Synthesis and Anticonvulsant Activity Evaluation of 4-Phenyl-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-one and Its Derivatives

Article abstract of DOI:10.1002/ardp.201500115

A series of 4-(substituted-phenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-ones (6a-x) with triazole and other heterocyclic substituents (7-14) were synthesized and the compounds were evaluated for their anticonvulsant activity and neurotoxicity by maximal electroshock (MES) and rotarod neurotoxicity tests. Among the compounds studied, 6o and 6q showed wide margins of safety with protective indices (PIs) that were much higher than those of currently used drugs (PI_6o > 25.5, PI_6q > 26.0). Compounds 6o and 6q showed significant oral activity against MES-induced seizures in mice, with ED₅₀ values of 88.02 and 94.6 mg/kg, respectively. The two compounds were also found to have potent activity against seizures that were induced by pentylenetetrazole and bicuculline. A series of 4-(substituted-phenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-ones with triazole and other heterocyclic substituents were synthesized and the compounds were evaluated for their anticonvulsant activity and neurotoxicity using maximal electroshock and rotarod neurotoxicity tests.

Full text of DOI:10.1002/ardp.201500115

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Arch. Pharm. Chem. Life Sci. 2015, 348, 564–574
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Full Paper
Synthesis and Anticonvulsant Activity Evaluation of 4-Phenyl-
[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-one and Its Derivatives
Hong-Jian Zhang1, Peng Jin2, Shi-Ben Wang1, Fu-Nan Li3, Li-Ping Guan4, and Zhe-Shan Quan1
1
College of Pharmacy, Yanbian University, Yanji, Jilin, China
Department of Pharmacology, Ischemic/Hypoxic Disease Institute, Seoul National University College of
Medicine, Seoul, Republic of Korea
School of Pharmaceutical Sciences, Xiamen University, Xiamen, Fujian, China
Zhejiang Provincial Key Engineering Technology Research Center of Marine Biomedical Products,
Food and Pharmacy College, Zhejiang Ocean University, Zhoushan, Zhejiang, China
2
3
4
A series of 4-(substituted-phenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-ones (6a–x) with triazole and
other heterocyclic substituents (7–14) were synthesized and the compounds were evaluated for their
anticonvulsant activity and neurotoxicity by maximal electroshock (MES) and rotarod neurotoxicity tests.
Among the compounds studied, 6o and 6q showed wide margins of safety with protective indices (PIs)
that were much higher than those of currently used drugs (PI6o > 25.5, PI6q > 26.0). Compounds 6o and 6q
showed significant oral activity against MES-induced seizures in mice, with ED50 values of 88.02 and
94.6 mg/kg, respectively. The two compounds were also found to have potent activity against seizures
that were induced by pentylenetetrazole and bicuculline.
Keywords: Anticonvulsant / BIC / Maximal electroshock / sc-PTZ / Synthesis / Triazole
Received: March 26, 2015; Revised: April 29, 2015; Accepted: May 6, 2015
DOI 10.1002/ardp.201500115
Additional supporting information may be found in the online version of this article at the publisher’s web-site
:
pharmaceutical industries [8]. Quinazoline was first prepared
in 1903, but breakthroughs in the late 20th century have
Introduction
Epilepsy is the most common neurological disorder in the
world, and affects about 45–100 million people [1]. Antiepi-
leptic drugs (AEDs) can control seizures to some extent;
however, about 30% of epilepsy patients are thought to be
undertreated [2]. Many currently available AEDs also have
serious side effects [3–7], and in general, patients require
increased its medicinal value [9, 10]. The pharmacology of
quinazoline and quinazolinone derivatives is broad and they
have been shown to possess anti-inflammatory, antimicrobial,
anticonvulsant, antiparasitic, and anticancer properties
[11–17]. The quinazoline motif has previously been referred
to as the “master key” to antiepileptic therapy [18–20].
Therefore, the potency and selectivity of quinazolines have
recently aroused the interest of many researchers in the field of
anticonvulsant design. In a previous study in our laboratory,
we synthesized several 5-substituted-[1,2,4]triazolo[4,3-a]-
quinazolines (I) and tested their anticonvulsant activities.
Amongthem,5-(heptyloxy)-[1,2,4]triazolo[4,3-a]quinazoline(II)
(ED50 ¼ 39.4 mg/kg, PI ¼ 8.3) was found to be especially potent
[21]. Among clinically active anticonvulsants such as
lifelong medication. This has resulted in
a continuous
challenge for us to find new antiepileptic agents with more
selectivity and lower toxicity. In this article, we describe the
synthesis and evaluation of several molecules with potential
anticonvulsant activity (only compounds 6d, 6f, 6h, 6i, 6u, 6v,
6w, and 11–13 are new).
Heterocyclic compounds are widely studied as potential
new bioactive scaffolds in both the agrochemical and
Correspondence: Dr. Zhe-Shan Quan, College of Pharmacy,
Yanbian University, No. 977, Park road, Yanji, Jilin 133002, China.
E-mail: zsquan@ybu.edu.cn
*Additional correspondence: Prof. Li-Ping Guan,
E-mail: glp730@zjou.edu.cn;
Fax: þ86-433-2436020
Prof. Fu-Nan Li, E-mail: fnlee5@xmu.edu.cn
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Triazolo-quinazolines as Anticonvulsants
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Figure 1. Clinically available antiepileptic drugs which have the major characteristics.
phenobarbital, carbamazepine, rufinamide, and phenytoin
(Fig. 1), we can see that a commonly reoccurring motif in their
structures is the presence of hydrophobic binding sites (A), a
hydrogen bonding domain (HBD), and an electron–donor
group (D).
Based on the observations above, we decided to attach a
phenyl group onto the NH group of quinazolin-4(3H)-one (III)
to serve as the hydrophobic binding site, and then combine
3-phenyl-2,3-dihydroquinazolin-4(1H)-one with triazole (as
the HBD) in order to reach our target compound (6a), and
the products (6b–x) after the chemical modification were
obtained. We also synthesized its derivatives (7–14) by using
bioisosterism, among other strategies. Here, we describe our
most recent work on the design, synthesis, and preliminary
triazolo[4,3-a]quinazolin-5(4H)-ones and their derivatives
(Fig. 2). In phase II, with quantitative anticonvulsant evalua-
tion of compounds (6j, 6m, 6o, and 6q) in mice after i.p.
injection, the most active compounds 6o and 6q after p.o.
injectionweredeterminedbyevaluatingtimeto peak. In order
to establish a structure–activity relationship, we compared the
activity of compounds with different substituted phenyl
groups and compounds where triazole had been replaced.
Following this, compounds 6o and 6q were used in PTZ- and
BIC-induced seizure tests and the potency of compounds 6o
and 6q against PTZ- and BIC-induced seizures was also
established in this study.
evaluation of
a series of 4-(substituted-phenyl)-[1,2,4]-
Results and discussion
Chemistry
All the compounds were synthesized by slightly modifying a
previously reported method as depicted in Scheme 1. To begin
with, the substituted aniline was dissolved in DMSO and
reacted with carbon disulfide and aqueous sodium hydroxide
to give the sodium salt of a 4-substituted phenylcarbamodi-
thioate (1a–x). This was then reacted with dimethyl sulfate to
afford a methyl 4-substituted phenylcarbamodithioate (2a–x).
Next, a solution of (2a–x) in ethanol was treated with
methyl anthranilate in the presence of anhydrous potassium
carbonate to obtain methyl 2-(3-substituted-phenyl-thiour-
eido)benzoate as an intermediate (3a–x), which upon basic
hydrolysis yielded the compounds 4a–x. Then, 4a–x was
reacted with hydrazine hydrate in ethanol to furnish a
2-hydrazono-3-substituted-phenyl-2,3-dihydroquinazolin-4(1H)-
one (5a–x). This was treated with formic acid and refluxed
overnight to acquire the compounds 6a–x, which were
recrystallized from ethanol as colorless crystals. To obtain the
target compounds (7–14), 5a was reacted with acetic acid, urea,
carbon disulfide, sodium nitrite, diethyl oxalate, ammonia,
pyruvic acid, and acetyl acetone, respectively [22–29].
Pharmacology
Anticonvulsant activity was screened using the MES test and
neurotoxicity was measured by rotarod test. The MES test
and rotarod test were carried out according to the standard
Figure 2. Design of compounds 6a–x and 7–14.
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Scheme 1. Synthesis of compounds 6a–x, and 7–
14. (a) HCOOH, reflux, 12 h; (b) CH3COOH,
reflux, 12–16 h; (c) NH2CONH2, 200°C, 1.5 h;
(d) CS2, KOH, ethanol, reflux, 8–12 h; (e) NaNO2,
10% HCl, 0–3°C, 6 h; (f) diethyl oxalate, reflux,
1 h; (g) NH3 ꢀ H2O, ethanol, rt, 3 h; (h) CH3CO-
COOH, ethanol, ref, 10 h; (i) (CH3CO)2CH2, 1, 4-
dioxane, ref, 3 h.
procedure described in the Antiepileptic Drug Development
Program of the National Institutes of Health (USA) [30, 31].
The described pharmacological evaluation was accepted by
Ethics Commission of China. All the compounds were
dissolved in DMSO, and Kunming mice (provided by the
Laboratory of Animal Research, College of Pharmacy, Yanbian
University) in the 18–22 g weight range were used. We
decided to determine the time–activity curve by administering
compounds orally because of their lower neurotoxicities, and
and five of these (6m, 6n, 6o, 6q, and 6x) were found to
remain active at a dose of 30 mg/kg. As shown in Table 1, it is
noteworthy that in the derivatives with triazole (6a) and other
heterocyclic substituents (7–14), four (6a, 11, 13, and 14) were
found to be active at a dose of 100 mg/kg. In these four
after that, we determined their median effective dose (ED50
)
and median toxic dose (TD50). The quantitative studies were
performed at estimated time of peak effect (TPE) for MES test.
(Fig. 3) Finally, we chose the two best compounds (6o and 6q),
which had similar ED50 values, and used them in PTZ- and BIC-
induced seizure tests.
In this text, to target grand-mal epilepsy, so phase I studies
only involved two tests: MES to detect agents that prevent the
spread of seizures and rotarod test used for evaluation of
neurotoxicity. This preliminary screening covered all of the
compounds that we synthesized and the results are summa-
rized in Table 1. Eleven compounds possessed anticonvulsant
activity against MES-induced seizures at a dose of 100 mg/kg,
Figure 3. Time-courseof6oand6qintheMES test(i.p., 50 mg/kg,
the number of animals was 10).
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Triazolo-quinazolines as Anticonvulsants
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Table 1. Phase I evaluation of anticonvulsant activity in mice (i.p.).
MESa)
TOX
Compounds
R
100
30
100
30
b)
6a
6b
6c
6d
6e
6f
6g
6h
6i
6j
6k
6l
6m
6n
6o
6p
6q
6r
6s
6t
6u
6v
6w
6x
7
8
9
10
11
12
13
14
–H
o-OCH3
p-OCH3
p-OC3H7
p-OC4H9
p-OC5H11
p-O(isoC5H11
p-OC6H13
p-OC8H17
o-F
m-F
p-F
o-Cl
m-Cl
p-Cl
m-Br
p-Br
o-CH3
m-CH3
p-CH3
p-CF3
3,4-Cl2
2,6-(CH3)2
3,4-(CH3)2
–H
1/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
3/3
0/3
0/3
3/3
2/3
3/3
0/3
3/3
1/3
0/3
0/3
0/3
0/3
0/3
3/3
0/3
0/3
0/3
0/3
1/3
0/3
1/3
1/3
–
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
1/3
0/3
0/3
2/3
1/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
0/3
3/3
0/3
0/3
0/3
0/3
2/3
2/3
2/3
2/3
–
–
–
–
–
–
–
–
–
–
–
)
–
–
–
–
–
–
0/3
–
–
–
–
–
1/3
1/3
1/3
–
0/3
0/3
0/3
–
1/3
–
0/3
–
–
–
–
–
–
–
–
–
–
–
1/3
–
0/3
–
–H
–H
–H
–H
–H
–H
–H
–
–
–
–
–
–
–
–
–
–
–
–
–
–
a) Maximal electroshock test (number of animals protected/number of animals tested), the number of mice is three; the dose
measured in mg/kg.
b) Not tested.
compounds, only compound 6a did not show toxicity at a dose
of 100 mg/kg. Naturally, triazole-containing compound 6a
was verified to be better than the compounds with other
heterocycle substituents, so we try to investigate the derivants
of 6a through structural modification. We hypothesize that
the inclusion of a triazole group is necessary for our
compounds to show antiepileptic activity. Although the
compounds that contained other heterocyclic substituents
were not suitable for our intended purpose, it is a great
achievementtohavesynthesizedsucha seriesof4-(substituted-
phenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-ones. Among
compounds 6b to 6i, none showed anticonvulsant activity
at a dose of 100 mg/kg. We can infer that the length of the
alkyl chain has a small effect on the anticonvulsant activity
of the 4-(4-phenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-one
derivatives. Among compounds 6j to 6q and 6v, most of the
compounds that contained a halogen atom at the 2- and
4-position on the phenyl ring showed anticonvulsant activity
against MES-induced seizures. It can also be seen that singly
substituted phenyls are better than doubly substituted and
that meta-substitution is not as good as ortho- and para-
substitution. However, some of the compounds showed
different degrees of neurotoxicity (6j, 1/3, 6m, 2/3, 6n, 1/3)
at the dose of 100 mg/kg.
On the basis of the results obtained in phase I testing, four
compounds (6j, 6m, 6o, and 6q) were subjected to trials with a
view to quantifying their anticonvulsant activity (indicated by
ED50) and neurotoxicity (indicated by TD50) in mice when
administered by intraperitoneal injection. The ED50 of their
anti-MES activity was not any better than that of the currently
used antiepileptic drug carbamazepine, phenytoin, and
phenobarbital. However, the neurotoxicity of two com-
pounds (6o and 6q) was minimal (TD50 > 700 mg/kg) and
was markedly lower than carbamazepine and valproate.
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rings is not conducive to increase the antiepileptic activity, but
a strong electron-withdrawing group can do it, especially the
group at the 2- or 4-position on the phenyl ring.
Finally, compounds 6o and 6q were tested against seizures
induced by PTZ and BIC in order to prove they displayed wide
spectrum activity in several models. Compounds 6o, 6q, and
the reference drug carbamazepine were administered (i.p.)
into mice at 50 mg/kg.
Compounds 6o, 6q, and carbamazepine did not inhibit the
clonic seizures induced by sc-PTZ, but they did inhibit the tonic
seizures and, to some extent, reduce lethality. Carbamazepine
inhibited clonic seizures, tonic seizures, and death induced by
sc-PTZ with success rates of 0, 100, and 100%, respectively. For
comparison, the values for compounds 6o and 6q were 0, 90,
20% and 0, 100, 60%, respectively (Table 3). In the BIC-induced
seizure model, both carbamazepine and 6o inhibited tonic
seizures and death, but did not inhibit clonic seizures.
Carbamazepine and 6o showed inhibition of clonic seizures,
tonic seizures, and death with success rates of 0, 100, 90% and 0,
80, 100%, respectively. Compound 6q showed inhibition of
clonicandtonicseizuresanddeathwithsuccessratesof0,60,and
10%, respectively (Table 3). Thus, compounds 6o and 6q can
protect the mice from tonic seizures in the sc-PTZ and BIC model
Figure 4. Time-course of 6o (p-Cl, 100 mg/kg) and 6q (p-Br,
120 mg/kg) in the MES test (p.o., the number of animals was 10).
Obviously, compounds 6o and 6q also had a higher protective
index than the positive control. According to the results of
phase II (i.p.), we conducted a time-course test of compounds
6o and 6q in the maximal electroshock seizure test (Fig. 4), in
which compound 6o reached the TPE at 2.5 h and 6q reached
the TPE at 1.5 h after administered orally, and then their anti-
MES activities decreased over time. Therefore, we choose
2.5 h as the testing time of the compound 6o in phase II
quantitative anticonvulsant evaluation in mice (p.o.). To our
surprise, they did not show neurotoxicity even at a dose of
2000 mg/kg. All the data from phase II are shown in Table 2.
Overall, bioevaluation demonstrated that the compounds
that possessed a triazole displayed the best anticonvulsant
activity in the MES test. The compounds that contained
halogen-substituted phenyl rings expressed significant anti-
convulsant activity. The trend in activity was p-Br > p-Cl > o-
F > o-Cl, and compounds 6o and 6q showed marked lower
neurotoxicity compared to carbamazepine and therefore a
higher protective index. What we really need now is to accept
that an electron donating group introduced to the phenyl
Conclusion
In the present study, 32 derivatives of 4-phenyl-[1,2,4]-
triazolo[4,3-a]quinazolin-5(4H)-ones have been designed,
synthesized, and evaluated for their anticonvulsant activity.
In the derivatives 6a–x, variation in the substituents on the
phenyl group affected activity. An electron-withdrawing
group was a more profitable structural feature than an
electron-donating group.
Compounds 6o and 6q displayed a wide margin of safety
with a protective index (PI) much higher than that of existing
Table 2. Quantitative anticonvulsant data in mice.
Compounds
ED50 (MES)a)
TD50 (NT)b)
PIc)
0.99
0.76
>25.56
>26.03
8.1
6j (i.p.)
6m (i.p.)
6o (i.p.)
6q (i.p.)
63.10 (53.83–73.96)d)
40.64 (30.41–54.32)
27.39 (17.20–43.61)
26.89 (20.20–35.79)
8.8 (5.5–14.1)
9.5 (8.1–10.4)
21.8 (21.8–25.5)
272 (247–338)
62.24 (46.34–82.04)
31.04 (24.72–38.99)
>700
>700
Carbamazepine (i.p.)e)
Phenytoin (i.p.)e)
Phenobarbital (i.p.)e)
Valproate (i.p.)e)
6o (p.o.)
71.6 (45.9–135)
65.5 (52.5–72.9)
69.0 (62.8–72.9)
426 (369–450)
>2000
6.9
3.2
1.6
88.02 (60.92–127.17)
94.60 (81.88–109.30)
30.4
>22.72
>21.14
7.7
6q (p.o.)
Carbamazepine (p.o.)
>2000
235.7
a) ED50: Median effective dose affording anticonvulsant protection in 50% of animals, the dose is measured in mg/kg.
b) TD50: Median toxic dose eliciting minimal neurological toxicity in 50% of animals, the dose is measured in mg/kg.
c) PI: Protective index (TD50/ED50).
d) 95% confidence intervals given in parentheses.
e) Data from Krall et al. [30].
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Triazolo-quinazolines as Anticonvulsants
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Table 3. Effects of compounds 6o and 6q on chemical-induced seizures in mice (i.p.).
Chemical
substances
Doses
(mg/kg)
Test time
(h)a)
Clonic
Tonic
seizures (%)
Lethality
Compounds
seizures (%)b)
(%)
DMSO
Carbamazepine
–
0.5
0.5
0.5
0.5
0.5
0.5
0.5
0.5
100
100
100
100
100
100
100
100
100
0
10
0
100
0
20
40
90
0
80
40
100
10
0
Pentylenetetrazol
Bicuculline
50
50
50
–
6o
6q
DMSO
Carbamazepine
50
50
50
6o
6q
90
a) At 0.5 h after the administration of the test compound, chemical substances were administered in mice.
b) The number of mice with clonic seizures, tonic seizures, and deaths/the number of animals tested ꢂ 100%.
drugs (PI6o > 25.5, PI6q > 26.0), and also showed significant
oral activity against MES-induced seizures in mice, with an
ED50 of 88.02 and 94.60 mg/kg, respectively. Moreover
compounds 6o and 6q could protect the mice from tonic
seizures and reduce the mortality rate in the sc-PTZ and BIC
model to a certain extent. Hence, the compounds 6o and 6q
displayed wide spectrum activity in several models.
(40 mL) was refluxed for 25–33 h. The reaction mixture was
poured into cold water. The solid methyl 2-(3-phenylthiour-
eido)benzoate derivative (3a–x) that was obtained was
filtered and refluxed in 10% alcoholic sodium hydroxide
solution for 2 h. After cooling to room temperature, it was re-
precipitated by treatment with dilute hydrochloric acid. The
solid obtained was washed with water and recrystallized from
ethanol to afford (4a–x).
Synthesis of 2-hydrazono-3-phenyl-2,3-
Experimental
dihydroquinazolin-4(1H)-one derivatives (5a–x) [34]
3-Phenyl-2-thioxo-2,3-dihydroquinazolin-4(1H)-one deriva-
tive (4a–x) (0.01 mol) was dissolved in ethanol (25 mL).
Hydrazine hydrate (60%, 0.12 mol) was added and refluxed
for 4 h under nitrogen. The reaction mixture was then poured
into cold water. The solid (5a–x) obtained was filtered,
washed with water, dried, and purified by silica gel column
chromatography using CH2Cl2/CH3OH (80:1) as the eluent.
Chemistry
Melting points were determined in open capillary tubes and
were uncorrected. IR spectra were recorded (in KBr) on IR
1
Prestige-21 (PerkineElmer, Waltham, MA, USA). H NMR and
13C NMR spectra were measured on an AV-300 (Bruker,
Switzerland), and all chemical shifts were given in ppm
relative to TMS. Mass spectra were measured on a HP1100LC
(Agilent Technologies, USA). High resolution mass spectra
were measured on an MALDI-TOF/TOF mass spectrometer
(Bruker Daltonik, Germany). The chemicals were purchased
from Aldrich Chemical Corporation.
Synthesis of 4-(4-phenyl)-[1,2,4]triazolo[4,3-a]quinazolin-
5(4H)-one derivatives (6a–x) [22]
Compounds 5a–x (0.01 mol) and formic acid (25 mL) were
added to a round-bottomed flask, refluxed overnight, and
then poured into ice water. The target compound (6a–x)
obtained was filtered, washed with water, dried, and purified
by silica gel column chromatography using CH2Cl2/CH3OH
(100:1) as the eluent.
Synthesis of methyl phenylcarbamodithioate derivatives
(2a–x) [32]
To a solution of substituted aniline (0.03 mol) in DMSO (20 mL),
carbon disulfide (2.74 g, 0.036mol) and an aqueous solution of
sodium hydroxide (1.5 mL, 20M) were added simultaneously
with stirring at room temperature to afford salt (1a–x) as an
intermediate. After 2–4 h, dimethyl sulfate (0.03 mol) was
added dropwise while the reaction mixture was kept stirring
in a freezing mixture for 5 h. After completion, the reaction
mixture was poured into ice water. The solid obtained was
filtered, washed, and re-crystallized from ethanol to obtain
methyl-substituted phenylcarbamodithioate (2a–x).
4-Phenyl-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-one (6a)
Yield: 30%, mp: 303–305°C. 1H NMR (CDCl3, 300 MHz) d: 7.48–
8.48(m,9H,Ar-H),8.81(s,1H,–N CH–).13CNMR(CDCl3,75 MHz)
–
–
d: 158.5, 148.9, 135.5, 134.2, 134.1, 132.5, 130.8, 129.8, 129.6,
128.1, 127.5, 117.3, 114.7. IR (KBr, cmꢁ1): 1688 (C O), 1614,
–
–
1599, 1300, 1148. ESI-HRMS calcd. for C15H11N4Oþ ([MþH]þ):
263.0927; found: 263.0934.
Synthesis of 3-phenyl-2-thioxo-2,3-dihydroquinazolin-
4(1H)-one derivatives (4a–x) [33]
A solution of 2a–x (0.02 mol), methyl anthranilate (0.02 mol),
4-(2-Methoxyphenyl)-[1,2,4]triazolo[4,3-a]quinazolin-
5(4H)-one (6b)
1
Yield: 35%, mp: 206–208°C. H NMR (CDCl3, 300 MHz) d: 3.78
–
anhydrous potassium carbonate (200 mg), and ethanol
(s, 3H, –CH ), 7.11–8.48 (m, 8H, Ar-H), 8.85 (s, 1H, –N CH–).
–
3
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Arch. Pharm. Chem. Life Sci. 2015, 348, 564–574
H.-J. Zhang et al.
Archiv der Pharmazie
13C NMR (CDCl3, 75 MHz) d: 162.8, 158.4, 154.9, 148.6, 135.3,
126.4, 117.3, 115.6, 114.8, 66.6, 37.9, 25.0, 22.6. IR (KBr, cmꢁ1):
–
134.2, 132.7, 131.5, 130.8, 129.7, 127.4, 122.6, 121.4, 114.9,
1690 (C O), 1614, 1596, 1290, 1141, 1178, 1252. ESI-HRMS
–
112.6, 55.8. IR (KBr, cmꢁ1): 1684 (C O), 1614, 1594, 1296, 1147,
calcd. for C20H21N4O2þ ([MþH]þ): 349.1659; found: 349.1660.
–
–
þ
1176, 1255. ESI-HRMS calcd. for C16H13N4O2 ([MþH]þ):
293.1033; found: 293.1036.
4-(4-(Hexyloxy)phenyl)-[1,2,4]triazolo[4,3-a]quinazolin-
5(4H)-one (6h)
Yield: 38%, mp: 223–225°C. H NMR (CDCl3, 300 MHz) d: 0.94
1
4-(4-Methoxyphenyl)-[1,2,4]triazolo[4,3-a]quinazolin-
5(4H)-one (6c)
(t, 3H, J ¼ 16.50 Hz, –CH3), 1.35–1.84 (m, 8H, –CH2–), 4.01 (t, 2H,
1
Yield: 39%, mp: 276–278°C. H NMR (CDCl3, 300 MHz) d: 3.88
J ¼ 7.50 Hz, –OCH2–), 7.05–8.48 (m, 8H, Ar-H), 8.80 (s, 1H,
–N CH–). 13C NMR (CDCl3, 75 MHz) d: 159.8, 158.9, 149.2,
–
–
–
–
(s, 3H, –CH ), 7.07–8.48 (m, 8H, Ar-H), 8.80 (s, 1H, –N CH–).
3
13C NMR (CDCl3, 75 MHz) d: 160.2, 158.8, 149.2, 135.4, 134.2,
135.4, 134.2, 132.5, 130.8, 129.1, 127.5, 126.4, 117.3, 115.6,
132.5, 130.8, 129.1, 127.5, 126.7, 117.3, 115.1, 114.7, 55.6. IR
114.8, 68.3, 31.6, 29.1, 25.7, 22.6, 11.1. IR (KBr, cmꢁ1): 1690
(KBr, cmꢁ1): 1684 (C O), 1614, 1595, 1296, 1148, 1177, 1256.
(C O), 1614, 1597, 1290, 1138, 1179, 1248. ESI-HRMS calcd.
–
–
–
–
ESI-HRMS calcd. for C16H13N4O2 ([MþH]þ): 293.1033; found:
for C21H23N4O2 ([MþH]þ): 363.1816; found: 363.1820.
þ
þ
293.1034.
4-(4-(Octyloxy)phenyl)-[1,2,4]triazolo[4,3-a]quinazolin-
4-(4-Propoxyphenyl)-[1,2,4]triazolo[4,3-a]quinazolin-
5(4H)-one (6i)
1
5(4H)-one (6d)
Yield: 41%, mp: 252–254°C. H NMR (CDCl3, 300 MHz) d: 1.06
Yield: 41%, mp: 221–223°C. H NMR (CDCl3, 300 MHz) d: 0.90
1
(t, 3H, J ¼ 4.50 Hz, –CH3), 1.31–1.83 (m, 12H, –CH2–), 4.01 (t, 2H,
(t, 3H, J ¼ 7.50 Hz, –CH3), 1.81–1.90 (m, 2H, –CH2–), 3.98 (t, 2H,
J ¼ 7.50 Hz, –OCH2–), 7.06–8.47 (m, 8H, Ar-H), 8.80 (s, 1H,
–N CH–). 13C NMR (CDCl3, 75 MHz) d: 159.8, 158.8, 149.9,
–
–
J ¼ 6.00 Hz, –OCH2–), 7.06–8.47 (m, 8H, Ar-H), 8.80 (s, 1H,
–N CH–). 13C NMR (CDCl3, 75 MHz) d: 159.8, 158.8, 149.2,
149.2, 135.4, 134.1, 132.5, 130.8, 129.1, 127.5, 126.4, 117.3,
–
–
135.4, 134.3, 132.5, 130.7, 129.1, 127.4, 126.4, 127.3, 115.6,
115.6, 114.7, 68.3, 31.8, 29.3, 29.3, 29.2, 26.0, 22.7, 14.1.
114.8, 69.8, 22.5, 10.5. IR (KBr, cmꢁ1): 1690 (C O), 1614, 1599,
IR (KBr, cmꢁ1): 1690 (C O), 1614, 1595, 1290, 1138, 1179,
–
–
–
–
þ
þ
1290, 1142, 1175, 1252. ESI-HRMS calcd. for C18H17N4O2
1249. ESI-HRMS calcd. for C23H27N4O2 ([MþH]þ): 391.2129;
([MþH]þ): 321.1346; found: 321.1349.
found:391.2134.
4-(4-Butoxyphenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-
4-(2-Fluorophenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-
one (6j)
one (6e)
1
Yield: 38%, mp: 231–233°C. H NMR (CDCl3, 300 MHz) d: 0.99
Yield: 54%, mp: 220–222°C. 1H NMR (CDCl3, 300 MHz) d: 7.35–
8.49 (m, 8H, Ar-H), 8.30 (s, 1H, –N CH–). 13C NMR (DMSO-d6,
–
–
(t, 3H, J ¼ 7.50 Hz, –CH3), 1.48–1.83 (m, 4H, –CH2–), 4.02 (t, 2H,
J ¼ 7.50 Hz, –OCH2–), 7.02–8.44 (m, 8H, Ar-H), 8.95 (s, 1H,
75 MHz) d: 151.9, 148.9, 142.0, 142.0, 134.5, 131.3, 131.2,
–N CH–). 13C NMR (DMSO-d6, 75 MHz) d: 159.6, 158.8, 135.4,
127.6, 127.2, 126.3, 125.4, 125.4, 124.0, 123.8, 122.3, 120.1,
–
–
117.6, 117.3, 117.0. IR (KBr, cmꢁ1): 1697 (C O), 1612, 1601,
–
134.7, 132.5, 130.4, 129.4, 129.1, 127.3, 126.5, 117.1, 115.4,
–
1298, 1147. ESI-HRMS calcd. for C15H10FN4Oþ ([MþH]þ):
281.0833; found: 281.0838.
115.1, 67.9, 31.1, 19.1, 13.8. IR (KBr, cmꢁ1): 1690 (C O), 1614,
–
–
þ
1598, 1290, 1141, 1176, 1251. ESI-HRMS calcd. for C19H19N4O2
([MþH]þ): 335.1503; found: 335.1502.
4-(3-Fluorophenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-
one (6k)
4-(4-(Pentyloxy)phenyl)-[1,2,4]triazolo[4,3-a]quinazolin-
5(4H)-one (6f)
Yield: 44%, mp: 273–275°C. 1H NMR (CDCl3, 300 MHz) d: 7.23–
1
8.48 (m, 8H, Ar-H), 8.82 (s, 1H, –N CH–). 13C NMR (CDCl3,
–
–
Yield: 50%, mp: 213–215°C. H NMR (CDCl3, 300 MHz) d: 0.95
(t, 3H, J ¼ 7.50 Hz, –CH3), 1.39–1.85 (m, 6H, –CH2–), 4.01 (t, 2H,
75 MHz) d: 164.7, 161.4, 158.4, 148.5, 135.7, 134.3, 132.5,
J ¼ 6.00 Hz, –OCH2–), 7.05–8.47 (m, 8H, Ar-H), 8.80 (s, 1H,
131.1, 131.0, 130.9, 130.8, 127.7, 124.1, 117.0, 116.8, 116.2,
–N CH–). 13C NMR (CDCl3, 75 MHz) d: 159.8, 149.2, 135.4,
115.9, 114.8. IR (KBr, cmꢁ1): 1697 (C O), 1612, 1601, 1298,
–
–
–
–
1146. ESI-HRMS calcd. for C15H10FN4Oþ ([MþH]þ): 281.0833;
found: 281.0827.
134.2, 132.5, 130.8, 129.1, 127.5, 126.4, 118.5, 117.3, 115.6,
114.7, 68.3, 28.9, 28.2, 22.5, 14.0. IR (KBr, cmꢁ1): 1690 (C O),
–
–
1614, 1597þ, 1290, 1140, 1177, 1250. ESI-HRMS calcd. for
C
20H21N4O2 ([MþH]þ): 349.1659; found: 349.1662.
4-(4-Fluorophenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-
one (6l)
4-(4-(Isopentyloxy)phenyl)-[1,2,4]triazolo[4,3-a]-
Yield: 39%, mp: 300–302°C. 1H NMR (CDCl3, 300 MHz) d:
7.25–8.48 (m, 8H, Ar-H), 8.81 (s, 1H, –N CH–). 13C NMR
–
–
quinazolin-5(4H)-one (6g)
Yield: 48%, mp: 216–218°C. H NMR (CDCl3, 300 MHz) d: 0.99
1
(CDCl3, 75 MHz) d: 161.2, 158.6, 148.8, 146.7, 139.2, 135.6,
(t, 6H, J ¼ 9.00 Hz, –CH3), 1.63–1.74 (m, 2H, –CH2–), 1.80–1.93
134.3, 132.5, 130.8, 130.1, 130.0, 127.6, 117.1, 117.1, 116.8,
(m, 1H, –CH), 4.04 (t, 2H, J ¼ 7.50 Hz, –OCH2–), 7.05–8.48 (m,
114.8. IR (KBr, cmꢁ1): 1697 (C O), 1612, 1601, 1298, 1145.
–
–
8H, Ar-H), 8.81 (s, 1H, –N CH–). 13C NMR (CDCl3, 75 MHz) d:
ESI-HRMS calcd. for
found: 281.0837.
C
15H10FN4Oþ ([MþH]þ): 281.0833;
–
–
159.8, 158.8, 149.2, 135.4, 134.2, 132.5, 130.8, 129.1, 127.5,
ß 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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Arch. Pharm. Chem. Life Sci. 2015, 348, 564–574
Triazolo-quinazolines as Anticonvulsants
Archiv der Pharmazie
4-(2-Chlorophenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-
one (6m)
13C NMR (CDCl3, 75 MHz) d: 158.6, 149.0, 140.0, 135.4, 134.2,
134.0, 132.5, 130.8, 130.6, 129.7, 128.6, 127.5, 125.0, 117.3,
Yield: 51%, mp: 240–242°C. 1H NMR (CDCl3, 300 MHz) d: 7.51–
114.8, 21.4. IR (KBr, cmꢁ1): 1692 (C O), 1612, 1597, 1300, 1142.
–
–
ESI-HRMS calcd. for C16H13N4Oþ ([MþH]þ): 277.1084; found:
277.1088.
8.49 (m, 8H, Ar-H), 8.81 (s, 1H, –N CH–). 13C NMR (CDCl3,
–
–
75 MHz) d: 157.9, 153.5, 149.0,135.7, 134.3, 132.8, 132.7, 132.0,
131.3, 130.9, 130.4, 128.4, 127.6, 116.9, 114.9. IR (KBr, cmꢁ1):
–
1699 (C O), 1614, 1599, 1294, 1144. ESI-HRMS calcd. for
C
4-(p-Tolyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-one (6t)
Yield: 41%, mp: 274–276°C. 1H NMR (CDCl3, 300 MHz) d: 2.45
(t, 3H, Ar–CH3), 7.38–8.48 (m, 8H, Ar-H), 8.80 (s, 1H,
–
15H10ClN4Oþ ([MþH]þ): 297.0538; found: 297.0541.
4-(3-Chlorophenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-
one (6n)
–N CH–). 13C NMR (CDCl3, 75 MHz) d: 158.7, 149.0, 139.8,
–
–
135.4, 134.2, 132.5, 131.5, 130.8, 130.5, 127.7, 127.5, 117.3,
Yield: 33%, mp: 275–277°C. 1H NMR (CDCl3, 300 MHz) d: 7.44–
114.7, 21.3. IR (KBr, cmꢁ1): 1692 (C O), 1612, 1597, 1300,
–
–
1141. ESI-HRMS calcd. for C16H13N4Oþ ([MþH]þ): 277.1084;
found: 277.1076.
8.38 (m, 8H, Ar-H), 9.29 (s, 1H, –N CH–). 13C NMR (DMSO-d6,
–
–
75 MHz) d: 163.3, 153.1, 146.0, 140.6, 140.4, 139.4, 137.5,
135.8, 135.4, 134.8, 134.3, 133.5, 133.2, 132.2, 131.7. IR (KBr,
cmꢁ1): 1699 (C O), 1614, 1599, 1294, 1144. ESI-HRMS calcd. for
C
4-(4-(Trifluoromethyl)phenyl)-[1,2,4]triazolo[4,3-a]-
quinazolin-5(4H)-one (6u)
–
–
15H10ClN4Oþ ([MþH]þ): 297.0538; found: 297.0543.
Yield: 35%, mp: 274–276°C. 1H NMR (CDCl3, 300 MHz) d: 7.61–
–
–
4-(4-Chlorophenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-
one (6o)
8.48 (m, 8H, Ar-H), 8.83 (s, 1H, –N CH–). 13C NMR (CDCl3,
75 MHz) d: 158.3, 148.4, 137.2, 135.8, 134.4, 132.5, 131.9,
Yield: 37%, mp: 291–293°C. 1H NMR (CDCl3, 300 MHz) d: 7.44–
131.4, 130.9, 128.9, 127.7, 127.0, 126.9, 116.9, 114.9. IR (KBr,
8.47 (m, 8H, Ar-H), 8.81 (s, 1H, –N CH–). 13C NMR (CDCl3,
cmꢁ1): 1695 (C O), 1614, 1600, 1294, 1134. ESI-HRMS calcd. for
–
–
–
–
75 MHz) d: 158.4, 148.6, 135.7, 135.6, 134.4, 132.6, 130.8,
C
16H10F3N4Oþ ([MþH]þ): 331.0801; found: 331.0809.
130.1, 129.5, 127.6, 124.4, 117.1, 114.9. IR (KBr, cmꢁ1): 1699
–
(C O), 1614, 1599, 1294, 1143. ESI-HRMS calcd. for
C
4-(3,4-Dichlorophenyl)-[1,2,4]triazolo[4,3-a]quinazolin-
5(4H)-one (6v)
–
15H10ClN4Oþ ([MþH]þ): 297.0538; found: 297.0537.
Yield: 28%, mp: 298–300°C. 1H NMR (CDCl3, 300 MHz) d: 7.37–
8.47 (m, 7H, Ar-H), 8.82 (s, 1H, –N CH–). 13C NMR (CDCl3,
–
–
4-(3-Bromophenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-
one (6p)
75 MHz) d: 148.3, 147.0, 135.9, 134.4, 134.2, 133.8, 133.1,
Yield: 42%, mp: 287–289°C. 1H NMR (CDCl3, 300 MHz) d: 7.46–
131.7, 131.4, 130.9, 130.5, 127.7, 127.7, 116.9, 114.9. IR (KBr,
8.47 (m, 8H, Ar-H), 8.82 (s, 1H, –N CH–). 13C NMR (CDCl3,
cmꢁ1): 1694 (C O), 1614, 1597, 1290, 1138. ESI-HRMS calcd. for
–
–
–
–
75 MHz) d: 158.4, 147.6, 135.7, 135.2, 132.9, 132.5, 131.5,
C
15H10Cl2N4Oþ ([MþH]þ): 331.0148; found: 331.0154.
131.0, 130.8, 127.7, 127.0, 123.0, 118.3, 117.0, 114.9. IR (KBr,
cmꢁ1): 1695 (C O), 1616, 1597, 1292, 1143. ESI-HRMS calcd. for
4-(3,4-Dimethylphenyl)-[1,2,4]triazolo[4,3-a]quinazolin-
–
–
C
15H10BrN4Oþ ([MþH]þ): 341.0032; found: 341.0040.
5(4H)-one (6w)
Yield: 47%, mp: 204–206°C. H NMR (CDCl3, 300 MHz) d: 2.15
1
4-(4-Bromophenyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-
one (6q)
(s, 3H, –CH3), 2.40 (s, 3H, –CH3), 7.21–8.48 (m, 7H, Ar-H), 8.81 (s,
1H, –N CH–). 13C NMR (CDCl3, 75 MHz) d: 158.3, 148.5, 145.8,
–
–
Yield: 41%, mp: 289–291°C. 1H NMR (CDCl3, 300 MHz) d: 7.37–
140.1, 135.5, 135.4, 134.4, 132.7, 132.4, 130.7, 128.3, 128.0,
8.47 (m, 8H, Ar-H), 8.82 (s, 1H, –N CH–). 13C NMR (CDCl3,
127.4, 117.1, 114.9, 21.3, 17.6. IR (KBr, cmꢁ1): 1692 (C O),
–
–
–
–
1614, 1599, 1292, 1148. ESI-HRMS calcd. for C17H15N4Oþ
([MþH]þ): 291.1240; found: 291.1244.
75 MHz) d: 158.4, 148.5, 135.7, 134.4, 133.3, 133.0, 132.5, 130.8,
129.8, 127.6, 123.7, 117.0, 114.9. IR (KBr, cmꢁ1): 1695 (C O),
–
–
1616, 1597, 1292, 1142. ESI-HRMS calcd. for C15H10BrN4Oþ
([MþH]þ): 341.0032; found: 341.0038.
Synthesis of 1-methyl-4-phenyl[1,2,4]triazolo[4,3-a]-
quinazolin-5(4H)-one (7) [32]
4-(o-Tolyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-one (6r)
Yield: 29%, mp: 245–247°C. 1H NMR (CDCl3, 300 MHz) d: 2.30 (s,
Compound 5a (0.01 mol) was dissolved in acetic acid (25 mL),
refluxed overnight, and then poured into ice water. The
resultant solid (7) was filtered, washed with water, dried,
and purified by silica gel column chromatography using
CH2Cl2/CH3OH (100:1) as the eluent. Yield: 31%, mp: 303–
305°C. 1H NMR (CDCl3, 300 MHz) d: 2.46 (s, 3H, –CH3), 7.34–8.47
(m, 9H, Ar-H). 13C NMR (CDCl3, 75 MHz) d: 158.6, 149.5, 145.8,
135.1, 134.4, 134.2, 131.0, 129.8, 129.5, 128.2, 126.9, 117.8,
–
3H, Ar–CH ), 7.38–8.50 (m, 8H, Ar-H), 8.11 (s, 1H, –N CH–).
–
3
13C NMR (CDCl3, 75 MHz) d: 156.7, 149.2, 145.6, 142.0, 135.7,
134.5, 132.0, 130.7, 127.7, 127.6, 127.4, 126.3, 123.9, 117.4, 113.0,
18.1.IR(KBr,cmꢁ1):1703(C O),1618,1549,1273,1130.ESI-HRMS
–
–
calcd. for C16H13N4Oþ ([MþH]þ): 277.1084; found: 277.1087.
4-(m-Tolyl)-[1,2,4]triazolo[4,3-a]quinazolin-5(4H)-one (6s)
115.0, 15.7. IR (KBr, cmꢁ1): 1682 (C O), 1610, 1597, 1317, 1180.
–
–
ESI-HRMS calcd. for C16H13N4Oþ ([MþH]þ): 277.1084; found:
277.1089.
1
Yield: 46%, mp: 240–242°C. H NMR (CDCl3, 300 MHz) d: 2.44
–
(s, 3H, Ar–CH ), 7.29–8.48 (m, 8H, Ar-H), 8.80 (s, 1H, –N CH–).
–
3
ß 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com
571

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Arch. Pharm. Chem. Life Sci. 2015, 348, 564–574
H.-J. Zhang et al.
Archiv der Pharmazie
Synthesis of 4-phenyl-[1,2,4]triazolo[4,3-a]quinazoline-
1,5(2H,4H)-dione (8) [23]
collected through filtration and washed with ethanol to
give pure compound 11. Yield: 38%, mp: 187–189°C. 1H NMR
(DMSO-d6, 300 MHz) d: 1.40 (t, 3H, J ¼ 7.50 Hz, –CH3), 4.54 (m,
2H, J ¼ 7.00 Hz, –CH2–), 7.53–8.42 (m, 9H, Ar-H). 13C NMR
(DMSO-d6, 75 MHz) d: 159.0, 158.8, 151.3, 141.3, 135.5, 135.2,
133.5, 129.8, 129.6, 129.4, 129.2, 128.1, 119.1, 118.6, 63.3, 14.4.
Compound 5a (0.01 mol) and carbamide (4.8 g, 0.08 mol) were
added to a round-bottomed flask and heating up to 200°C to
melt them. The reaction was followed using TLC and, upon
completion, the mixture was cooled and then washed with
enough hot water to wash off the excess urea. The target
compound (8) obtained was filtered, dried, and purified by
silica gel column chromatography using CH2Cl2/CH3OH (60:1)
as the eluent. Yield: 36%, mp: >300°C. 1H NMR (DMSO-d6,
300 MHz) d: 7.47–8.70 (m, 9H, Ar-H), 11.83 (s, 1H, NH). 13C NMR
(DMSO-d6, 75 MHz) d: 159.1, 152.7, 151.1, 142.1, 135.3, 135.3,
134.4, 129.6, 129.5, 129.4, 128.9, 126.0, 117.3, 114.9. IR (KBr,
IR (KBr, cmꢁ1): 1724 (C O), 1692 (C O), 1611, 1541, 1481,
–
–
–
–
þ
1273, 1192. ESI-HRMS calcd. for C18H15N4O3 ([MþH]þ):
335.1139; found: 335.1135.
Synthesis of 5-oxo-4-phenyl-4,5-dihydro-[1,2,4]-
triazolo[4,3-a]quinazoline-1-carboxamide (12) [27]
Compound 11 (0.01 mol) was dissolved in methanol (10 mL),
ammonia (10 mL) was added and the mixture was stirred for
3 h at room temperature. After this time, the precipitate was
collected through filtration, washed with water, dried, and
purified by silica gel column chromatography using CH2Cl2/
CH3OH (40:1) as the eluent to obtain the product 12. Yield:
30%, mp: 266–268°C. 1H NMR (DMSO-d6, 300 MHz) d: 7.53–
8.62 (m, 9H, Ar-H), 8.24 (s, 1H, NH), 8.66 (s, 1H, NH). 13C NMR
(DMSO-d6, 75 MHz) d: 160.4, 158.8, 150.8, 144.2, 135.7, 135.3,
133.8, 129.7, 129.5, 129.4, 129.2, 127.8, 118.9, 118.4. IR (KBr,
cmꢁ1): 3177 (N–H), 1748 (C O), 1709 (C O), 1614, 1491, 1352,
–
–
–
–
1287, 1128, 1031. ESI-HRMS calcd. for C15H11N4O2þ ([MþH]þ):
279.0877; found: 279.0873.
Synthesis of 4-phenyl-1-thioxo-1,2-dihydro-[1,2,4]-
triazolo[4,3-a]quinazolin-5(4H)-one (9) [24]
To an ice-cooled solution of 5a (0.01 mol) in absolute ethanol
(10 mL) was added potassium hydroxide (0.56 g, 0.01 mol)
followed by the dropwise addition of carbon disulfide (1.52 g,
0.02 mol) with stirring. The mixture was diluted with absolute
ethanol (5 mL), filtered, concentrated, diluted with water, and
neutralized with acetic acid. The solvent was evaporated and
the material was purified by silica gel column chromatogra-
phy using CH2Cl2/CH3OH (60:1) as the eluent to receive the
product 9. Yield: 30%, mp: 187–189°C. 1H NMR (DMSO-d6,
300 MHz) d: 7.45–10.39 (m, 9H, Ar-H), 13.85 (s, 1H, NH).
13C NMR (DMSO-d6, 75 MHz) d: 162.2, 158.8, 147.0, 136.0,
134.9, 129.7, 129.6, 129.2, 129.0, 127.4, 118.5, 116.1. IR (KBr,
cmꢁ1): 3468 (N–H), 3349 (N–H), 1701 (C O), 1678 (C O), 1612,
–
–
–
–
1584, 1440, 1288. ESI-HRMS calcd. for C18H12N5O2þ ([MþH]þ):
306.0986; found: 306.0977.
Synthesis of 2-methyl-5-phenyl-1H-[1,2,4]triazino[4,3-a]
quinazoline-1,6(5H)-dione (13) [28]
A mixture of 5a (0.02 mol) and pyruvic acid (0.03 mol) in
absolute ethanol (10 mL) and glacial acetic acid (10 mL) was
refluxed for 10 h. After cooling, the precipitate was collected.
A mixture of the precipitate and acetic acid (20 mL) was
refluxed for 46 h. The crystal formed on cooling was collected
by filtration, washed with water, dried, and purified by silica
gel column chromatography using CH2Cl2/CH3OH (80:1) as the
eluent to give the product 13. Yield: 28%, mp: 187–189°C.
1H NMR (DMSO-d6, 300 MHz) d: 2.88 (s, 3H, –CH3), 7.48–8.30
(m, 9H, Ar-H). 13C NMR (DMSO-d6, 75 MHz) d: 158.9, 152.1,
149.6, 146.0, 135.7, 135.7, 134.5, 129.8, 129.7, 129.3, 129.2,
cmꢁ1): 1703 (C O), 1618, 1549, 1273, 1130. ESI-HRMS calcd. for
–
–
C
15H11N4OSþ ([MþH]þ): 295.0648; found: 295.0653.
Synthesis of 4-phenyltetrazolo[1,5-a]quinazolin-5(4H)-one
(10) [25]
Compound 5a (0.01 mol) was dissolved in 20 mL dilute hydro-
chloric acid and 10% NaNO2 (0.69 g, 0.01 mol) solution was
added dropwise to the mixture in an ice bath such that the
reaction temperature remained below 5°C. The mixture was
then stirred at room temperature and monitored by TLC. At the
end of the reaction, the mixture was extracted with dichloro-
methane (20 mL ꢂ 3), dried over anhydrous MgSO4, evaporated
to dryness and purified by silica gel column chromatography
using CH2Cl2 as the eluent to give the product 10. Yield: 34%,
mp: 187–189°C. 1H NMR (CDCl3, 300MHz) d: 7.49–8.51 (m, 9H,
Ar-H). 13C NMR (CDCl3, 75MHz) d: 158.7, 150.7, 136.1, 133.9,
132.8, 130.3, 130.0, 129.9, 128.9, 127.7, 116.7, 116.0. IR (KBr,
127.0, 118.0, 116.5, 15.4. IR (KBr, cmꢁ1): 1712 (C O), 1686
–
–
–
(C O), 1612, 1597, 1568, 1487, 1439, 1315. ESI-HRMS calcd. for
–
þ
C
17H13N4O2 ([MþH]þ): 305.1033; found: 305.1040.
Synthesis of 2-(3,5-dimethyl-1H-pyrazol-1-yl)-3-
phenylquinazolin-4(3H)-one (14) [29]
A mixture of the hydrazine 5a (0.01 mol) and acetylacetone
(0.012 mmol) in absolute 1,4-dioxane (20 mL) was heated
under reflux for 3 h. The reaction mixture was cooled and the
resultant precipitate was filtered, washed with ethanol, dried,
and purified by silica gel column chromatography using
CH2Cl2 as the eluent. Yield: 34%, mp: 178–179°C. 1H NMR
cmꢁ1): 1703 (C O), 1618, 1549, 1273, 1130. ESI-HRMS calcd. for
–
–
C
14H10N5Oþ ([MþH]þ): 264.0880; found: 264.0884.
–
Synthesis of ethyl 5-oxo-4-phenyl-4,5-dihydro-[1,2,4]-
triazolo[4,3-a]quinazoline-1-carboxylate (11) [26]
Compound 5a (0.02 mol) was added to diethyl oxalate (30 mL)
and the mixture was stirred and refluxed for 1 h. After the
reaction mixture was cooled, the white precipitate was
(CDCl , 300 MHz) d: 2.00 (s, 3H, N C–CH ), 2.31 (s, 3H,
–
3
3
–
–
–
C C–CH ), 5.71 (s, 1H, C CH–C), 7.17–8.38 (m, 9H, Ar-H).
–
3
13C NMR (CDCl3, 75 MHz) d: 162.5, 150.6, 146.2, 144.1, 141.4,
135.5, 135.0, 128.6, 128.0, 127.9, 127.9, 127.6, 121.3, 114.9,
106.8, 13.2, 11.5. IR (KBr, cmꢁ1): 1692 (C O), 1611, 1595, 1287,
–
–
ß 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
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Arch. Pharm. Chem. Life Sci. 2015, 348, 564–574
Triazolo-quinazolines as Anticonvulsants
Archiv der Pharmazie
1273, 1153. ESI-HRMS calcd. for C19H17N4Oþ ([MþH]þ):
[2] P. Yogeeswari, D. Sriram, R. Thirumurugan, J. V.
Raghavendran, K. Sudhan, R. K. Pavana, J. Stables, J.
Med. Chem. 2005, 48, 6202–6211.
317.1397; found: 317.1402.
Pharmacology
[3] G. M. Kennedy, S. D. Lhatoo, CNS Drugs 2008, 22, 739–760.
[4] P. E. Penovich, L. J. Willmore, Epilepsia 2009, 50, 37–41.
[5] H. P. Bootsma, L. Ricker, Y. A. Hekster, J. Hulsman,
D. Lambrechts, M. Majoie, A. Schellekens, M. de Krom,
A. P. Aldenkamp, Seizure 2009, 18, 327–331.
[6] V. Belcastro, P. Striano, G. Gorgone, C. Costa, C. Ciampa,
D. Caccamo, L. R. Pisani, G. Oteri, M. G. Marciani,
U. Aguglia, S. Striano, R. Ientile, P. Calabresi, F. Pisani,
Epilepsia 2010, 51, 274–279.
Maximal electroshock seizure
Seizures were elicited in mice using a 60 Hz alternating
current of 50 mA. The current was applied via corneal
electrodes for 0.2 s. Protection against the spread of MES-
induced seizures was defined as the abolition of tonic hind leg
extension. At 0.5 h after the administration of the com-
pounds, the activities were evaluated using the MES test. In
phase I screening, each compound was administered at the
dose levels of 30 and 100 mg/kg as a preliminary investigation
of anticonvulsant activity. In phase II screening, groups of 10
mice were given a range of intraperitoneal and peroral doses
of the tested compound until at least three points were
established in the range of 10–90% seizure prevention or
minimal neurotoxicity was observed. From the plot of these
data, the respective ED50 and TD50 values, 95% confidence
intervals, were calculated by a computer program based on
the methods described by Finney [35].
ꢀ
€
[7] J. Remi, A. Huttenbrenner, B. Feddersen, S. Noachtar,
Epilepsy Res. 2010, 88, 145–150.
[8] I. Khan, A. Ibrar, N. Abbas, A. Saeed, Eur. J. Med. Chem.
2014, 76, 193–244.
[9] S. Manjula, E. Bharath, B. Divya, Int. J. Pharm Bio. Sci.
2011, 2, 780–809.
[10] T. P. Selvam, P. V. Kumar, Res. Pharm. 2011, 1, 1–21.
[11] R. A. Smits, M. Adami, E. P. Istyastono, O. P. Zuiderveld,
C. M. van Dam, F. J. de Kanter, A. Jongejan, G. Coruzzi,
R. Leurs, I. J. de Esch, J. Med. Chem. 2010, 53, 2390–2400.
[12] V.Alagarsamy,V.RajaSolomon,M.Murugan,K.Dhanabal,
P. Parthiban, G. V. Anjana, J. Enzyme Inhib. Med. Chem.
2008, 23, 839–847
[13] G. Grover, S. G. Kini, Eur. J. Med. Chem. 2006, 41, 256–262.
[14] H. Georgey, N. Abdel-Gawad, S. Abbas, Molecules 2008,
13, 2557–2569.
Neurotoxicity (NT) screening
The mice were given i.p. or p.o. injections of the test
compounds. Animals were trained to stay on an accelerating
rotarod of 1-inch diameter that rotates at 6 rpm for 1 min
after the specific time, respectively. Neurotoxicity was
indicated by the inability of the animal to maintain
equilibrium on the rod for at least 1 min in each of three trials.
[15] V. Jatav, P. Mishra, S. Kashaw, J. P. Stables, Eur. J. Med.
Chem. 2008, 43, 1945–1954.
sc-PTZ-induced seizures
[16] A. Rosowsky, A. T. Papoulis, R. A. Forsch, S. F. Queener, J.
Med. Chem. 1999, 42, 1007–1017.
[17] A. Chilin, M. T. Conconi, G. Marzaro, A. Guiotto,
L. Urbani, F. Tonus, P. Parnigotto, J. Med. Chem. 2010,
53, 1862–1866.
At 0.5 h after the administration of the test compound, 85 mg/
kg PTZ dissolved in saline (0.9% NaCl) was administered s.c.
The animals (10 mice in one group) were placed in isolation
cages and observed for 0.5 h. The numbers of clonic seizure,
tonic seizure, and deaths were noted.
[18] A. S. El-Azab, K. E. ElTahir, Bioorg. Med. Chem. Lett.
2012, 22, 1879–1885.
Bicuculline-induced seizure test
[19] A. Bhaduri, N. Khanna, M. Dhar, Indian J. Chem. 1964, 2,
159–166.
[20] M. Z. A. Badr, H. A. H. El-Sherief, A. M. Mahmoud, Bull
Chem. Soc. Jpn. 1980, 53, 2389–2392.
[21] X. Q. Deng, C. R. Xiao, C. X. Wei, Z. S. Quan, Chin. J. Org.
Chem. 2011, 31, 2082–2087.
[22] V. Alagarsamy, M. Rupeshkumar, R. Rajesh, K. Kavitha,
S. Meena, D. Shankar, A. A. Siddiqui, Eur. J. Med. Chem.
2008, 43, 2331–2337.
[23] J. P. Yang, Y. Y. Hong, C. X. Miao, Chem. Reagents 2008,
30, 460, 474.
[24] J. T. Su, Z. L. Shang, Jing Xi Yu Zhuan Yong Hua Xue Pin
2010, 18, 40–41.
At 0.5 h after the administration of the compounds, the
animals (10 mice in one group) were given an s.c. dose of
5.4 mg/kg bicuculline. Individual mice were then placed in
isolation cages and observed for at least 0.5 h for the presence
or absence of clonic seizures, and tonic seizures, and lethality
was also recorded.
This work was supported by the National Natural Science
Foundation of China (No. 81160382 and 81360468) and
National Science and Technology Major Project of China (No.
2011ZX09102-003-03).
The authors have declared no conflict of interest.
[25] X. Y. Sun, C. X. Wei, X. Q. Deng, Z. G. Sun, Z. S. Quan,
Arzneim Forsch 2010, 60, 289–292.
[26] C. X. Wei, X. Q. Deng, K. Y. Chai, Z. G. Sun, Z. S. Quan,
Arch. Pharm. Res. 2010, 33, 655–662.
[27] A. M. Kadry, A. M. Al-Mahmoudy, Chem. Biol. Interface
2011, 1, 44–58.
References
[1] B. Malawska, Curr. Top. Med. Chem. 2005, 5, 69–85.
ß 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com
573

RCHH HARM
A P
Arch. Pharm. Chem. Life Sci. 2015, 348, 564–574
H.-J. Zhang et al.
Archiv der Pharmazie
[28] A. Sh. Oganisyan, G. O. Grigoryan, A. S. Noravyan, Chem.
Heterocycl. Compd. 2001, 37, 1025–1028.
[32] V. Alagarsamy, M. Rupeshkumar, K. Kavitha, S. Meena,
D. Shankar, A. A. Siddiqui, R. Rajesh, Eur. J. Med. Chem.
2008, 43, 2331–2337.
[33] V. Alagarsamy, S. V. Raja, K. Dhanabal, Bioorg. Med.
Chem. 2007, 15, 235–241.
[34] A. Saeed, S. ul Mahmood, H. Ishida, Crystals 2011, 1, 171–
177.
[35] D. J. Finney, Probit Analysis, 3rd edn., Cambridge
University Press, London 1971.
[29] H. M. Ashour, M. H. El-Wakil, M. A. Khalil, K. A. Ismail,
I. M. Labouta, Med. Chem. Res. 2013, 22, 1909–1924.
[30] R. L. Krall, J. K. Penry, E. A. Swinyard, B. G. White, H. J.
Kupferberg, E. A. Swinyard, Epilepsia 1978, 19, 409–428.
[31] R. J. Porter, J. J. Cereghino, G. D. Gladding, B. J. Hessie,
H. J. Kupferberg, B. Scoville, B. G. White, Cleve. Clin. Q.
1984, 51, 293–305.
ß 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
www.archpharm.com
574