Synthesis and anticonvulsant activity of 8-alkoxy-5,6-dihydro-4H-[1,2,4] triazolo[4,3-a][1]benzazepin-1-one derivatives

Article abstract of DOI:10.1016/j.ejmech.2011.01.017

A series of novel 8-alkoxy-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a][1] benzazepin-1-one derivatives were synthesized and screened for their anticonvulsant activities by the maximal electroshock (MES) test, subcutaneous pentylenetetrazol (scPTZ) test, and the

Full text of DOI:10.1016/j.ejmech.2011.01.017

European Journal of Medicinal Chemistry 46 (2011) 1050e1055
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and anticonvulsant activity of 8-alkoxy-5,6-dihydro-4H-[1,2,4]triazolo
[4,3-a][1]benzazepin-1-one derivatives
*
Feng-Yu Piao , Rong-Bi Han, Wei Zhang, Wen-Bin Zhang, Ri-Shan Jiang
Department of Chemistry, College of Science, Yanbian University, Yanji City, 133002 Jilin Province, P.R. China
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of novel 8-alkoxy-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a][1]benzazepin-1-one derivatives were
synthesized and screened for their anticonvulsant activities by the maximal electroshock (MES) test,
subcutaneous pentylenetetrazol (scPTZ) test, and their neurotoxicity was evaluated by the rotarod
neurotoxicity test (Tox). The results of these tests demonstrated that 8-heptyloxy-5,6-dihydro-4H-
[1,2,4]triazolo[4,3-a][1]benzazepin-1-one (3f) and 8-hexyloxy -5,6-dihydro-4H-[1,2,4]triazolo[4,3-a]
[1]benzazepin-1-one (3e) were the most promising compounds, with median effective dose (ED50) of
17.6 and 17.9 mg/kg, and protective index (PI) of greater than 63.4 and 62.4 in the MES test,
respectively. These PI values were higher than the PI value of the prototype antiepileptic drug car-
bamazepine. The scPTZ test showed that 8-pentyloxy-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a][1]benza-
zepin-1-one (3d) was the most potent with ED50 value of 38.0 mg/kg and PI value of greater than 29.4,
which is much safer than marketed drug carbamazepine. The possible structureeactivity relationship
was discussed.
Received 6 September 2010
Received in revised form
1 January 2011
Accepted 12 January 2011
Available online 21 January 2011
Keywords:
[1,2,4]Triazolo[4,3-a][1]benzazepin-1-one
Anticonvulsant activity
Maximal electroshock test
Pentylenetetrazole
Neurotoxicity
Structureeactivity relationship
Ó 2011 Elsevier Masson SAS. All rights reserved.
1. Introduction
target compounds were synthesized through a convenient
synthetic sequence. The new compounds were evaluated as
anticonvulsant agents in experimental epilepsy models, i.e., the
maximal electroshock (MES) test, subcutaneous pentylenetet-
razol (scPTZ) test, and neurotoxicity were evaluated by using the
rotarod test.
According to literature reports, currently available antiepileptic
drugs (AEDs) provide adequate seizure control in many patients,
still about 28e30% of patients are estimated to be poorly treated
[1,2]. Therefore, continued search for safer and more effective AEDs
is urgently necessary. Much efforts devoted in the recent years for
the development of novel compounds as potential anticonvulsant
agents [3e11].
2. Results and discussion
Benzazepine derivatives exhibit a broad spectrum of phar-
macological activity [12e15]. Triazole compounds have wide
variety of biological activities, the introduction of triazole ring to
some active molecules may significantly improve the biological
activity of the parent molecule due to the superposition of bio-
logical activity [16e20]. In our search for new compounds with
anticonvulsant activity, 1,3,4,5-tetrahydro-7- alkoxy-2H-1-ben-
zazepin-2-one derivatives showed a moderate anticonvulsant
activity, among which 1,3,4,5-tetrahydro-7-butyloxy-2H-1-ben-
zazepin-2-one (1b), revealed as the best anticonvulsant activity
with an effective dose of 52.8 mg/kg in the anti-MES test. In order
to obtain compounds with better anticonvulsant activity, the
2.1. Chemistry
Target compounds were prepared according to Scheme 1.
The starting material 1,3,4,5-tetrahydro-7-hydroxy -2H-1-ben-
zazepin-2-one was synthesized using the method described in
a former paper of our group [12], which reacted with appro-
priate alkyl halide to produce the compounds 1aep [12].
Compounds 1aep then reacted with phosphorus pentasulfide in
acetonitrile in the presence of triethylamine under protection of
nitrogen, and the resulting compounds 2aep reacted further
with methyl hydrazine carboxylate in n-butanol to produce
the target compounds 3aep. The structures of all the new
compounds were confirmed by IR, 1H NMR, MS and elemental
analyses and their anticonvulsant activities have been initially
screened.
* Corresponding author. Tel./fax: þ86 433 2633443.
E-mail address: fypiao4989@yahoo.com.cn (F.-Y. Piao).
0223-5234/$ e see front matter Ó 2011 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2011.01.017

F.-Y. Piao et al. / European Journal of Medicinal Chemistry 46 (2011) 1050e1055
1051
Scheme 1. The synthesis route of compounds 3aep.
2.2. Pharmacology
3a to 3g, as alkyl chain length increased, ED50 gradually increased
with the compound 3f being the most active. However, the anti-
convulsant activity decreased when alkyl chain number lengthened
to 8.
In the anti-scPTz test, the synthesized compounds exhibited
a less- to moderate-degree of anticonvulsant activity. As a result of
preliminary screening, eight compounds (3cej) were quantitatively
evaluated for their anticonvulsant activity. They showed less
effective against scPTZ-induced seizures but exhibited a high
degree of protection against scPTz-induced seizures. 8-Pentyloxy-
Based on previous reports [21e23], we knew that trazoles have
activity against both major and minor seizures. The MES test is
regarded as the pharmacologic model of grand mal, and the scPTz
test as the pharmacologic model of petit mal seizures. Therefore we
carried out those two tests to evaluate the anticonvulsant activity of
the synthesized compounds.
The results of preliminary (phase I) screening of compounds
3aep are summarized in Table 1. In the anti-MES test, all the
synthesized compounds exhibited anticonvulsant activity, among
which eight compounds (3deg, 3j, and 3len) possessed anticon-
vulsant activity against MES-induced seizure at the dose of 30 mg/
kg, and seven compounds (3bec, 3hei, 3k and 3oep) were active
at the dose of 100 mg/kg. The remaining one compound 3a
exhibited anti-MES effect only under the high dose of 300 mg/kg.
As a result of preliminary screening, compounds 3bep were sub-
jected to phase II trials for quantification of their anticonvulsant
activity (indicated by ED50) and neurotoxicity (indicated by TD50) in
mice (Table 2). Among these derivatives, the most potent
compounds 3f and 3m exhibited similar activity with ED50 value of
17.6 mg/kg, furthermore, they had significantly lower neurotoxicity
(TD50 ＞ 1117.4 mg/kg, TD50 ＞ 931.2 mg/kg, respectively) than the
marked antiepileptic drug carbamazepine. And their PI value
(PI ＞ 63.4, PI ＞ 52.6, respectively) was superior to that of carba-
mazepine (TD50 ¼ 71.6 mg/kg, PI ¼ 8.1) in the MES test.
5,6-dihydro-4H-[1,2,4]triazolo[4,3-a][1]benzazepin-1-one
(3d)
was among the most active but also has the lowest toxicity. It
showed the ED50 value of 38.0 mg/kg, and the PI of greater than
29.4, which is also much greater than the PI of the marked anti-
epileptic drug carbamazepine.
Pentylenetetrazole has been reported to produce seizures by
inhibiting g-aminobutyric acid (GABA) neurotransmission [24,25].
GABA is the main inhibitory neurotransmitter substance in the
brain, and is widely implicated in epilepsy. Inhibition of GABAergic
neurotransmission has been shown to promote and facilitate
seizures [26], while enhancement of GABAergic neurotransmission
is known to inhibit or attenuate seizures. The compound 3d might
enhance GABAergic neurotransmission.
Table 1
Analyzing the activities of the synthesized compounds the
following structureeactivity relationships (SAR) were obtained.
Generally, the anticonvulsant activity of an organic compound
might be increased remarkably after the introduction of a halogen
atom. So, some halogen substituted derivatives were designed and
synthesized in this paper. Comparison of the halogen substituted
derivatives indicated that different halogen atoms contributed to
the anticonvulsant activity in the order of F ＞ Cl ＞ Br; the intro-
duction of F atom on the benzyl ring led to stronger activity.
Comparing the derivatives with different F-substitution positions
on the benzyl ring, their activity order was m-F ＞ o-F ＞ p-F, and
activity order of the Cl- and Br-atom substituted derivatives was m-
Cl ＞ o-Cl ＞ p-Cl ＞ p-Br. One electron donor derivative (3o) was
also designed and prepared, and its activity was slightly low. The
anticonvulsant activity of compounds containing substituted ben-
zyloxy (m-F, o-F, p-F, m-Cl) was stronger than that of the compound
with non-substituted benzyloxy (3h). The anticonvulsant activity of
another four substituted-benzyloxy derivatives 3i, 3k, 3o and 3p
was lower than that of the compound 3h. The m-F-substituted
derivative 3m exhibited the strongest anticonvulsant activity.
Length of the alkyl chain appeared to have a direct impact on
anticonvulsant activity of the 7-alkoxyl derivatives. From compound
Phase Ⅰ anticonvulsant data in mice of compounds 3aep (i.p.).a
Comp.
R
MESb
30c
scPTZb
30c
100
300
100
300
3a
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
3o
3p
eCH3
eC3H7
eC4H9
eC5H11
eC6H13
eC7H15
eC8H17
ePhCH2
eCH2C6H4(o-Cl)
CH2C6H4(m-Cl)
eCH2C6H4(p-Cl)
eCH2C6H4(o-F)
eCH2C6H4(m-F)
eCH2C6H4(p-F)
eCH2C6H4(p-CH3)
eCH2C6H4(p-Br)
1/5
1/5
2/5
5/5
5/5
5/5
4/5
3/5
3/5
4/5
2/5
5/5
5/5
4/5
3/5
1/5
1/5
4/5
5/5
ed
5/5
ed
ed
ed
ed
ed
ed
ed
ed
ed
ed
ed
ed
ed
ed
ed
0/5
0/5
1/5
1/5
1/5
1/5
1/5
1/5
1/5
1/5
1/5
0/5
0/5
0/5
0/5
1/5
0/5
1/5
5/5
5/5
5/5
5/5
5/5
1/5
0/5
1/5
1/5
1/5
0/5
1/5
0/5
1/5
0/5
1/5
ed
ed
ed
ed
ed
ed
ed
ed
5/5
5/5
ed
1/5
1/5
1/5
0/5
0/5
1/5
1/5
1/5
1/5
5/5
ed
ed
ed
4/5
5/5
a
All of tested compounds were dissolved in DMSO.
The maximal electroshock test was induced after 30 min past administration of
b
the tested compounds.
c
Doses are denoted in milligrams per kilogram.
Not tested.
d

1052
F.-Y. Piao et al. / European Journal of Medicinal Chemistry 46 (2011) 1050e1055
Table 2
Phase II quantitative anticonvulsant data in mice (test drug administered i.p.).
a
b
Comp.
ED50
MES
TD50
PIc
scPTZ
Rotarod toxicity
MES
scPTZ
3b
3c
3d
3e
3f
3g
3h
3i
3j
3k
3l
3m
3n
3o
3p
Carbam.
75.5 (100e65.4)d
37.3 (49.7e28.1)
24.6 (28.4e21.3)
17.9 (18.6e17.2)
17.6 (18.3e16.9)
20.7 (25.6e15.8)
30.5 (37.3e24.9)
32.9 (39.5e27.4)
26.4 (31.0e22.5)
40.1 (55.2e29.1)
18.4 (21.6e15.7)
17.6 (20.2e15.5)
22.8 (27.4e19.0)
50.0 (64.6e38.7)
55.8 (75.7e41.2)
9.2 (6.9e11.7)
ee
＞931.2
＞1117.4
＞1117.4
＞1117.4
＞1117.4
＞1117.4
＞931.2
＞931.2
＞931.2
＞931.2
＞931.2
＞931.2
＞931.2
＞931.2
＞931.2
＞12.3
＞29.9
＞45.4
＞62.4
＞63.4
＞54.0
＞30.5
＞28.3
＞35.3
＞23.2
＞50.6
＞52.9
＞40.8
＞18.6
＞16.7
8.1
ee
65.8 (83.0e55.8)d
＞17.0
＞29.4
＞24.0
＞25.9
＞22.2
e
38.0 (50.3e28.2)
46.5 (54.5e41.2)
43.2 (54.3e38.3)
50.2 (60.6e44.5)
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
e
＞100
74.4 (59.1e87.5)
＜0.74
a
ED50-median effective dose required to assure anticonvulsant protection in 50% animals.
TD50-median toxic dose eliciting minimal neurological toxicity in 50% animals.
PI protective index (TD50/ED50).
95% confidence limits given in parentheses.
d ¼ No activity at the corresponding dose.
b
c
d
e
3. Conclusions
1aep (1.7 mmol) was added while stirring. The mixture was refluxed
for 4e6 h in a nitrogen atmosphere. Afterremoving thesolvent under
reduced pressure, the residue was dissolved in 60 mL of dichloro-
methane, washed with water (60 ꢁ 3), and dried over anhydrous
MgSO4. Evaporation of the solvents gave a crude product.
A series of novel 8-alkoxy-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a]
[1]benzazepin-1-one derivatives were synthesized. In the anti-MES
test, all synthesized compounds displayed varying degrees of
anticonvulsant activity, the compounds 3f and 3e possessed the
most potential anticonvulsant activity with ED50 value of 17.6 mg/
kg and 17.9 mg/kg, and had PI of greater than 63.4 and 62.4
respectively, which is much greater than the PI of the marked
antiepileptic drug carbamazepine. Although 3m with ED50 value of
17.6 mg/kgꢀ1, its PI (PI ＞ 52.9 mg/kg) is less than that of 3e
(PI ＞ 62.4). They can be used as a lead for further development of
more potent anticonvulsant agents, and they might exhibit sodium
channel blocker activity.
In the anti-scPTz test, the compound 3d was among the most
active but also has the lowest toxicity. It showed ED50 of 38.0 mg/kg,
and PI of greater than 29.4, which is much safer than marketed drug
carbamazepine. It might enhance GABAergic neurotransmission
and exhibit sodium channel blocker activity.
4.3. General procedure for preparation of compounds 3aep
Crude product 2aep (2 mmol) reacted with methyl hydrazine
carboxylate (4mmol) in n-butanol 10 mL under nitrogen atmo-
sphere for 40e48 h, the solvent was removed under reduced
pressure, and the residue dissolved with ethy1 acetate and washed
with water three times. The ethy1 acetate layer was dried over
anhydrous MgSO4, filtered, and concentrated the solvent, and
the residue was purified by silica gel column chromatography
(dichloromethaneemethanol ¼ 35:1) to afford target compounds
3aep.
4.3.1. 8-Methoxy-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a][1]
benzazepin-1-one (3a)
4. Experimental section
IR (KBr,
n
, cmꢀ1): 3180 (NeH), 1714 (C]O), 1578, 1504, 1442 (C]
N, C]C),1264 (CeO); 1H NMR (300 MHz,
d
, ppm, DMSO-d6): 2.05 (t,
4.1. Chemistry
2H, J ¼ 7.1 Hz, C5eH), 2.45e2.55 (m, C6eH and DMSO), 2.58 (t, 2H,
J ¼ 6.8 Hz, C4eH), 3.79 (s, OeCH3), 6.90e7.00 (m, 2H, ar), 7.39 (d,1H,
J ¼ 8.6 Hz, ar), 11.66 (s, 1H, NH); 13C NMR (75 MHz,
d, ppm, DMSO-
Melting points were determined on X-5 microscope melting
point apparatus, which were uncorrected. IR spectra were recorded
(in KBr) on an FT-IR (IRPRESTIGE-21). 1H NMR spectra were
measured on an AV-300 (Bruker, Switzerland), and all chemical
shifts were given in parts per million relative to tetramethylsilane.
Mass spectra were measured on a HP1100LC (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 Alderich Chemical Corporation. All other chemicals
were of analytical grade.
0
d6): 23.1 (C5), 27.4 (C4), 30.0 (C6), 55.8 (C1 ), 112.8 (C7), 115.6 (C9),
125.5 (C10), 126.0 (C10a), 136.3 (C6a), 147.0 (C3a, C]N), 153.7 (C1, C]
O),158.6 (C8); MS (APCI) m/z (%): 260.1 (Mþþ1, 100); Anal. Calcd. for
C12H13N3O2: C, 62.33; H, 5.67; N, 18.17. Found: C, 62.27; H, 5.81; N,
18.12.
4.3.2. 8-Propyloxy-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a][1]
benzazepin-1-one (3b)
IR (KBr,
n
, cmꢀ1): 3180 (NeH), 1714 (C]O), 1580, 1504, 1441 (C]
N, C]C), 1262 (CeO); 1H NMR (300 MHz,
d, ppm, DMSO-d6): 0.98 (t,
0
3H, J ¼ 7.4 Hz, CH3),1.67e1.80 (m, 2H, alkyl C2 eH),1.90e2.10 (m, 2H,
C5eH), 2.42e2.61 (m, C4eH, C6eH and DMSO), 3.95 (t, 2H, J ¼ 6.5 Hz,
OeCH2), 6.91e6.98 (m, 2H, ar), 7.37 (d,1H, J ¼ 8.6 Hz, ar),11.66 (s,1H,
4.2. General procedure for the preparation of 2aep
NH); 13C NMR (75 MHz,
d
, ppm, DMSO-d6): 10.8 (C3 ), 22.5 (C2 ), 23.1
0
0
Acetonitrile (1.0 mL) and triethylamine (0.6 mL) were placed in
a three-necked round-bottomed flask, towhich P2S5 (0.4 g,1.9 mmol)
was added slowly in an ice bath and stirred until dissolved. Then
0
(C5), 27.4 (C4), 30.1 (C6), 69.6 (C1 ), 113.2 (C7), 116.2 (C9), 125.5 (C10),
125.9 (C10a),136.3 (C6a),147.0 (C3a, C]N),153.7 (C1, C]O),158.0 (C8);

F.-Y. Piao et al. / European Journal of Medicinal Chemistry 46 (2011) 1050e1055
1053
MS (APCI) m/z (%): 260.1 (Mþþ1,100); Anal. Calcd. for C14H17N3O2: C,
0.70e0.90 (m, 3H, CH3), 1.20e1.45 (m, 10H, alkyl C3 eH, C4 eH,
0
0
0
0
0
0
64.85; H, 6.61; N, 16.20. Found: C, 64.65; H, 6.74; N, 16.15.
C5 eH, C6 eH, C7 eH), 1.66e1.90 (m, 2H, alkyl C2 eH), 1.90e2.20 (m,
2H, C5eH), 2.42e2.60 (m, C4eH, C6eH and DMSO), 3.98 (t, 2H,
J ¼ 6.3 Hz, OeCH2), 6.90e7.00 (m, 2H, ar), 7.36 (d, 1H, J ¼ 8.6 Hz, ar),
0
4.3.3. 8-Butyloxy-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a][1]
benzazepin-1-one (3c)
11.66 (s, 1H, NH); 13C NMR (75 MHz,
d, ppm, DMSO-d6): 13.9 (C8 ),
, cmꢀ1): 3181 (NeH), 1714 (C]O), 1577, 1503, 1441 (C]
0 0 0 0
22.1 (C7 ), 23.1 (C5), 25.2 (C3 ), 27.4 (C4), 28.6 (C5 ), 28.8 (C4 ), 29.1
IR (KBr,
n
N, C]C),1263 (CeO); 1H NMR (300 MHz,
d
, ppm, DMSO-d6): 0.94 (t,
(C2 ), 30.0 (C6), 31.1 (C6 ), 68.1 (C1 ), 113.1 (C7), 116.2 (C9), 125.5 (C10),
125.9 (C10a), 136.2 (C6a), 147.0 (C3a, C]N), 153.7 (C1, C]O), 158.0
(C8); MS (APCI) m/z (%): 330.1 (Mþþ1, 100); Anal. Calcd. for
C19H27N3O2: C, 69.27; H, 8.26; N, 12.76. Found: C, 69.20; H, 8.42; N,
12.72.
0
0
0
0
3H, J ¼ 7.0 Hz, CH3), 1.40e1.48 (m, 2H, alkyl C3 eH), 1.68e1.73 (m,
0
2H, alkyl C2 eH), 1.90e2.20 (m, 2H, C5eH), 2.45e2.58 (m, C4eH,
C6eH and DMSO), 3.99 (t, 2H, J ¼ 5.6 Hz, OeCH2), 6.90e7.00 (m, 2H,
ar), 7.37 (d, 1H, J ¼ 8.4 Hz, ar), 11.66 (s, 1H, NH); 13C NMR (75 MHz,
d,
0
0
ppm, DMSO-d6): 14.2 (C4 ), 19.2 (C3 ), 23.1 (C5), 27.4 (C4), 30.1 (C6),
0
0
31.2 (C2 ), 67.9 (C1 ), 113.2 (C7), 116.2 (C9), 125.5 (C10), 125.9 (C10a),
136.3 (C6a), 147.0 (C3a, C]N), 153.8 (C1, C]O), 158.1 (C8); MS (APCI)
m/z (%): 274.1 (Mþþ1, 100); Anal. Calcd. for C15H19N3O2: C, 65.91; H,
7.01; N, 11.71. Found: C, 65.85; H, 7.08; N, 11.67.
4.3.8. 8-Benzyloxy-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a][1]
benzazepin-1-one (3h)
IR (KBr,
n
, cmꢀ1): 3167 (NeH), 1703 (C]O), 1585, 1504, 1437 (C]
N, C]C), 1244 (CeO); 1H NMR (300 MHz,
d, ppm, DMSO-d6):
2.00e2.08 (m, 2H, C5eH), 2.44e2.60 (m, C4eH, C6eH and DMSO),
5.13 (s, 2H, CH2), 7.00e7.10 (m, 2H, ar), 7.33e7.50 (m, 6H, ar), 11.67
4.3.4. 8-Pentyloxy-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a][1]
benzazepin-1-one (3d)
(s, 1H, NH); 13C NMR (75 MHz,
d
, ppm, DMSO-d6): 23.1 (C5), 27.4
(C4), 30.0 (C6), 69.9 (CH2), 113.5 (C7), 116.6 (C9), 125.3 (C10), 126.2
(C10a), 128.2 (C2, phenyl, C6, phenyl), 128.4 (C4, phenyl), 128.9 (C3, phenyl,
IR (KBr, n
, cmꢀ1):3186(NeH),1713 (C]O),1580,1504,1443(C]N,
C]C),1267 (CeO); 1H NMR (300 MHz,
d, ppm, DMSO-d6): 0.73e0.10
0
0
(m, 3H, CH3),1.16e1.39 (m, 4H, alkyl C3 eH, C4 eH),1.60e1.90 (m, 2H,
C5, phenyl), 136.4 (C6a), 137.3 (C1, phenyl), 147.0 (C3a, C]N), 153.7 (C1,
C]O), 157.5 (C8); MS (APCI) m/z (%): 284.1 (Mþþ1,100); Anal. Calcd.
for C18H17N3O2: C, 70.34; H, 5.58; N, 13.67. Found: C, 70.33; H, 5.70;
N, 13.64.
0
alkyl C2 eH), 1.90e2.18 (m, 2H, C5eH), 2.45e2.58 (m, C4eH, C6eH
andDMSO), 3.98 (t, 2H, J ¼ 6.0Hz, OeCH2), 6.90e7.00 (m, 2H, ar), 7.36
(d, 1H, J ¼ 8.6 Hz, ar), 11.66 (s, 1H, NH); 13C NMR (75 MHz,
d, ppm,
0
0
0
DMSO-d6): 14.4 (C5 ), 22.3 (C4 ), 23.1 (C5), 27.4 (C4), 28.2 (C3 ), 28.8
0
0
(C2 ), 30.0 (C6), 68.1 (C1 ),113.1 (C7),116.1 (C9),125.5 (C10),125.8 (C10a),
136.3 (C6a), 147.0 (C3a, C]N), 153.7 (C1, C]O), 158.0 (C8); MS (APCI)
m/z (%): 288.1 (Mþþ1, 100); Anal. Calcd. for C16H21N3O2: C, 66.88; H,
7.37; N, 14.62. Found: C, 66.68; H, 7.55; N, 14.59.
4.3.9. 8-(4-Chlorobenzyloxy)-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a]
[1]benzazepin-1-one (3i)
IR (KBr,
n
, cmꢀ1): 3179 (NeH), 1715 (C]O), 1580, 1501, 1441 (C]
N, C]C), 1261 (CeO); 1H NMR (300 MHz,
d
, ppm, DMSO-d6):
2.00e2.10 (m, 2H, C5eH), 2.43e2.60 (m, C4eH, C6eH and DMSO),
5.14 (s, 2H, CH2), 6.90e7.10 (m, 2H, ar), 7.39 (d, 1H, J ¼ 8.6 Hz, ar),
4.3.5. 8-Hexyloxy-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a][1]
benzazepin-1-one (3e)
7.43e7.50 (m, 4H, ar), 11.67 (s, 1H, NH); 13C NMR (75 MHz,
d, ppm,
IR (KBr,
N, C]C), 1263 (CeO); 1H NMR (300 MHz,
0.70e0.10 (m, 3H, CH3), 1.27e1.50 (m, 6H, alkyl C3 eH, C4 eH,
n
, cmꢀ1): 3186 (NeH), 1713 (C]O), 1578, 1503, 1443 (C]
DMSO-d6): 23.1 (C5), 27.3 (C4), 30.0 (C6), 69.0 (CH2), 113.5 (C7), 116.6
(C9), 125.6 (C10), 126.3 (C10a), 128.9 (C2,6, phenyl), 130.0 (C3,5,
phenyl), 132.9 (C4, phenyl), 136.4 (C6a, C1, phenyl), 147.0 (C3a, C]N),
153.7 (C1, C]O), 157.5 (C8); MS (APCI) m/z (%): 342.0 (Mþþ1, 100);
Anal. Calcd. for C18H16ClN3O2: C, 63.25; H, 4.72; N, 12.29. Found: C,
63.24; H, 4.84; N, 12.28.
d, ppm, DMSO-d6):
0
0
0
0
C5 eH), 1.55e1.74 (m, 2H, alkyl C2 eH), 1.90e2.18 (m, 2H, C5eH),
2.45e2.58 (m, C4eH, C6eH and DMSO), 3.98 (t, 2H, J ¼ 6.2 Hz,
OeCH2), 6.82e7.01 (m, 2H, ar), 7.36 (d, 1H, J ¼ 8.6 Hz, ar), 11.66 (s,
1H, NH); 13C NMR (75 MHz,
d
0 0
, ppm, DMSO-d6): 14.4 (C6 ), 22.5 (C5 ),
0
0
0
23.1 (C5), 25.6 (C4 ), 27.4 (C4), 29.1 (C3 ), 30.0 (C6), 31.4 (C2 ), 68.1
4.3.10. 8-(2-Chlorobenzyloxy)-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a]
0
(C1 ), 113.1 (C7), 116.1 (C9), 125.5 (C10), 125.8 (C10a), 136.3 (C6a), 147.0
[1]benzazepin-1-one (3j)
(C3a, C]N), 153.7 (C1, C]O), 158.0 (C8); MS (APCI) m/z (%): 302.1
(Mþþ1, 100); Anal. Calcd. for C17H23N3O2: C, 67.75; H, 7.69; N, 13.94.
Found: C, 67.68; H, 7.84; N, 13.91.
IR (KBr,
n
, cmꢀ1): 3163 (NeH), 1694 (C]O), 1587, 1504, 1439 (C]
N, C]C), 1244 (CeO); 1H NMR (300 MHz,
d, ppm, DMSO-d6):
2.00e2.10 (m, 2H, C5eH), 2.43e2.63 (m, C4eH, C6eH and DMSO),
5.19 (s, 2H, CH2), 7.00e7.13 (m, 2H, ar), 7.38e7.43 (m, 3H, ar),
7.51e7.60 (m, 1H, ar), 7.61e7.65 (m, 1H, ar), 11.68 (s, 1H, NH); 13C
4.3.6. 8-Heptyloxy-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a][1]
benzazepin-1-one (3f)
NMR (75 MHz, d, ppm, DMSO-d6): 23.1 (C5), 27.3 (C4), 30.0 (C6), 67.6
IR (KBr,
N, C]C), 1265 (CeO); 1H NMR (300 MHz,
0.72e0.91 (m, 3H, CH3), 1.27e1.50 (m, 8H, alkyl C3 eH, C4 eH,
n
, cmꢀ1): 3186 (NeH), 1713 (C]O), 1580, 1503, 1443 (C]
(CH2), 113.5 (C7), 116.5 (C9), 125.6 (C10), 126.5 (C10a), 127.9 (C5,
phenyl), 129.9 (C6, phenyl), 130.4 (C3, phenyl), 130.7 (C4, phenyl),
133.2 (C2, phenyl), 134.6 (C1, phenyl), 136.5 (C6a), 147.0 (C3a, C]N),
153.7 (C1, C]O), 157.5 (C8); MS (APCI) m/z (%): 342.0 (Mþþ1, 100);
Anal. Calcd. for C18H16ClN3O2: C, 63.25; H, 4.72; N, 12.29. Found: C,
63.19; H, 4.81; N, 12.25.
d, ppm, DMSO-d6):
0
0
0
0
0
C5 eH, C6 eH), 1.63e1.82 (m, 2H, alkyl C2 eH), 1.90e2.20 (m, 2H,
C5eH), 2.43e2.58 (m, C4eH, C6eH and DMSO), 3.98 (t, 2H,
J ¼ 6.3 Hz, OeCH2), 6.82e7.01 (m, 2H, ar), 7.36 (d, 1H, J ¼ 8.6 Hz, ar),
11.65 (s, 1H, NH); 13C NMR (75 MHz,
d, ppm, DMSO-d6): 14.4 (C7 ),
0
0
0
0
0
22.5 (C6 ), 23.1 (C5), 25.9 (C5 ), 27.4 (C4), 28.9 (C4 ), 29.1 (C3 ), 30.0
4.3.11. 8-(3-Chlorobenzyloxy)-5,6-dihydro-4H-[1,2,4]triazolo[4,3-
0
0
(C6), 31.7 (C2 ), 68.1 (C1 ), 113.1 (C7), 116.1 (C9), 125.5 (C10), 125.9
(C10a), 136.2 (C6a), 147.0 (C3a, C]N), 153.7 (C1, C]O), 158.0 (C8); MS
(APCI) m/z (%): 316.1 (Mþþ1, 100); Anal. Calcd. for C18H25N3O2: C,
68.54; H, 7.99; N, 13.32. Found: C, 68.53; H, 8.07; N, 13.29.
a][1]benzazepin-1-one (3j)
IR (KBr,
n
, cmꢀ1): 3175 (NeH), 1713 (C]O), 1578, 1503, 1443 (C]
N, C]C), 1263 (CeO); 1H NMR (300 MHz,
d
, ppm, DMSO-d6):
2.00e2.10 (m, 2H, C5eH), 2.43e2.63 (m, C4eH, C6eH and DMSO),
5.16 (s, 2H, CH2), 7.00e7.13 (m, 2H, ar), 7.37e7.50 (m, 4H, ar), 7.54 (s,
4.3.7. 8-Octyloxy-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a][1]
1H, ar), 11.68 (s, 1H, NH); 13C NMR (75 MHz,
d, ppm, DMSO-d6): 23.1
benzazepin-1-one (3g)
(C5), 27.3 (C4), 30.0 (C6), 68.9 (CH2), 113.5 (C7), 116.7 (C9), 125.6 (C10),
126.4 (C10a),126.7 (C6, phenyl),127.8 (C2, phenyl),128.3 (C4, phenyl),
130.9 (C5, phenyl), 133.6 (C3, phenyl), 136.4 (C6a), 139.9 (C1, phenyl),
IR (KBr,
n
, cmꢀ1): 3186 (NeH), 1710 (C]O), 1581, 1503, 1443 (C]
N, C]C), 1264 (CeO); 1H NMR (300 MHz,
d, ppm, DMSO-d6):

1054
F.-Y. Piao et al. / European Journal of Medicinal Chemistry 46 (2011) 1050e1055
147.0 (C3a, C]N), 153.7 (C1, C]O), 157.5 (C8); MS (APCI) m/z (%):
342.0 (Mþþ1, 100); Anal. Calcd. for C18H16ClN3O2: C, 63.25; H, 4.72;
N, 12.29. Found: C, 63.21; H, 4.77; N, 12.27.
4.3.16. 8-(4-Bromobenzyloxy)-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a]
[1]benzazepin-1-one (3p)
IR (KBr,
n
, cmꢀ1): 3163 (NeH), 1697 (C]O), 1584, 1503, 1441 (C]
N, C]C), 1261 (CeO); 1H NMR (300 MHz,
d
, ppm, DMSO-d6):
4.3.12. 8-(4-Fluorobenzyloxy)-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a]
1.98e2.11 (m, 2H, C5eH), 2.42e2.63 (m, C4eH, C6eH and DMSO),
5.12 (s, 2H, CH2), 7.00e7.10 (m, 2H, ar), 7.37e7.48 (m, 3H, ar), 7.61 (d,
[1]benzazepin-1-one (3k)
IR (KBr,
n
, cmꢀ1): 3177 (NeH), 1715 (C]O), 1580, 1508, 1443 (C]
2H, J ¼ 8.1 Hz, ar), 11.68 (s, 1H, NH); 13C NMR (75 MHz,
d, ppm,
N, C]C), 1263 (CeO); 1H NMR (300 MHz,
d, ppm, DMSO-d6):
DMSO-d6): 23.1 (C5), 27.4 (C4), 30.0 (C6), 69.1 (CH2), 113.5 (C7), 116.5
(C9), 121.5 (C4, phenyl), 125.6 (C10), 126.3 (C10a), 130.3 (C2,6, phenyl),
131.8 (C3,5, phenyl), 136.4 (C6a), 136.8 (C1, phenyl), 147.0 (C3a, C]N),
153.7 (C1, C]O), 157.5 (C8); MS (APCI) m/z (%): 346.0 (Mþþ1, 100);
Anal. Calcd. for C18H16BrN3O2: C, 55.97; H, 4.18; N, 10.88. Found: C,
55.81; H, 4.27; N, 10.84.
2.00e2.10 (m, 2H, C5eH), 2.43e2.60 (m, C4eH, C6eH and DMSO),
5.11 (s, 2H, CH2), 7.00e7.10 (m, 2H, ar), 7.20e7.27 (m, 2H, ar), 7.39 (d,
1H, J ¼ 8.6 Hz, ar), 7.50e7.55 (m, 2H, ar), 11.67 (s, 1H, NH); 13C NMR
(75 MHz, d, ppm, DMSO-d6): 23.1 (C5), 27.4 (C4), 30.1 (C6), 69.2
(CH2), 113.5 (C7), 115.7 (d, JCeF ¼ 21.2 Hz, C3,5, phenyl), 116.6 (C9),
125.5 (C10), 126.3 (C10a), 130.5 (d, JCeF ¼ 8.3 Hz, C2,6, phenyl), 133.6
(d, JCeF ¼ 2.6 Hz, C1, phenyl), 136.4 (C6a), 147.0 (C3a, C]N), 153.8 (C1,
C]O), 157.5 (C8), 162.3 (d, JCeF ¼ 242.6 Hz, C4, phenyl); MS (APCI)
m/z (%): 326.0 (Mþþ1, 100); Anal. Calcd. for C18H16FN3O2: C, 66.45;
H, 4.96; N, 12.92. Found: C, 66.32; H, 5.07; N, 12.89.
4.4. Pharmacology
The MES test, scPTZ test, and rotarod test were carried out by the
Antiepileptic Drug Development Program (ADD), Epilepsy Branch,
National Institutes of Health, Bethesda, MD, USA [27,28]. All
compounds were tested for anticonvulsant activity with Swiss mice
in the 18e22 g weight range purchased from the Laboratory of
Animal Research, College of Pharmacy, Yanbian University. The
tested compounds were dissolved in DMSO. In phase I screening
(Table 1) each compound was administered at three dose levels (30,
100, and 300 mg/kg i.p.) with anticonvulsant activity and neuro-
toxicity assessed at 30 min and 4 h intervals after administration.
Anticonvulsant efficacy was measured in the MES test and the
scPTZ test. In the 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. Abolition of the hind-leg
tonic-extensor component of the seizure indicated protection
against the spread of MES-induced seizures. The scPTZ test
involved subcutaneous injection of a convulsant dose of pentyl-
enetetrazol (85 mg/kg in mice). Elevation of the pentylenetrazol-
induced seizure threshold was indicated by the absence of clonic
spasms for at least 5 s duration over a 30 min period following
administration of the test compound. Anticonvulsant drug-induced
neurologic deficit was detected in mice by using the rotarod ataxia
test. Anticonvulsant activity was expressed in terms of the median
effective dose (ED50), and neurotoxicity was expressed as the
median toxic dose (TD50). For determination of the ED50 and TD50
values, groups of 10 mice were given a range of intraperitoneal
doses of the tested compounds until at least three points were
established in the range of 10e90% seizure protection or minimal
observed neurotoxicity. From the plots of these data, the respective
ED50, TD50 values and 95% confidence intervals were calculated by
means of Trimmed Spearman-Karber method [29].
4.3.13. 8-(2-Fluorobenzyloxy)-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a]
[1]benzazepin-1-one (3l)
IR (KBr,
n
, cmꢀ1): 3167 (NeH), 1699 (C]O), 1587, 1506, 1439 (C]
N, C]C), 1242 (CeO); 1H NMR (300 MHz,
d
, ppm, DMSO-d6):
2.00e2.10 (m, 2H, C5eH), 2.44e2.62 (m, C4eH, C6eH and DMSO),
5.17 (s, 2H, CH2), 7.00e7.12 (m, 2H, ar), 7.20e7.31 (m, 2H, ar),
7.38e7.49 (m, 2H, ar), 7.55e7.62 (m, 1H, ar), 11.68 (s, 1H, NH); 13C
NMR (75 MHz, d, ppm, DMSO-d6): 23.1 (C5), 27.3 (C4), 30.0 (C6), 64.3
(d, JCeF ¼ 2.5 Hz, CH2), 113.5 (C7), 115.9 (d, JCeF ¼ 20.9 Hz, C3,
phenyl), 116.5 (C9), 124.1 (d, JCeF ¼ 14.4 Hz, C1, phenyl), 125.0 (d,
JCeF ¼ 2.8 Hz, C5, phenyl), 125.6 (C10), 126.4 (C10a), 131.0 (d,
JCeF ¼ 8.1 Hz, C4, phenyl), 131.2 (d, JCeF ¼ 3.5 Hz, C6, phenyl), 136.4
(C6a), 147.0 (C3a, C]N), 153.7 (C1, C]O), 157.5 (C8), 160.9 (d,
JCeF ¼ 244.5 Hz, C2, phenyl); MS (APCI) m/z (%): 326.0 (Mþþ1, 100);
Anal. Calcd. for C18H16FN3O2: C, 66.45; H, 4.96; N, 12.92. Found: C,
66.37; H, 4.98; N, 12.88.
4.3.14. 8-(3-Fluorobenzyloxy)-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a]
[1]benzazepin-1-one (3m)
IR (KBr,
(C]N, C]C), 1263 (CeO); 1H NMR (300 MHz,
n
, cmꢀ1): 3179 (NeH), 1713 (C]O), 1578, 1503, 1443
d
, ppm, DMSO-d6):
1.98e2.17 (m, 2H, C5eH), 2.40e2.70 (m, C4eH, C6eH and DMSO),
5.18 (s, 2H, CH2), 7.02e7.65 (m, 7H, ar), 11.69 (s, 1H, NH); 13C NMR
(75 MHz, d, ppm, DMSO-d6): 23.1 (C5), 27.4 (C4), 30.1 (C6), 69.1
(CH2), 113.6 (C7), 114.7 (d, JCeF ¼ 22.6 Hz, C2, phenyl), 115.1 (d,
JCeF ¼ 20.3 Hz, C4, phenyl), 116.7 (C9), 124.0 (C6, phenyl), 125.6
(C10), 126.4 (C10a), 131.0 (d, JCeF ¼ 7.4 Hz, C5, phenyl), 136.4 (C6a),
140.3 (d, JCeF ¼ 5.0 Hz, C1, phenyl), 147.0 (C3a, C]N), 153.7 (C1, C]
O), 157.5 (C8), 162.7 (d, JCeF ¼ 242.6 Hz, C3, phenyl); MS (APCI) m/z
(%): 326.0 (Mþþ1, 100); Anal. Calcd. for C18H16FN3O2: C, 66.45; H,
4.96; N, 12.92. Found: C, 66.34; H, 5.04; N, 12.85.
Acknowledgment
This work was supported by the National Natural Science
Foundation of China (Nos. 30460151 and No. 30760290) and
Important Item Foundation of Ministry of Education PR China (No.
20070422029).
4.3.15. 8-(4-Methylbenzyloxy)-5,6-dihydro-4H-[1,2,4]triazolo[4,3-a]
[1]benzazepin-1-one (3o)
IR (KBr,
n
, cmꢀ1): 3177 (NeH), 1711 (C]O), 1578, 1499, 1441
(C]N, C]C), 1260 (CeO); 1H NMR (300 MHz,
d, ppm, DMSO-d6):
1.98e2.10 (m, 2H, C5eH), 2.31 (s, 3H, CH3), 2.40e2.62 (m, C4eH,
C6eH and DMSO), 5.08 (s, 2H, CH2), 6.95e7.10 (m, 2H, ar),
7.18e7.25 (m, 2H, ar), 7.32e7.45 (m, 3H, ar), 11.67 (s, 1H, NH); 13C
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