected i.p. with solvent (con-
trol), reference drug clozapine, and test compounds (IV,
V
a–h, VI, XI) at a dose of 3 mg/kg body weight 30 min
3-Isonicotinoyl-1-methyl-3,4-dihydro-1H-
benzo[e][1,2,4]triazepin-5(2H)-one (XI)
before the test session. Two swim sessions were conducted;
an initial 15 min pre-test followed by a 5 min test 24 h later.
The animals were placed in a chamber (diameter: 45 cm,
height: 20 cm) containing water up to height of 15 cm at
25 2 °C. The period of immobility (passive floating
without struggling and making only those movements which
are necessary to keep its head above the surface of water)
during the 5 min test period was measured and recorded.
To
a
solution of N0-(2-(methylamino)benzoyl)ison-
icotinohydrazide (IX, 1.77 g, 0.01 mol) in ethanol (50 ml),
40 % formalin (1 ml), and ten drops of glacial acetic acid
were added. The reaction mixture was stirred at room
temperature for 18 h and then neutralized with ammonia
solution. The formed solid was filtered and crystallized
from ethanol to give the titled compound.
Neurotoxicity screening
Yield: 77 %; m.p. = 187–188 °C. IR: m = 3185 (NH),
3045 (CH, aromatic), 2995 (CH, aliphatic), 1702 (CO),
Rotarod test
1
1630 (CO), 1504 (C=C) cm-1; HNMR: d = 2.91 (s, 3H,
NCH3), 4.78 (s, 2H, CH2N), 6.87–8.83 (m, 8H, ArH) 11.31
(s, 1H, NH, exch.) ppm; MS m/z (rel.int.) = 283(M? ? 1,
2.9), 282 (M?, 5), 120 (15.1), 106 (20.9), 78 (100). Anal-
ysis for C15H14 N4O2 (282): Calcd: C; 63.82; H, 4.96; N,
19.85. Found: C, 63.69; H, 4.65; N, 19.52 %.
Minimal motor impairment was measured in mice by the
rotarod test (Dunham and Miya, 1957). The mice were
trained to stay on an accelerating rotarod that rotates at 4–
10 rpm. The rod diameter was 3.2 cm. Trained mice were
classified into 13 groups, each of six and then injected i.p.
with DMSO (control), clozapine, and test compounds (IV,
Pharmacological studies
Va–h, VI, XI) at a dose of 3 mg/kg body weight. Neuro-
toxicity was determined 30 min post treatment as the
inability of the animal to maintain equilibrium on the rod
for at least 1 min in each of three trials.
Male albino mice weighing 20–25 g were obtained from
the Laboratory Animal Services Center, Faculty of Veter-
inary Medicine, Zagazig University, Zagazig, Egypt. The
animals were maintained on a 12-h light/dark cycle
under regulated temperature (25 2 °C) and humidity
(50 10 %) as well as fed with standard diet and water
ad libitum. They were allowed to acclimate 7 days before
use. This protocol was approved by the Animal Care and
Use Committee of the Pharmacology department, Faculty
of Veterinary Medicine, Zagazig University.
Horizontal screen test
Neural impairment was also determined by failure of mice
to perform successfully the horizontal screen test
(Coughenour et al., 1977). The apparatus consisted of a
13 9 14 cm2 wire screens which was mounted horizon-
tally on a steel rod. The rod was supported at both ends and
could be inverted through an arc of 180°. Trained mice
were classified into 13 groups, each of six and then injected
i.p. with DMSO (control), clozapine, and test compounds
(IV, Va–h, VI, XI) at a dose of 3 mg/kg body weight. The
animals were placed individually on the top of the screen
and the rod was then rotated (mice unable to climb to an
upright position within 1 min were rated as failures 30 min
after drugs administration, two values were recorded: (A)
The number of mice that fall from the screen and (B) The
number of mice that fail to climb the top of the screen (i.e.,
the sum of those that remain clinging to the bottom of the
screens and those that falls from the screen).
Ptosis test
It was carried out according to the method described by
Chen and Bohner (1965). Mice were divided into 13 equal
groups (n = 6). The first group was labelled as control and
injected i.p. with the solvent (DMSO) while the second
group was injected (i.p.) with clozapine at a dose of 3 mg/
kg. The tested compounds (IV, Va–h, VI, XI) were injected
(i.p.) to the other groups at a dose of 3 mg/kg. Every mouse
was observed for the presence or absence of complete
ptosis. The ptosis was rated as the fraction of the eyelid
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Pentylenetetrazole seizure pattern test (PTZ)
first two the myoclonic jerks of the forelimbs. This has
been considered to be the first sign of the beginning of
seizure activity (Osonoe et al., 1994). Animals devoid of
generalized convulsions were considered to be protected
and their results were represented as protection percentage.
Mice were divided into 13 equal groups (n = 6). The first
group was injected i.p. with DMSO (control) while clo-
zapine and tested compounds were injected (i.p.) to the
other groups at the same dose level. The anticonvulsant
activities of the compounds were determined against pen-
tylenetetrazole-induced seizures (Fisher, 1989). One hour
later, mice were injected with pentylenetetrazole 70 mg/kg
subcutaneously in scruff of neck. After 2–4 min of PTZ
injection, the animals develop sequence of excitement,
myoclonic jerks, clonic seizures, one or more maximal
tonic seizures and finally death. Seizure latency was
defined as the time elapsed from injection of PTZ to the
Results and discussion
Chemistry
In this study, the novel benzotriazepin-5(2H)-one deriva-
tives (IV, Va–h, VI) were prepared starting from the ben-
zohydrazide key intermediate II which was obtained
O
H
N
O
H2N
+
N
O
CH3
EtOH/AcOH
Reflux
I
O
H
N
N
H
NH
x
u
l
f
e
r
,
e
n
CH3
i
l
a
H
O
m
r
c
o
A
/
F
H
II
O
t
E
2
O
H
N
O
N
CHO
H
N
Formaline
, rt
R
N
N
AcOH,reflux
CH3
EtOH/AcOH
N
S
III
CH3
VII
O
O
NH
NH
O
N
N
NH
N
N
N
S
H3
C
H3
C
N
VI
IV
H3
C
R
Va-h
a: R=H
b: R = -Cl
p
c: R= p-OCH3
e: R= p-OH
d: R = p-NO2
f: R = o-NO2
h: R = 3,4,5-tri-OCH3
g:R= -Br
p
Scheme 1 Synthetic pathways for preparation of the novel benzotriazepinones (IV, Va–h, VI)
123

Med Chem Res (2013) 22:1488–1496
1493
through condensation of N-methylisatoic anhydride (I)
with phenylhydrazine as shown in Scheme 1.
deshielded than those, (N–CH2–N) at d = 4.67 ppm and
(N–NH) at d = 8.38 ppm, of compound III which is a 2,3-
dihydroquinazolinone derivative. This result is also docu-
mented by the fragmentation study of mass spectra for both
compounds whereas the presence of fragment of m/z = 161
(1-methyl-2,3-dihydroquinazolin-4(1H)-one), in the mass
spectrum of compound III and its absence in that of com-
pound IV is a good evidence that the compound III is a 2,3-
dihydroquinazolinone derivative while compound IV is a
benzo[e][1,2,4]triazepin-5(2H)-one derivative.
The benzohydrazide intermediate II underwent internal
Mannich reaction at two different reaction conditions. The
first method depends on heating the intermediate II and
formalin at reflux in ethanol-containing catalytic amount of
glacial acetic acid to afford the six-membered quinazoli-
none derivative III. The second one depends on stirring the
same reactants at room temperature to afford the seven-
membered benzotriazepin-5(2H)-one derivative IV.
The difference in the appearance of methylene and NH
signals in each of the obtained compounds IV and III in the
1HNMR spectra indicates the difference in their cyclization,
whereas in compound IV, benzotriazepin-5(2H)-one deriv-
ative, the singlet of methylene (N–CH2–N) at d = 5.12 ppm
and that of CONH at d = 10.03 ppm appeared more
Acid catalyzed condensation of benzohydrazide II with
different aromatic aldehydes furnished a new series of
benzo[e][1,2,4] triazepin-5(2H)-ones (Va–h),whereas the
1HNMR of benzotriazepin-5(2H)-one compounds (Va,c,h
)
revealed the appearance of benzylic proton singlets at
d = 5.88, 5.82, and 5.81 ppm, respectively, and the methyl
O
O
N
O
CH3
O
O
I
NHNH2
NHNH2
N
N
EtOH/AcOH
Reflux
EtOH/AcOH
Reflux
N
O
N
O
H
N
H
N
N
H
N
H
O
O
NH
NH
CH3
VIII
IX
CH3
Formaline
Formaline
EtOH/AcOH
EtOH/AcOH
N
O
H
N
N
O
N
N
O
N
X
O
CH3
H
N
NH
N
N
O
N
O
N
CH3
XII
H3
C
XI
Scheme 2 Synthetic pathways for preparation of the novel compounds X and XI
123

1494
Med Chem Res (2013) 22:1488–1496
singlet of NCH3 at 2.95, 2.93, and 2.97 ppm, respectively, in
addition to D2O exchangeable NH-proton which appeared as
broad singlets at d = 8.31, 8.29, and 8.41 ppm, respectively.
Also the mass spectra for such compounds (Va–h) revealed
the absence of the fragment of m/z = 161 which is charac-
teristic for 2,3-dihydroquinazolinone.
clozapine as a reference drug. In addition, the CNS
depressant activities for such compounds were also
examined using forced swim pool test (Porsolt et al., 1978).
Also, their neurotoxicity was determined using both rota-
rod (Dunham and Miya, 1957) and horizontal screen
(Coughenour et al., 1977) tests. These compounds were
also screened for their anticonvulsant activities against
pentylenetetrazole (PTZ)-induced seizures (Fisher, 1989).
This is to explore the highly active compound as antipsy-
chotic with least side effects in comparison with reference
drug clozapine. It was observed from Table 1 that com-
pounds IV, VI, and XI showed the same antipsychotic
activity as the reference drug clozapine whereas they
caused complete ptosis in mice at a dose of 3 mg/kg body
weight. Moreover, other benzotriazepin-5(2H)-one deriva-
tives containing phenyl ring, with electron donating group
at para position, at 2-position (Vc,e) showed a high anti-
psychotic activity but their values still 25 % lesser than that
of the reference drug clozapine.
Moreover, cyclocondensation of benzohydrazide II was
conducted using carbon disulfide in hot ethanolic KOH
solution to afford the novel benzo[e][1,2,4]triazepin-5(2H)-
one (VI) rather than the expected 2,3-dihydroquinazolin-
5(2H)-one (VII). This is attributed to the availability of the
electron pair of the aniline nitrogen rather than that of the
amidic nitrogen.
The appearance of NH-proton and N–CH3 protons singlets
in 1HNMR spectrum for the formed compound VI at
d = 8.83and4.14 ppm, respectively, which seemstobemore
deshielded than those for the 2,3-dihydroquinazolinone is an
indication that the formed compound is benzo[e][1,2,4]tria-
zepin-5(2H)-one derivative. Also, mass spectrum of com-
pound VI confirmed its seven-membered structure.
The results presented in Table 2 revealed that, in general,
benzotriazepinones (IV, Vb,c,e,f,g, XI) and clozapine caused
significant CNS depressant activity in mice upon using
forced swim test as indicated from their higher immobility
times. Other benzotriazepinones showed non significant
change in the immobility time and so, these derivatives may
be useful as antidepressants (Mao et al., 2008).
Similarly, condensation of N-methyl-isatoic anhydride
(I) with nicotinic acid hydrazide or isonicotinic acid
hydrazide afforded the benzohydrazides VIII or IX as shown
in Scheme 2. The intermediate VIII was cyclized through
internal Mannich reaction using formalin at room tempera-
ture to afford the six-membered quinazolinone derivative X.
On the other side, cyclization of the intermediate IX
using the same reaction condition afforded the seven-
membered benzotriazepin-5(2H)-one derivative XI rather
than the expected six-membered quinazolinone derivative
XII. This may be attributed to the higher reactivity of
isonicotinic nitrogen rather than the benzamide nitrogen.
The chemical structures of the compounds X and XI
In addition, the neurotoxicity for such novel compounds
were determined using both rotarod and horizontal screen
tests in comparison with the reference drug clozapine
(Tables 3, 4). Through analysis of Table 3, it was observed
that benzotriazepinones Va,d,h and VI showed no neuro-
toxicity at all while clozapine exhibited the highest toxicity
in mice at a dose level of 3 mg/kg upon using rotarod test. It
was observed from the results presented in Table 4 that
1
were verified using HNMR and mass spectra whereas the
mass spectra is the most differential tool between the
chemical structures for compounds X and XI. Both com-
pounds X and XI have the same molecular weight which
appears at m/z = 282 with intensity of 25 and 5, respec-
tively. The fragmentation study of mass spectra of these
compounds indicates the great difference in fused ring
structure of each whereas the existence of fragment of
m/z = 161 (100 %),1-methyl-2,3-dihydroquinazolin-4(1H)-
one, is associated with the mass spectrum of compound X,
while its absence in the mass spectrum of compound XI is
an indication that cyclization of N0-[2-(methylamino)ben-
zoyl]isonicotinohydrazide (IX) afforded benzo[e] [1,2,4]
triazepin-5(2H)-one structure.
Table 1 Effect of test compounds and clozapine (3 mg/kg, i.p.) on
mice using ptosis test
Compounds
Ptotic scoring
% Effect
Control
IV
0 (no ptosis)
0.0
100.0
0.0
4 (complete ptosis)
0 (no ptosis)
Va
Vb
2 (1/2 ptosis)
50.0
75.0
50.0
75.0
0.0
Vc
3 (3/4 ptosis)
Vd
2 (1/2 ptosis)
Ve
3 (3/4 ptosis)
Vf
0 (no ptosis)
Vg
0 (no ptosis)
0.0
Pharmacological studies
Vh
2 (1/2 ptosis)
50.0
100.0
100.0
100.0
VI
4 (complete ptosis)
4 (complete ptosis)
4 (complete ptosis)
The newly synthesized benzotriazepin-5(2H)-one deriva-
tives (IV, Va–h, VI, XI) were tested for their antipsychotic
activities via ptosis test (Chen and Bohner, 1965) using
XI
Clozapine
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Med Chem Res (2013) 22:1488–1496
1495
Table 2 Effect of test compounds and clozapine (3 mg/kg, i.p.) on
mice using the forced swim test
Table 4 Horizontal screen test in mice injected by the test com-
pounds or clozapine (3 mg/kg i.p.)
Compounds
Immobility time (s)
Before treatment
Compound
A
%Neurotoxicity
B
%Neurotoxicity
Post treatmenta
Control
IV
0/6
3/6
0/6
2/6
1/6
0/6
1/6
1/6
1/6
0/6
0/6
2/6
3/6
0
0/6
0/6
0/6
2/6
0/6
0/6
0/6
1/6
1/6
0/6
0/6
1/6
1/6
0
50
0
Control
IV
117 4.2
129 5.1
120 3.8
125 4.3
123 3.4
129 7.2
128 3.7
120 3.5
115 7.1
119 4.1
127 4.3
120 4.2
121 6.6
120 5.1
178 7.2*
118 6.2
156 5.3*
141 3.5*
125 6.3
151 5.4*
141 6.5*
140 5.2*
135 6.1
129 6.9
190 8.2*
194 5.2*
Va
0
0
Vb
33.3
16.7
0
33.3
0
Va
Vc
Vb
Vd
0
Vc
Ve
16.7
16.7
16.7
0
0
Vd
Vf
16.7
16.7
0
Ve
Vg
Vf
Vh
Vg
VI
0
0
Vh
XI
33.3
50
16.7
16.7
VI
Clozapine
XI
Clozapine
A number of mice fall from the screen. B number of mice that fail to
climb the top of the screen
Significantly different at P \ 0.05 (unpaired student’s t test)
Each value represents the mean SD of six animals
a
After 30 min from injection reference drug or tested compounds
activity was equal to that of the reference drug clozapine
(Table 1). Moreover, these compounds were characterized
by being of lower side effects which often associated with
clozapine treatment such as prolonged sedation (Table 2)
and neurotoxicity (Tables 3, 4), among them compound VI
had the least side effects. It was also noted that benzo-
triazepinone derivatives (Va–h)-containing phenyl ring at
2-position in general have lower antipsychotic activity than
that of the unsubstituted analog IV.
Table 3 Rotarod test in mice injected by the test compounds or
clozapine (3 mg/kg i.p.)
Compound
Rotarod toxicitya
30 min
Control
0/6
4/6
0/6
4/6
2/6
0/6
2/6
2/6
2/6
0/6
0/6
5/6
5/6
IV
Va
Studying the effect of different substitution of the phe-
nyl ring on the antipsychotic activity (Table 1) revealed
that the presence of electron donating groups at para
position (compounds Vc,e) showed a higher activity than
that containing electron withdrawing substitution (com-
pounds Vb,d,g) but additional substitution on the phenyl
ring even by electron donating group led to decreasing the
activity (compound Vh) may be due to steric factor. Ortho
substitution with electron withdrawing group as seen in
compound Vf abolish the activity at all.
Vb
Vc
Vd
Ve
Vf
Vg
Vh
VI
XI
Clozapine
a
Rotarod toxicity (number of animals exhibiting toxicity/number of
animals tested). Each value represents the mean SD of six animals
Conclusions
compounds Va,d,h and VI showed neither severe (A) nor
minor (B) neurotoxicity at all while clozapine exhibited the
highest severe toxicity (A) on using horizontal screen test. It
was found that all benzotriazepinones (IV,Va–h,VI, X) and
also clozapine can not protect animals against pentylen-
etetrazole (PTZ)-induced seizures and so, these compounds
were considered to be devoid of any anticonvulsant activity.
It is apparent from Table 1 that compounds IV, VI, and
XI, were the most active ones whereas their antipsychotic
It could be concluded that a new series of 3,4-dihydro-1H-
benzo[e][1,2,4]triazepin-5(2H)-one derivatives (IV, Va–h
,
VI, and XI) were synthesized with high purity and excel-
lent yield starting from benzohydrazides II and IX,
respectively. Benzotriazepinone VI had the same antipsy-
chotic activity as clozapine but with lesser side effects
whereas it showed nonsignificant CNS depressant activity
on using forced swim test as well as no neurotoxicity
upon using rotarod or horizontal screen tests. Also,
123

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Med Chem Res (2013) 22:1488–1496
Fisher RS (1989) Animal models of the epilepsies. Brain Res Rev
14:245–278
Kaur K, Talele TT (2008) D QSAR studies of benzotriazepine
derivatives as CCK receptor antagonists. J Mol Graph Model
27:409–420
benzotriazepinones IV and XI showed the same antipsy-
chotic activity as the reference drug clozapine whereas they
caused complete ptosis in mice. All benzotriazepinones
were devoid from any anticonvulsant activity and cloza-
pine as well.
Kim SH, Taylor JE (1992) 2H-1,3,4-benzotriazepin-2-ones. US Patent
5, 091, 381
Legrand L, Lozac’h N (1984) Heterocyclic sulfur compounds. CIII.
Effect of phenylhydrazine on 1,2-dihydro-3,1-benzothiazine-
4-thiones. J Heterocycl Chem 21:1625–1632
Acknowledgments The authors would like to express their thanks
to Dr. Sameh El-Nabtity, department of pharmacology, Faculty of
Veterinary Medicine, Zagazig University, Egypt, for performing the
antipsychotic evaluation.
Mao QQ, Ip SP, Tsai SH, Che CT (2008) Antidepressant-like effect of
peony glycosides in mice. J Ethnopharmacol 119:272–275
Osonoe K, Mori N, Suzuki K, Osonoe M (1994) Antiepileptic effects
of inhibitors of nitric oxide synthase examined in pentylenetet-
razol induced seizures in rats. Brain Res 663:338–340
Pestellini V, Ghelardoni M, Volterra G, Del Soldato P (1978) Anti-
inflammatory and antalgic activity of fused ring polycyclic
compounds: 2,10-dioxo-pyridazino[3,2-b]quinazolines. Eur J Med
Chem 13:296
Conflict of interest The authors have declared that there are no
conflicts of interest.
References
Porsolt RD, Anton G, Blavet N, Jalfre M (1978) Behavioural despair
in rats: a new model sensitive to antidepressant treatments. Eur J
Pharmacol 47:379–391
Reddy PSN, Reddy PP (1988) Reaction of 2-aminobenzoylhydrazines
with carboxylic acids: formation of quinazolin-4(3H)-one, 1,3,4-
oxadiazole and 1,3,4-benzotriazepin-5-one derivatives. Indian J
Chem, Sect B 27B:763–765
Schuler E, Juanico N, Teixido J, Michelotti EL, Borrell JI (2006) A
diversity oriented synthesis of 2,10-dioxo-10H-1,2,3,4,4a,5-
hexahydropyridazino[3,2-b]quinazolines. Heterocycles 67:161–
173
Spencer J, Gaffen J, Griffin E, Harper EA, Linney ID, McDonald IM,
Roberts SP, Shaxted ME, Adatia T, Bashall A (2008) Achiral,
selective CCK2 receptor antagonists based on a 1,3,5-ben-
zotriazepine-2,4-dione template. Bioorg Med Chem 16:2974–
2983
Britton TC, Trepanier DL (1980) Method for preparing 6-phenyl-
triazolo or imidazolo-(1,3,4)-benzotriazepines and the novel
intermediates used therewith. US Patent, 4, 189, 588
Chen G, Bohner B (1965) Cited in screening methods in pharmacol-
ogy, 1st edn. Academic Press, New York, p 182
Coughenour LL, Mclean JR, Parker RB (1977) A new device for the
rapid measurement of impaired motor function in mice. Phar-
macol Biochem Behav 6:351–353
Dunham NW, Miya TS (1957) A note on a simple apparatus for
detecting neurological deficit in rats and mice. J Am Pharm
Assoc Sci Ed 46:208–209
0
´
Fernandeza P, Guille n MI, Gomarc F, Aller E, Molina P, Alcaraz MJ
(2004) A novel cyclo-oxygenase-2 inhibitor modulates catabolic
and antiinflammatory mediators in osteoarthritis. Biochem
Pharmacol 68:417–421
Fischer R, Ku¨nzle FM, Schmuz J (1984) Pyrrolobenzotriazepines. US
Patent 4, 450, 108
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