Synthesis and bioassay of a new class of heterocycles pyrrolyl oxadiazoles/thiadiazoles/triazoles

Article abstract of DOI:10.1016/j.ejmech.2008.04.003

A new class of heterocycles pyrrolyl thiadiazoles, pyrrolyl oxadiazoles and pyrrolyl triazoles were prepared from arylsulfonylethenesulfonylacetic acid methyl ester and tested for their antimicrobial and cytotoxic activities.

Full text of DOI:10.1016/j.ejmech.2008.04.003

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European Journal of Medicinal Chemistry 44 (2009) 2313e2321
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Laboratory note
Synthesis and bioassay of a new class of heterocycles
pyrrolyl oxadiazoles/thiadiazoles/triazoles
a
a
b
V. Padmavathi a, , A.V. Nagendra Mohan , P. Thriveni , A. Shazia
*
a Department of Chemistry, Sri Venkateswara University, Tirupati 517 502, Andhra Pradesh, India
b Department of Molecular Reproduction, Development and Genetics, Indian Institute of Science,
Bangalore 560 012, Karnataka, India
Received 10 January 2008; received in revised form 29 March 2008; accepted 8 April 2008
Available online 27 April 2008
Abstract
A new class of heterocycles pyrrolyl thiadiazoles, pyrrolyl oxadiazoles and pyrrolyl triazoles were prepared from arylsulfonylethenesulfonyl-
acetic acid methyl ester and tested for their antimicrobial and cytotoxic activities.
Ó 2008 Elsevier Masson SAS. All rights reserved.
Keywords: Pyrroles; 1,3,4-Thiadiazoles; 1,3,4-Oxadiazoles; Antimicrobial activity; Cytotoxic activity
1. Introduction
pharmacological relevance due to their anti-inflammatory
and analgesic properties [20]. Hence, it is considered worth-
while to prepare a new class of heterocycles from synthetically
vulnerable intermediate arylsulfonylethenesulfonylacetic acid
methyl ester (4).
Among different five-membered heterocyclic systems pyr-
role, oxadiazole, thiadiazole, triazole and their derivatives
have gained importance as they constitute the structural fea-
tures of many bioactive compounds. 1,3,4-Oxadiazoles are
of significant interest in medicinal chemistry in a number of
biological targets including benzodiazepine receptor agonists
[1], 5-HT receptor agonists [2], muscarinic agonists [3],
5-HT antagonists [4], human NK1 antagonists [5], antirhinovi-
ral compounds [6] and anti-inflammatory agents [7]. They
have been used as peptide mimetics due to their particular geo-
metric and electrostatic properties [8,9]. Apart from these,
1,2,3-substituted thiadiazole derivatives were associated with
diverse biological activities [10,11]. Various substituted
1,2,4-triazolo[3,4-b]-1,3,4-thiadiazoles and their dihydro
analogues possess diverse pharmacological activities such as
antimicrobial [12], antibacterial [13], antitubercular [14],
anti-inflammatory [15e17], and antifungal [18,19]. A number
of pyrrole derivatives viz., tolmetin, ketorolac, etc., were of
2. Chemistry
The compound, E-arylsulfonylethenesulfonylacetic acid
methyl ester (4) was obtained by the condensation of 1-
arylsulfonyl-2-chloroethene with mercaptoacetic acid fol-
lowed by oxidation and esterification (Scheme 1 and Table 1).
Earlier, we have studied the reactivity of phenacylsulfonylace-
tic acid methyl ester and aroylethenesulfonylacetic acid
methyl ester towards the development of heterocycles. When
phenacylsulfonylacetic acid methyl ester was treated with
hydrazine hydrate instead of the expected acid hydrazide,
1,1-dioxo-6-phenyl-1,2,4,7-tetrahydro-1l6-1,4,5-thiadiazepin-
3-one was obtained [21]. In order to get the desired heterocy-
cles, keto group in phenacylsulfonylacetic acid methyl ester
was protected by oximation. The ester functionality was
exploited for oxadiazoles, thiadiazoles and triazoles. The
deoximation of keto group was affected by b-cyclodextrin in
the presence of oxidizing agent [22]. However,
* Corresponding author. Tel.: þ91 877 2289303x303; fax: þ91 877
2249532.
E-mail address: vkpuram2001@yahoo.com (V. Padmavathi).
0223-5234/$ - see front matter Ó 2008 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2008.04.003

2314
V. Padmavathi et al. / European Journal of Medicinal Chemistry 44 (2009) 2313e2321
O
O
O
O
moiety in 4 to construct pyrazole ring. When 4 was treated
i
ii
S
S
S
S
S
CO2H
Ar
Ar
Cl
with diazomethane in the presence of Et3N at ꢀ20 to
ꢀ15 ꢁC for 48 h a solid was obtained and identified as N-
methyl-3-arylsulfonylpyrazole (6) by spectral parameters
(Scheme 2). It seems the 1-pyrazoline formed during the
course of the reaction in the presence of carbene generated
from diazomethane led to a bicyclic compound which was
ultimately aromatized by the elimination of sulfonylacetic
ester moiety (mechanism). In our interest to develop heterocy-
cles from 4, it was treated with tosylmethyl isocyanide (Tos-
MIC) in the presence of sodium hydride in a solvent mixture
of ether and DMSO. The compound obtained was identified
as (4-arylsulfonyl-1H-pyrrole-3-sulfonyl)acetic acid methyl
ester (7). The articulation of oxadiazole, thiadiazole and
triazole rings was made by the use of ester moiety in 7. The
compound 7 on reaction with hydrazine hydrate gave the cor-
responding acid hydrazide 8. The potassium dithiocarbazate
of acid hydrazide 9 was prepared from 8 on treatment with
carbon disulfide in the presence of potassium hydroxide under
ultrasonic conditions. This on refluxing in acetic acid cyclized
0-(4-arylsulfonyl-1H-pyrrole-3-sulfonylmethyl)-[10,30,40]
1
2
O
O
O
O
iii
CO2Me
Ar
S
Ar
S
CO2H
O
O
O
O
4
3
Ar = a) Ph
(i) SHCH2CO2H / NaOH / MeOH
(ii) H2O2 / AcOH
b) 4-Me.Ph
c) 4-Cl.Ph
(iii) H2SO4 / MeOH
Scheme 1.
aroylethenesulfonylacetic acid methyl ester on treatment with
hydrazine hydrate produced 1,1-dioxo-6-phenacyl-[1,4,5]thia-
diazinan-3-one
and
(3-aryl-4,5-dihydro-1H-pyrazole-5-
sulfonyl)acetic acid methyl ester instead of acid hydrazide
[23]. As such, first the olefinic moiety in the former was uti-
lized to develop pyrazole ring by 1,3-dipolar cycloaddition
methodology with diazomethane. The resultant pyrazolyl ester
was used to construct oxadiazoles, thiadiazoles and triazoles
[23]. As unexpected products were obtained in both the cases
when a molecule having two different functional groups was
treated with hydrazine hydrate, we thought of exploiting olefin
to
5
thiadiazole-20-thiol (10). Acid catalysed hydrolysis of 9 re-
sulted in 50-(4-arylsulfonyl-1H-pyrrole-3-sulfonylmethyl)-[10,30,40]
oxadiazole-20-thiol (11). Further, the compound 9 on treatment
with hydrazine hydrate produced 40-amino-50-(4-arylsulfonyl-1
Table 1
Characterization data of compounds 2e4 and 6e12
Compound
Mp (ꢁC)/(colour)
Ar
Yield (%)
Molecular formula (M.Wt)
Analysis % calcd./(found)
C
H
N
2a
43e45 (white crystals)
40e42 (white crystals)
51e53 (white solid)
Ph
72
68
76
84
85
82
86
87
85
68
64
67
69
71
74
72
70
75
82
79
81
73
69
68
67
68
71
67
70
72
C10H10O4S2 (258.31)
C11H12O4S2 (272.34)
46.50 (46.74)
48.51 (48.61)
41.03 (40.95)
41.37 (41.32)
43.41 (43.50)
36.98 (37.04)
43.41 (43.36)
45.27 (45.31)
39.00 (38.92)
54.04 (54.00)
55.91 (55.97)
46.79 (46.83)
45.47 (45.51)
47.05 (47.01)
41.33 (41.37)
41.97 (41.93)
43.69 (43.72)
38.15 (38.12)
e
3.90 (3.87)
4.44 (4.46)
3.10 (3.05)
3.47 (3.52)
3.97 (4.00)
2.79 (2.81)
3.97 (4.01)
4.43 (4.39)
3.27 (3.29)
4.53 (4.50)
5.12 (5.00)
3.53 (3.57)
3.82 (3.80)
4.23 (4.20)
3.20 (3.22)
3.82 (3.84)
4.23 (4.26)
3.20 (3.23)
e
e
e
2b
2c
4-MePh
4-ClPh
Ph
C10H9ClO4S2 (292.76)
C10H10O6S2 (290.31)
C11H12O6S2 (304.34)
e
3a
146e148 (white solid)
163e165 (white solid)
157e159 (white solid)
118e120 (white crystals)
124e126 (white crystals)
131e133 (white crystals)
78e80 (yellow solid)
66e68 (yellow solid)
87e89 (Yellow solid)
141e143 (yellow solid)
158e160 (yellow solid)
164e166 (yellow solid)
156e158 (yellow solid)
163e165 (Yellow solid)
172e174 (yellow solid)
e (white solid)
e
e
3b
3c
4-MePh
4-ClPh
Ph
C10H9ClO6S2 (324.76)
C11H12O6S2 (304.34)
C12H14O6S2 (318.37)
e
4a
e
4b
4c
4-MePh
4-ClPh
Ph
e
e
C11H11ClO6S2 (338.78)
C10H10N2O2S (222.26)
C11H12N2O2S (236.29)
C10H9ClN2O2S (256.71)
C13H13NO6S (343.38)
C14H15NO6S2 (357.4)
C13H12ClNO6S2 (377.82)
C12H13N3O5S2 (343.38)
C13H15N3O5S2 (357.41)
C12H12ClN3O5S2 (377.82)
C13H12KN3O5S4 (457.61)
C14H14KN3O5S4 (471.64)
C13H11ClKN3O5S4 (492.05)
C13H11N3O4S4 (401.5)
C14H13N3O4S4 (415.53)
C13H10ClN3O4S4 (435.95)
C13H11N3O5S3 (385.44)
C14H13N3O5S3 (399.47)
C13H10ClN3O5S3 (419.88)
C13H13N5O4S3 (399.47)
C14H15N5O4S3 (413.5)
C13H12ClN5O4S3 (433.91)
6a
12.60 (12.71)
11.86 (11.94)
10.91 (10.83)
4.08 (4.05)
3.92 (3.98)
3.71 (3.77)
12.24 (12.21)
11.76 (11.71)
11.12 (11.16)
e
6b
6c
4-MePh
4-ClPh
Ph
7a
7b
7c
4-MePh
4-ClPh
Ph
8a
8b
8c
4-MePh
4-ClPh
Ph
9a
9b
9c
e (white solid)
e (white solid)
4-MePh
4-ClPh
Ph
e
e
e
e
e
e
10a
10b
10c
11a
11b
11c
12a
12b
12c
196e198 (yellow solid)
189e191 (yellow solid)
206e208 (yellow solid)
167e169 (yellow solid)
180e182 (Yellow solid)
174e176 (yellow solid)
212e214 (yellow solid)
209e211 (yellow solid)
234e236 (yellow solid)
38.89 (38.86)
40.47 (40.51)
35.82 (35.85)
40.51 (40.47)
42.09 (42.04)
37.19 (37.22)
39.09 (39.06)
40.67 (40.65)
35.98 (36.01)
2.76 (2.75)
3.15 (3.17)
2.31 (2.29)
2.88 (2.92)
3.28 (3.30)
2.40 (2.39)
3.28 (3.26)
3.66 (3.68)
2.79 (2.80)
10.47 (10.54)
10.11 (10.20)
9.64 (9.69)
10.90 (10.97)
10.52 (10.45)
10.01 (10.05)
17.53 (17.49)
16.94 (16.98)
16.14 (16.20)
4-MePh
4-ClPh
Ph
4-MePh
4-ClPh
Ph
4-MePh
4-ClPh

V. Padmavathi et al. / European Journal of Medicinal Chemistry 44 (2009) 2313e2321
2315
O
susceptibility method [25]. Ciprofloxacin and ketoconazole
were used as control drugs.
O
O
O
O
S
S
OMe
Ar
X
N
N
H
3.2. MTT assay for cell viability
O
H
O
O
O
5
Ar
O
S
i
S
OMe
Toxicity of compounds in different cell lines in the pres-
ence of 10 and 0.2% FBS, respectively, was determined using
3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium
H
O
O
S
4
Ar
bro-
N
mide reduction assay [26,27]. The compounds were dissolved
in DMSO at 10 mM concentration and stored at ꢀ20 ꢁC. The
dilutions were made in culture medium before treatment.
Nearly 8000 cells/well were plated in 96-well plates. After
3e4 h, the compounds were added to the cells at different con-
centrations. After 72 h of incubation, 20 ml of MTT solution was
added and the cells were incubated further for 4 h. Blue forma-
zan crystals were seen at well when checked under microscope.
Media was removed and 200 ml of DMSO was added per well.
The absorbance was measured using microtiter plate reader.
Control treatments were performed with DMSO. The % viabil-
ity was then calculated as [{A590 (treated cells)ꢀbackground]/
[A590 (untreated cells)ꢀbackground}] ꢂ 100.
N
CH3
6
Ar = a) Ph
i) CH2N2 / Et3N / Et2O
b) 4-Me.Ph
c) 4-Cl.Ph
Scheme 2.
H-pyrrole-3-sulfonylmethyl)-[10,20,40]-triazole-30-thiol (12)
(Scheme 3 and Table 1).
Mechanism:
O
O
O
O
O
O
O
O
O
O
S
S
S
S
OMe
OMe
Ar
Ar
N
4. Results, discussion and conclusion
N
+
-
H
N
N
CH
2
:
C
The structures of the compounds synthesized in the present
1
work were established by spectral parameters. The H NMR
H
spectrum of 4a showed two doublets at d 7.93 and 7.41 ppm
for HA and HB. The coupling constant value J ¼ 14.7 Hz indi-
cates that it possess trans geometry. Besides, two singlets were
observed at d 4.15 and 3.78 ppm for methylene and methoxy
O
O
O
O
O
O
O
O
O
O
S
H
S
S
S
Ar
OMe
Ar
OMe
N
N
1
H
N
N
protons of carbomethoxy group. The H NMR spectrum of
H
CH
6a displayed a singlet and two doublets at d 3.94, 6.78 and
7.39 ppm which were accounted for NeCH3, C5eH and
C4eH, respectively. The mass spectrum of 6a exhibited
a molecular ion peak at m/z 222 corresponding to its molecular
formula. The 1H NMR spectrum of 7a showed two singlets at
d 6.96 and 7.09 ppm for pyrrole ring protons, C2eH and C5e
H. In addition two singlets were observed at d 3.72 and
4.21 ppm due to methoxy and methylene protons. A broad sin-
glet observed at d 10.21 ppm due to NH disappeared on deu-
teration. The 1H NMR spectrum of 8a displayed broad signals
in the regions d 9.46 and 5.10 ppm for NH and NH2 which dis-
appeared on deuteration in addition to signals due to other
protons.
3
H
O
O
O
H
S
OMe
O
O
S
Ar
N
N
CH
3
3. Biology
3.1. Antimicrobial activity
1
The H NMR spectra of 10e12 displayed a singlet in the
region d 10.18e10.28 ppm for SH besides signals due to pyr-
role ring and methylene protons. In addition to these, 12a
showed a broad singlet at d 5.42 ppm for NH2 which disap-
peared on deuteration. The structures of 10e12 were further
confirmed by 13C NMR spectra (Table 2).
The synthesized compounds were tested for their in vitro
antimicrobial activity against the Gram-positive bacteria
Staphylococcus aureus, Bacillus subtilis, the Gram-negative
bacteria Escherichia coli, Klebsiella pneumoniae and fungi
Fusarium solani, Curvularia lunata and Aspergillus niger.
The primary screening was carried out by agar disc-diffusion
method [24] using nutrient agar medium. The minimal inhib-
itory concentration for the most active compounds 10c, 12a
and 12c against the same microorganisms used in the prelim-
inary screening was carried out using microdilution
4.1. Biological results
The results on preliminary antibacterial testing of the final
compounds (10e12) are shown in Table 3. The results
revealed that in general, the inhibitory activity against the
Gram-positive bacteria was higher than that of the Gram-

2316
V. Padmavathi et al. / European Journal of Medicinal Chemistry 44 (2009) 2313e2321
O
O
O
O
O
O
H
O
S
O
O
S
i
ii
OMe
Ar
O
S
Ar
OMe
S
S
H
N
H
4
7
O
O
O
O
O
O
O
O
O
O
S
S
-
S
iii
+
NHNH2
NHNHCS K
S
Ar
Ar
N
N
H
H
8
9
iv
O
v
vi
N
N
N
N
N
N
O
O
O
O
O
O
O
O
O
O
O
S
S
S
S
S
S
SH
SH
SH
Ar
S
O
N
Ar
Ar
NH2
N
N
N
H
H
H
10
11
12
(i) TosMIC / NaH /Et2O / DMSO
(ii) N2H4.H2O / Pyridine / EtOH
(iii) CS2 / KOH / EtOH / US
Ar = a) Ph
b) 4-Me.Ph
c) 4-Cl.Ph
(iv) AcOH
(v) HCl / H2O
(vi) N2H4.H2O / H2O
Scheme 3.
negative bacteria. The compounds 10c, 12a and 12c showed
excellent activity against Gram-positive bacteria (inhibitory
zone > 28 mm) and good activity against Gram-negative bac-
teria (inhibitory zone > 22 mm). All the tested compounds
showed moderate (11aec) to high (10aec and 12aec) inhib-
itory effect towards tested fungi. The presence of chloro sub-
stituent at position 4 of arylsulfonyl group caused good
antimicrobial activity (Table 4).
lead compounds showed that all compounds tested are more
active towards fungi than bacteria. The compound pyrrole in
combination with triazole showed greater antimicrobial
activity.
5. Experimental
5.1. Chemistry
The MIC values were determined as the lowest concentra-
tion that completely inhibited visible growth of the microor-
ganisms (Table 5). The structureeantimicrobial activity
relationship of the synthesized compounds revealed that the
compounds having pyrrole in combination with oxadiazole
moiety exhibited least activity when compared with com-
pounds having pyrrole with thiadiazole and triazole moieties.
Among the substituents on the aryl group, 4-chlorophenyl
derivatives were the most active. The maximum activity was
attained with compound 12c.
The cytotoxic activity of the compounds 10a, 11a and 12a
in A549 and CCl64 cell lines in the presence of 10 and 0.2%
FBS, respectively, was determined using 3-(4,5-dimethylthia-
zole-2-yl)-2,5-diphenyltetrazolium bromide reduction assay.
The compounds were dissolved in DMSO at 10 mM concentra-
tion and stored at ꢀ20 ꢁC. The dilutions were made in culture
medium before treatment. The compounds tested did not
exhibit cytotoxic activity up to 100 mM concentration.
In conclusion, a new class of heterocycles, pyrrole in
combination with thiadiazole, oxadiazole and triazole are
developed adopting simple, elegant and well-versed methodol-
ogies from a vulnerable substrate, arylsulfonylethenesulfonyl-
acetic acid methyl ester. The in vitro antimicrobial activity of
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
acetate/hexane, 0.5:2). The IR spectra were recorded on
a Thermo Nicolet IR 200 FT-IR spectrometer as KBr pellets
and the wave numbers were given in cmꢀ1. The 1H NMR spec-
tra were recorded in CDCl3/DMSO-d6 on a Varian EM-360
spectrometer (300 MHz). The 13C NMR spectra were recorded
in CDCl3/DMSO-d6 on a Varian VXR spectrometer operating
at 75.5 MHz. All chemical shifts are reported in d (ppm) using
TMS as an internal standard. The microanalyses were per-
formed on PerkineElmer 240C elemental analyzer.
The starting compound 1-arylsulfonyl-2-chloroethene was
prepared according to literature procedure [28].
5.1.1. General procedure for the synthesis
of E-arylsulfonylethenemercapto
acetic acid 2aec
To a solution of sodium hydroxide (2 mmol) in methanol
(10 ml), mercaptoacetic acid (1 mmol) was added dropwise.
To this compound 1 (1 mmol) was added in portions and the
reaction mixture was stirred at 0 ꢁC for 3 h. The contents

V. Padmavathi et al. / European Journal of Medicinal Chemistry 44 (2009) 2313e2321
2317
Table 2
Spectral data of the compounds 2e4 and 6e12
Compound
no.
IR (KBr) cmꢀ1
1H NMR (CDCl3) d ppm
13C NMR (CDCl3) d ppm
Mass m/z
)
ꢃ
(Mþ
2a
1122, 1330 (SO2),
1704 (C]O), 3242
(OH)
3.61 (s, 2H, CH2), 7.59 (d, J ¼ 13.4 Hz, 1H, HB),
7.87 (d, J ¼ 13.4 Hz, 1H, HA), 7.38e7.79
(m, 5H, ArH), 9.84 (br s, 1H, OH)
52.2 (CH2), 135.9 (SO2CH), 142.4 (CHS),
170.2 (COOH), 128.2, 129.5, 130.2, 132.8
(aromatic carbons)
e
2b
1125, 1333 (SO2),
1710 (C]O), 3247
(OH)
2.23 (s, 3H, AreCH3), 3.57 (s, 2H, CH2), 7.62
(d, J ¼ 13.7 Hz, 1H, HB), 7.94 (d, J ¼ 13.7 Hz,
1H, HA), 7.34e7.82 (m, 4H, ArH), 9.89
(br s, 1H, OH)
22.3 (AreCH3), 51.8 (CH2), 136.4 (SO2CH),
141.6 (CHS), 169.7 (COOH), 127.4, 129.3,
130.7, 131.6 (aromatic carbons)
e
2c
3a
3b
1120, 1338 (SO2),
1708 (C]O), 3249
(OH)
3.68 (s, 2H, CH2), 7.56 (d, J ¼ 14.0 Hz, 1H, HB),
7.89 (d, J ¼ 13.8 Hz, 1H, HA), 7.51e7.84
(m, 4H, ArH), 9.82 (br s, 1H, OH)
52.9 (CH2), 135.4 (SO2CH), 142.9 (CHS),
171.0 (COOH), 128.6, 130.2, 131.6, 134.6
(aromatic carbons)
e
e
e
1118, 1334 (SO2),
1706 (C]O), 3251
(OH)
4.36 (s, 2H, SO2CH2), 7.61 (d, J ¼ 14.3 Hz, 1H,
HB), 7.84 (d, J ¼ 14.3 Hz, 1H, HA), 7.51e7.79
(m, 5H, ArH), 9.79 (br s, 1H, OH)
58.8 (eSO2CH2), 135.9 (SO2CH), 141.4
(CHSO2), 170.7 (COOH), 127.5, 128.8,
130.2, 131.4 (aromatic carbons)
1115, 1340 (SO2),
1714 (C]O), 3254
(OH)
2.26 (s, 3H, ArCH3), 4.31 (s, 2H, CH2), 7.63
(d, J ¼ 14.6 Hz, 1H, HB), 7.93 (d, J ¼ 14.6 Hz,
1H, HA), 7.37e7.85 (m, 4H, ArH), 9.83
(br s, 1H, OH)
22.6 (AreCH3), 58.4 (SO2CH2), 136.2
(SO2CH), 140.7 (CHSO2), 171.1 (COOH),
127.1, 128.3, 129.4, 130.8 (aromatic
carbons)
3c
4a
4b
1119, 1339 (SO2),
1716 (C]O), 3252
(OH)
4.37 (s, 2H, eSO2CH2), 7.68 (d, J ¼ 14.8 Hz,
1H, HB), 7.99 (d, J ¼ 14.8 Hz, 1H, HA),
7.42e7.88 (m, 4H, ArH), 9.91 (br s, 1H, OH)
3.78 (s, 3H, OCH3), 4.15 (s, 2H, eSO2CH2),
7.41 (d, J ¼ 14.7 Hz, 1H, HB), 7.93 (d,
J ¼ 14.7 Hz, 1H, HA), 7.57e7.82 (m, 5H, ArH)
2.25 (s, 3H, ArCH3), 3.74 (s, 3H, OCH3), 4.21
(s, 2H, eSO2CH2), 7.48 (d, J ¼ 14.3 Hz, 1H,
HB), 7.84 (d, J ¼ 14.3 Hz, 1H, HA), 7.42e7.75
(m, 4H, ArH)
57.9 (CH2), 136.7 (SO2CH), 142.2 (CHSO2),
172.3 (COOH), 127.8, 128.6, 131.2, 135.2
(aromatic carbons)
e
1124, 1332 (SO2),
1746 (C]O)
53.5 (OCH3), 59.0 (CH2), 137.8 (SO2CH),
143.6 (CHSO2), 167.6 (CO2CH3), 128.6,
129.8, 135.0, 137.3 (aromatic carbons)
22.6 (AreCH3), 52.4 (OCH3), 58.2
(SO2CH2), 136.9 (SO2CH), 144.3 (CHSO2),
168.5 (CO2CH3), 128.4, 130.6, 132.3, 136.4
(aromatic carbons)
304.34
318.37
1127, 1334 (SO2),
1743 (C]O)
4c
1123, 1339 (SO2),
1749 (C]O)
3.68 (s, 3H, OCH3), 4.17 (s, 2H, CH2), 7.45
(d, J ¼ 13.9 Hz, 1H, HB), 7.78 (d, J ¼ 13.9 Hz,
1H, HA), 7.49e7.78 (m, 4H, ArH)
22.1 (AreCH3), 52.9 (OCH3), 59.1
(SO2CH2), 138.2 (SO2CH), 142.9 (CHSO2),
169.7 (CO2CH3), 128.2, 130.4, 132.7, 136.8
(aromatic carbons)
338.78
6a
6b
6c
7a
1129, 1341 (SO2),
1574 (C]N)
3.94 (s, 3H, NeCH3), 6.78 (d, 1H, C5eH,
J ¼ 2.7 Hz), 7.39 (d, 1H, C4eH, J ¼ 2.7 Hz),
7.26e8.04 (m, 5H, AreH)
38.4 (NeCH3), 107. 9 (C-4), 141.1 (C-5),
151.6 (C-3), 127.7, 129.0, 131.9, 133.3
(aromatic carbons)
222.26
236.29
256.71
e
1130, 1336 (SO2),
1579 (C]N)
2.27 (s, 3H, AreCH3), 3.91 (s, 3H, NeCH3),
6.74 (d, 1H, C5eH, J ¼ 2.6 Hz), 7.36 (d, 1H,
C4eH, J ¼ 2.6 Hz), 7.20e7.89 (m, 4H, AreH)
3.98 (s, 3H, NeCH3), 6.80 (d, 1H, C5eH,
J ¼ 2.9 Hz), 7.32 (d, 1H, C4eH, J ¼ 2.9 Hz),
7.27e7.86 (m, 4H, AreH)
22.4 (AreCH3), 39.1 (NeCH3), 107.4 (C-4),
142.7 (C-5), 151.1 (C-3), 127.2, 128.6,
131.1, 133.6 (aromatic carbons)
1124, 1338 (SO2),
1582 (C]N)
39.6 (NeCH3), 108.8 (C-4), 143.2 (C-5),
152.6 (C-3), 127.6, 128.4, 131.4, 134.2
(aromatic carbons)
1122, 1334 (SO2),
1744 (C]O), 3375
(NH)
3.72 (s, 3H, OCH3), 4.21 (s, 2H, SO2eCH2),
6.96 (s, 1H, C2eH), 7.09 (s, 1H, C5eH), 10.21
(br s, 1H, NH), 7.35e7.81 (m, 5H, AreH)
53.2 (OCH3), 59.5 (SO2eCH2), 106.8 (C-3),
109.6 (C-4), 115.4 (C-2), 118.3 (C-5), 168.2
(CO2CH3), 128.2, 129.4, 132.4, 133.3
(aromatic carbons)
7b
7c
8a
8b
1132, 1323 (SO2),
1743 (C]O), 3368
(NH)
2.31 (s, 3H, AreCH3), 3.65 (s, 3H, OCH3), 4.18
(s, 2H, SO2eCH2), 6.86 (s, 1H, C2eH), 7.02
(s, 1H, C5eH), 10.15 (br s, 1H, NH), 7.31e7.78
(m, 4H, AreH)
22.7 (AreCH3), 52.7 (OCH3), 59.2
(SO2eCH2), 105.6 (C-3), 108.9 (C-4), 115.8
(C-2), 117.1 (C-5), 168.5 (CO2CH3), 128.8,
129.6, 131.2, 132.1 (aromatic carbons)
53.5 (OCH3), 58.7 (SO2eCH2), 104.8 (C-3),
109.1 (C-4), 115.2 (C-2), 117.9 (C-5), 169.3
(CO2CH3), 128.4, 129.2, 131.4, 133.8
(aromatic carbons)
e
e
e
e
1120, 1332 (SO2),
1749 (C]O), 3378
(NH)
3.74 (s, 3H, OCH3), 4.25 (s, 2H, SO2eCH2),
6.88 (s, 1H, C2eH), 7.11 (s, 1H, C5eH), 10.26
(br s, 1H, NH), 7.24e7.84 (m, 4H, AreH)
1132, 1331 (SO2),
1646 (C]O), 3219
(NH2), 3381 (NH)
4.24 (s, 2H, SO2eCH2), 5.10 (br s, 2H, NH2),
6.90 (s, 1H, C2eH), 7.06 (s, 1H, C5eH), 9.46
(br s, 1H, NH), 10.12 (br s, 1H, NH), 7.29e7.74
(m, 5H, AreH)
59.2 (SO2eCH2), 103.6 (C-3), 108.2 (C-4),
114.9 (C-2), 117.2 (C-5), 167.4 (CO), 128.1,
129.4, 131.3, 132.8 (aromatic carbons)
1128, 1329 (SO2),
1642 (C]O), 3221
(NH2), 3374 (NH)
2.35 (s, 3H, AreCH3), 4.20 (s, 2H, SO2eCH2),
5.04 (br s, 2H, NH2), 6.84 (s, 1H, C2eH), 7.13
(s, 1H, C5eH), 9.20 (br s, 1H, NH), 10.06
(br s, 1H, NH), 7.22e7.76 (m, 4H, AreH)
22.4 (AreCH3), 58.7 (SO2eCH2), 103.9
(C-3), 108.4 (C-4), 115.2 (C-2), 116.8 (C-5),
167.7 (CO), 127.8, 128.9, 130.6, 131.4
(aromatic carbons)
(continued on next page)

2318
V. Padmavathi et al. / European Journal of Medicinal Chemistry 44 (2009) 2313e2321
Table 2 (continued)
Compound
no.
IR (KBr) cmꢀ1
1H NMR (CDCl3) d ppm
13C NMR (CDCl3) d ppm
Mass m/z
)
ꢃ
(Mþ
8c
1135, 1333 (SO2),
1650 (C]O), 3227
(NH2), 3389 (NH)
4.22 (s, 2H, SO2eCH2), 5.14 (br s, 2H, NH2),
6.87 (s, 1H, C2eH), 7.08 (s, 1H, C5eH), 9.27
(br s, 1H, NH), 10.09 (br s, 1H, NH), 7.27e7.81
(m, 4H, AreH)
59.5 (SO2eCH2), 103.2 (C-3), 108.9 (C-4),
115.8 (C-2), 117.2 (C-5), 167.9 (CO), 128.2,
131.3, 132.6, 133.9 (aromatic carbons)
e
9a
1125, 1307 (SO2),
1038 (C]S), 1690
(CO), 3436 (NH)
1120, 1310 (SO2),
1042 (C]S), 1682
(CO), 3436 (NH)
1128, 1314 (SO2),
1043 (C]S), 1692
(CO), 3442 (NH)
1125, 1330 (SO2),
1628 (C]N), 2551
(SH), 3368 (NH)
e
e
e
e
e
e
e
9b
9c
e
e
10a
4.24 (s, 2H, SO2eCH2), 6.91 (s, 1H, C2eH),
7.12 (s, 1H, C5eH), 10.18 (br s, 1H, NH), 10.21
(s, 1H, SH), 7.22e7.73 (m, 5H, AreH)
58.1 (SO2eCH2), 102.8 (C-3), 108.2 (C-4),
115.2 (C-2), 116.6 (C-5), 163.7 (C-20), 168.2
(C-50), 128.9, 129.3, 131.8, 132.8 (aromatic
carbons)
401.5
10b
10c
11a
11b
11c
12a
12b
12c
1132, 1337 (SO2),
1632 (C]N), 2556
(SH), 3352 (NH)
2.29 (s, 3H, AreCH3), 4.23 (s, 2H, SO2eCH2),
6.97 (s, 1H, C2eH), 7.08 (s, 1H, C5eH), 10.18
(br s, 1H, NH), 10.23 (s, 1H, SH), 7.24e7.78
(m, 4H, AreH)
22.8 (AreCH3), 58.4 (SO2eCH2), 102.4
(C-3), 109.4 (C-4), 114.9 (C-2), 118.2 (C-5),
163.4 (C-20), 168.6 (C-50), 128.4, 129.7,
131.3, 131.6 (aromatic carbons)
415.53
435.95
385.44
399.47
419.88
399.47
413.5
1137, 1331 (SO2),
1639 (C]N), 2552
(SH), 3364 (NH)
4.26 (s, 2H, SO2eCH2), 6.91 (s, 1H, C2eH),
7.13 (s, 1H, C5eH), 10.06 (br s, 1H, NH), 10.27
(s, 1H, SH), 7.28e7.84 (m, 4H, AreH)
58.9 (SO2eCH2), 101.9 (C-3), 109.7 (C-4),
115.4 (C-2), 119.4 (C-5), 163.2 (C-20), 168.9
(C-50), 128.1, 129.9, 131.7, 133.4 (aromatic
carbons)
1131, 1338 (SO2),
1621 (C]N), 3347
(NH)
4.27 (s, 2H, SO2eCH2), 6.87 (s, 1H, C2eH),
7.09 (s, 1H, C5eH), 10.02 (br s, 1H, NH), 10.24
(s, 1H, SH), 7.27e7.81 (m, 5H, AreH)
58.8 (SO2eCH2), 102.4 (C-3), 110.3 (C-4),
114.9 (C-2), 119.5 (C-5), 161.2 (C-20), 168.6
(C-50), 128.3, 129.6, 131.7, 132.2 (aromatic
carbons)
1127, 1330 (SO2),
1633 (C]N), 2634
(SH), 3338 (NH)
2.26 (s, 3H, AreCH3), 4.24 (s, 2H, SO2eCH2),
6.84 (s, 1H, C2eH), 7.12 (s, 1H, C5eH), 10.07
(br s, 1H, NH), 10.18 (s, 1H, SH), 7.23e7.77 (m,
4H, AreH)
22.3 (AreCH3), 58.4 (SO2eCH2), 102.8
(C-3), 109.6 (C-4), 114.3 (C-2), 119.1 (C-5),
160.8 (C-20), 168.2 (C-50), 128.4, 129.3,
130.9, 131.7 (aromatic carbons)
1134, 1337 (SO2),
1622 (C]N), 2631
(SH), 3332 (NH)
4.30 (s, 2H, SO2eCH2), 6.89 (s, 1H, C2eH),
7.16 (s, 1H, C5eH), 10.08 (br s, 1H, NH), 10.21
(s, 1H, SH), 7.25e7.84 (m, 4H, AreH)
58.8 (SO2eCH2), 103.3 (C-3), 109.9 (C-4),
114.8 (C-2), 119.7 (C-5), 160.6 (C-20), 168.5
(C-50), 128.7, 129.8, 130.4, 132.3 (aromatic
carbons)
1126, 1334 (SO2),
1632 (C]N), 2571
(SH), 3256 (NH2),
3328 (NH)
4.23 (s, 2H, SO2eCH2), 6.85 (s, 1H, C2eH),
7.05 (s, 1H, C5eH), 5.42 (s, 2H, NH2), 10.03
(br s, 1H, NH), 10.19 (s, 1H, SH), 7.24e7.79
(m, 5H, AreH)
2.25 (s, 3H, AreCH3), 4.26 (s, 2H, SO2eCH2),
6.82 (s, 1H, C2eH), 7.10 (s, 1H, C5eH), 5.36
(s, 2H, NH2), 9.98 (br s, 1H, NH), 10.25
(s, 1H, SH), 7.32e7.83 (m, 4H, AreH)
4.21 (s, 2H, SO2eCH2), 6.47 (s, 1H, C2eH),
6.72 (s, 1H, C5eH), 5.45 (s, 2H, NH2), 10.06
(br s, 1H, NH), 10.28 (s, 1H, SH), 7.29e7.79
(m, 4H, AreH)
58.2 (SO2eCH2), 102.6 (C-3), 109.4 (C-4),
114.5 (C-2), 119.5 (C-5), 143.8 (C-30), 167.3
(C-50), 128.1, 129.4, 131.2, 132.7 (aromatic
carbons)
1133, 1332 (SO2),
1637 (C]N), 2564
(SH), 3261 (NH2),
3321 (NH)
22.6 (AreCH3), 58.2 (SO2eCH2), 102.4
(C-3), 109.2 (C-4), 114.7 (C-2), 119.2 (C-5),
143.2 (C-30), 167.9 (C-50), 128.7, 129.9,
131.7, 132.5 (aromatic carbons)
1139, 1341 (SO2),
1643 (C]N), 2579
(SH), 3252 (NH2),
3334 (NH)
58.4 (SO2eCH2), 102.9 (C-3), 109.7 (C-4),
114.8 (C-2), 119.8 (C-5), 144.6 (C-30), 168.4
(C-50), 128.4, 129.5, 131.1, 132.3
(aromatic carbons)
433.91
were poured onto crushed ice and neutralized with conc. HCl.
The aqueous layer was extracted with ethyl acetate and the
solvent was removed under reduced pressure. The resultant
solid was recrystallized from water.
36 h. Then the reaction mixture was poured onto crushed
ice. The solid separated was filtered, dried and recrystallized
from water.
5.1.2. General procedure for the synthesis
of E-arylsulfonylethenesulfonylacetic
acid 3aec
5.1.3. General procedure for the synthesis
of E-arylsulfonylethenesulfonylacetic
acid methyl ester 4aec
The compound 2 (1 mmol) was subjected to oxidation with
30% hydrogen peroxide (4.37 ml) in glacial acetic acid (7 ml).
The contents were stirred at 0 ꢁC for 4 h and kept aside for
To a solution of compound 3 (1 mmol) in methanol
(10 ml), sulfuric acid (2 ml) was added and refluxed for
6e8 h. The contents were cooled and poured onto crushed

V. Padmavathi et al. / European Journal of Medicinal Chemistry 44 (2009) 2313e2321
2319
Table 3
Antibacterial activity of compounds 10e12
Table 4
Antifungal activity of compounds 10e12
Compound
Concentration Zone of inhibition (mm)
(mg/disc)
Compound
Concentration (mg/disc) Zone of inhibition (mm)
Gram-positive
bacteria
Gram-negative
bacteria
F. solani C. lunata A. niger
10a
10b
10c
11a
11b
11c
12a
12b
12c
100
200
25
27
28
29
24
29
S. aureus B. subtilis E. coli K. pneumoniae
10a
10b
10c
11a
11b
11c
12a
12b
12c
100
200
18
20
21
23
16
20
17
21
100
200
25
27
22
24
21
24
100
200
16
17
17
19
18
20
16
19
100
200
26
31
23
25
26
28
100
200
25
30
28
32
22
27
23
28
100
200
18
20
17
21
15
20
100
200
12
15
11
13
14
17
13
16
100
200
16
19
15
18
17
21
100
200
11
14
12
16
11
14
11
13
100
200
18
21
17
20
15
18
100
200
14
17
14
18
10
12
11
13
100
200
33
36
34
36
30
34
100
200
28
32
31
35
22
26
21
22
100
200
29
33
28
35
34
36
100
200
24
28
25
27
20
24
21
23
100
200
35
40
38
41
34
37
100
200
32
35
34
38
23
25
26
28
Ketoconazole 100
200
38
42
41
44
36
39
Ciprofloxacin 100
200
34
38
36
42
40
45
37
42
5.1.6. General procedure for the synthesis of
(4-arylsulfonyl-1H-pyrrole-3-sulfonyl)-acetic
acid hydrazide 8aec
ice. The solid separated was filtered, dried and recrystallized
from methanol.
To a solution of 7aec (1 mmol) in absolute ethanol (5 ml),
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, dried and recrystallized from ethanol.
5.1.4. General procedure for the synthesis
of N-methyl-3-arylsulfonylpyrazole 6aec
5.1.7. General procedure for the preparation of potassium
(4-arylsulfonyl-1H-pyrrole-3-sulfonylacetyl)-hydrazine-
N0-carbodithioate 9aec
To a mixture of potassium hydroxide (2 mmol) and 8aec
(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.
To a cooled solution of arylsulfonylethenesulfonylacetic
acid methyl ester 4aec (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 (hexane/ethyl acetate,
4:1).
5.1.8. General procedure for the synthesis of 50-
(4-arylsulfonyl-1H-pyrrole-3-sulfonylmethyl)-
[10,30,40]thiadiazole-20-thiol 10aec
A mixture of 9aec (1 mmol) and acetic acid (4 ml) was re-
fluxed for 24 h. The contents of the flask were cooled and
poured onto crushed ice. The solid obtained was filtered, dried
and recrystallized from 2-propanol.
5.1.5. General procedure for the synthesis
of (4-arylsulfonyl-1H-pyrrole-3-sulfonyl)-
acetic acid methyl ester 7aec
An equimolar mixture (1 mmol) of TosMIC and 4aec in
Et2O/DMSO (10 ml, 2:1) was added dropwise to a stirred sus-
pension of NaH (50 mg) in dry Et2O (10 ml) at room temper-
ature. Then stirring was continued for 24 h and diluted with
water. It was extracted with Et2O and the organic layer was
dried over anhydrous Na2SO4. Removal of the solvent gave
crude product which was purified by filtration through a col-
umn of silica gel (BDH, 60e120 mesh with hexane/EtOAc,
4:1) as eluent.
5.1.9. General procedure for the synthesis of 50-
(4-arylsulfonyl-1H-pyrrole-3-sulfonylmethyl)-
[10,30,40]oxadiazole-20-thiol 11aec
The compound 9aec (1 mmol) was dissolved in 6 ml of water
and acidifiedwithconc. HCl (1e2 ml). The regenerated solid was
filtered, dried and purified by recrystallization from 2-propanol.

2320
V. Padmavathi et al. / European Journal of Medicinal Chemistry 44 (2009) 2313e2321
Table 5
The minimal inhibitory concentration (MIC, mg/ml) of compounds 10c, 12a and 12c
Compound
Minimal inhibitory concentration (MIC, mg/ml)
S. aureus
B. subtilis
E. coli
K. pneumoniae
F. solani
C. lunata
A. niger
10c
12a
100
25
200
100
50
200
100
50
200
100
50
100
100
50
100
100
12.5
e
200
100
25
12c
Ciprofloxacin
Ketoconazole
12.5
6.25
e
6.25
e
6.25
e
6.25
e
e
12.5
e
6.25
6.25
5.1.10. General procedure for the preparation of 40-
amino-50-(4-arylsulfonyl-1H-pyrrole-3-sulfonylmethyl)-
[10,20,40]triazole-30-thiol 12aec
Acknowledgements
The authors are thankful to DST New Delhi, India for the
financial assistance under major research project and to Prof.
P. Kondaiah, Department of Molecular Reproduction, Devel-
opment and Genetics, Indian Institute of Science, Bangalore
for providing necessary facilities to carryout the cytotoxic
activity of the compounds.
To a solution of 9aec (1 mmol) in 6 ml of water, hydrazine
hydrate (2 mmol) was added and refluxed for 8e9 h. The con-
tents of the flask were cooled, diluted with water and acidified
with acetic acid (2 ml). The separated solid was filtered, dried
and recrystallized from 2-propanol.
References
5.2. Biological assays
[1] W.R. Tully, C.R. Gardner, R.J. Gillespie, R. Westwood, J. Med. Chem.
34 (1991) 2060.
5.2.1. Compounds
The compounds 10e12 were dissolved in DMSO at
different concentrations of 100, 200 and 800 mg/ml.
[2] C. Chen, C.H. Senanayake, T.J. Bill, R.D. Larsen, T.R. Veshoeven,
P.J. Reider, J. Org. Chem. 59 (1994) 3738.
[3] J. Saunders, M. Cassidy, S.B. Freedman, E.A. Harley, L.L. Iversen,
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(1991) 140.
5.2.2. Cells
Bacterial strains S. aureus, B. subtilis, E. coli, K. pneumonie
and fungi F. solani, C. lunata and A. niger were obtained from
NCIM, Pune, India.
[5] T. Ladduwahetty, R. Baker, M.A. Cascieri, M.S. Chambers, K. Haworth,
L.E. Keown, D.E. Maclntyre, J.M. Metzer, S. Owen, W. Rycroft,
S. Sadowski, E.M. Seward, S.L. Shepheard, C.J. Swain, F.D. Tattersall,
A.P. Watt, D.W. Williamson, R.J. Hargreaves, J. Med. Chem. 39
(1996) 2907.
5.2.3. Antibacterial and antifungal assays
[6] G.D. Diana, D.L. Volkots, T.J. Nitz, T.R. Baily, M.A. Long, N. Vesico,
A. Aldous, D.C. Pevear, F.J. Dukto, J. Med. Chem. 37 (1994) 2421.
[7] F.A. Omar, N.M. Mahfouz, M.A. Rahman, Eur. J. Med. Chem. 31 (1996)
819.
Preliminary antimicrobial activities of 10e12 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 and 200 mg/
disc were carefully placed on the agar culture plates that had
been previously inoculated separately with the microorgan-
isms. The plates were incubated at 37 ꢁC and the diameter
of the growth inhibition zones were measured after 24 h in
case of bacteria and after 48 h in case of fungi.
[8] S. Borg, G. Estenne-Bouhtou, K. Luthman, I. Csoregh, W. Hesselink,
U. Hacksell, J. Org. Chem. 60 (1995) 3112.
[9] S. Borg, R. Vollinga, M. Labarre, K. Payza, L. Terenius, K. Luthman, J.
Med. Chem. 42 (1999) 4331.
[10] S.K. Srivastava, R.B. Pathak, S.C. Bahel, J. Indian Chem. Soc. 66 (1989)
210.
[11] A.J. Srivastava, S. Swarup, B.L. Chowdhuri, J. Indian Chem. Soc. 68
(1991) 103.
The MICs of the compound assays were carried out using
microdilution susceptibility method. Ciprofloxacin was used
as reference antibacterial agent. Ketoconazole was used as ref-
erence antifungal agent. The test compounds, ciprofloxacin
and ketoconazole were dissolved in DMSO at concentration
of 800 mg/ml. The twofold dilution of the solution was pre-
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and fungi, respectively. The minimum inhibitory concentra-
tions of the compounds were recorded as the lowest concentra-
tion of each chemical compounds in the tubes with no
turbidity (i.e. no growth) of inoculated bacteria/fungi.
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