Synthesis and anticonvulsant activity of 9-alkoxy-6,7-dihydro-2 H-benzo[c][1,2,4]triazolo[4,3-a]azepin-3[5 H[-ones

Article abstract of DOI:10.1080/00397911.2011.553762

A series of novel 9-alkoxy-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a] azepin-3(5H)-one derivatives was designed and synthesized starting from 2,3,4,5-tetrahydro-7-hydroxy-1H-2-benzazepin-1-one. The structures of these compounds were confirmed by mass, ¹H NMR infrared spectra, and elemental analysis. Their anticonvulsant activity was evaluated by maximal electroshock (MES) test, and their neurotoxic effects were determined by the rotarod neurotoxicity test. The results shown that 3k was the most active compound with median effective dose (ED₅₀) of 27.3mg/kg, median toxicity dose (TD₅₀) of 118.3mg/kg, and protective index (PI) of 4.3. Possible structure-activity relationship is discussed.

Full text of DOI:10.1080/00397911.2011.553762

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Synthesis and Anticonvulsant Activity
of 9-Alkoxy-6,7-dihydro-2H-benzo[c]
[1,2,4]triazolo[4,3-a]azepin-3[5H]-ones
Feng-Yu Piao a , Cheng-Xi Wei b , Rong-Bi Han a , Wen-Bin Zhang a ,
Wei Zhang a & Ri-Shan Jiang a
a Department of Chemistry, College of Science , Yanbian University ,
Yanji , Jilin , China
b Institute of Neurosurgery, Inner Mongolia Univercity for
Nationalities , Tongliao , China
Accepted author version posted online: 06 Feb 2012.Published
online: 14 May 2012.
To cite this article: Feng-Yu Piao , Cheng-Xi Wei , Rong-Bi Han , Wen-Bin Zhang , Wei Zhang
& Ri-Shan Jiang (2012) Synthesis and Anticonvulsant Activity of 9-Alkoxy-6,7-dihydro-2H-
benzo[c][1,2,4]triazolo[4,3-a]azepin-3[5H]-ones, Synthetic Communications: An International
Journal for Rapid Communication of Synthetic Organic Chemistry, 42:16, 2337-2345, DOI:
10.1080/00397911.2011.553762
To link to this article: http://dx.doi.org/10.1080/00397911.2011.553762
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Synthetic Communications1, 42: 2337–2345, 2012
Copyright # Taylor & Francis Group, LLC
ISSN: 0039-7911 print=1532-2432 online
DOI: 10.1080/00397911.2011.553762
SYNTHESIS AND ANTICONVULSANT ACTIVITY OF
9-ALKOXY-6,7-DIHYDRO-2H-BENZO[C][1,2,4]TRIAZOLO
[4,3-a]AZEPIN-3(5H)-ONES
Feng-Yu Piao,1 Cheng-Xi Wei,2 Rong-Bi Han,1
Wen-Bin Zhang,1 Wei Zhang,1 and Ri-Shan Jiang1
1Department of Chemistry, College of Science, Yanbian University,
Yanji, Jilin, China
2Institute of Neurosurgery, Inner Mongolia Univercity for Nationalities,
Tongliao, China
GRAPHICAL ABSTRACT
Abstract
A series of novel 9-alkoxy-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]
azepin-3(5H)-one derivatives was designed and synthesized starting from 2,3,4,5-
tetrahydro-7-hydroxy-1H-2-benzazepin-1-one. The structures of these compounds were
confirmed by mass, 1H NMR infrared spectra, and elemental analysis. Their anticonvulsant
activity was evaluated by maximal electroshock (MES) test, and their neurotoxic effects
were determined by the rotarod neurotoxicity test. The results shown that 3k was the most
active compound with median effective dose (ED50) of 27.3 mg=kg, median toxicity dose
(TD50) of 118.3 mg=kg, and protective index (PI) of 4.3. Possible structure–activity
relationship is discussed.
Keywords 9-Alkoxy-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]azepin-3(5H)-one; anti-
convulsant; synthesis
INTRODUCTION
Benazepine derivatives have always received much more attention because of
their wide spread biological activities.[1–3] The present anti-hypertension drugs such
as libezapril and benazeprilat contain the 2-oxo-benazepine basic skeleton, and
growth hormones secretagogue L-692, 429, and L-739, 943 also contain the skeleton.[4]
Synthesis and modification of their structures are the research focus in organic
chemistry nowdays.[5–7]
Received September 15, 2010.
Address correspondence to Feng-Yu Piao, Department of Chemistry, College of Science, Yanbian
University, Yanji City 133002, Jilin Province, China. E-mail: fypiao4989@yahoo.com.cn, fypiao4989@
hotmail.com.in
2337

2338
F.-Y. PIAO ET AL.
Triazole compounds have a wide variety of biological activities, and the intro-
duction of a triazole ring to some active molecules may significantly improve the
biological activity of the parent molecule because of the superposition of biological
activity.[8,9]
This study designed and synthesized a series of novel 9-alkoxy-6,7-dihydro-2H-
benzo[c][1,2,4]triazolo[4,3-a]azepin-3(5H)-one derivatives, which have not been
reported in the literature, and their structures were confirmed by mass spectrometry,
infrared (IR), and NMR spectra. The anticonvulsant activity was evaluated by the
maximal electroshock test (MES), and the neurotoxicity was measured by the
rotarod test (Tox).[10,11]
RESULTS AND DISCUSSION
Chemistry
Target compounds 3a–3n were prepared following the reaction sequence shown
in Scheme 1.
The compounds 1a–1n were synthesized using the method described in a
previous paper by our group.[12] Compounds 1a–1n then reacted with phosphorus
pentasulfide in acetonitrile in the presence of triethylamine under a nitrogen atmos-
phere, and the resulting compounds (2a–2n) reacted further with methyl hydrazine
carboxylate in n-butanol to produce the target compounds 9-alkoxy-6,7-dihydro-2-
H-benzo[c][1,2,4]triazolo[4,3-a]azepin-3(5H)-one (3a–3n).[9,13,14]
Pharmacological Evaluations
The results of preliminary (phase I) screening of 3a–3n are summarized in
Table 1. Among all synthesized compounds at the dose of 100 mg=kg, all the five
straight-chain alkoxy compounds could not exhibit anticonvulsant activity. Seven
of nine substituted-benzyloxy compounds (except for 3h and 3j) exhibited different
anticonvulsant activities, especially compound 3k, (9-(2-chlorobenzyloxy)-6,7-
dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]azepin-3(5H)-one, which exhibited the most
potential activity. As a result of this preliminary screening, compounds 3g and 3k
were then subjected to phase II trials for quantification of their anticonvulsant
activity and neurotoxicity in mice. This phase provides an evaluation of the ED50
and TD50 values. The 95% confidence interval, slope of the regression line, and
Scheme 1. Synthetic route of compounds 3a–3n. Reagents: (a) RX=C2H5OH, 80–92 ꢀC; (b) P2S5,
(C2H5)3N=CH3CN, 86–92 ꢀC, 5–7 h; (c) H2NNHCOOCH3=(CH3)(CH2)3OH, 140–150 ꢀC, 5–8 d where
R: 3a ¼ n-C4H9, 3b ¼ n-C5H11
,
3c ¼ n-C6H13
,
3d ¼ -CH3, 3f ¼ CH2C6H4(m-F), 3g ¼ CH2C6H4(p-F),
3i ¼ CH2C6H4(m-Cl), 3j ¼ CH2C6H4(p-cl), 3k ¼ CH2C6H4(o-Cl), 3m ¼ CH2C6H4(p-Br), 3n ¼ CH2C6H5.

[1,2,4]TRIAZOLO[4,3-a][2]BENZAZEPIN
2339
Table 1. Primary evaluation of the synthesized compounds in
anticonvulsant activity (ip)a
MESb
Compound
R
(100c)
3a
3b
3c
3d
3e
3f
n-C4H9
n-C5H11
n-C6H13
n-C7H15
-CH3
0=3
0=3
0=3
0=3
0=3
1=3
2=3
0=3
1=3
0=3
3=3
1=3
1=3
1=3
-CH2C6H4(m-F)
-CH2C6H4(p-F)
-CH2C6H4(o-F)
-CH2C6H4(m-Cl)
-CH2C6H4(p-Cl)
-CH2C6H4(o-Cl)
-CH2C6H4(p-CH3)
-CH2C6H4(p-Br)
-CH2C6H5
3g
3h
3i
3j
3k
3l
3m
3n
aAll of tested compounds were dissolved in DMSO.
bThe maximal electroshock test was carried out 30 min after
administration of the test compounds.
cDoses are denoted in milligrams per kilogram.
standard error (SE) of the slope were then calculated. These data are shown in
Table 2, which also includes comparisons with marketed antiepileptic drug carbama-
zepine. As shown in Table 2, compound 3g displayed anticonvulsant activity in the
MES test, with ED50 values of 73.5 mg=kg, and compound 3k displayed anticonvul-
sant activity in the MES test with ED50 values of 27.3 mg=kg and also displayed a
TD50 of 118.3 mg=kg. No compounds exhibited more activity than reference drug
Carbamazepine. In the sc-PTZ model, compound 3k showed partial inhibition of
the clonic and tonic seizures and death induced by PTZ (Table 3). PTZ has been
reported to produce seizures by inhibiting c-aminobutyric acid (GABA) neurotrans-
mission.[15,16] Inhibition of GABAergic neurotransmission or activity has been
shown to promote and facilitate seizures,[17] whereas enhancement of GABAergic
neurotransmission is known to inhibit or attenuate seizures.
Analyzing the results of these pharmacology tests, the following simple
structure-activity relationship was obtained. The straight–chain alkoxy compounds
Table 2. Quantitative anticonvulsant data in mice (ip)
PIe
a
c
Compound
R
ED50
TD50
d
3g
3k
-CH2C6H4 (p-F)
-CH2C6H4 (o-Cl)
73.5 (68.5–78.8)b
27.3 (20.9–36.6)
8.8 (5.5–14.1)
—
118.3 (102.6–136.5)
71.6 (45.9–135.0)
4.3
8.1
Carbamazepine
aMedian effective dose required to assure anticonvulsant protection in 50% of animals.
b95% confidence limits given in parentheses.
cMedian toxic dose eliciting minimal neurological toxicity in 50% of animals.
dNot tested.
eProtective index (TD50=ED50).

2340
F.-Y. PIAO ET AL.
Table 3. Effect of compound 3k on PTZ-induced convulsion in mice
Compound
Doses (mg=kg)
N
Test time (h)
Clonic (%)
Tonic (%)
Death (%)
DMSO
Carbam
3k
—
50
50
10
10
10
0.5
0.5
0.5
100
100
70
100
0
0
10
30
20
exhibit very low anticonvulsant activity, and the substituted groups on the benzyloxy
and the position of the substituted group were greatly influenced the anticonvulsant
activity. The activity order of the F position on the benzyloxy was p-F>m-F>o-F,
and the activity order of the Cl position on the benzyloxy was o-Cl>m-Cl>p-Cl.
CONCLUSIONS
In conclusion, the results of this study demonstrated that 9-alkoxy-6,7-
dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]azepin-3(5H)-one derivatives have potent
anticonvulsant activity. Compound 3k has the strongest anticonvulsant activity,
and it much more active compared with the same substituted group without triazo-
lone (2,3,4,5-tetrahydro-7-(2-chlorobenzyloxy)-1H-2-benzazepin-1-one). In addition,
compound 3k demonstrated antagonistic activity against seizures induced by PTZ.
These experiments suggested that compound 3k might activate glutamate decarbox-
ylase (GAD) or inhibit (GABA)–aoxoglutarate aminotransferase (GABA-T).
EXPERIMENTAL
Chemistry
Melting points were determined on X-5 microscope melting-point apparatus,
which were uncorrected. IR spectra were recorded (in KBr) on a FT-IR instrument
(IRPRESTIGE-21). 1HNMR spectra were measured on an AV-300 instrument (Bru-
ker, Switzerland), and all chemical shifts were given in parts per million relative to
tetramethylsilane. Mass spectra were measured on a HP1100LC instrument
(Agilent Technologies, USA). Combustion analyses (C, H, and N) were performed
on a PE-2400 (Shimadzu). Microanalyses of C, N, and H were performed using a
Heraeus CHN rapid analyzer. The major chemicals were purchased from Aldrich
Chemical Corporation. All other chemicals were of analytical grade.
Preparation of Compounds 3a–n
General procedure. Acetonitrile (1.0 mL) and triethylamine (0.6 mL) were
placed in a three-necked, round-bottomed flask, to which P2S5 (0.4 g, 1.9 mmol)
was added slowly in an ice bath and stirred until dissolved. Then 2a–2n (1.7 mmol)
were added with stirring. The mixture was refluxed for 7 h in a nitrogen atmosphere.
After removing the solvent under reduced pressure, the residue was dissolved in
60 mL of dichloromethane, washed with water (60 mL ꢁ 3), and dried over anhy-
drous MgSO4. Evaporation of the solvents gave a crude product. Crude product
2a–2n reacted with methyl hydrazinocarboxylate (3.4 mmol) in n-butanol 10 mL
under a nitrogen atmosphere for 4–8 days. The solvent was removed under reduced

[1,2,4]TRIAZOLO[4,3-a][2]BENZAZEPIN
2341
pressure, and the residue was dissolved with ethy1 acetate and washed with water
three times. The ethy1 acetate layer was dried with anhydrous MgSO4, filtered,
and concentrated, and the residue was purified by silica-gel column chromatography
(dichloromethane ꢂ methanol ¼ 35:1) to afford target compounds 3a–3n.
(9-Butoxy-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]azepin-3(5H)-
one (3a). Yield: 30.8%, mp 212.2–213.6 ꢀC. 1H NMR (DMSO-d6, 300 MHz) d: 0.93
(t, 3H, J ¼ 7.3 Hz, CH3), 1.39–1.49 (m, 2H, CH2), 1.65–1.74 (m, 2H, CH2), 2.04–2.08
(m, 2H, CH2), 2.73 (t, 2H, J ¼ 6.7 Hz, CH2), 3.53 (t, 2H, J ¼ 6.7 Hz, CH2), 4.01 (t,
2H, J ¼ 6.4 Hz, CH2), 6.89–6.93 (m, 2H, Ar-H), 7.55 (d, 1H, J ¼ 8.4 Hz, Ar-H),
11.75 (s, 1H, N-H). MS: m=z 273.2 (Mþ); 13C NMR (75 MHz, DMSO-d6): d
160.6, 155.1, 147.7, 141.2, 129.3, 119.9, 116.2, 113.3, 67.8, 38.9, 31.2, 27.9, 19.2,
14.1. IR (KBr), cmꢂ1: 3150, 1688. Anal. calcd. for C15H19N3O2: C, 65.91; H, 7.01;
N, 15.37. Found: C, 65.74; H, 7.21; N, 15.29.
9-Pentyloxy-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]azepin-3(5H)-
one (3b). Yield: 52.9%, mp 200.0–201.1 ꢀC. 1H NMR (DMSO-d6, 300 MHz) d: 0.90
(t, 3H, J ¼ 6.8 Hz, CH3), 1.37–1.38 [m, 4H, (CH2)2], 1.70–1.73 (m, 2H, CH2),
2.05–2.09 (m, 2H, CH2), 2.74 (t, 2H, J ¼ 6.5 Hz, CH2), 3.54 (t, 2H, J ¼ 6.6 Hz,
CH2), 4.01 (t, 2H, J ¼ 6.4 Hz, CH2), 6.90–6.95 (m, 1H, Ar-H), 7.57 (d, 1H, J ¼8.4 Hz,
Hz, Ar-H), 11.76 (s, 1H, N-H); 13C NMR (75 MHz, DMSO-d6): d 160.6, 155.1,
147.7, 141.2, 129.3, 119.9, 116.2, 113.3, 68.0, 38.9, 31.2, 28.8, 28.1, 27.9, 22.3, 14.4.
MS: m=z 287.2 (Mþ). IR (KBr), cmꢂ1: 3150, 1690. Anal. calcd. for C16H21N3O2:
C, 66.88; H, 7.37; N, 14.62. Found: C, 66.94; H, 7.54; N, 14.49.
9-Hexyloxy-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]azepin-3(5H)-
1
one (3c). Yield: 40.4%, mp 204.0–205.6 ꢀC. H NMR (DMSO-d6, 300 MHz) d:
0.85–0.88 [m, 3H, CH3], 1.31–1.41 (m, 6H, (CH2)3), 1.70–1.74 (m, 2H, CH2),
2.01–2.09 (m, 2H, CH2), 2.74 (t, 2H, J ¼ 6.3 Hz, CH2), 3.54 (t, 2H, J ¼ 6.4 Hz,
CH2), 4.01 (t, 2H, J ¼ 6.4 Hz, CH2), 6.93–6.94 (m, 2H, Ar-H), 7.55 (d, 1H,
J ¼ 8.4 Hz, Ar-H), 11.76 (s, 1H, N-H); 13C NMR (75 MHz, DMSO-d6): d 160.6,
155.1, 147.7, 141.2, 129.3, 119.9, 116.2, 113.3, 68.0, 38.9, 31.4, 31.2, 29.0, 27.9,
25.6, 22.5, 14.4. MS: m=z 301.2 (Mþ). IR (KBr), cmꢂ1: 3150, 1688. Anal. calcd.
for C17H23N3O2: C, 67.75; H, 7.69; N, 13.94. Found: C, 67.49; H, 7.76; N, 13.78.
9-Heptyloxy-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]azepin-3(5H)-
1
one (3d). Yield: 48.8%, mp 193.4–195.5 ꢀC. H NMR (DMSO-d6, 300 MHz) d:
0.86–0.88 (m, 3H, CH3), 1.28–1.40 (m, 8H, (CH2)4), 1.70–1.72 (m, 2H, CH2), 2.04–
2.09 (m, 2H, CH2), 2.74 (t, 2H, J ¼ 6.3 Hz, CH2), 3.53 (t, 2H, J ¼ 6.4 Hz, CH2), 4.01
(t, 2H, J ¼ 6.1 Hz, CH2), 6.90–6.95 (m, 2H, Ar-H), 7.57 (d, 1H, J ¼ 8.3 Hz, Ar-H),
11.77 (s, 1H, N-H); 13C NMR (75 MHz, DMSO-d6): d 160.6, 155.1, 147.7, 141.2,
129.3, 119.9, 116.2, 113.3, 68.0, 38.9, 31.7, 31.2, 29.1, 28.9, 27.9, 25.9, 22.5, 14.4.
MS: m=z 315.2 (Mþ). IR (KBr), cmꢂ1: 3160, 1634. Anal. calcd. for C18H25N3O2:
C, 68.54; H, 7.99; N, 13.32. Found: C, 68.47; H, 8.00; N, 13.29.
9-Methoxy-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]azepin-3(5H)-
1
one (3e). Yield: 45.0%, mp 213.1–214.5 ꢀC. H NMR (DMSO-d6, 300 MHz) d:
2.08–2.10 (m, 2H, CH2), 2.73–2.77 (m, 2H, CH2), 3.52–3.56 (m, 2H, CH2), 3.81 (s,
3H, CH3), 6.92–6.96 (m, 2H, Ar-H), 7.59 (d, 1H, J ¼ 8.1 Hz, Ar-H). 11.79 (s, 1H,

2342
F.-Y. PIAO ET AL.
N-H); 13C NMR (75 MHz, DMSO-d6): d 161.1, 155.0, 147.7, 141.2, 129.3, 120.0,
115.7, 112.9, 55.7, 38.9, 31.2, 27.9. MS: m=z 231.1 (Mþ). IR (KBr), cmꢂ1: 3190,
1690. Anal. calcd. for C12H13N3O2: C, 62.33; H, 5.67; N, 18.17. Found: C, 62.51;
H, 5.77; N, 18.01.
(9-(3-Fluorobenzyloxy)-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]
1
azepin-3(5H)-one (3f). Yield: 48.7%, mp 184.9–185.8 ꢀC. H NMR (DMSO-d6,
300 MHz) d: 2.06–2.10 (m, 2H, CH2), 2.75 (t, 2H, J ¼ 6.4 Hz, CH2), 3.54 (t, 2H,
J ¼ 6.6 Hz, CH2), 5.18 (s, 2H, CH2), 7.01–7.62 (m, 7H, Ar-H), 11.78 (s, 1H, N-H);
13C NMR (75 MHz, MeOD): d 163.0 (d, JC-F ¼ 243.6 Hz), 160.6, 155.4, 148.8,
141.0, 139.8 (d, J ¼ 7.6 Hz), 130.0 (d, J ¼ 8.2 Hz), 129.0, 122.7, 119.6, 116.0, 114.2
(d, J ¼ 21.2 Hz), 113.7 (d, JC-F ¼ 22.6 Hz), 113.0, 68.7, 38.4, 30.4, 27.9. MS: m=z
325.1 (Mþ). IR (KBr), cmꢂ1: 3160, 1688. Anal. calcd. for C18H16FN3O2: C, 66.45;
H, 4.96; N, 12.92. Found: C, 66.32; H, 5.16; N, 12.85.
(9-(4-Fluorobenzyloxy)-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]
azepin-3(5H)-one (3g). Yield: 60.8%, mp 186.2–188.1 ꢀC.1H NMR (DMSO-d6,
300 MHz) d: 1.97–2.02 (m, 2H, CH2), 2.62 (t, 2H, J ¼ 6.9 Hz, CH2), 3.00–3.06 (m,
2H, CH2), 5.12 (s, 2H, CH2), 6.89–7.69 (m, 7H, Ar-H), 10.44 (s, 1H, N-H); 13C
NMR (75 MHz, CDCl3): d 163.0 (d, JC-F ¼ 243.6 Hz), 160.6, 155.4, 148.8, 141.0,
139.8 (d, J ¼ 7.6 Hz), 130.0 (d, J ¼ 8.2 Hz), 129.0, 122.7, 119.6, 116.0, 114.2 (d,
J ¼ 21.2 Hz), 113.7 (d, JC-F ¼ 22.6 Hz), 113.0, 68.7, 38.4, 30.4, 27.9. MS: m=z
325.1(Mþ). IR (KBr), cmꢂ1: 3180, 1699. Anal. calcd. for C18H16FN3O2: C, 66.45;
H, 4.96; N, 12.92. Found: C, 66.31; H, 5.19; N, 12.79.
(9-(2-Fluorobenzyloxy)-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]
1
azepin-3(5H)-one (3h). Yield: 52.1%, mp 229.6–230.7 ꢀC. H NMR (DMSO-d6,
300 MHz) d: 2.05–2.10 (m, 2H, CH2), 2.75 (t, 2H, J ¼ 6.5 Hz, CH2), 3.54 (t, 2H,
J ¼ 6.6 Hz, CH2), 5.14 (s, 2H, CH2), 6.99–7.62 (m, 7H, Ar-H), 11.78 (s, 1H, N-H);
13C NMR (75 MHz, DMSO-d6): d 162.3 (d, JC-F ¼ 241.9 Hz), 160.2, 155.1, 147.6,
141.2, 133.4, 130.5, 129.3, 120.3, 116.6, 115.8 (d, JC-F ¼ 21.1 Hz), 113.6, 68.1, 39.0,
31.2, 27.8. MS: m=z 325.1 (Mþ). IR (KBr), cmꢂ1: 3150, 1688. Anal. calcd. for
C18H16FN3O2: C, 66.45; H, 4.96; N, 12.92. Found: C, 66.40; H, 5.06; N, 12.77.
(9-(3-Chlorobenzyloxy)-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]
1
azepin-3(5H)-one (3i). Yield: 48.7%, mp 194.0–197.4 ꢀC. H NMR (DMSO-d6,
300 MHz) d: 2.06–2.10 (m, 2H, CH2), 2.73–2.77 (m, 2H, CH2), 3.53–3.57 (m, 2H,
CH2), 5.18 (s, 2H, CH2), 7.03–7.62 (m, 7H, Ar-H), 11.78 (s, 1H, N-H); 13C NMR
(75 MHz, DMSO-d6): d 160.0, 155.1, 147.6, 141.3, 139.8, 133.6, 130.9, 129.4,
128.3, 127.9, 126.7, 120.5, 116.7, 113.6, 68.8, 38.9, 31.2, 27.8. MS: m=z 341.0
(Mþ). IR (KBr), cmꢂ1: 3160, 1688. Anal. calcd. for C18H16ClN3O2: C, 63.25; H,
4.72; N, 12.29. Found: C, 63.11; H, 4.92; N, 12.31.
(9-(4-Chlorobenzyloxy)-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]
1
azepin-3(5H)-one (3j). Yield: 50.8%, mp 246.6–249.1 ꢀC. H NMR (DMSO-d6,
300 MHz) d: 2.05–2.21 (m, 2H, CH2), 2.75 (t, 2H, J ¼ 6.4 Hz, CH2), 3.54 (t, 2H,
J ¼ 6.5 Hz, CH2), 5.16 (s, 2H, CH2), 6.99–7.80 (m, 7H, Ar-H), 11.79 (s, 1H, N-H);
13C NMR (75 MHz, DMSO-d6): d 160.1, 155.0, 147.6, 141.3, 136.3, 133.0, 130.1,
129.4, 128.9, 120.4, 116.7, 113.6, 68.9, 38.9, 31.2, 27.8. MS: m=z 341.0 (Mþ). IR

[1,2,4]TRIAZOLO[4,3-a][2]BENZAZEPIN
2343
(KBr), cmꢂ1: 3148, 1692. Anal. calcd. for C18H16ClN3O2: C, 63.25; H, 4.72; N, 12.29.
Found: C, 63.09; H, 4.94; N, 12.35.
(9-(2-Chlorobenzyloxy)-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]
1
azepin-3(5H)-one (3k). Yield: 50.1%, mp 194.4–197.6 ꢀC. H NMR (DMSO-d6,
300 MHz) d: 2.06–2.10 (m, 2H, CH2), 2.74–2.78 (m, 2H, CH2), 3.53–3.57 (m, 2H,
CH2), 5.21 (s, 2H, CH2), 7.02–7.62 (m, 7H, Ar-H), 11.80 (s, 1H, N-H); 13C NMR
(75 MHz, DMSO-d6): d 160.0, 155.1, 147.6, 141.3, 134.4, 133.2, 130.8, 129.9,
129.4, 127.9, 120.6, 116.5, 113.5, 67.4, 38.9, 31.2, 27.8. MS: m=z 341.0 (Mþ). IR
(KBr), cmꢂ1: 3102, 1638. Anal. calcd. for C18H16ClN3O2: C, 63.25; H, 4.72; N,
12.29. Found: C, 63.19; H, 4.94; N, 12.43.
(9-(4-Methylbenzyloxy)-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]
azepin-3(5H)-one (3l). Yield: 30.1%, mp 212.2–213.6 ꢀC.1H NMR (DMSO-d6,
300 MHz) d: 2.05–2.09 (m, 2H, CH2), 2.31 (s, 3H, CH3), 2.74 (t, 2H, J ¼ 6.4 Hz,
CH2), 3.54 (t, 2H, J ¼ 6.6 Hz, CH2), 5.10 (s, 2H, CH2), 6.97–7.60 (m, 7H, Ar-H),
11.77 (s, 1H, NH); 13C NMR (75 MHz, CDCl3): d 161.3, 156.1, 148.7, 142.3,
138.7, 135.2, 130.5, 130.4, 129.4, 121.3, 117.7, 114.7, 70.8, 40.0, 32.3, 28.9, 22.3.
MS: m=z 321.2 (Mþ). IR (KBr), cmꢂ1: 3150, 1692. Anal. calcd. for C19H19N3O2:
C, 71.01; H, 5.96; N, 13.08. Found: C, 71.11; H, 5.74; N, 13.13.
(9-(4-Brominebenzyloxy)-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]
1
azepin-3(5H)-one(3m). Yield: 31.7%, mp 246.4–246.8 ꢀC. H NMR (DMSO-d6,
300 MHz) d: 2.05–2.10 (m, 2H, CH2), 2.75 (t, 2H, J ¼ 6.5 Hz, CH2), 3.54 (t, 2H,
J ¼ 6.6 Hz, CH2), 5.15 (s, 2H, CH2), 6.99–7.62 (m, 7H, Ar-H), 11.78 (s, 1H, NH);
13C NMR (75 MHz, CDCl3): d 160.0, 155.1, 147.6, 141.2, 136.7, 131.9, 130.3,
129.3, 121.5, 120.4, 116.7, 113.6, 69.0, 38.9, 31.2, 27.8. MS: m=z 385.0 (M þ 1). IR
(KBr), cmꢂ1: 3125, 1692. Anal. calcd. for C18H16BrN3O2: C, 55.97; H, 4.18; N,
10.88. Found: C, 55.78; H, 4.01; N, 10.75.
9-Benzyloxy-6,7-dihydro-2H-benzo[c][1,2,4]triazolo[4,3-a]azepin-3(5H)-
1
one (3n). Yield: 40.2%, mp 246.4–246.8 ꢀC. H NMR (DMSO-d6, 300 MHz) d:
2.05–2.10 (m, 2H, CH2), 2.73–2.77 (m, 2H, CH2), 3.54 (t, 2H, J ¼ 6.4 Hz, CH2),
5.15 (s, 2H, CH2), 6.99–7.61 (m, 8H, Ar-H), 11.78 (s, 1H, NH); 13C NMR
(75 MHz, DMSO-d6): d 160.2, 155.1, 147.6, 141.2, 137.2, 129.3, 128.9, 128.4,
128.3, 120.3, 116.6, 113.6, 69.8, 38.9, 31.2, 27.8. MS: m=z 307.1 (Mþ). IR (KBr),
cmꢂ1: 3160, 1690. Anal. calcd. for C18H17N3O2: C, 70.34; H, 5.58; N, 13.67. Found:
C, 70.29; H, 5.67 N, 13.76.
Pharmacology
The MES test and the rotarod test were carried out by the standard described
in the Antiepileptic Drug Development Program (ADD) of the National Institutes of
Health (USA).[10,11] All compounds were tested for anticonvulsant activities with
KunMing mice in the 18 to 22-g weight range purchased from the Laboratory of
Animal Research, College of Pharmacy, Yanbian University. The tested compounds
were dissolved in dimethylsulfoxide (DMSO). In phase I screening (Table 1), each
compound was administered at the dose levels of 100 mg=kg for evaluating the antic-
onvulsant activity. Anticonvulsant efficacy was measured in the MES test. In the

2344
F.-Y. PIAO ET AL.
MES test, seizures were elicited with a 60-Hz alternating current of 50-mA intensity
in mice. The current was applied via corneal electrodes for 0.2 s. The protection
against the spread of MES-induced seizures was defined as the abolition of the hind
leg and tonic maximal extension component of the seizure. Anticonvulsant drug–
induced neurologic deficit was detected in mice by the rotarod ataxia test. Anticon-
vulsant activity was expressed in terms of ED50, and neurotoxicity was expressed as
TD50. For determination of the ED50 and TD50 values, groups of 10 mice were given
a range of intraperitoneal doses of the tested compound until at least three points
were established in the range of 10–90% seizure protection or minimal observed neu-
rotoxicity. From the plots of these data, the respective ED50, TD50 values, and 95%
confidence intervals were calculated by means of trimmed Spearman–Karber
method.[18]
In chemically induced seizures, mice were given doses of convulsant drugs that
could induce seizures at least 97% of animals. The dose of PTZ was 85 mg=kg. The
test compounds and standard AED were administered ip in a volume of 50 mg=kg
to groups of 10 mice 30 min before either ip and sc injection of PTZ. The mice were
placed in individual cages and observed for 30 min, and the number of clonic seizures,
tonic seizures, and the lethality were recorded.[10,11,19]
ACKNOWLEDGMENTS
This work was supported by the National Natural Science Foundation of China
(No. 30760290 and No.30860340) and Important Item Foundation of Ministry of
Education P.R. China (No. 20070422029).
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