Synthesis and antimicrobial activity of novel sulfone-linked bis heterocycles

Article abstract of DOI:10.1016/j.ejmech.2007.06.011

Novel sulfone-linked bis heterocycles pyrazolines in combination with thiadiazoles, oxadiazoles and triazoles were prepared from E-styrylsulfonylacetic acid methyl ester and tested for their antimicrobial activity. The compound 8 showed pronounced activit

Full text of DOI:10.1016/j.ejmech.2007.06.011

Available online at www.sciencedirect.com
European Journal of Medicinal Chemistry 43 (2008) 917e924
http://www.elsevier.com/locate/ejmech
Original article
Synthesis and antimicrobial activity of novel
sulfone-linked bis heterocycles
*
V. Padmavathi , P. Thriveni, G. Sudhakar Reddy, D. Deepti
Department of Chemistry, Sri Venkateswara University, Tirupati 517 502, India
Received 19 February 2007; received in revised form 14 June 2007; accepted 15 June 2007
Available online 6 July 2007
Abstract
Novel sulfone-linked bis heterocycles pyrazolines in combination with thiadiazoles, oxadiazoles and triazoles were prepared from E-styryl-
sulfonylacetic acid methyl ester and tested for their antimicrobial activity. The compound 8 showed pronounced activity than the compounds
6 and 7.
Ó 2007 Elsevier Masson SAS. All rights reserved.
Keywords: 2-Pyrazolines; 1,3,4-Thiadiazoles; 1,3,4-Oxadiazoles; 1,2,4-Triazoles; Antimicrobial activity
1. Introduction
celecoxib, a pyrazole derivative is now widely used in the mar-
ket as an anti-inflammatory drug [14]. In view of these, we
aimed the synthesis and bioassay of compounds having both
pyrazoline and thiadiazole/oxadiazole/triazole rings.
Compounds incorporating heterocyclic ring systems con-
tinue to attract considerable interest due to the wide range of
biological activities they possess. Amongst them five mem-
bered heterocyclic compounds particularly azoles occupy
a unique place in the realm of natural and synthetic organic
chemistry. 1,3,4-Thiadiazoles find wide application in the
design of compounds possessing useful properties [1e3].
5-Unsubstituted 1,3,4-thiadiazoles are of interest as they are
used as intermediates in the synthesis of therapeutically useful
antibiotic cefazolin [4]. Nowadays, the most frequently used
triazoles are flucanazole and itraconazole. They possess
a broad spectrum of antifungal activity and reduced toxicity
when compared with the imidazole antifungals [5e10]. More-
over, 1,3,4-oxadiazoles find wide usage as dyes, photosensitive
and electrical materials [11]. They also exhibit broad spectrum
of biological activities such as HIV, antibacterial and antifun-
gal [12,13]. In addition, pyrazolines have gained importance
due to their various chemotherapeutic properties. In fact,
2. Chemistry
The reactivity of E-styrylsufonylacetic acid methyl ester (1)
towards the development of bis heterocycles, pyrazoline in
combination with thiadiazole, oxadiazole and triazole was
studied. When E-styrylsulfonylacetic acid methyl ester (1)
was treated with hydrazine hydrate instead of the expected
acid hydrazide, a cyclic product was obtained. It seems that
initially formed Michael addition product undergoes intramo-
lecular cyclocondensation to 1,1-dioxo-6-phenyl-1l6-[1,4,5]
thiadiazepan-3-one (2). In order to achieve the desired bis het-
erocycles, the olefin in 1 was first exploited to develop pyrazo-
line ring. The 1,3-dipolar cycloaddition of diazomethane to 1
at ꢀ15 ꢁC for 48 h gave a solid which was identified as (4-
phenyl-4,5-dihydro-1H-pyrazole-3-sulfonyl)-acetic acid methyl
ester (3). The articulation of thiadiazole, triazole and oxadia-
zole rings was made from the ester moiety of 3. The
reaction of 3 with 1 equiv of hydrazine hydrate produced
(4-phenyl-4,5-dihydro-1H-pyrazole-3-sulfonyl)-acetic acid
* Corresponding author. Tel.: þ91 877 2249666x303; fax: þ91 877
2248499.
E-mail address: vkpuram2001@yahoo.com (V. Padmavathi).
0223-5234/$ - see front matter Ó 2007 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2007.06.011

918
V. Padmavathi et al. / European Journal of Medicinal Chemistry 43 (2008) 917e924
hydrazide (4). The potassium dithiocarbazate of acid hydra-
zide (5) was prepared from 4 on treatment with carbon disul-
fide in the presence of potassium hydroxide under ultrasonic
conditions. This on refluxion in acetic acid cyclized to
50-(4-phenyl-4,5-dihydro-1H-pyrazole-3-sulfonylmethyl)-[10,
30,40]thiadiazole-20-thiol (6). On the other hand, acid catalyzed
hydrolysis of 5 resulted in 50-(4-phenyl-4,5-dihydro-1H-pyra-
zole-3-sulfonylmethyl)-[10,30,40]oxadiazole-20-thiol (7). The
compound 5 on treatment with hydrazine hydrate produced
40-amino-50-(4-phenyl-4,5-dihydro-1H-pyrazole-3-sulfonyl-
methyl)-4H-[10,20,40]triazole-30-thiol (8) (Scheme 1).
3. Biology
3.1. Antimicrobial activity
The synthesized compounds were tested for their in vitro
antimicrobial activity against the Gram-positive bacteria
O
H
N
O
H
HN
O
O
O
S
S
i
OMe
O
H
R
R
1
2
ii
R
O
O
O
HA
S
OMe
H
N
iii
M
N
H
HX
3
R
O
O
O
HA
S
NHNH2
H
N
M
N
H
HX
4
iv
R
O
O
O
HA
-
+
S
NHNHCS K
S
H
N
M
N
H
HX
5
v
vi
vii
O
R
R
R
N1' 2N'
N
N
N
N
O
3'
4'
O
O
HA
3'
4'
HA
O
O
3'
5'
HA
5' 2'
S
S
4'
N
5' 2'
1'
S
S
SH
SH
1'
SH
4
5
3
4
5
3
O
4
5
3
H
H
2
2 N
H
N
M
NH2
M
1
2 N
1
M
1
N
H
N
H
X
N
H
X
H
H
X
H
7
8
6
v. AcOH
vi. HCl / H2O
i. N2H4.H2O / MeOH
ii. CH2N2 / Et2O / Et3N
R= a) H, b) Me, c) Cl
vii. N2H4.H2O
iii. N2H4.H2O / Pyridine / EtOH
iv. CS2 / KOH / EtOH
Scheme 1.

V. Padmavathi et al. / European Journal of Medicinal Chemistry 43 (2008) 917e924
919
Table 2
The in vitro antifungal activity of compounds 6, 7 and 8
Staphylococcus aureus, Bacillus subtilis, the Gram-negative
bacteria Escherichia coli, Klebsiella pneumoniae and fungi
Fusarium solani, Curvularia lunata and Aspergillus niger.
The primary screen was carried out by agar disc-diffusion
method [15] using nutrient agar medium. The minimal inhib-
itory concentration for the most active compounds 6c, 8a and
8c against the same microorganisms used in the preliminary
screening was carried out using microdilution susceptibility
method [16]. Chloramphenicol and ketoconazole were used
as control drugs. The observed data on the antimicrobial
activity of the compounds and control drugs are given in
Tables 1e3.
Compound
Concentration (mg)
Zone of inhibition (mm)
F. solani
C. lunata
A. niger
6a
100
200
22
24
26
29
25
28
6b
100
200
24
26
20
23
22
24
6c
100
200
28
31
23
26
26
29
7a
100
200
17
19
17
22
16
21
7b
100
200
16
20
16
18
17
21
4. Results, discussion and conclusion
7c
100
200
15
18
16
19
14
18
In the present work, 1,3,4-thiadiazoles, 1,3,4-oxadiazoles
and 1,2,4-triazoles were synthesized. The structures of the
1
compounds were elucidated by spectral data. The H NMR
8a
100
200
39
44
37
41
36
39
spectrum of 2a displayed a singlet and two multiplets at
d 4.35, 4.17e4.22 and 3.84e3.89 ppm for C2eH, C6eH and
C7eH, respectively. A broad singlet was observed at
d 10.58 ppm for NH which disappeared on deuteration. The
13C NMR spectrum of this compound displayed signals at
d 60.6, 165.7, 58.9 and 66.8 ppm for C2, C3, C6 and C7. The
8b
100
200
32
37
34
39
35
38
8c
100
200
40
43
39
42
36
40
Ketoconazole
100
200
38
42
41
44
36
39
ꢂ
mass spectrum of 2a showed Mþ peak at m/z 240, which is
in agreement with its chemical composition.
The 1H NMR spectrum of 3a showed an AMX splitting pat-
tern for the pyrazoline ring protons. The doublet of doublets
observed at d 4.48, 3.76 and 3.52 ppm were assigned to HA,
HM and HX. Two singlets were observed at d 4.36 and
3.66 ppm for methylene and methoxy protons as well as sig-
nals due to aromatic protons. The 13C NMR spectrum showed
signals at d 38.4, 44.7, 49.8, 52.2, 152.6 and 171.6 ppm for the
carbons C4, C5, SO2eCH2, OCH3, C3 and CO, respectively.
Table 1
The in vitro antibacterial activity of compounds 6, 7 and 8
Compound
Concentration Zone of inhibition (mm)
(mg)
1
The H NMR spectrum of 4a displayed broad signals in the
Gram-positive
bacteria
Gram-negative
bacteria
region d 9.51 and 5.16 ppm for NH and NH2 which disap-
peared on deuteration, apart from the signals due to pyrazoline
ring protons.
The 1H NMR spectra of compounds 6e8 displayed a singlet
in the region 10.21e10.31 ppm for SH besides the signals due
to pyrazoline ring protons. Apart from this, 8a showed signals
at 5.62 ppm for NH2 which disappeared on deuteration. The
13C NMR spectra of these compounds exhibited signals at
d 38.8, 44.7, 49.4, 144.6, 154.7 and 168.5 ppm for the carbons
S. Aureus B. subtilis E. coli K. pneumoniae
6a
6b
6c
7a
7b
7c
8a
8b
8c
100
200
18
21
20
23
15
20
17
20
100
200
14
17
16
19
18
21
16
19
100
200
25
29
28
31
22
27
24
26
100
200
14
16
13
15
15
18
14
16
0
C4, C5, SO2eCH2, C3 , C3, C5 , respectively.
0
100
200
12
15
13
16
12
14
10
12
4.1. Biological results
100
200
13
17
15
18
11
13
11
14
The results of the final compounds of preliminary antibac-
terial testing are shown in Table 1. The results revealed that
majority of the synthesized compounds showed varying
degrees of inhibition against the tested microorganisms. In
general, the inhibitory activity against the Gram-positive bac-
teria was higher than that of the Gram-negative bacteria. The
oxadiazole derivatives 7aec were displayed least activity. The
compounds 6c, 8a, 8b and 8c showed excellent activity against
Gram-positive bacteria (inhibitory zone >25 mm), good activ-
ity against Gram-negative bacteria (inhibitory zone >20 mm).
100
200
28
30
31
33
22
25
21
24
100
200
25
28
27
29
24
26
22
24
100
200
32
35
34
36
23
25
26
28
Chloramphenicol 100
200
35
39
38
41
40
44
42
45

920
V. Padmavathi et al. / European Journal of Medicinal Chemistry 43 (2008) 917e924
All the tested compounds showed moderate (7aec) to high
(6aec and 8aec) inhibitory effect towards tested fungi
(Table 2).
The MIC values were determined as the lowest concentration
that completely inhibited visible growth of the microorganisms
(Table 3). The structureeantimicrobial activity relationship of
the synthesized compounds revealed that the compounds hav-
ing oxadiazole moiety exhibited least activity when compared
with compounds having thiadiazole and triazole moieties.
Among the substituents on the aryl group, the compounds
having 4-chlorophenyl derivatives were the most active. The
maximum activity was attained with compound 8c, having
triazole nucleus with chloro substituent in the aryl group.
In conclusion, a new class of bis heterocycles, pyrazoline in
combination with thiadiazole, triazole and oxadiazole are
developed adopting simple, elegant and well-versed methodol-
ogies from a vulnerable substrate, E-styrylsulfonylacetic acid
methyl ester. We have also evaluated in vitro antimicrobial
activity of some compounds. The results obtained from
antifungal and antibacterial tests together showed that all com-
pounds tested are more active towards fungi than bacteria. The
compounds pyrazoline in combination with triazole showed
greater antimicrobial activity.
5. Experimental
5.1. Chemistry
Melting points were determined in open capillaries on
a Mel-Temp apparatus and are uncorrected. The purity of
the compounds was checked by TLC (silica gel H, BDH, ethyl
acetateehexane, 1:3). IR spectra were recorded on a Thermo
1
Nicolet IR 200 FT-IR in KBr pellets. H NMR spectra were
recorded at 300 MHz on a Varian EM-360 spectrometer.13C
NMR spectra were run on a Varian VXR spectrometer operat-
ing at 75.5 MHz. All chemical shifts are reported in parts per
million from TMS as an internal standard. Mass spectra were
recorded on a Joel JMS-D 300 instrument at 70 eV. Elemental
analyses were performed using a PerkineElmer 240 C
elemental analyzer.
The starting compound E-styrylsulfonylacetic acid methyl
ester 1 was prepared by standard procedure [17].
5.1.1. Preparation of 1,1-dioxo-6-aryl-1l6-[1,4,5]
thiadiazepan-3-one 2aeb
A mixture of 1 (0.25 mmol) and hydrazine hydrate
(0.5 mmol) in methanol (15 ml) was refluxed for 10 h. It
was cooled and the solid separated was filtered and dried.
5.1.1.1. 1,1-Dioxo-6-phenyl-1l6-[1,4,5]thiadiazepan-3-one 2a.
White crystals (0.91 g, 76%); m.p. 210e212 ꢁC; IR (KBr):
1
1129, 1322 (SO2), 1638 (C]O), 3304 (NH) cmꢀ1; H NMR
(DMSO-d6) d (ppm): 3.84e3.89 (m, 2H, C7-H), 4.17e4.22
(m, 1H, C6-H), 4.35 (s, 2H, C2-H), 7.24e7.56 (m, 5H, Ph),
10.58 (br s, 2H, NH); 13C NMR (DMSO-d6) d (ppm): 58.9
(C6), 60.6 (C2), 66.8 (C7), 165.7 (C3), 128.4, 129.5, 130.8,
ꢂ
131.2 (aromatic carbons); Ms (m/z): 240 (Mþ ). Anal. Calcd.

V. Padmavathi et al. / European Journal of Medicinal Chemistry 43 (2008) 917e924
921
for C10H12N2O3S : C, 49.99; H, 5.03; N, 11.66; Found: C,
50.08; H, 5.08; N, 11.60%.
d (ppm): 3.49 (dd, 1H, HX), 3.68 (s, 3H, OCH3), 3.88 (dd,
1H, HM, JMX ¼ 10.4 Hz), 4.38 (s, 2H, SO2CH2), 4.52 (dd,
1H, HA, JAM ¼ 12.9 Hz, JAX ¼ 5.9 Hz), 10.20 (br s, 1H,
NH), 7.23e7.41 (m, 4H, Ar); 13C NMR (CDCl3) d (ppm):
38.6 (C4), 44.9 (C5), 50.1 (SO2CH2), 54.2 (OCH3), 152.8
(C3), 171.8 (C]O), 129.4, 130.5, 135.2, 136.6 (aromatic car-
bons). Anal. Calcd. for C12H13ClN2O4S: C, 45.50; H, 4.14; N,
8.84; Found: C, 45.53; H, 4.12; N, 8.91%.
5.1.1.2. 1,1-Dioxo-6-p-tolyl-1l6-[1,4,5]thiadiazepan-3-one 2b.
White crystals (1.00 g, 79%); m.p. 225e227 ꢁC; IR
(KBr): 1125, 1324 (SO2), 1640 (C]O), 3310 (NH)
cmꢀ1 1H NMR (DMSO-d6) d (ppm): 2.34 (s, 3H, Ar-CH3),
;
3.71e3.75 (m, 2H, C7-H), 4.15e4.19 (m, 1H, C6-H), 4.32 (s,
2H, C2-H), 7.32e7.66 (m, 4H, Ar), 10.52 (br s, 2H, NH); 13C
NMR (DMSO-d6) d (ppm): 20.4 (Ar-CH3), 56.5 (C6), 58.7
(C2), 64.2 (C7), 164.6 (C3), 128.8, 129.3, 131.8, 133.2 (aromatic
5.1.3. General procedure for the synthesis of (4-aryl-4,5-
dihydro-1H-pyrazole-3-sulfonyl)-acetic acid hydrazide 4aec
To a solution of (4-aryl-4,5-dihydro-1H-pyrazole-3-sulfo-
nyl)-acetic acid methyl ester 3aec (1 mmol) in absolute etha-
nol, hydrazine hydrate (4.5 mmol) and pyridine (0.4 ml) were
added and stirred for 6 h at room temperature. The resultant
solid was filtered and recrystallized from ethanol.
ꢂ
carbons); MS (m/z) 254 (Mþ ). Anal. Calcd. for C11H14N2O3S:
C, 51.95; H, 5.55; N, 11.02; Found: C, 51.83; H, 5.52; N,
12.00%.
5.1.2. General procedure for the synthesis of (4-aryl-4,5-
dihydro-1H-pyrazole-3-sulfonyl)-acetic acid methyl ester
3aec
To a cooled solution of E-styrylsulfonylacetic acid methyl
ester 1aec (5 mmol) in dichloromethane (20 ml), an ethereal
solution of diazomethane (40 ml, 0.4 M) and triethylamine
(0.12 g) were added. The reaction mixture was kept at ꢀ20
to ꢀ15 ꢁC for 40e48 h. The solvent was removed under
reduced pressure. The resultant solid was purified by column
chromatography (hexaneeethyl acetate 4:1).
5.1.3.1. (4-Phenyl-4,5-dihydro-1H-pyrazole-3-sulfonyl)-acetic
acid hydrazide 4a. Yellow solid (0.18 g, 65%); m.p. 162e
164 ꢁC; IR (KBr): 1135, 1320 (SO2), 1567 (C]N), 1665
1
(C]O), 3214 (NH), 3226 (NH2) cmꢀ1; H NMR (CDCl3)
d
(ppm): 3.51 (dd, 1H, HX), 3.83 (dd, 1H, HM,
JMX ¼ 10.2 Hz), 4.28 (s, 2H, SO2CH2), 4.43 (dd, 1H, HA,
JAM ¼ 12.5 Hz, JAX ¼ 5.6 Hz), 5.16 (br s, 2H, NH2), 7.26e
7.34 (m, 5H, Ph), 9.51 (br s, 1H, NH), 10.16 (br s, 1H,
NH); 13C NMR (CDCl3) d (ppm): 38.9 (C4), 44.9 (C5), 48.6
(SO2CH2), 153.5 (C3), 169.6 (C]O), 128.5, 129.8, 130.1,
132.4 (aromatic carbons). Anal. Calcd. for C11H14N4O3S: C,
46.80; H, 5.00; N, 19.85; Found: C, 46.85; H, 5.03; N,
19.94%.
5.1.2.1. (4-Phenyl-4,5-dihydro-1H-pyrazole-3-sulfonyl)-acetic
acid methyl ester 3a. Yellow solid (1.01 g, 72%); m.p.
129e131 ꢁC; IR (KBr): 1146, 1325 (SO2), 1565 (C]N),
1
1745 (C]O), 3183 (NH) cmꢀ1; H NMR (CDCl3) d (ppm):
3.52 (dd, 1H, HX), 3.66 (s, 3H, OCH3), 3.76 (dd, 1H, HM,
JMX ¼ 10.0 Hz), 4.36 (s, 2H, SO2CH2), 4.48 (dd, 1H, HA,
JAM ¼ 12.6 Hz, JAX ¼ 5.5 Hz), 10.18 (br s, 1H, NH),
7.32e7.58 (m, 5H, Ph); 13C NMR (CDCl3) d (ppm): 38.4
(C4), 44.7 (C5), 49.8 (SO2CH2), 52.2 (OCH3), 152.6 (C3),
171.6 (C]O), 125.7, 127.9, 128.4, 140.2 (aromatic carbons).
Anal. Calcd. for C12H14N2O4S: C, 51.05; H, 5.00; N, 9.92;
Found: C, 51.09; H, 5.02; N, 9.98%.
5.1.3.2. (4-p-Tolyl-4,5-dihydro-1H-pyrazole-3-sulfonyl)-acetic
acid hydrazide 4b. Yellow solid (0.20 g, 68%); m.p. 159e
161 ꢁC; IR (KBr): 1138, 1330 (SO2), 1564 (C]N), 1668
1
(C]O), 3212 (NH), 3224 (NH2) cmꢀ1; H NMR (CDCl3)
d (ppm): 2.27 (s, 3H, Ph-CH3), 3.49 (dd, 1H, HX), 3.81 (dd,
1H, HM, JMX ¼ 10.1 Hz), 4.26 (s, 2H, SO2CH2), 4.41 (dd,
1H, HA, JAM ¼ 12.4 Hz, JAX ¼ 5.4 Hz), 4.98 (br s, 2H,
NH2), 7.18e7.25 (m, 4H, Ar), 9.49 (br s, 1H, NH), 10.14
(br s, 1H, NH); 13C NMR (CDCl3) d (ppm): 21.2 (Ar-CH3),
38.7 (C4), 44.3 (C5), 48.3 (SO2CH2), 153.1 (C3), 169.4
(C]O), 129.4, 131.6, 133.4, 134.3 (aromatic carbons). Anal.
Calcd. for C12H16N4O3S: C, 48.64; H, 5.44; N, 18.91; Found:
C, 48.59; H, 5.40; N, 18.83%.
5.1.2.2. (4-p-Tolyl-4,5-dihydro-1H-pyrazole-3-sulfonyl)-acetic
acid methyl ester 3b. Yellow solid (0.96 g, 76%); m.p. 142e
144 ꢁC; IR (KBr): 1142, 1328 (SO2), 1568 (C]N), 1742
1
(C]O), 3174 (NH) cmꢀ1; H NMR (CDCl3) d (ppm): 2.31
(s, 3H, Ar-CH3), 3.46 (dd, 1H, HX), 3.64 (s, 3H, OCH3),
3.84 (dd, 1H, HM, JMX ¼ 10.2 Hz), 4.34 (s, 2H, SO2CH2),
4.46 (dd, 1H, HA, JAM ¼ 12.4 Hz, JAX ¼ 5.2 Hz), 10.15 (br
s, 1H, NH), 7.14e7.35 (m, 4H, Ar); 13C NMR (CDCl3)
5.1.3.3. 4-(4-Chlorophenyl-4,5-dihydro-1H-pyrazole-3-sulfo-
nyl)-acetic acid hydrazide 4c. Yellow solid (0.22 g, 71%);
m.p. 164e166 ꢁC; IR (KBr): 1136, 1335 (SO2), 1569
;
(C]N), 1670 (C]O), 3216 (NH), 3229 (NH2) cmꢀ1 1H
NMR (CDCl3) d (ppm): 3.58 (dd, 1H, HX), 3.85 (dd, 1H,
HM, JMX ¼ 10.4 Hz), 4.31 (s, 2H, SO2CH2), 4.45 (dd, 1H,
HA, JAM ¼ 12.6 Hz, JAX ¼ 5.7 Hz), 5.18 (br s, 2H, NH2),
7.29e7.40 (m, 4H, Ar), 9.56 (br s, 1H, NH), 10.20 (br s,
1H, NH); 13C NMR (CDCl3) d (ppm): 39.4 (C4), 45.1 (C5),
48.8 (SO2CH2), 153.9 (C3), 169.8 (C]O), 129.8, 132.4,
133.8, 136.9 (aromatic carbons). Anal. Calcd. for
d
(ppm): 20.6 (Ar-CH3), 38.2 (C4), 44.6 (C5), 49.6
(SO2CH2), 51.9 (OCH3), 152.5 (C3), 171.4 (C]O), 129.1,
130.3, 131.8, 133.6 (aromatic carbons). Anal. Calcd. for
C13H16N2O4S: C, 52.69; H, 5.44; N, 9.45; Found: C, 52.64;
H, 5.45; N, 9.52%.
5.1.2.3. 4-(4-Chlorophenyl-4,5-dihydro-1H-pyrazole-3-sulfo-
nyl)-acetic acid methyl ester 3c. Yellow solid (1.25 g, 79%);
m.p. 151e153 ꢁC; IR (KBr): 1150, 1332 (SO2), 1570
1
(C]N), 1748 (C]O), 3178 (NH) cmꢀ1; H NMR (CDCl3)

922
V. Padmavathi et al. / European Journal of Medicinal Chemistry 43 (2008) 917e924
C11H13ClN4O3S: C, 41.71; H, 4.14; N, 17.69; Found: C,
41.73; H, 4.12; N, 17.63%.
Ar), 9.95 (br s, 1H, NH), 10.29 (s, 1H, SH); 13C NMR
(DMSO-d6) d (ppm): 39.8 (C4), 45.8 (C5), 52.8 (SO2CH2),
0
0
155.5 (C3), 160.9 (C2 ), 168.7 (C5 ), 128.4, 132.3, 134.8,
ꢂ
5.1.4. General procedure for the preparation of potassium
(4-aryl-4,5-dihydro-1H-pyrazole-3-sulfonylacetyl)-hydrazine-N0-
carbodithioate 5aec
138.5 (aromatic carbons). MS (m/z) 374.89 (Mþ ). Anal.
Calcd. for C12H11ClN4O2S3 : C, 38.45; H, 2.96; N, 14.94;
Found: C, 38.47; H, 2.97; N, 14.89%.
To a mixture of potassium hydroxide (2 mmol) and (4-aryl-
4,5-dihydro-1H-pyrazole-3-sulfonyl)-acetic acid hydrazide
4aec (1 mmol) in absolute ethanol (5 ml), carbon disulfide
(4 mmol) was added and sonicated for 12 h. The separated
solid was filtered and dried.
5.1.6. General procedure for the synthesis of
50-(4-aryl-4,5-dihydro-1H-pyrazole-3-sulfonylmethyl)-
[10,30,40]oxadiazole-20-thiol 7aec
Potassium(4-aryl-4,5-dihydro-1H-pyrazole-3-sulfonylacetyl)-
hydrazine-N0-carbodithioate 5aec (1 mmol) was dissolved in
6 ml of water and acidified with 1e2 ml of concd. HCl. The
regenerated solid was collected by filtration, dried and purified
by recrystallization from 2-propanol.
5.1.5. General procedure for the synthesis of
50-(4-aryl-4,5-dihydro-1H-pyrazole-3-sulfonylmethyl)-
[10,30,40]thiadiazole-20-thiol 6aec
A mixture of potassium (4-aryl-4,5-dihydro-1H-pyrazole-3-
sulfonylacetyl)-hydrazine-N0-carbodithioate 5aec (1 mmol)
and acetic acid (4 ml) were refluxed for 24 h. The contents
of the flask were cooled and poured into crushed ice. The solid
obtained was filtered, dried and recrystallized from 2-
propanol.
5.1.6.1.
50-(4-Phenyl-4,5-dihydro-1H-pyrazole-3-sulfonyl-
methyl)-[10,30,40]oxadiazole-20-thiol 7a. Yellow solid (0.21 g,
64%); m.p. 180e182 ꢁC; IR (KBr): 1138, 1330 (SO2), 1564
(C]N), 2560 (SH), 3239 (NH) cmꢀ1; H NMR (DMSO-d6)
1
d
(ppm): 3.56 (dd, 1H, HX), 3.82 (dd, 1H, HM,
5.1.5.1.
50-(4-Phenyl-4,5-dihydro-1H-pyrazole-3-sulfonyl-
JMX ¼ 10.5 Hz), 4.55 (dd, 1H, HA, JAM ¼ 12.7 Hz,
JAX ¼ 5.6 Hz), 4.75 (s, 2H, SO2CH2), 7.31e7.55 (m, 5H,
Ph), 9.92 (br s, 1H, NH), 10.24 (s, 1H, SH); 13C NMR
(DMSO-d6) d (ppm): 39.5 (C4), 45.7 (C5), 52.6 (SO2CH2),
methyl)-[10,30,40]thiadiazole-20-thiol 6a. Yellow solid (0.21 g,
61%); m.p. 202e204 ꢁC; IR (KBr): 1144, 1335 (SO2), 1566
(C]N), 2558 (SH), 3220 (NH) cmꢀ1; H NMR (DMSO-d6)
1
d
(ppm): 3.54 (dd, 1H, HX), 3.84 (dd, 1H, HM,
0
0
155.5 (C3), 161.4 (C2 ), 168.9 (C5 ), 125.8, 129.9, 132.4,
ꢂ
138.2 (aromatic carbons); MS (m/z) 324.38 (Mþ ). Anal.
Calcd. for C12H12N4O3S2: C, 44.43; H, 3.73; N, 17.27; Found:
C, 44.46; H, 3.75; N, 17.22%.
JMX ¼ 10.3 Hz), 4.51 (dd, 1H, HA, JAM ¼ 12.8 Hz,
JAX ¼ 5.7 Hz), 4.73 (s, 2H, SO2CH2), 7.36e7.68 (m, 5H,
Ph), 9.89 (br s, 1H, NH), 10.26 (s, 1H, SH); 13C NMR
(DMSO-d6) d (ppm): 39.6 (C4), 45.4 (C5), 52.5 (SO2CH2),
0
0
155.2 (C3), 160.7 (C2 ), 168.5 (C5 ), 127.2, 130.5, 131.7,
5.1.6.2. 50-[4-( p-Tolyl)-4,5-dihydro-1H-pyrazole-3-sulfonyl-
methyl)-[10,30,40]oxadiazole-20-thiol 7b. Yellow solid (0.23 g,
67%); m.p. 210e212 ꢁC; IR (KBr): 1136, 1335 (SO2), 1562
ꢂ
133.1 (aromatic carbons); MS (m/z) 340.45 (Mþ ). Anal.
Calcd. for C12H12N4O2S3: C, 42.33; H, 3.55; N, 16.46; Found:
C, 42.37; H, 3.56; N, 16.49%.
1
(C]N), 2564 (SH), 3246 (NH) cmꢀ1; H NMR (DMSO-d6)
d (ppm): 2.31 (s, 3H, Ar-CH3), 3.53 (dd, 1H, HX), 3.80 (dd,
1H, HM, JMX ¼ 10.3 Hz), 4.51 (dd, 1H, HA, JAM ¼ 12.5 Hz,
JAX ¼ 5.4 Hz), 4.72 (s, 2H, SO2CH2), 7.26e7.66 (m, 4H,
Ar), 9.88 (br s, 1H, NH), 10.21 (s, 1H, SH); 13C NMR
(DMSO-d6) d (ppm): 22.7 (Ar-CH3), 39.3 (C4), 45.4 (C5),
5.1.5.2. 50-[4-( p-Tolyl)-4,5-dihydro-1H-pyrazole-3-sulfonyl-
methyl]-[10,30,40]thiadiazole-20-thiol 6b. Yellow solid (0.23 g,
66%); m.p. 225e227 ꢁC; IR (KBr): 1141, 1328 (SO2), 1562
1
(C]N), 2556 (SH), 3224 (NH) cmꢀ1; H NMR (DMSO-d6)
d (ppm): 2.28 (s, 3H, Ar-CH3), 3.52 (dd, 1H, HX), 3.82 (dd,
1H, HM, JMX ¼ 10.2 Hz), 4.50 (dd, 1H, HA, JAM ¼ 12.7 Hz,
JAX ¼ 5.4 Hz), 4.68 (s, 2H, SO2CH2), 7.28e7.59 (m, 4H,
Ar), 9.76 (br s, 1H, NH), 10.22 (s, 1H, SH); 13C NMR
(DMSO-d6) d (ppm): 22.4 (Ar-CH3), 39.2 (C4), 45.2 (C5),
0
52.3 (SO2CH2), 155.2 (C3), 161.1 (C2 ), 168.7 (C5 ), 127.5,
0
128.3, 133.6, 139.8 (aromatic carbons); MS (m/z) 338.41
ꢂ
(Mþ ). Anal. Calcd. for C13H14N4O3S2: C, 46.14; H, 4.17;
N, 16.56; Found: C, 46.18; H, 4.16; N, 16.49%.
0
0
51.9 (SO2CH2), 155.0 (C3), 160.3 (C2 ), 168.3 (C5 ), 128.9,
129.1, 134.5, 137.2 (aromatic carbons); MS (m/z) 354.47
(Mþ$). Anal. Calcd. for C13H14N4O2S3 : C, 44.05; H, 3.98;
N, 15.81; Found: C, 44.01; H, 3.95; N, 15.88%.
5.1.6.3.
50-[4-(4-Chlorophenyl)-4,5-dihydro-1H-pyrazole-3-
sulfonylmethyl]-[10,30,40]oxadiazole-20-thiol 7c. Yellow solid
(0.26 g, 73%); m.p. 232e234 ꢁC; IR (KBr): 1145, 1338
(SO2), 1573 (C]N), 2568 (SH), 3248 (NH) cmꢀ1; H NMR
1
5.1.5.3.
50-[4-(4-Chlorophenyl)-4,5-dihydro-1H-pyrazole-3-
(DMSO-d6) d (ppm): 3.58 (dd, 1H, HX), 3.85 (dd, 1H, HM,
JMX ¼ 10.4 Hz), 4.57 (dd, 1H, HA, JAM ¼ 12.9 Hz,
JAX ¼ 5.7 Hz), 4.78 (s, 2H, SO2CH2), 7.39e7.70 (m, 4H,
Ar), 9.98 (br s, 1H, NH), 10.27 (s, 1H, SH); 13C NMR
(DMSO-d6) d (ppm): 39.7 (C-4), 46.1 (C5), 52.9 (SO2CH2),
sulfonylmethyl]-[10,30,40]thiadiazole-20-thiol 6c. Yellow solid
(0.26 g, 69%); m.p. 244e246 ꢁC; IR (KBr): 1146, 1339
(SO2), 1565 (C]N), 2561 (SH), 3232 (NH) cmꢀ1; H NMR
1
(DMSO-d6) d (ppm): 3.55 (dd, 1H, HX), 3.88 (dd, 1H, HM,
JMX ¼ 10.4 Hz), 4.54 (dd, 1H, HA, JAM ¼ 12.9 Hz,
JAX ¼ 5.8 Hz), 4.76 (s, 2H, SO2CH2), 7.40e7.66 (m, 4H,
0
0
155.7 (C3), 161.8 (C2 ), 169.1 (C5 ), 128.1, 131.4, 134.5,
137.6 ppm (aromatic carbons); MS (m/z) 358.83 (Mþ ).
ꢂ

V. Padmavathi et al. / European Journal of Medicinal Chemistry 43 (2008) 917e924
923
Anal. Calcd. for C12H11ClN4O3S2 : C, 40.17; H, 3.09; N,
15.61; Found: C, 40.20; H, 3.11; N, 15.68%.
C, 38.66; H, 3.51; N, 22.54; Found: C, 38.62; H, 3.54; N,
22.59%.
5.2. Biological assays
5.1.7. General procedure for the preparation of 40-amino-
50-(4-aryl-4,5-dihydro-1H-pyrazole-3-sulfonylmethyl)-40H-
[10,20,40]triazole-30-thiol 8aec
5.2.1. Compounds
The compounds 6e8 were dissolved in DMSO at different
concentrations of 100, 200 and 800 mg/ml.
To
a solution of potassium (4-aryl-4,5-dihydro-1H-
pyrazole-3-sulfonylacetyl)-hydrazine-N0-carbodithioate 5aec
(1 mmol) in 6 ml of water, hydrazine hydrate (2 mmol) was
added and refluxed for 8e9 h. The contents of the flask
were cooled, diluted with water and acidified with 2 ml of ace-
tic acid. The separated solid was collected by filtration, dried
and recrystallized from 2-propanol.
5.2.2. Cells
Bacterial strains S. aureus, B. subtilis, E. coli, K. pneumo-
niae and fungi F. solani, C. lunata and A. niger were obtained
from NCIM, Pune, India.
5.1.7.1. 40-Amino-50-(4-phenyl-4,5-dihydro-1H-pyrazole-3-sul-
fonylmethyl)-40H-[10,20,40]triazole-30-thiol 8a. Yellow solid
(0.22 g, 65%); m.p. 218e220 ꢁC; IR (KBr): 1135, 1332
(SO2), 1568 (C]N), 2554 (SH), 3226 (NH), 3240 (NH2)
5.2.3. Antibacterial and antifungal assays
Preliminary antimicrobial activities of 6e8 compounds
were tested by Agar disc-diffusion method. Sterile filter paper
discs (6 mm diameter) moistened with the test compound
solution in DMSO of specific concentration 100 mg and
200 mg/disc were carefully placed on the agar culture plates
that had been previously inoculated separately with the micro-
organisms. The plates were incubated at 37 ꢁC and the diam-
eter of the growth inhibition zones were measured after 24 h in
case of bacteria and after 48 h in case of fungi.
cmꢀ1 1H NMR (DMSO-d6) d (ppm): 3.48 (dd, 1H, HX),
;
3.79 (dd, 1H, HM, JMX ¼ 10.4 Hz), 4.46 (dd, 1H, HA,
JAM ¼ 12.6 Hz, JAX ¼ 5.5 Hz), 4.66 (s, 2H, SO2CH2), 5.62
(br s, 2H, NH2), 7.30e7.65 (m, 5H, Ph), 10.13 (br s, 1H,
NH), 10.27 (s, 1H, SH); 13C NMR (DMSO-d6) d (ppm):
0
38.8 (C4), 44.7 (C5), 49.4 (SO2CH2), 144.6 (C3 ), 154.7 (C3),
The MICs of the compound assays were carried out using
microdilution susceptibility method. Chloramphenicol was
used as reference antibacterial agent. Ketoconazole was used
as reference antifungal agent. The test compounds, chloram-
phenicol and ketoconazole were dissolved in DMSO at con-
centration of 800 mg/ml. The twofold dilution of the solution
was prepared (400, 200, 100, ., 6.25 mg/ml). The microor-
ganism suspensions were inoculated to the corresponding
wells. The plates were incubated at 36 ꢁC for 24 and 48 h
for bacteria and fungi, respectively. The minimum inhibitory
concentrations of the compounds were recorded as the lowest
concentration of each chemical compounds in the tubes with
no turbidity (i.e. no growth) of inoculated bacteria/fungi.
0
168.5 (C5 ), 126.7, 127.8, 129.2, 132.9 (aromatic carbons);
ꢂ
MS (m/z) 338.41 (Mþ ). Anal. Calcd. for C12H14N6O2S2: C,
42.59; H, 4.17; N, 24.83; Found: C, 42.61; H, 4.13; N,
24.88%.
5.1.7.2. 40-Amino-50-[4-( p-tolyl)-4,5-dihydro-1H-pyrazole-3-
sulfonylmethyl]-40H-[10,20,40]triazole-30-thiol 8b. Yellow solid
(0.22 g, 63%); m.p. 234e236 ꢁC; IR (KBr): 1139, 1338 (SO2),
1572 (C]N), 2557 (SH), 3224 (NH), 3243 (NH2) cmꢀ1; H
1
NMR (DMSO-d6) d (ppm): 2.25 (s, 3H, Ar-CH3), 3.46 (dd,
1H, HX), 3.75 (dd, 1H, HM, JMX ¼ 10.1 Hz), 4.43 (dd, 1H,
HA, JAM ¼ 12.5 Hz, JAX ¼ 5.1 Hz), 4.63 (s, 2H, SO2CH2),
5.60 (br s, 2H, NH2), 7.28e7.58 (m, 4H, Ar), 10.11 (br s,
1H, NH), 10.25 (s, 1H, SH); 13C NMR (DMSO-d6) d (ppm):
22.9 (Ar-CH3), 38.4 (C4), 44.2 (C5), 49.1 (SO2CH2), 144.3
Acknowledgements
0
0
(C3 ), 154.5 (C3), 168.2 (C5 ), 128.3, 131.4, 136.1, 137.2 (aro-
ꢂ
matic carbons); MS (m/z) 352.44 (Mþ ). Anal. Calcd. for
The authors are thankful to DST New Delhi, India for the
financial assistance under major research project. One of the
authors P. Thriveni is thankful to CSIR, New Delhi, India
for the sanction of Senior Research Fellowship.
C13H16N6O2S2: C, 44.30; H, 4.58; N, 23.85; Found: C,
44.34; H, 4.62; N, 23.91%.
5.1.7.3. 40-Amino-50-[4-(4-chlorophenyl)-4,5-dihydro-1H-pyr-
azole-3-sulfonylmethyl]-40H-[10,20,40]triazole-30-thiol 8c. Yel-
low solid (0.26 g, 71%); m.p. 252e254 ꢁC; IR (KBr): 1142,
1343 (SO2), 1574 (C]N), 2558 (SH), 3229 (NH), 3245
References
[1] A. Katrizky, Comprehensive Heterocyclic Chemistry, vol. 6, Pergamon,
Oxford, 1984.
1
(NH2) cmꢀ1; H NMR (DMSO-d6) d (ppm): 3.51 (dd, 1H,
[2] S. Diamond, C. Sevrain, PCT Int. Appl.., WO 2003016870, 2003 Chem.
Abstr. 138 (2003) 198554.
HX), 3.81 (dd, 1H, HM, JMX ¼ 10.5 Hz), 4.49 (dd, 1H, HA,
JAM ¼ 12.7 Hz, JAX ¼ 5.4 Hz), 4.70 (s, 2H, SO2CH2), 5.66
(br s, 2H, NH2), 7.34e7.80 (m, 4H, Ar), 10.17 (br s, 1H,
NH), 10.31 (s, 1H, SH); 13C NMR (DMSO-d6) d (ppm):
[3] H. Nakao, Y. Matsuzaki, M. Tohnishi, M. Mmorimoto, S. Fujioka,
T. Takemoto, K. Mamezuka, PCT Int.Appl.., WO 2002092584, 2002
Chem Abstr. 137 (2002) 384845.
[4] K. Kariyone, H. Harada, M. Kuritha, T. Takaano, Antibiot J. 23 (1970)
131e136.
0
39.1 (C4), 44.9 (C5), 49.8 (SO2CH2), 144.8 (C3 ), 154.9 (C3),
0
168.7 (C5 ), 129.8, 132.5, 134.6, 139.1 (aromatic carbons);
[5] L.L. Lutwick, W.M. Rytel, J. Am. Med. Assoc. 241 (1979) 271e272.
[6] R.A. Fromtling, Clin. Microbiol. Rev. 1 (1988) 187e208.
ꢂ
MS (m/z) 372.86 (Mþ ). Anal. Calcd. for C12H13ClN6O2S2 :

924
V. Padmavathi et al. / European Journal of Medicinal Chemistry 43 (2008) 917e924
[7] E.F. Godefroi, J. Heeres, J. Van Cutsem, J. Med. Chem. 12 (1969)
784e791.
[13] B. Tinperciuc, A. Parvu, M. Palage, O. Oniga, D. Ghiran, Farmacia
(Bucharest) 47 (1999) 77.
[8] F.C. Odds, A.B. Abbott, J. Antimicrob. Chemother 14 (1984)
105e114.
[9] S. Shadomy, S.C. White, H.P. Yu, J. Infect. Dis. 152 (1985) 1249e1256.
[14] G. Dannahardt, W. Kiefer, G. Kramer, S. Maehrlein, U. Nowe,
B. Fiebich, Eur. J. Med. Chem. 35 (2000) 499e510.
[15] National Committee for Clinical Laboratory Standards (NCCLS)
Approved standard document M-7A, Villanova, PA, 1985.
[16] P.R. Murray, E.J. Baron, M.A. Pfaller, F.C. Tenover, R.H. Yolken, in:
G.L. Wood, J.A. Washington (Eds.), Manual of Clinical Microbiology,
American Society for Microbiology, Washington, DC, 1995.
[17] D. Bhaskar Reddy, M. Muralidhar Reddy, G.V. Subbaraju, Indian J.
Chem. 34B (1995) 816e822.
¨
˘
[10] D. Demir-Erol, U. C¸ alıxs, R. Demirdamar, N. Yulug, M. Ertan, J.Pharm.
Sci. 84 (4)(1995) 462e465.
[11] K. Naito, Y. Watanabe, S. Egusa, Jpn. J. Appl. Phys. Part I 38 (1999)
2792.
[12] B.S. Holla, R. Gonsalves, S. Shenoy, Eur. J. Med. Chem. 35 (2000)
267e271.