Synthesis of new 2,5-disubstituted-1,3,4-thiadiazole derivatives and their in vivo anticonvulsant activity

Article abstract of DOI:10.1134/S1068162014010051

A series of 2,5-disubstituted-1,3,4-thiadiazole derivatives were synthesized by the reaction of 3-(2-cyanopropan-2-yl)-N-(5-(piperazine-1-yl)-1, 3,4-thiadiazol-2-yl)benzamide with various sulfonyl chlorides and evaluated for their anticonvulsant activity in MES test. Rotorod method was employed to determine the neurotoxicity. The purity of the compounds is confirmed on the basis of their elemental analysis. The structures of all the new compounds are established on the basis of ¹H NMR and mass spectral data. Out of fifteen compounds, three were found to be potent anticolvunstants. The same compounds showed no neurotoxicity at the maximum dose administered (100 mg/kg).

Full text of DOI:10.1134/S1068162014010051

ISSN 1068ꢀ1620, Russian Journal of Bioorganic Chemistry, 2014, Vol. 40, No. 1, pp. 97–105. © Pleiades Publishing, Ltd., 2014.
Synthesis of New 2,5ꢀDisubstitutedꢀ1,3,4ꢀThiadiazole Derivatives
and Their in vivo Anticonvulsant Activity1
2
K. P. Harisha, , K. N. Mohanaa, and L. Malleshab
a Department of Studies in Chemistry, University of Mysore, Manasagangotri, Mysore, 570 006 India
b PG Department of Chemistry, JSS College of Arts, Commerce and Science, Ooty Road, Mysore–25, India
Received May 17, 2013; in final form, July 3, 2013
Abstract—A series of 2,5ꢀdisubstitutedꢀ1,3,4ꢀthiadiazole derivatives were synthesized by the reaction of
3ꢀ(2ꢀcyanopropanꢀ2ꢀyl)ꢀNꢀ(5ꢀ(piperazineꢀ1ꢀyl)ꢀ1,3,4ꢀthiadiazolꢀ2ꢀyl)benzamide with various sulfonyl
chlorides and evaluated for their anticonvulsant activity in MES test. Rotorod method was employed to
determine the neurotoxicity. The purity of the compounds is confirmed on the basis of their elemental analꢀ
ysis. The structures of all the new compounds are established on the basis of 1H NMR and mass spectral data.
Out of fifteen compounds, three were found to be potent anticolvunstants. The same compounds showed no
neurotoxicity at the maximum dose administered (100 mg/kg).
Keywords: 1,3,4ꢀthiadiazole, anticonvulsant, neurotoxicity
DOI: 10.1134/S1068162014010051
2 1
INTRODUCTION
Fiveꢀmember heterocyclic compounds showed
various types of biological activities, among them
1,3,4ꢀthiadiazoles are associated with diverse biologiꢀ
cal activities, probably by the virtue of –N=C–S–
grouping [10]; some of them possess antibacterial [11],
antifungal [12], and anticonvulsant [13] activities.
Similarly, 2,5ꢀdisubstitutedꢀ1,3,4ꢀthiadiazoles also
display wide spectrum of activities such as antibacteꢀ
rial [14] and anticonvulsant [15]. The therapeutic
importance of these rings have prompted us to develop
selective molecules in which a substituent could be
arranged in a pharmacophore pattern to display higher
pharmacological activity. In the present study, some
new 2,5ꢀdisubstitutedꢀ1,3,4ꢀthiadiazole derivatives
Epilepsy is usually described as a group of common
chronic neurological disorders characterized by recurꢀ
rent unprovoked seizures due to excessive neuronal
firing or synchronous neuronal activity in the brain
[1]. The known potential causes of epilepsy include
brain tumors, infections, traumatic head injuries,
perinatal insults, developmental malformations, cereꢀ
brovascular diseases, and febrile seizures [2]. The antiꢀ
convulsants are a diverse group of pharmaceuticals
used in the treatment of epileptic seizures. Anticonꢀ
vulsants are also being increasingly used in the treatꢀ
ment of bipolar disorder. Anticonvulsants are more
accurately called antiepileptic drugs (AEDs), someꢀ
times referred to as antiseizure drugs.
(VIIa–o) have been synthesized and their anticonvulꢀ
sant effects were determined through maximal elecꢀ
troshock (MES) seizure test.
Several generations of anticonvulsants are availꢀ
able, such as phenytoin, phenobarbital, benzodiazꢀ
epines, etosuximide, carbamazepine, and valproate.
They are useful in the treatment of other diseases, such
as neuropathic pain and bipolar disorders, conditions
associated with significant morbidity and mortality
[3–5]. The newest generation of anticonvulsants,
including vigabatrin, lamotrigine, gabapentin, tiagabꢀ
ine, topiramate, felbamate, and zonisamide, repreꢀ
sents a step forward toward better anticonvulsant drugs
[6–9]. New anticonvulsant agents are discovered
through conventional screening and/or structure
modification rather than a mechanism driven design.
RESULTS AND DISCUSSION
The new 2,5ꢀdisubstitutedꢀ1,3,4ꢀthiadiazole
derivatives (VIIa–o) were synthesized according to
Scheme. We believe that this synthesizing approach
represents the most efficient route to a diverse array
of 2,5ꢀdisubstituted heterocycles yet reported [16–
21]. Readily available starting materials and simple
synthesizing procedures make this method very
attractive and convenient for the synthesis of various
thiadiazoles. Formation of products was confirmed
1
1
by elemental analyses, H NMR, and mass spectra.
The article is published in the original.
Corresponding author: phone: +91ꢀ9845677501; eꢀmail: dhruvaꢀ
harishp@gmail.com.
1
2
The H NMR spectra of (VIIg) showed piperazine
ring in the region of δ, 3.243.56. The mass spectra of
97

98
HARISH et al.
(
VIIg) showed molecular ion peak at
m
/
z
909.07
,
experimentally determined values and the theoretiꢀ
which is in agreement with the molecular formula, cally calculated values. The chemical structures and
C33H24F12N6O5S3. The elemental analysis data physical data of all the synthesized compounds are
showed good agreement (within
S
0
.4%) between the presented in Table 1.
N
N
HCOOH
HCl
CH COOH
3
N
N
Br
N
NH2
CH COONa, Br
3
2
H2N
N
S
S
H
H2N
H2N
I
II
III
O
O
N
N
N
S
O
O
N
N
O
NH
mono BOC piperazine
K CO
TBTU, TEA
N
N
III
O
OH
2
3
S
H2N
CN
CN
IV
V
O
N
N
N
⋅
3HCl
N
NH
N
N
N S
O
R
S
S
O
N
O
NH
4 N HCl in dioxane
RSO Cl,
2
V
R1
CN
TEA
CN
VI
VIIa–o
R1 = H, RSO2
Scheme. Synthetic route of 2,5ꢀdisubstitutedꢀ1,3,4ꢀthiadiazole derivatives (VIIa–o).
In vivo Anticonvulsant Activity
observed when compared to the standard group. Comꢀ
pounds (VIIa, c, h) have relatively low anticonvulsant
potencies.
All the compounds were examined for their neuꢀ
rotoxicity using rotorod method given in the dose of
100 mg/kg. Except compounds (VIIa), (VIIc), and
All the synthesized thiadiazole analogues were
screened for their anticonvulsant potential through
MES model. For several decades, antiepileptic drug
research has focused on identifying new potential
drugs based on their anticonvulsant activity against a
single acute seizure induced by various stimulators,
usually in mice and rats. All the established antiepilepꢀ
tic drugs have anticonvulsant activity at least in the
MES model [22]. In the present study, the anticonvulꢀ
(
VIIh) none of the compounds showed neurotoxicity.
These compounds showed 25% toxicity compared to
the standard 2 h after oral administration (Table 3).
From the results obtained, the structure activity
sant activity of the fifteen newly synthesized 2,5ꢀdisꢀ relationship (SAR) can be drawn for the (VIIa–o
)
ubstitutedꢀ1,3,4ꢀthiadiazole derivatives (VIIa ) was series. In this connection, different electron donating
–o
evaluated by MES model at the dose of 100 mg/kg and or electron withdrawing groups attached to phenyl
the results are summarized in Table 2. Compounds ring as substituent linked to sulfonyl group are studied
(VIIg), (VIIj), and (VIIo) demonstrated significant for anticonvulsant efficacy. In the present series of
protective effect on MES induced seizure and the compounds, the active compounds possess all the
effect of (VIIg) was similar to that of the standard requirements essential for anticonvulsant activity, as
(phenytoin). Similarly, compounds (VIIb), (VIId–f), proposed by Dimmock et al. [23]. On correlating the
(VIIi), and (VIIk–n) also showed moderate protective structures of the synthesized compounds with their
effect and a significant difference in protectiveness was anticonvulsant activity, it has been observed that comꢀ
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 40
No. 1
2014

SYNTHESIS OF NEW 2,5ꢀDISUBSTITUTEDꢀ1,3,4ꢀTHIADIAZOLE
99
Table 1. Chemical structure and melting range of 2,5–disubstitutedꢀ1,3,4–thiadiazole derivatives (VIIa–o
)
Compound
(VIIa)
R
Structure
mp (°C)
243–245
O
S
N
S
N
N
N
N
O
O
H
CN
(
VIIb
)
212–214
O
S
N
N
N
N
S
N
H
O
O
CN
(
VIIc
)
–CH3
92–94
O
S
N
N
CH3
N
N
S
N
H
O
O
CN
(
VIId
)
122–124
Cl
Cl
O
N
S
S
S
N
N
N
S
Cl
N
Cl
O
O
H
CN
(
VIIe
)
162–164
N
O
CN
N
O
S
N
N
S
N
O
O
S O
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 40
No. 1
2014

100
HARISH et al.
Table 1. (Contd.)
Compound
R
Structure
mp (°C)
106–108
(VIIf)
N
N
O
CN
O
S
N
O
N
O
N
N
S
N
O
O S O
N O
(
VIIh
)
100–102
N
N
O
O
O
CN
O
S
N
N
N
S
S
O
(
VIIi
)
170–172
N
O
N
CN
O
N
N
S
N
S
O
O
S O
(
VIIj
)
149–141
F
F
F
F
N
N
O
CN
O
F
F
N
N
S
N
S
O
O S O
F
F
F
(
VIIk
)
170–172
N
O
N
CN
O
S
I
N
N
N
S
S
I
O
O
O
N
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 40
No. 1
2014

SYNTHESIS OF NEW 2,5ꢀDISUBSTITUTEDꢀ1,3,4ꢀTHIADIAZOLE
101
Table 1. (Contd.)
Compound
R
Structure
N
mp (°C)
185–187
(VIIl)
O
N
O
CN
O
S
N
N
S
N
N
S
N
O
O
N
O
(
VIIm
)
162–164
N
N
CN
O
S
N
N
N
S
S
O
O
O
O2N
NO2
(
VIIn
)
222–224
N
N
O
CN
O
Br
N
N
S
N
S
Br
O
O
S
O
Br
(
VIIo
)
154–156
N
F
N
O
CN
O
F
N
F
N
S
N
S
F
F
O
O
S O
F
F
F
F
pounds bearing the groups like nitro, phenoxy and model. Both compounds did not exhibit neurotoxicity
at the highest administered dose.
halogens on phenyl ring possess high potency in MES.
The SAR study of these compounds indicate that the
introduction of a piperazine group at position 5 of thiꢀ
adiazole ring and 3,5ꢀbis(trifluoromethyl) positions of
the benzenesulfonyl moiety (compound (VIIg))
showed the best anticonvulsant activity. Compounds
The presence of nitro group in (VIIm) and halogen
groups in (VIId), (VIIk), and (VIIn) showed moderate
anticonvulsant activity. The presence of cyano group
in (VIIl) at aryl ring has moderate activity. Although
naphthalene group in (VIIe), dimethyl, in (VIIb), and
tertꢀbutyl, in (VIIi) were moderately active in the MES
(
VIIj) and (VIIo) possessing trifluoromethyl substituꢀ
ent at different positions of the benzenesulfonyl moiꢀ
ety showed good anticonvulsant activity in the MES exhibited considerable anticonvulsant activity in comꢀ
test; compounds with phenyl ring in (VIIa) and (VIIh
)
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 40
No. 1
2014

102
HARISH et al.
Table 2. Effect of the tested compounds in the maximal
electroshock seizure test
system [23]. Thus the proposed pharmacophore
model for (VIIg) includes all the above factors imporꢀ
tant for bioactivity (see figure).
Treatment
E/F
% Protection
In conclusion, a series of new 2,5ꢀdisubstitutedꢀ
1,3,4ꢀthiadiazole derivatives (VIIa–o) were syntheꢀ
sized in good yield, characterized by different spectral
studies, and their anticonvulsant activity has been
evaluated. Various thiadiazole derivatives with elecꢀ
tron withdrawing groups showed potent anticonvulꢀ
sant activity. Among the synthesized compounds,
(
(
(
(
(
(
(
(
(
(
(
(
(
(
(
VIIa
)
)
)
7.32
6.64
8.14
5.48
6.12
2.97
2.00
7.00
6.54
2.21
6.26
6.50
6.10
6.35
2.29
1.98
8.21
12.00
31.54
10.13
59.64
41.32
69.25
75.81
17.31
48.43
71.23
52.42
48.12
53.01
50.03
71.18
75.88
–
VIIb
VIIc
VIId
VIIe
VIIf
VIIg
VIIh
)
)
(
VIIg), (VIIj), and (VIIo) showed excellent anticonꢀ
)
vulsant activity. Therefore, the nature of groups in sulꢀ
fonyl moiety is very important for anticonvulsant
activity in MES model.
)
)
VIIi
VIIj
VIIk
)
)
EXPERIMENTAL
)
Melting range was determined by Veego Melting
Point VMP III apparatus. Elemental analyses were
performed on VarioMICRO superuser V1.3.2 Elemenꢀ
VIIl
)
VIIm
)
tar. 1H NMR spectra (
, ppm; J, Hz) were recorded on
δ
VIIn
)
Bruker DRXꢀ500 spectrometer at 400 MHz using
DMSOꢀd6 as solvent and TMS as an internal standard.
Mass spectral data were obtained by LC/MSD Trap XCT
at 70 eV. Silica gel column chromatography was perꢀ
formed using Merck 7734 silica gel (60–120 mesh) and
Merckꢀmade TLC plates.
VIIo
)
Standard
Control, vehicle
E/F = Extension/Flexion [Decrease in ratio of extension phase
(in seconds)/flexion phase (in seconds]. % Protection = (control –
test)/(Control) 100.
×
1,3,4ꢀThiadiazolꢀamine (II). Thiosemicarbazide (I)
(50.0 g, 0.5486 mol) was taken in 100 mL formic acid
and the reaction mixture was stirred at room temperaꢀ
ture for 1 h. After cooling the reaction mass, 100 mL
conc. hydrochloric acid was added. Reaction compleꢀ
tion was monitored by TLC. After cooling the reaction
parison to methyl group in (VIIc). These compounds
((VIIa), (VIIc), and (VIIh)) contribute to the 25%
neurotoxicity at 2 h. Among the synthesized comꢀ
pounds (VIIa–o), all the compounds showed activity
in the range of 10.13–75.81% in comparison to
phenytoin, which completely inhibited the convulꢀ
sions produced by electroꢀconvulsometer, but comꢀ
pound (VIIg), having electron withdrawing groups,
showed excellent anticonvulsant activity. It has been
established that there are at least three parameters for
anticonvulsant drugs, that is (i) lipophilic domain (L),
(ii) hydrophobic unit (R), and (iii) electron donar (D)
mass to 0°C, it was basified with ammonium hydroxꢀ
ide solution. The solid formed was filtered, washed
with water, and dried to yield the above compound as
a white solid. Recrystallization from methanol
afforded 45.5 g (82%)
4.21 (s, 2 H); MS:
(
z
II). 1H NMR:
= 102.14 (M+
).
δ
= 9.31 (s, 1 H),
m
/
5ꢀBromoꢀ1,3,4ꢀthiadiazolꢀ2ꢀamine (III). To a
stirred solution of compound (II) (40.0 g) and sodium
acetate (64.89 g) in 200 mL acetic acid (4% by vol.)
bromine was added dropwise (37.92 g) at 10°C. The
reaction mass was stirred at room temperature for
3 hours. The reaction mass was concentrated to syrup
and basified with saturated sodium bicarbonate soluꢀ
tion. The compound was extracted with ethyl acetate
and the ethyl acetate layer was washed with water folꢀ
lowed by brine, dried over sodium sulphate, and conꢀ
centrated to syrup. The crude syrup was crystallized
using ethyl acetate to yield the above compound as offꢀ
D
N
L
F
F
F
O
S
O
N
CN
N
N
S
N
R
O
O S
O
F
F
F
F
F
white solid. Recrystallization from methanol afforded
1
53.4 g (75%)
(s, w, 2 H); MS:
(
III). H NMR:
δ
= 9.31 (s, 1 H), 4.21
).
F
F
= 181.10 (M+
F
F
m/
z
tertꢀButyl 4ꢀ(5ꢀaminoꢀ1,3,4ꢀthiadiazoleꢀ2ꢀyl)pipeꢀ
razineꢀ1ꢀcarboxylate (IV). To a stirred solution of
amine (III) (25.0 g, 0.1388 mol), potassium carbonate
(57.57 g, 0.4165 mol) in dimethyl formamide (250 mL)
(VIIg)
The pharmacophore model of (VIIg) for anticonvulsant
activity.
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 40
No. 1
2014

SYNTHESIS OF NEW 2,5ꢀDISUBSTITUTEDꢀ1,3,4ꢀTHIADIAZOLE
103
Table 3. Neurotoxicity screening of the compounds (VIIa–o
)
and
NꢀBocꢀpiperazine (31.03 g, 0.1666 mol) were
added, and the reaction mass was stirred for 10 h at
room temperature. The reaction mass was quenched
in ice water (2.0 L) and stirred at room temperature for
1 h. The solid formed was filtered and dried to yield the
above compound as offꢀwhite solid. Recrystallization
Neurotoxicity screen
Comꢀ
pound
0.5 h
1 h
2 h
4 h
(
(
(
(
(
(
(
(
(
(
(
(
(
(
VIIa
VIIb
VIIc
VIId
VIIe
VIIf
VIIg
VIIh
)
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
1/4
1/4
1/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
1/4
1/4
1/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
0/4
1
)
from ethanol afforded 33.6 g (85%) (IV). H NMR:
δ
= 4.21 (s, 2 H), 3.77 (t,
J
= 5.36, 4 H), 3.10 (t,
J
=
)
4.80, 4 H), 1.41 (s, 9 H); MS:
m/z
= 286.03 (M+
).
)
tertꢀButylꢀ4ꢀ(5ꢀ(3ꢀ(2ꢀcyanopropaneꢀ2ꢀyl)benzamiꢀ
do)ꢀ1,3,4ꢀthiadiazolꢀ2ꢀyl) piperazineꢀ1ꢀcarboxylate (V).
To a stirred solution of carbonate (IV) (25.0 g, 0.0876
mol) in dichloromethane (250 mL), triethylamine
(26.59 g, 0.2628 mol), 3ꢀ(2ꢀcyanopropanꢀ2ꢀyl)benꢀ
zoic acid (19.89 g, 0.1051 mol), and TBTU (33.75 g,
0.1051 mol) were added. The reaction mass was stirred
overnight at room temperature and the reaction comꢀ
pletion was monitored by TLC. The reaction mass was
washed with saturated bicarbonate solution followed
by 1.0 N HCl, water and brine. The organic layer was
dried over sodium sulphate, concentrated to syrup,
and crystallized using dichloromethane to yield the
above compound as offꢀwhite solid. Recrystallization
)
)
)
)
VIIi
VIIj
VIIk
)
)
)
VIIl
VIIm
VIIn
)
)
)
Standard
from dichloromethane afforded 33.99 g (85%)
NMR: = 11.45 (s, 1 H), 8.33 (s, 1 H), 8.02 (d,
8.00, 1 H), 7.79 (d, = 7.88, 1 H), 7.66 (t, = 7.60, 1
H), 3.59 (t, = 5.20, 4 H), 3.50 (t, = 4.40, 4 H), 2.07
(s, 6 H),1.48 (s, 9 H); MS:
= 457.00 (M+
(V
). 1H The data in the table represent ratio between the numbers of the
J =
animals that exhibited neurotoxicity against the number of tested
δ
animals.
J
J
J
J
m/z
).
7.84–7.90 (m, 2 H), 7.72–7.80 (m, 3 H), 7.58–7.62
3ꢀ(2ꢀCyanopropanꢀ2ꢀyl)ꢀNꢀ(5ꢀ(piperazineꢀ1ꢀyl)ꢀ
1,3,4ꢀthiadiazolꢀ2ꢀyl)benzamide hydrochloride (VI). To a
stirred solution of carboxylate ( ) (20 g, 0.0438 mol) in
1,4ꢀdioxane at 0–5 C, 4 N HCl in dioxane (80.0 mL)
(m, 1 H), 7.50–7.54 (m, 2 H), 7.45 (t,
3.77 (t, = 5.36, 4 H), 3.21 (t, = 4.00, 4 H), 1.74 (s,
6 H); MS:
J = 7.32, 1 H),
J
J
5
m
/
z
= 573.18 (M+
3ꢀ(2ꢀCyanopropanꢀ2ꢀyl)ꢀ
)
.
°
N
ꢀ(5ꢀ(4ꢀ((2,4ꢀdimethꢀ
was added. The reaction mixture was stirred at room
temperature for 10 h. The solid was filtered, washed
with diethyl ether, and packed in air tight container to
ylphenyl)sulfonyl)piperazineꢀ1ꢀyl)ꢀ1,3,4ꢀthiadiazolꢀ2ꢀ
yl)benzamide (VIIb). Yield: 0.99 g (81%); white solid;
1H NMR:
= 9.6 (s, 1 H), 8.64 (s, 1 H), 8.21–8.24
(m, 3 H), 8.02 (d, = 8.00, 1 H), 7.79 (d, = 7.92,
1 H), 7.45 (t, = 7.32, 1 H), 3.77 (t, = 5.36, 4 H),
3.20 (t, = 4.10, 4 H), 3.06 (s, 3 H), 1.73 (s, 6 H), 1.18
(s, 3 H); MS: m/z = 525.18 (M+
δ
yield the above compound as pale yellow hygroscopic
1
J
J
solid 16.9 g (90%)
8.21 (s, 1 H), 8.02 (d,
1 H), 7.60 (t, = 7.80, 1 H), 3.77 (t,
3.21 (t, = 4.00, 4 H), 1.73 (s, 6 H); MS: m/z = 357.05
M+
(
VI). H NMR:
J
δ
= 9.81 (s, 2 H),
= 7.92,
= 5.36, 4 H),
J
J
= 8.00, 1 H), 7.79 (d, J
J
J
J
).
J
(
).
3ꢀ(2ꢀCyanopropaneꢀ2ꢀyl)ꢀ
5ꢀ(4ꢀ(methylsulfonyl)piperazineꢀ1ꢀyl)ꢀ1,3,4ꢀthiadiaꢀ
zoleꢀ2ꢀyl)benzamide (VIIc). Yield: 0.89 g (75%); white
solid; 1H NMR:
= 8.16 (s, 1 H), 7.95–7.98 (m, 1 H),
7.82–7.85 (m, 1 H), 7.70 (t, = 7.85, 1 H), 3.40 (t,
5.10, 4 H), 3.10 (t, = 4.32, 4 H), 2.84 (s, 3 H), 2.81
(s, 3 H), 1.72 (s, 6 H); MS: m/z = 513.09 (M+
Nꢀ(methylsulfonyl)ꢀNꢀ
General procedure for the synthesis of 2,5ꢀdisubstiꢀ
tutedꢀ1,3,4ꢀthiadiazole derivatives (VIIa–o). To a
mixture of (VI) (1.0 eq) and triethyl amine (4.5 eq) in
dichloromethane (10 vol), substituted sulphonyl chloꢀ
δ
J
J =
J
ride (2.4 eq) was added at 5–10°C and stirred overꢀ
)
.
night at room temperature. Reaction completion was
confirmed through TLC (Rf value 0.30 to 0.38). The
reaction mixture was poured into separating funnel,
washed with water followed by brine solution, dried
over anhydrous sodium sulphate, and concentrated to
syrup. Crude syrup was purified by crystallization
using ethyl acetate to yield the thiadiazol substituted
sulfonamide as white to pale yellow solids.
3ꢀ(2ꢀCyanopropanꢀ2ꢀyl)ꢀ ꢀ(5ꢀ(4ꢀ((2,5ꢀdichloꢀ
rothiophenꢀ3ꢀyl)sulfonyl)piperazineꢀ1ꢀyl)ꢀ1,3,4ꢀthiaꢀ
diazoleꢀ2ꢀyl)benzamide (VIId). Yield: 1,05 g (79%);
white solid; 1H NMR:
= 9.23 (s, 1 H), 8.28 (s, 1 H),
8.01–8.08 (m, 1 H), 7.79–7.85 (m, 1 H), 7.63 (t,
7.48, 1H), 7.42 (s, 1 H), 3.60 (t, = 4.84, 4 H), 3.31
N
δ
J
=
J
(t,
(
J
)
= 4.00, 4 H), 1.74 (s, 6 H); MS: m/z = 572.01
M+
.
N
ꢀ(5ꢀ((1,1'ꢀBiphenyl)sulfonyl)piperazineꢀ1ꢀyl)ꢀ1,3,4ꢀ
thiadiazolꢀ2ꢀyl)ꢀ3ꢀ(2ꢀcyanopropanꢀ2ꢀyl)benzamide
(VIIa). Yield: 1.06 g (80%); white solid; 1H NMR:
12.71 (s, 1 H), 8.19 (s, 1 H), 7.96–8.01 (m, 3 H), 1ꢀyl)ꢀ1,3,4ꢀthiadiazolꢀ2ꢀyl)benzamide (VIIe). Yield:
3ꢀ(2ꢀCyanopropanꢀ2ꢀyl)ꢀNꢀ(naphthaleneꢀ2ꢀylsulfoꢀ
δ
=
nyl)ꢀ ꢀ(5ꢀ(4ꢀ(naphthaleneꢀ2ꢀylsulfonyl) piperazineꢀ
N
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 40
No. 1
2014

104
HARISH et al.
1.28 g (75%); pale yellow solid; 1H NMR:
δ
= 8.93 (s,
Nꢀ((4ꢀCyanophenyl)sulfonyl)ꢀNꢀ(5ꢀ(4ꢀ((4ꢀcyanoꢀ
1 H), 8.48 (s, 1 H), 8.31 (s, 1 H), 8.18–8.24 (m, 3 H), phenyl)sulfonyl)piperazineꢀ1ꢀyl)ꢀ1,3,4ꢀthiadiazoleꢀ2ꢀ
8.07–8.10 (m, 3 H), 8.01 (d, = 8.12, 1 H), 7.94 (dd, yl)ꢀ3ꢀ(2ꢀcyanopropaneꢀ2ꢀyl)benzamide (VIIl). Yield:
= 1.92, 8.76 Hz, 1 H), 7.66–7.73 (m, 6 H), 7.60 (t,
= 7.76, 1 H), 3.57 (t, = 5.04, 4 H), 3.13 (t, = 5.00,
= 737.16 (M+
J
1.20 g (75%); white solid; 1H NMR:
8.11 (d, = 7.76, 1 H), 8.04 (d, = 6.98, 2 H), 7.81 (dd,
= 0.92, 4.86 Hz, 1 H), 7.43–7.48 (m, 3 H), 7.09–7.11
(m, 4 H), 3.52 (t, = 5.20, 4 H), 3.03 (t, = 4.84, 4 H),
1.73 (s, 6 H); MS: m/z = 687.78 (
+).
3ꢀ(2ꢀCyanopropaneꢀ2ꢀyl)ꢀ ꢀ((2ꢀnitrophenyl)sulꢀ
fonyl)ꢀ ꢀ(5ꢀ(4ꢀ((2ꢀnitrophenyl)sulfonyl) piperazineꢀ
1ꢀyl)ꢀ1,3,4ꢀthiadiazoleꢀ2ꢀyl)benzamide (VIIm). Yield:
δ
= 8.32 (s, 1 H),
J
J
J
J
J
J
4 H), 1.72 (s, 6 H); MS:
m
/
z
).
J
J
J
3ꢀ(2ꢀCyanopropaneꢀ2ꢀyl)ꢀ ꢀ((3,5ꢀdimethylisoxꢀ
azolꢀ4ꢀyl)sulfonyl)ꢀ ꢀ(5ꢀ(4ꢀ((3,5ꢀdimethylisoxazolꢀ4ꢀ
yl)sulfonyl)piperazineꢀ1ꢀyl)ꢀ1,3,4ꢀthiadiazolꢀ2ꢀyl)benzaꢀ
mide (VIIf). Yield: 1.25 g (80%); white solid; 1H NMR:
= 8.21 (s, 1 H), 8.02 (d, = 7.72, 1 H), 7.80 (d,
7.76, 1 H), 7.61 (t, = 7.80, 1 H), 3.56 (t, = 4.84,
4 H), 3.24 (t, = 4.32, 4 H), 2.64 (s, 3 H), 2.43 (s, 3 H),
2.36 (s, 3 H), 2.23 (s, 3 H), 1.75 (s, 6 H); MS:
675.15 (M+
ꢀ((3,5ꢀBis(trifluoromethyl)phenyl)sulfonyl)ꢀ
N
M
N
N
N
δ
J
J =
1
J
J
1.32 g (78%); offꢀwhite solid; H NMR:
1 H), 8.10 (d, = 7.68, 1 H), 8.05 (d, = 8.48, 2 H),
7.82 (d, = 7.60, 1 H), 7.62–7.68 (m, 7 H), 3.52 (t,
= 4.80, 4 H), 3.10 (t, = 4.00, 4 H), 1.75 (s, 6 H);
MS: m/z = 727.01 (
+).
ꢀ((4ꢀBromophenyl)sulfonyl)ꢀ
mophenyl)sulfonyl)piperazineꢀ1ꢀyl)ꢀ1,3,4ꢀthiadiazoleꢀ
2ꢀyl)ꢀ3ꢀ(2ꢀcyanopropaneꢀ2ꢀyl)benzamide (VIIn). Yield:
1.39 g (75%); white solid; 1H NMR:
= 8.20 (s, 1 H),
8.01 (d, = 7.68, 2 H), 7.89 (dd, = 1.56, 8.40 Hz,
= 1.56, 6.92 Hz,
= 7.80 Hz, 1 H), 7.53 (d, = 0.92 Hz,
= 4.80 Hz, 4 H), 3.00 (t, = 4.00 Hz,
+).
ꢀ((4ꢀ(trifluoromethꢀ
ꢀ(5ꢀ(4ꢀ((4ꢀ(trifluoromethyl)
phenyl)sulfonyl)piperazineꢀ1ꢀyl)ꢀ1,3,4ꢀthiadiazoleꢀ
2ꢀyl)benzamide (VIIo) Yield: 1.35 g (75%); white solꢀ
= 8.32 (s, 1 H), 8.04–8.10 (m, 5 H),
7.83–7.87 (m, 3 H), 7.65 (t, = 7.80, 1 H), 7.52 (d,
= 8.44, 2 H), 3.51 (t, = 4.80, 4 H), 3.10 (t, = 4.00,
4 H), 1.74 (s, 6 H); MS: = 773.10 (
+).
Anticonvulsant evaluation Male Wistar rats (190–
δ
= 8.36 (s,
J
J
J
m
/z =
J
)
.
J
J
M
N
N
ꢀ(5ꢀ
(4ꢀ((3,5ꢀbis(trifluoromethyl)phenyl)sulfonyl) piperaꢀ
zineꢀ1ꢀyl)ꢀ1,3,4ꢀthiazolꢀ2ꢀyl)ꢀ3ꢀ(2ꢀcyanoprppanꢀ2ꢀ
yl)benzamide (VIIg). Yield: 1.58 g (75%); pale yellow
N
Nꢀ(5ꢀ(4ꢀ((4ꢀbroꢀ
solid; 1H NMR:
δ
= 8.89 (s, 1 H), 8.57 (s, 2 H), 8.32
(s, 2 H), 8.19 (s, 1 H), 8.12 (s, 1 H), 7.99 (d, = 7.60,
1 H), 7.78 (d, = 8.00, 1 H), 7.59 (t, = 8.00, 1 H),
3.56 (t, = 4.84, 4 H), 3.24 (t, = 4.32, 4 H), 1.73 (s,
6 H); MS:
= 909.07 (M+
δ
J
J
J
J
J
2 H), 7.79 (d,
2 H), 7.60 (t,
2 H), 3.51 (t,
J = 7.84, 2 H), 7.71 (dd, J
J
J
J
J
J
J
m
/z
).
3ꢀ(2ꢀCyanopropanꢀ2ꢀyl)ꢀ
NꢀtosylꢀNꢀ(5ꢀ(4ꢀtosylpipꢀ
erazineꢀ1ꢀyl)ꢀ1,3,4ꢀthiadiazolꢀ2ꢀyl)benzamide (VIIh).
Yield: 1.23 g (80%); pale yellow solid; H NMR:
4 H), 1.74 (s, 6 H); MS: m/z = 792.94 (
3ꢀ(2ꢀCyanopropanꢀ2ꢀyl)ꢀ
yl)phenyl)sulfonyl)ꢀ
M
N
1
δ
=
N
8.36 (s, 1H), 8.11 (d, = 7.76, 1 H), 8.04 (d, = 6.88,
2 H), 7.81 (dd, = 0.92, 4.86 Hz, 1 H), 7.42–7.48 (m,
3 H), 7.09–7.11 (m, 4 H), 3.52 (t, = 5.20, 4 H), 3.03
(t, = 4.84, 4 H), 2.40 (s, 3 H), 2.34 (s, 3 H), 1.73 (s,
6 H); MS: m/z = 665.15 (M+
J
J
J
.
J
1
id; H NMR:
δ
J
J
).
J
J
J
N
ꢀ((4ꢀ(tertꢀButyl)phenyl)sulfonyl)ꢀNꢀ(5ꢀ(4ꢀ((ꢀtertꢀ
butyl)phenyl)sulfonyl)piperazineꢀ1ꢀyl)ꢀ1,3,4ꢀthiadiaꢀ
zoleꢀ2ꢀyl)ꢀ3ꢀ(2ꢀcyanopropaneꢀ2ꢀyl)benzamide (VIIi).
Yield: 1.30g (79%); pale yellow solid; H NMR:
m/z
M
.
220 g) procured from National Institute of Nutrition,
Hyderabad, were used in the present study. The aniꢀ
mals were kept in individual cages for one week to
acclimatize for the laboratory conditions. They were
allowed to access water and food freely.
1
δ
=
8.37 (s, 1 H), 8.10 (d,
2 H), 7.82 (d, = 7.60, 1 H), 7.62–7.68 (m, 7 H), 3.51
(t, = 4.80, 4 H), 3.00 (t, = 4.00, 4 H), 1.75 (s, 6 H),
1.29 (s, 9 H), 1.19 (s, 9 H); MS:
= 749.25 (M+
J = 7.68, 1 H), 8.05 (d, J = 8.48,
J
J
J
m/
z
).
All the experimental procedures were carried out in
accordance with Committee for the Purpose of Conꢀ
trol and Supervision of Experiments on Animals
(CPCSEA) guidelines. The study was reviewed and
approved by the Institutional Animal Ethics Commitꢀ
tee, G Pulla Reddy College of Pharmacy, Hyderabad,
India.
Maximal electroshock seizure model was used in
the present study to evaluate the anticonvulsant activity
of the compounds on male Wistar rats. Seizures were
induced in rats by delivering electroshock of 150 mA for
0.2 s by means of a convulsiometer through a pair of
ear clip electrodes. The test compounds (100 mg/kg)
were administered by oral route in the form of solution
(the compounds were dissolved in 1% sodium carꢀ
boxymethyl cellulose), 30 minutes before the maximal
electroshock seizure test. The animals were observed
closely for 2 min. The percentage of inhibition of seiꢀ
3ꢀ(2ꢀCyanopropanꢀ2ꢀyl)ꢀ ꢀ((3ꢀ(trifluoromethyl)pheꢀ
nyl)sulfonyl)ꢀ ꢀ(5ꢀ(4ꢀ((3ꢀ(trifluoromethyl) phenyl)sulfoꢀ
nyl)piperazineꢀ1ꢀyl)ꢀ1,3,4ꢀthiadiazoleꢀ2ꢀyl)benzamide
N
N
1
(VIIj)
= 8.43 (s, 1 H), 8.38 (s, 1 H), 8.34 (d,
8.17 (t, = 8.76, 2 H), 8.08 (d, = 7.72, 2 H), 7.95 (s,
1 H), 7.92 (d, = 7.88, 1 H), 7.83 (d, = 6.36, 2 H),
7.63 (t, = 8.04, 1 H), 3.51 (t, = 4.80, 4 H), 3.00 (t,
= 4.00, 4 H), 1.73 (s, 6 H); MS: = 773.09 (
+).
.
Yield: 1.35 g (75%); white solid; H NMR:
δ
J
= 7.36, 1 H),
J
J
J
J
J
J
J
m/
z
M
3ꢀ(2ꢀCyanopropanꢀ2ꢀyl)ꢀ ꢀ((4ꢀiodophenyl)sulfoꢀ
nyl)ꢀ ꢀ(5ꢀ(4ꢀ((4ꢀiodophenyl)sulfonyl) piperazineꢀ1ꢀ
yl)ꢀ1,3,4ꢀthiadiazoleꢀ2ꢀylꢀ)benzamide (VIIk). Yield:
1.57 g (76%); white solid; 1H NMR:
= 8.34 (s, 1 H),
8.05–8.11 (m, 5 H), 7.82–7.86 (m, 3 H), 7.65 (t,
= 7.80, 1 H), 7.52 (d, = 8.44, 2 H), 3.51 (t,
4.80, 4 H), 3.00 (t, = 4.00, 4 H), 1.74 (s, 6 H); MS:
m/z = 888.92 (
+).
N
N
δ
J
J
J =
J
M
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 40
No. 1
2014

SYNTHESIS OF NEW 2,5ꢀDISUBSTITUTEDꢀ1,3,4ꢀTHIADIAZOLE
105
11. Sharma, K.S. and Sarita, S., Indian J. Heterocycl.
Chem., 1994, vol. 4, pp. 137–144.
zure relative to control was recorded and calculated
[24]. Phenytoin (100 mg/kg) was used as a standard
drug.
12. Mohan, J. and Kumar, A., Indian J. Heterocycl. Chem.
,
2001, vol. 11, pp. 71–74.
The minimal motor impairment, reflecting acute
neurological toxicity, was measured in mice by the
rotorod test [24]. The mice were trained to stay on the
accelerating rotorod that rotates at 10. The rod diamꢀ
eter was 3.2 cm. Trained animals were administered
with the test compounds at dose of 100 mg/kg. Neuroꢀ
toxicity was evidenced by the inability of the animal to
maintain equilibrium on the rod for at least one
13. Siddiqui, N., Rana, A., Khan, S.A., Bhat, M.A. and
Haque, S.E., Bioorg. Med. Chem. Lett., 2007, vol. 17,
pp. 4178–4182.
14. Andotra, C.S. and Manhas, B.S., Acta Cienc. Indica
Chem., 1992, vol. 18, pp. 99–104.
15. Omar, A., Mohsen, M.E., and Aboul Wafa, O.M.,
J. Heterocycl. Chem., 1984, vol. 21, pp. 1415–1418.
minute in each of the three trails. Phenytoin was used 16. Vchal, P., Toth, L.M., Hale, J.J., Yan, L., Mills, S.G.,
Chrebet, G.L., Koehane, C.A., Hajdu, R., Milligan, J.A.,
Rosenbach, M.J., and Mandala, S., Bioorg. Med. Chem.
Lett., 2006, vol. 16, pp. 3684–3687.
as a standard drug.
REFERENCES
17. Vachal, P. and Toth, L.M., Tetrahedron Lett., 2004,
vol. 45, pp. 7157–7161.
18. Kawano, T., Hirano, K., Satoh, T., and Miura, M.,
1. Fisher, R.S., Van Emde Boas, W., Blume, W., Elger C.,
Genton, P., Lee, P., and Engel, J., Epilepsia, 2005,
vol. 46, pp. 470–472.
J. Am. Chem. Soc., 2010, vol. 132, pp. 6900–6901.
2. Amic, D., Davidovic, D., Beslo, D., and Trinajstic, N.,
Croat. Chem. Acta, 2003, vol. 76, pp. 55–61.
3. Soderpalm, B., Eur. J. Pain, 2002, vol. 6, pp. 3–9.
19. Zarudnitskii, E.V., Perevak, I.I., Aleksandr, A.S.,
Yurchenko, A., and Tolmachev, A.A., Tetrahedron
2008, vol. 64, pp. 10431–10437.
,
4. Berk, M., Segal, J., Janet, L., and Vorster, M., Drugs
2001, vol. 61, pp. 1407–1414.
5. Macdonald, K.J. and Young, L.T., CNS Drugs, 2002,
,
20. Ohmoto, K., Yamamoto, T., Okuma, M., Horiuchi, T.,
Imanishi, H., Odagaki, Y., Kawabata, K., Sekioka, T.,
Hirota, Y., Matsuoka, S., Nakai, H., and Toda, M.,
J. Med. Chem., 2001, vol. 44, pp. 1268–1285.
vol. 16, pp. 549–562.
21. Braslau, R., Anderson, M.O., Frank, A., Jimenez, A.,
Haddad, T., and Axon, J.R., Tetrahydron, 2002, vol. 58,
pp. 5513–5523.
6. Bialer, M., Johannessen, S.I., Kupferberg, H.J.,
Levy, R.H., and Loiseau, P., Epilepsy Res., 1999,
vol. 34, pp. 1–41.
7. Duncan, J.S., Br. J. Clin. Pharmacol., 2002, vol. 53,
22. Loscher, W. and Schmidt, D., Epilep. Res., 1994,
pp. 123–131.
vol. 17, pp. 95–134.
8. Perucca, E., Fund Clin. Pharmacol., 2001, vol. 15,
23. Dimmock, J.R., Vashishtha, S.C., and Stables, J.P.,
pp. 405–407.
Pharmazie, 2000, vol. 55, pp. 490–494.
9. Tomson, T., Curr. Sci., 2002, vol. 82, pp. 698–702.
10. Pandey, K.A., Nag, V.L., and Panda, C.S., Indian J.
Chem., 1999, vol. 38, pp. 998–1001.
24. Vogel, H.G. and Vogel, W.H., Drug Discovery and Evalꢀ
uation. Pharmacological Assays, Berlin: SpringerꢀVerꢀ
lag, 1997, vol. 2, pp. 260–261.
RUSSIAN JOURNAL OF BIOORGANIC CHEMISTRY Vol. 40
No. 1
2014