Synthesis and biological evaluation of some 4-functionalized-pyrazoles as antimicrobial agents

Article abstract of DOI:10.1016/j.ejmech.2011.01.060

1,3-Diaryl-4-formylpyrazoles 8 bearing benzenesulfonamide moiety at position-1 were synthesized as important intermediates following Vilsmeier-Haack strategy. Aldehyde moiety of 4-formylpyrazole was then converted into carboxylic acid 9, cyano 10 and carbothioamide 11 using established procedures. Out of these 4-functionalized pyrazoles, pyrazole-4-carboxylic acids 9 and carbothioamides 11 were evaluated for their in vitro antibacterial activity against four pathogenic bacterial strains namely, Staphylococcus aureus, Bacillus subtilis (Gram-positive), Escherichia coli, Pseudomonas aeruginosa (Gram-negative), and in vitro antifungal activity against two pathogenic fungal strains namely, Aspergillus niger and Aspergillus flavus. Three tested compounds, 9e, 11b and 11f exhibited moderate antibacterial activity against Gram-positive bacteria and 9g showed moderate antifungal activity against the tested fungi. However, none of the compounds showed any activity against Gram-negative bacteria.

Full text of DOI:10.1016/j.ejmech.2011.01.060

European Journal of Medicinal Chemistry 46 (2011) 1425e1432
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Short communication
Synthesis and biological evaluation of some 4-functionalized-pyrazoles
as antimicrobial agents
,
a
a
b
b
Pawan K. Sharma a , Navneet Chandak , Pawan Kumar , Chetan Sharma , Kamal R. Aneja
*
a Department of Chemistry, Kurukshetra University, Kurukshetra 136 119, India
b Department of Microbiology, Kurukshetra University, Kurukshetra 136 119, India
a r t i c l e i n f o
a b s t r a c t
Article history:
1,3-Diaryl-4-formylpyrazoles 8 bearing benzenesulfonamide moiety at position-1 were synthesized as
important intermediates following VilsmeiereHaack strategy. Aldehyde moiety of 4-formylpyrazole was
then converted into carboxylic acid 9, cyano 10 and carbothioamide 11 using established procedures. Out
of these 4-functionalized pyrazoles, pyrazole-4-carboxylic acids 9 and carbothioamides 11 were evalu-
ated for their in vitro antibacterial activity against four pathogenic bacterial strains namely, Staphylo-
coccus aureus, Bacillus subtilis (Gram-positive), Escherichia coli, Pseudomonas aeruginosa (Gram-negative),
and in vitro antifungal activity against two pathogenic fungal strains namely, Aspergillus niger and
Aspergillus flavus. Three tested compounds, 9e, 11b and 11f exhibited moderate antibacterial activity
against Gram-positive bacteria and 9g showed moderate antifungal activity against the tested fungi.
However, none of the compounds showed any activity against Gram-negative bacteria.
Received 10 September 2010
Received in revised form
6 January 2011
Accepted 26 January 2011
Available online 3 February 2011
Keywords:
4-Functionalizedpyrazoles
Carboxylic acids
Carbothioamides
Antibacterial activity
Antifungal activity
Benzenesulfonamide
Ó 2011 Elsevier Masson SAS. All rights reserved.
1. Introduction
difference between 1 and 3, a direct comparison of the antimicro-
bial potential of 1 and 3 was possible which revealed that the
Increasing resistance of microorganisms to currently available
antimicrobial drugs is the major cause of morbidity and mortality
throughout the world. Thus development of novel antimicrobial
drugs is still in demand. Pyrazoles represent a key motif in
heterocyclic chemistry and occupy a prime place in medicinal and
pesticide chemistry due to their capability to exhibit a wide range
of bioactivities such as antimicrobial [1e7], anticancer [8], anti-
inflammatory [9e12], antidepressant [13,14], anticonvulsant
[15,16], antipyretic [17], selective enzyme inhibitory activities [18],
etc. Amongst a large array of medicinally important pyrazole
derivatives, 4-functionalized pyrazoles occupy a unique position
and their evaluation as antimicrobial agents has attracted much
attention in the past [7,19e24]. Pyrazoles with various functional
groups at position-4 such as cyano or oxime (1) [7], aldehyde or
carboxylate (2) [19], etc., have been known to show good antimi-
crobial properties. Recently, Bekhit et al. [25] reported that
1,3-diaryl-4-functionalizedpyrazoles (3) bearing a benzenesulfona-
mide moiety at position-1 possess antimicrobial as well as anti-
inflammatory activities. Thus the presence of an additional
sulfonamide group at position-4 of the phenyl ring being the only
presence of a sulfonamide group increases the activity against
Gram-negative bacteria Escherichia coli especially in case of 4-oxi-
mepyrazole derivatives while retaining the activity against Gram-
positive bacteria.
O2N
H2NO2S
NO2
N
N
N
N
N N
aryl
alkyl/carboxylate
aryl
CHNOH/CN
COOC2H5/CHO
CHNOH/CN
1
2
3
Presence of carboxylic acid [26e29] and carbothioamide
[30e34] functionalities in a number of bioactive molecules has
attracted the attention of chemists towards these moieties in the
recent past. Motivated by these findings, we set out to synthesize
some novel 4-functionalized pyrazoles bearing benzenesulfona-
mide moiety at position-1 and a carboxylic acid or carbothioamide
moiety at position-4 for their evaluation as antibacterial and anti-
fungal agents.
* Corresponding author Tel.: þ91 9416457355; fax: þ91 1744 238277.
E-mail address: talk2pawan@gmail.com (P.K. Sharma).
0223-5234/$ e see front matter Ó 2011 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2011.01.060

1426
P.K. Sharma et al. / European Journal of Medicinal Chemistry 46 (2011) 1425e1432
2. Results and discussion
in aqueous pyridine [36,37] to afford carboxylic acids 9. On the
other hand, oxidation of 8 using ammoniacal solution of iodine [38]
in THF afforded 4-cyanopyrazoles 10. This transformation
presumably proceeded with an intermediate N-iodoaldimine,
which eliminated an HI molecule in ammonia to afford 4-cyano-
pyrazoles 10. While we achieved the synthesis of eight 4-cyano-
pyrazoles 10 from 4-formylpyrazoles 8 using a single step protocol,
a recent report described the synthesis of five of these 4-cyano-
pyrazoles (10a, 10b, 10e, 10f and 10g) by a two step protocol
involving the conversion of aldehyde to the oxime followed by
dehydration of oxime using POCl3 [25]. The single step protocol
adopted by us seems to be advantageous over two step protocol in
terms of using milder and greener materials (I2, NH3 as compared to
POCl3) as well as in terms of yields which are generally higher. 4-
Cyanopyrazoles 10 were converted into the corresponding carbo-
thioamides 11 by passing H2S gas through their solution in pyridine
2.1. Chemistry
The synthetic route used to synthesize the target pyrazole-4-
carboxylic acids 9 and carbothioamides 11 is outlined in Scheme 1.
The treatment of aqueous solution of 4-hydrazinobenzenesulfo-
namide hydrochloride 4 with sodium acetate generated free
hydrazine which on condensation with various substituted meth-
ylketones 5 in aqueous ethanol afforded corresponding hydrazones
6. Subsequent reactions of hydrazones 6 under VilsmeiereHaack
[35] conditions afforded 4-formylpyrazoles
7 with protected
sulfonamide group. The deprotection of sulfonamide group to
afford aldehyde 8 with free SO2NH2 group was accomplished under
basic conditions using methanolic solution of NaOH with THF as co-
solvent. It is pertinent to mention here that just after we finished
the synthesis of 4-formylpyrazoles 8 in our lab in the beginning of
2009, an article by Bekhit et al. [25] appeared revealing the
synthesis and characterization of some of the 4-formylpyrazoles
(8a, 8b, 8e, 8f and 8g) synthesized by us. However, in our group,
deprotection of sulfonamide group was achieved under basic
conditions while their group reported acidic conditions for the
same. Oxidation of aldehyde 8 underwent smoothly using KMnO4
in the presence of triethylamine [39,40]. Spectral data (1H NMR, 13
C
NMR, IR and mass) of the newly synthesized compounds were in
full agreement with the proposed structures. In general, pyrazole-
4-carboxylic acids 9aeh were characterized by a broad exchange-
able singlet in the range of d
12.62e12.93 due to COOH group in 1H
NMR spectra and a broad absorption band from 2500 to 3150 cmꢀ1
due to OeH stretching of COOH along with a sharp band at
CH3
CH3
C
POCl3
55-60 °C
DMF,
CH3COONa
.
R
H2NO2S
NHN
H2NO2S
NHNH2
C
HCl
+
R
EtOH/H2O, reflux
O
4
5
6
N
HC NO2S
H2NO2S
H2NO2S
N N
N N
N N
NaOH/MeOH/THF
rt
KMnO4
Pyridine/H2O, rt
R
R
R
CHO
CHO
COOH
7
8
9
rt
I2/NH3/THF
H2NO2S
H2NO2S
N N
N N
H2S/Et3N
Pyridine
R
R
CN
CSNH2
10
11
H
CH3
OCH3
Cl
Br
NO2
F
R =
S
a
b
c
d
e
f
g
h
Scheme 1. Synthesis of 1,3-diaryl-4-functionalized pyrazoles.

P.K. Sharma et al. / European Journal of Medicinal Chemistry 46 (2011) 1425e1432
1427
Table 1
Table 2
In vitro antibacterial activity and MIC of compounds 9 and 11.
In vitro antifungal activity of compounds 9 and 11 through poisoned food method.
Compounda
Diameter of growth of inhibition zoneb
(mm)
Minimum
inhibitory
concentration
Compounda
Mycelial growth inhibition (%)
A. niger
A. flavus
9a
9b
9c
9d
9e
9f
9g
9h
50.0
46.6
44.4
52.5
45.5
51.1
61.1
57.7
50.0
44.4
55.5
44.4
50.0
44.4
61.1
75.3
55.5
51.1
44.4
48.8
44.4
45.5
57.7
55.5
53.3
51.1
57.7
61.1
52.5
51.1
55.5
74.6
(MIC) (
mg/mL)
S. aureus B. subtilis E. coli P. aeruginosa S. aureus B. subtilis
9a
9b
9c
9d
9e
9f
9g
9h
11a
11b
11c
11d
11e
11f
11h
15.3
14.6
15.6
15.0
18.6
15.6
14.6
18.6
15.3
21.6
16.6
17.6
18.3
21.6
20.3
16.6
17.3
17.0
18.6
21.6
14.3
15.0
15.6
15.0
16.3
15.6
15.3
14.6
18.3
17.6
26.3
e
e
e
e
128
>128
128
128
64
128
>128
64
128
32
128
64
128
64
64
64
32
>128
128
128
128
128
128
128
>128
64
e
e
e
e
e
e
e
e
11a
11b
11c
11d
11e
11f
11h
Fluconazole
e
e
e
e
e
e
e
e
e
e
e
e
e
e
64
32
64
5
e
e
a
Concentration 4.0 mg/mL.
e
e
64
Ciprofloxacin 27.6
25.3
25.0
5
e No activity.
a
Concentration 4.0 mg/mL.
Values, including diameter of the well (8 mm), are means of three replicates.
antibacterial activity against Staphylococcus aureus (MTCC 96) and
Bacillus subtilis (MTCC 121) representing Gram-positive bacteria,
and E. coli (MTCC 1652) and Pseudomonas aeruginosa (MTCC 741)
representing Gram-negative bacteria (Table 1) by agar well diffu-
sion method [41] using ciprofloxacin as the reference drug. The
results were recorded for each tested compound as the average
diameter of inhibition zones of bacterial growth surrounding the
well in millimetres. The Minimum Inhibitory Concentration (MIC)
measurements were performed using a macrodilution tube method
[42,43] (Table 1).
Results revealed that in general, all the tested compounds
possessed moderate to good antibacterial activity against Gram-
positive bacteria (S. aureus, B. subtilis). However, none of them was
found to be effective against any of the Gram-negative bacteria
(E. coli, P. aeruginosa). On the basis of zone of inhibition against the
test bacterium, compounds 11b and 11f were found to be the most
effective against S. aureus showing the maximum zone of inhibition
of 21.6 mm and compound 9e against B. subtilis producing 21.6 mm
zone of inhibition (Table 1) as compared with the standard drug
ciprofloxacin which showed the zone of inhibition 27.6 mm against
b
1690e1705 cmꢀ1 corresponding to C]O stretch in FT-IR. 4-Cya-
nopyrazoles 10aeh were characterized by disappearance of
a singlet due to CHO group in 1H NMR spectra and a sharp band
resonating at 2230e2236 cmꢀ1 due to C^N stretch in FT-IR. Pyr-
azole-4-carbothiamides 11aef and 11h were characterized by two
exchangeable singlets in the range of d 9.84e10.03 and d 9.25e9.56
corresponding to NH and SH protons in 1H NMR. 1-[4-(Amino-
sulfonyl)phenyl]-3-(4-nitrophenyl)-1H-pyrazole-4-carbothioa-
mide 11g could not be synthesized by the same method inspite of
repeated attempts. We are at loss to explain this exceptional
behavior in case of nitro substituent.
2.2. Biological evaluation
2.2.1. In vitro antibacterial activity
All the newly synthesized carboxylic acids (9aeh) and carbo-
thioamides (11aef and 11h) were evaluated for their in vitro
Fig. 1. Comparison of antifungal activity of newly synthesized compounds and standard antifungal drug against test microorganisms.

1428
P.K. Sharma et al. / European Journal of Medicinal Chemistry 46 (2011) 1425e1432
S. aureus and 26.3 mm against B. subtilis. Besides 11b and 11f,
compounds 9e, 9h, 11e and 11h showed moderate antibacterial
activity against S. aureus with zone of inhibition >18.0 mm while
compounds 9d and 11f showed moderate antibacterial activity
against B. subtilis with zone of inhibition >18.0 mm. However, in
terms of MIC, none of the compounds was found to possess
appreciable antibacterial activity. Amongst all the compounds, the
300/400 MHz and 75.5/100 MHz respectively using tetramethylsi-
lane (TMS) as internal standard. Chemical shifts are expressed in
d
,
ppm. Mass spectra (DART-MS) were recorded on a JEOL-AccuTOF
JMS-T100LC Mass spectrometer having a DART (Direct Analysis in
Real Time) source in ESþ mode. The purity of the compounds was
checked by 1H NMR and thin layer chromatography (TLC) on silica
gel plates using a mixture of petroleum ether and ethyl acetate as
eluent. Iodine or UV lamp was used as a visualizing agent. Abbre-
viations ‘s’ for singlet, ‘m’ for multiplet, ‘ex’ for exchangeable proton
are used for NMR assignments; ‘s’ for strong, ‘m’ for medium for IR
and ‘br’ for broad in NMR as well as IR assignments. ‘d’ stands for
decomposition in melting point data.
MIC ranged between 32 (11b, 11f, 9e) and 128 mg/mL against Gram-
positive bacteria (Table 1). A comparison between the two series of
compounds (9 and 11) indicates that in general, 4-carbothioamide
derivatives (11) exhibit better activity against S. aureus while
a reverse trend is observed against B. subtilis. Within the individual
series, no correlation between the antibacterial activity with
respect to the substituent on phenyl ring is observed. However, in
general, compounds containing a halogen substituent showed
better antibacterial activity than the compounds with other
substituents. A comparative study with corresponding 4-cyano
derivatives (3) [25] revealed that replacement of cyano group with
carboxylic acid moiety (9) or carbothioamide moiety (11) resulted
in complete loss of activity against Gram-negative bacteria and
a decreased activity against Gram-positive bacteria. It is an estab-
lished fact that Gram-negative bacteria are hard to target owing to
their cell wall structure, however, it seems from the comparison
that increased hydrophilicity due to the replacement of a cyano
group with carboxylic acid moiety or carbothioamide moiety is
detrimental to activity against Gram-negative bacteria.
4.1. General procedure for the synthesis of hydrazones, 6aeh
To a solution of 4-hydrazinobenzenesulfonamide hydrochloride
(4, 5.3 mmol) in water (15 mL) was added anhydrous sodium
acetate (5.3 mmol) whereupon a solid separated out which was
dissolved by the addition of ethanol (20 mL). Subsequently, an
appropriate methylketone (5, 5.3 mmol) was added and the
resulting reaction mixture was refluxed for 1 h. On cooling, a solid
separated out which was filtered, dried and crystallized from
ethanol to afford hydrazones 6.
Hydrazones 6a, 6b, 6ee6g were identified by the comparison of
their melting point and spectral data with those reported in liter-
ature [25].
2.2.2. In vitro antifungal activity
4.1.1. 4-{2-[1-(4-Methoxyphenyl)ethylidene]hydrazino}
benzenesulfonamide (6c)
Carboxylic acids 9 and carbothioamides 11 were also evaluated
for their in vitro antifungal activity against two fungal strains,
Aspergillus niger (MTCC 282) and Aspergillus flavus (MTCC 871) by
poisoned food method [44]. Fluconazole was used as the reference
drug and the results were recorded as the percentage inhibition of
mycelial growth. When compared with reference drug (75.3% and
74.6% inhibition against A. niger and A. flavus respectively), it was
noted that compounds 9g, 9h, 11c and 11h showed moderate
antifungal activity with ꢁ55% inhibition of mycelial growth against
A. niger and compounds 9a, 9g, 9h, 11c, 11d and 11h showed ꢁ55%
inhibition of mycelial growth against A. flavus (Table 2). Compar-
ison of antifungal activity of newly synthesized compounds with
standard drug fluconazole against both fungal strains in terms of %
mycelial growth inhibition is shown in Fig. 1.
Yield 86%; m.p. 230e232 ꢂC; IR (KBr, cmꢀ1): 3386, 3267 and
3078 (m, NeH stretch), 1605 (s, C]N stretch), 1512 (s, NeH bend),
1311 and 1142 (s, SO2 stretch); 1H NMR (CDCl3/DMSO-d6,
400 MHz):
d
8.99 (s, ex, 1H, NH), 7.75 (d, 2H, J ¼ 8.8 Hz, Ar), 7.71 (d,
2H, J ¼ 8.8 Hz, Ar), 7.28 (d, 2H, J ¼ 8.8 Hz, Ar), 6.90 (d, 2H, J ¼ 8.8 Hz,
Ar), 6.53 (s, ex, 2H, SO2NH2), 3.83 (s, 3H, OCH3), 2.27 (s, 3H, CH3).
4.1.2. 4-{2-[1-(4-Fluorophenyl)ethylidene]hydrazino}
benzenesulfonamide (6d)
Yield 89%; m.p. 210e212 ꢂC; IR (KBr, cmꢀ1): 3357, 3251 and 3110
(m, NeH stretch), 1604 (s, C]N stretch), 1512 (s, NeH bend), 1319
and 1149 (s, SO2 stretch); 1H NMR (CDCl3/DMSO-d6, 300 MHz):
d
9.70 (s, ex, 1H, NH), 7.86e7.90 (m, 2H, Ar), 7.65 (d, 2H, J ¼ 8.7 Hz,
Ar), 7.31 (d, 2H, J ¼ 8.7 Hz, Ar), 7.23 (t, 2H, J ¼ 8.7 Hz, Ar), 7.08 (s, ex,
3. Conclusions
2H, SO2NH2), 2.28 (s, 3H, CH3).
In the present study, some novel 1,3-diaryl-4-functionali-
zedpyrazoles bearing benzenesulfonamide moiety at position-1
and an aldehyde, carboxylic acid, cyano and carbothioamide func-
tionality at position-4 were synthesized. Newly synthesized pyr-
azole-4-carboxylic acids 9 and carbothioamides 11 were screened
for their in vitro antibacterial activity and antifungal activity. Out of
the tested compounds, 9e, 11b and 11f exhibited moderate anti-
bacterial activity against Gram-positive bacteria and 9g showed
moderate antifungal activity against the tested fungi. However,
none of the newly synthesized compounds was found to be supe-
rior over the reference drugs.
4.1.3. 4-{2-[1-(2-Thienyl)ethylidene]hydrazino}
benzenesulfonamide (6h)
Yield 82%; m.p. 230e232 ꢂC; IR (KBr, cmꢀ1): 3325, 3240 and
3109 (m, NeH stretch), 1597 (s, C]N stretch), 1512 (s, NeH bend),
1319 and 1149 (s, SO2 stretch); 1H NMR (DMSO-d6, 300 MHz):
d 9.73
(s, ex, 1H, NH), 7.66 (d, 2H, J ¼ 8.7 Hz, Ar), 7.47 (d, 1H, J ¼ 4.8 Hz,
thienyl), 7.32 (d, 1H, J ¼ 3.0 Hz, thienyl), 7.23 (d, 2H, J ¼ 8.7 Hz, Ar),
7.04e7.06 (m, 3H, SO2NH2, thienyl), 2.31 (s, 3H, CH3).
4.2. General procedure for the synthesis of sulfonamide protected-
4-formylpyrazoles, 7aeh
4. Experimental protocols
To a cold, stirred solution of dimethylformamide (30 mL) and
phosphorous oxychloride (83.58 mmol) was added hydrazone
(6, 20.24 mmol) following the literature procedure [35]. The
reaction mixture was stirred at 55e60 ꢂC for 5 h, cooled to room
temperature, poured into ice cold water and neutralized with
saturated aqueous sodium bicarbonate solution whereupon a solid
separated out that was filtered, washed with excess of cold water,
dried and crystallized from acetic acid to afford aldehydes 7.
Melting points were determined in open glass capillaries in an
electrical melting point apparatus and are uncorrected. The
infrared (IR) spectra were recorded on Shimadzu-21 FT-IR or Per-
kineElmer IR Spectrophotometer using the KBr pellet technique. 1H
NMR and 13C NMR spectra were recorded either in pure DMSO-d6
or in CDCl3/DMSO-d6 mixture on Bruker NMR spectrometers at

P.K. Sharma et al. / European Journal of Medicinal Chemistry 46 (2011) 1425e1432
1429
Aldehydes 7a, 7b, 7eeg were identified by the comparison of
4.3.2. 4-[3-(4-Fluorophenyl)-4-formyl-1H-pyrazol-1-yl]
their melting point and spectral data with those reported in liter-
ature [25].
benzenesulfonamide (8d)
Yield 78%; m.p. 192e193 ꢂC; IR (KBr, cmꢀ1): 3435 and 3327 (m,
NeH stretch), 2930 (m, aldehyde, CeH stretch), 1671 (s, C]O
stretch), 1597 (s, C]N stretch), 1327 and 1165 (s, SO2 stretch); 1H
4.2.1. N-[(Dimethylamino)methylidene]-4-[4-formyl-3-(4-
methoxyphenyl)-1H-pyrazol-1-yl]-benzenesulfonamide (7c)
Yield 88%; m.p. 162e163 ꢂC; IR (KBr, cmꢀ1): 2930 (m, aldehyde,
CeH stretch), 1684 (s, C]O stretch), 1630 (s, C]N stretch), 1339
NMR (DMSO-d6, 300 MHz):
d 10.03 (s, 1H, CHO), 9.10 (s, 1H, pyr-
azole C5eH), 8.08 (d, 2H, J ¼ 8.7 Hz, Ar), 8.03 (d, 2H, J ¼ 8.7 Hz, Ar),
7.94e7.98 (m, 2H, Ar), 7.22 (t, 2H, J ¼ 8.7 Hz, Ar), 7.17 (s, ex, 2H,
and 1147 (s, SO2 stretch); 1H NMR (DMSO-d6, 300 MHz):
d
9.86
SO2NH2); 13C NMR (DMSO-d6, 75.5 MHz):
d 184.9 (CHO), 163.2 (d,
(s, 1H, CHO), 8.80 (s, 1H, pyrazole C5eH), 8.10 (s, 1H, CH]N),
7.92e7.96 (m, 4H, Ar), 7.75 (d, 2H, J ¼ 8.7 Hz, Ar), 6.94 (d, 2H,
J ¼ 8.7 Hz, Ar), 3.80 (s, 3H, OCH3), 3.18 (s, 3H, NeCH3), 3.02 (s, 3H,
1JCF ¼ 249.1 Hz), 152.3, 143.3, 141.0, 136.5, 131.4, 131.3 (d,
3JCF ¼ 8.3 Hz), 127.96, 122.91, 127.8, 122.9, 119.8, 115.9 (d,
2JCF ¼ 22.6 Hz).
NeCH3); 13C NMR (DMSO-d6, 75.5 MHz):
d 184.6 (CHO),160.1,159.9,
152.8, 141.6, 140.6, 135.6, 130.0, 127.6, 123.3, 122.4, 119.3, 113.9, 55.2
(OCH3), 40.9 (NCH3), 35.1 (NCH3).
4.3.3. 4-[4-Formyl-3-(2-thienyl)-1H-pyrazol-1-yl]
benzenesulfonamide (8h)
Yield 80%, m.p. 187e188 ꢂC; IR (KBr, cmꢀ1): 3302 and 3124 (m,
NeH stretch), 2929 (m, aldehyde, CeH stretch), 1674 (s, C]O
stretch), 1597 (s, C]N stretch), 1335 and 1165 (s, SO2 stretch); 1H
4.2.2. N-[(Dimethylamino)methylidene]-4-[3-(4-fluorophenyl)-4-
formyl-1H-pyrazol-1-yl]-benzenesulfonamide (7d)
Yield 87%; m.p. 188e189 ꢂC; IR (KBr, cmꢀ1): 2928 (m, aldehyde,
CeH stretch), 1684 (s, C]O stretch), 1623 (s, C]N stretch), 1340
NMR (DMSO-d6, 300 MHz): d 10.06 (s, 1H, CHO), 9.47 (s, 1H, pyr-
azole C5-H), 7.99e8.15 (m, 5H, Ar, thienyl), 7.77 (d, 1H, J ¼ 4.8 Hz,
and 1143 (s, SO2 stretch); 1H NMR (DMSO-d6, 300 MHz):
d 10.06
thienyl), 7.51 (s, ex, 2H, SO2NH2), 7.20e7.23 (m, 1H, thienyl); 13C
(s, 1H, CHO), 8.61 (s, 1H, pyrazole C5eH), 8.19 (s, 1H, CH]N), 8.06
(d, 2H, J ¼ 8.7 Hz, Ar), 7.91 (d, 2H, J ¼ 8.7 Hz, Ar), 7.85e7.88 (m, 2H,
Ar), 7.22 (t, 2H, J ¼ 8.7 Hz, Ar), 3.18 (s, 3H, NeCH3), 3.07 (s, 3H,
NMR (DMSO-d6, 75.5 MHz): d 184.6 (CHO), 147.4, 143.3, 140.8, 137.4,
133.4, 129.8, 128.6, 128.4, 127.9, 122.3, 119.7.
NeCH3); 13C NMR (DMSO-d6, 75.5 MHz):
d 184.5 (CHO), 162.8 (d,
3
1JCF ¼ 241.6 Hz), 159.1, 151.9, 141.5, 136.1, 130.9 (d, JCF ¼ 8.3 Hz),
4.4. General procedure for conversion of 4-formylpyrazoles into
respective pyrazole-4-carboxylic acids, 9aeh
2
127.7, 127.5, 122.5, 119.4, 115.5 (d, JCF ¼ 21.8 Hz), 41.0 (NCH3), 35.1
(NCH3).
To a cold, stirred solution of appropriate 4-formylpyrazole (8,
2 mmol) in aqueous pyridine (20 mL, 1:1 v/v) was added potas-
sium permanganate (2 mmol) in small portions maintaining the
temperature below 20 ꢂC. The mixture was stirred till the violet
color disappeared whereupon aqueous NaOH solution (30 mL, 5%
w/v) was added and reaction mixture was further stirred for half
an hour. Solid thus formed was filtered and to the filtrate was
added cold dilute hydrochloric acid with vigorous stirring till
precipitates were obtained. The precipitates were filtered, washed
with excess of cold water, dried and crystallized from ethanol to
afford acids 9.
4.2.3. N-[(Dimethylamino)methylidene]-4-[4-formyl-3-(2-thienyl)-
1H-pyrazol-1-yl]benzene-sulfonamide (7h)
Yield 84%; m.p. 143e144 ꢂC; IR (KBr, cmꢀ1): 2932 (m, aldehyde,
CeH stretch), 1682 (s, C]O stretch), 1628 (s, C]N stretch), 1335
and 1142 (s, SO2 stretch); 1H NMR (DMSO-d6, 300 MHz):
d 10.06
(s, 1H, CHO), 9.43 (s, 1H, pyrazole C5eH), 8.24 (s, 1H, CH]N),
8.07e8.13(m, 3H, Ar, thienyl), 7.94 (d, 2H, J ¼ 8.7 Hz, Ar), 7.60 (d, 1H,
J ¼ 4.8 Hz, thienyl), 7.14e7.17 (m, 1H, thienyl), 3.17 (s, 3H, NeCH3),
2.94 (s, 3H, NeCH3); 13C NMR (DMSO-d6, 75.5 MHz):
d 184.6 (CHO),
160.3, 147.4 142.3, 140.7, 137.5, 133.5, 129.8, 128.6, 128.4, 128.2,
122.3, 119.8, 41.4 (NCH3), 35.5 (NCH3).
4.4.1. 1-[4-(Aminosulfonyl)phenyl]-3-phenyl-1H-pyrazole-4-
carboxylic acid (9a)
4.3. General procedure for the synthesis of 4-formylpyrazoles, 8aeh
Yield 65%; m.p. 262 ꢂC (d); IR (KBr, cmꢀ1): 3325 and 3232 (m,
NeH stretch), 2550e3100 (br m, OeH stretch), 1674 (s, C]O
stretch), 1597 (s, C]N stretch), 1535 (s, NeH bend), 1342 and
To a stirred solution of NaOH (23.56 mmol) in methanol (20 mL)
was added N-protected formylpyrazole (7, 7.85 mmol) followed by
THF (60 mL) to get a clear homogeneous solution. Subsequently
reaction mixture was stirred for 14 h, whereupon it was poured
into ice cold water and neutralized with dilute hydrochloric acid.
Solid separated out which was filtered, washed with excess of cold
water, dried and crystallized from ethanol to afford aldehydes 8.
Aldehydes 8a, 8b, 8eeg were identified by the comparison of
their melting point and spectral data with those reported in liter-
ature [25].
1157 (s, SO2 stretch); 1H NMR (DMSO-d6, 400 MHz):
d 12.68 (br s,
ex, 1H, COOH), 9.20 (s, 1H, pyrazole C5eH), 8.20 (d, 2H, J ¼ 8.4 Hz,
Ar), 7.97 (d, 2H, J ¼ 8.4 Hz, Ar), 7.84 (d, 2H, J ¼ 8.4 Hz, Ar), 7.46 (m,
5H, SO2NH2, Ar); 13C NMR (DMSO-d6, 100 MHz):
d 163.5, 153.3,
142.3, 140.8, 134.2, 131.7, 129.1, 129.0, 128.6, 127.8, 127.2, 119.0,
114.6; DART MS m/z 344.11 (M þ H)þ, C16H13N3O4SHþ calcd.
344.07.
4.4.2. 1-[4-(Aminosulfonyl)phenyl]-3-(4-methylphenyl)-1H-
pyrazole-4-carboxylic acid (9b)
4.3.1. 4-[4-Formyl-3-(4-methoxyphenyl)-1H-pyrazol-1-yl]
benzenesulfonamide (8c)
Yield 75%; m.p. 258 ꢂC (d); IR (KBr, cmꢀ1): 3356 and 3232 (m,
NeH stretch), 2650e3150 (br m, OeH stretch), 1705 (s, C]O
stretch), 1597 (s, C]N stretch), 1528 (s, NeH bend), 1342 and 1157
Yield 86%; m.p. 213e214 ꢂC; IR (KBr, cmꢀ1): 3325 and 3240 (m,
NeH stretch), 2939 (m, aldehyde, CeH stretch), 1666 (s, C]O
stretch), 1597 (s, C]N stretch), 1327 and 1165 (s, SO2 stretch); 1H
(s, SO2 stretch); 1H NMR (DMSO-d6, 400 MHz):
d 12.65 (br s, ex, 1H,
NMR (DMSO-d6, 300 MHz):
d
10.02 (s, 1H, CHO), 9.05 (s, 1H, pyr-
COOH), 9.17 (s, 1H, pyrazole C5eH), 8.18 (d, 2H, J ¼ 8.4 Hz, Ar), 7.98
(d, 2H, J ¼ 8.4 Hz, Ar), 7.74 (d, 2H, J ¼ 8.0 Hz, Ar), 7.47 (s, ex, 2H,
SO2NH2), 7.26 (d, 2H, J ¼ 8.0 Hz, Ar), 2.36 (s, 3H, CH3); 13C NMR
azole C5-H), 8.09 (d, 2H, J ¼ 8.7 Hz, Ar), 8.03 (d, 2H, J ¼ 8.7 Hz, Ar),
7.87 (d, 2H, J ¼ 8.7 Hz, Ar), 7.29 (s, ex, 2H, SO2NH2), 7.01 (d, 2H,
J ¼ 8.7 Hz, Ar), 3.85 (s, 3H, OCH3); 13C NMR (DMSO-d6, 75.5 MHz):
(DMSO-d6, 100 MHz): d 163.6, 153.4, 142.3, 140.8, 138.1, 134.1, 129.0,
d
185.1 (CHO), 160.6, 153.3, 143.1, 141.1, 136.0, 130.5, 127.8, 122.9,
128.9, 128.4, 127.3, 119.0, 114.5, 20.9 (CH3); DART MS m/z 358.11
119.7, 114.4, 55.7 (OCH3).
(M þ H)þ, C17H15N3O4SHþ calcd. 358.09.

1430
P.K. Sharma et al. / European Journal of Medicinal Chemistry 46 (2011) 1425e1432
4.4.3. 1-[4-(Aminosulfonyl)phenyl]-3-(4-methoxyphenyl)-1H-
pyrazole-4-carboxylic acid (9c)
4.4.8. 1-[4-(Aminosulfonyl)phenyl]-3-(2-thienyl)-1H-pyrazole-4-
carboxylic acid (9h)
Yield 80%; m.p. 265 ꢂC (d); IR (KBr, cmꢀ1): 3256 (m, NeH
stretch), 2500e3150 (br m, OeH stretch), 1697 (s, C]O stretch),
1597 (s, C]N stretch), 1528 (s, NeH bend), 1342 and 1157 (s, SO2
Yield 70%; m.p. 240 ꢂC (d); IR (KBr, cmꢀ1): 3248 (m, NeH stretch),
2550e3150 (br m, OeH stretch),1705 (s, C]O stretch),1597 (s, C]N
stretch),1528 (s, NeH bend),1335 and 1165 (s, SO2 stretch); 1H NMR
stretch); 1H NMR (DMSO-d6, 400 MHz):
d
12.63 (br s, ex,1H, COOH),
(DMSO-d6, 400 MHz): d 12.88 (br s, ex, 1H, COOH), 9.20 (s, 1H, pyr-
9.16 (s, 1H, pyrazole C5eH), 8.18 (d, 2H, J ¼ 8.4 Hz, Ar), 7.96 (d, 2H,
J ¼ 8.4 Hz, Ar), 7.82 (d, 2H, J ¼ 8.0 Hz, Ar), 7.46 (s, ex, 2H, SO2NH2),
7.01 (d, 2H, J ¼ 8.0 Hz, Ar), 3.81 (s, 3H, OCH3); 13C NMR (DMSO-d6,
azole C5-H), 8.14e8.21 (m, 3H, Ar, thienyl), 7.98 (d, 2H, J ¼ 8.4 Hz, Ar),
7.62 (d,1H, J ¼ 5.2 Hz, thienyl), 7.47 (s, ex, 2H, SO2NH2), 7.16e7.18 (m,
1H, thienyl); 13C NMR (DMSO-d6, 100 MHz):
d 163.5, 147.4, 142.4,
100 MHz):
d
163.7,159.6,153.1,142.2, 140.8,134.1,130.4, 127.2,124.1,
140.5,134.7,133.4,129.4,127.6,127.4,127.3,119.0,113.6; DART MS m/
118.9, 114.3, 113.2, 55.1 (OCH3); DART MS m/z 374.12 (M þ H)þ,
z 350.05 (M þ H)þ, C14H11N3O4S2Hþ calcd. 350.03.
C17H15N3O5SHþ calcd. 374.08.
4.5. General procedure for conversion of 4-formylpyrazoles into
respective 4-cyanopyrazoles, 10aeh
4.4.4. 1-[4-(Aminosulfonyl)phenyl]-3-(4-fluorophenyl)-1H-
pyrazole-4-carboxylic acid (9d)
Yield 85%; m.p. 266 ꢂC (d); IR (KBr, cmꢀ1): 3371 and 3240 (m,
NeH stretch), 2500e3150 (br m, OeH stretch), 1697 (s, C]O
stretch), 1597 (s, C]N stretch), 1535 (s, NeH bend), 1342 and 1157
To
a stirred solution of appropriate 4-formylpyrazole (8,
1 mmol) in THF (6 mL) was added aqueous NH3 (30%, 8 mL) fol-
lowed by I2 (1.2 mmol). Reaction mixture was stirred at room
temperature until dark violet/brown solution became colorless
whereupon it was poured into aqueous Na2S2O3 solution (25 mL,
5% w/v). The precipitates so obtained were filtered, washed with
excess of cold water, dried and crystallized from ethanol to afford
cyanopyrazoles 10.
4-Cyanopyrazoles 10a, 10b, 10eeg were identified by the
comparison of their melting point and spectral data with those
reported in literature [25].
(s, SO2 stretch); 1H NMR (DMSO-d6, 400 MHz):
d 12.74 (br s, ex, 1H,
COOH), 9.20 (s, 1H, pyrazole C5eH), 8.19 (d, 2H, J ¼ 8.0 Hz, Ar),
7.90e7.98 (m, 4H, Ar), 7.47 (s, ex, 2H, SO2NH2), 7.27e7.31 (m, 2H,
Ar); 13C NMR (DMSO-d6, 100 MHz):
d
163.5, 162.4 (d,
3
1JCF ¼ 244.3 Hz), 152.4, 142.4, 140.7, 134.3, 131.3 (d, JCF ¼ 8.7 Hz),
2
128.24, 128.21, 127.2, 119.1, 114.7 (d, JCF ¼ 21.1 Hz); DART MS m/z
362.10 (M þ H)þ, C16H13FN3O4SHþ calcd. 362.06.
4.4.5. 1-[4-(Aminosulfonyl)phenyl]-3-(4-chlorophenyl)-1H-
pyrazole-4-carboxylic acid (9e)
4.5.1. 4-[4-Cyano-3-(4-methoxyphenyl)-1H-pyrazol-1-yl]
benzenesulfonamide (10c)
Yield 78%; m.p. 261 ꢂC (d); IR (KBr, cmꢀ1): 3364 and 3263 (m,
NeH stretch), 2500e3150 (br m, OeH stretch), 1697 (s, C]O
stretch), 1597 (s, C]N stretch), 1535 (s, NeH bend), 1335 and 1157
Yield 96%; m.p. 222e224 ꢂC; IR (KBr, cmꢀ1): 3364 and 3271 (m,
NeH stretch), 2230 (s, C^N stretch), 1605 (s, C]N stretch), 1535 (s,
NeH bend), 1336 and 1163 (s, SO2 stretch); 1H NMR (DMSO-d6,
(s, SO2 stretch); 1H NMR (DMSO-d6, 400 MHz):
d 12.77 (br s, ex, 1H,
300 MHz):
d
9.51 (s, 1H, pyrazole C5-H), 8.14 (d, 2H, J ¼ 8.7 Hz, Ar),
COOH), 9.21 (s, 1H, pyrazole C5eH), 8.19 (d, 2H, J ¼ 7.2 Hz, Ar), 7.97
(d, 2H, J ¼ 7.2 Hz, Ar), 7.89 (d, 2H, J ¼ 7.6 Hz, Ar), 7.52 (d, 2H,
J ¼ 7.6 Hz, Ar), 7.47 (s, ex, 2H, SO2NH2); 13C NMR (DMSO-d6,
8.01 (d, 2H, J ¼ 8.7 Hz, Ar), 7.94 (d, 2H, J ¼ 8.7 Hz, Ar), 7.51 (s, ex, 2H,
SO2NH2), 7.14 (d, 2H, J ¼ 8.7 Hz, Ar), 3.84 (s, 3H, OCH3); 13C NMR
(DMSO-d6, 75.5 MHz): d 161.0,153.4, 143.4, 140.8, 137.2,128.4, 127.8,
100 MHz):
d 163.5, 152.1, 142.4, 140.7, 134.4, 133.5, 130.9, 130.8,
122.7, 119.8, 115.0, 114.7, 91.3 (C^N), 55.8 (OCH3).
130.6, 127.9, 127.29, 127.25, 119.1, 119.0, 114.6; DART MS m/z 378.06
(M þ H)þ, C16H13ClN3O4SHþ calcd. 378.03.
4.5.2. 4-[4-Cyano-3-(4-fluorophenyl)-1H-pyrazol-1-yl]
benzenesulfonamide (10d)
Yield 96%; m.p. 232e234 ꢂC; IR (KBr, cmꢀ1): 3356 and 3262 (m,
NeH stretch), 2235 (s, C^N stretch), 1597 (s, C]N stretch), 1528 (s,
NeH bend), 1339 and 1161 (s, SO2 stretch); 1H NMR (DMSO-d6,
4.4.6. 1-[4-(Aminosulfonyl)phenyl]-3-(4-bromophenyl)-1H-
pyrazole-4-carboxylic acid (9f)
Yield 63%; m.p. 258 ꢂC (d); IR (KBr, cmꢀ1): 3364 and 3263 (m,
NeH stretch), 2500e3150 (br m, O-H stretch), 1690 (s, C]O
stretch), 1597 (s, C]N stretch), 1535 (s, NeH bend), 1335 and 1157
300 MHz):
d
9.54 (s, 1H, pyrazole C5-H), 8.14 (d, 2H, J ¼ 7.8 Hz, Ar),
8.01e8.03 (m, 4H, Ar), 7.52 (s, ex, 2H, SO2NH2), 7.43 (t, 2H,
(s, SO2 stretch); 1H NMR (DMSO-d6, 400 MHz):
d 12.73 (br s, ex, 1H,
J ¼ 8.1 Hz, Ar); 13C NMR (DMSO-d6, 75.5 MHz):
d 163.4 (d,
1JCF ¼ 248.3 Hz), 152.7, 143.3, 140.7, 137.0, 129.2 (d, JCF ¼ 9.0 Hz),
3
COOH), 9.20 (s, 1H, pyrazole C5-H), 8.19 (d, 2H, J ¼ 8.4 Hz, Ar), 7.98
(d, 2H, J ¼ 8.4 Hz, Ar), 7.83 (d, 2H, J ¼ 8.0 Hz, Ar), 7.66 (d, 2H,
J ¼ 8.0 Hz, Ar), 7.47 (s, ex, 2H, SO2NH2); 13C NMR (DMSO-d6,
127.8, 126.6, 119.9, 116.6 (d, 2JCF ¼ 21.9 Hz), 114.3, 91.7 (C^N).
100 MHz):
d 163.6, 152.2, 142.4, 140.75, 140.71, 134.3, 131.1, 131.0,
4.5.3. 4-[4-Cyano-3-(2-thienyl)-1H-pyrazol-1-yl]
130.8, 130.6, 127.3, 127.2, 122.2, 119.1, 114.8; DART MS m/z 422.03
benzenesulfonamide (10h)
(M þ H)þ, C16H13BrN3O4SHþ calcd. 421.98.
Yield 98%; m.p. 216e220 ꢂC; IR (KBr, cmꢀ1): 3296 and 3126 (m,
NeH stretch), 2236 (s, C^N stretch), 1596 (s, C]N stretch), 1531 (s,
NeH bend), 1335 and 1164 (s, SO2 stretch); 1H NMR (DMSO-d6,
4.4.7. 1-[4-(Aminosulfonyl)phenyl]-3-(4-nitrophenyl)-1H-
pyrazole-4-carboxylic acid (9g)
300 MHz):
d
9.52 (s, 1H, pyrazole C5eH), 8.09 (d, 2H, J ¼ 8.7 Hz, Ar),
Yield 64%; m.p. 263 ꢂC (d); IR (KBr, cmꢀ1): 3356 and 3263 (m,
NeH stretch), 2500e3150 (br m, OeH stretch), 1705 (s, C]O
stretch), 1597 (s, C]N stretch), 1535 (s, NeH bend), 1342 and 1157
8.01 (d, 2H, J ¼ 8.7 Hz, Ar), 7.76e7.78 (m, 2H, thienyl), 7.52 (s, ex, 2H,
SO2NH2), 7.24e7.27 (m, 1H, thienyl); 13C NMR (DMSO-d6,
75.5 MHz):
d 148.9, 143.6, 140.5, 137.2, 132.11, 129.0, 128.8, 127.9,
(s, SO2 stretch); 1H NMR (DMSO-d6, 400 MHz):
d
12.93 (br s, ex, 1H,
127.4, 119.9, 114.1, 91.1 (C^N).
COOH), 9.27 (s, 1H, pyrazole C5eH), 8.31 (d, 2H, J ¼ 8.4 Hz, Ar), 8.15
(d, 2H, J ¼ 8.0 Hz, Ar), 7.99 (d, 2H, J ¼ 8.4 Hz, Ar), 7.91 (d, 2H,
J ¼ 8.0 Hz, Ar), 7.49 (s, ex, 2H, SO2NH2); 13C NMR (DMSO-d6,
4.6. General procedure for conversion of 4-cyanopyrazoles into
respective pyrazole-4-carbothioamides, 11aef and g
100 MHz):
d 163.3, 151.2, 147.4, 142.7, 140.6, 138.2, 134.7, 130.3,
127.3, 123.0, 119.3, 115.2; DART MS m/z 389.09 (M þ H)þ,
To an ice cold solution of appropriate 4-cyanopyrazole (10,
2 mmol) in pyridine (20 mL) was added triethylamine (5 mL)
C16H12N4O6SHþ calcd. 389.06.

P.K. Sharma et al. / European Journal of Medicinal Chemistry 46 (2011) 1425e1432
1431
whereupon H2S gas was passed through the solution for 10 h with
occasional stirring. Color of the solution changed first from yellow
to green and finally to dark brown indicating the reaction
progression. Reaction mixture was kept as such for overnight
whereupon it was poured into ice cold water (150 mL) and
neutralized with cold dilute hydrochloric acid with vigorous stir-
ring till precipitates were obtained. The resulting precipitates were
filtered, washed with excess of cold water, dried and crystallized
from ethanol to afford carbothioamides 11.
stretch), 1551 (s, NeH bend), 1342 and 1157 (s, SO2 stretch); 1H
NMR (DMSO-d6, 300 MHz): 9.88 (s, ex, 1H, NH/SH), 9.37 (s, ex, 1H,
d
NH/SH), 8.91 (s, 1H, pyrazole C5eH), 8.13 (d, 2H, J ¼ 8.4 Hz, Ar), 7.96
(d, 2H, J ¼ 8.4 Hz, Ar), 7.73 (d, 2H, J ¼ 7.8 Hz, Ar), 7.53 (d, 2H,
J ¼ 7.8 Hz, Ar), 7.46 (s, ex, 2H, SO2NH2); 13C NMR (DMSO-d6,
75.5 MHz):
d 194.1, 149.3, 142.5, 141.3, 133.6, 130.2, 129.9, 128.8,
127.8, 126.3, 119.0; DART MS m/z 393.06 (M þ H)þ,
C16H13ClN4O2S2Hþ calcd. 393.03.
4.6.6. 1-[4-(Aminosulfonyl)phenyl]-3-(4-bromophenyl)-1H-
pyrazole-4-carbothioamide (11f)
4.6.1. 1-[4-(Aminosulfonyl)phenyl]-3-phenyl-1H-pyrazole-4-
carbothioamide (11a)
Yield 85%; m.p. 211e213 ꢂC; IR (KBr, cmꢀ1): 3564, 3441, 3348
and 3171 (m, NeH stretch), 1643 (s, C]N stretch), 1597 (s, C]N
stretch),1551 (s, NeH bend),1335 and 1157 (s, SO2 stretch); 1H NMR
Yield 68%; m.p. 210e212 ꢂC; IR (KBr, cmꢀ1): 3441, 3302, 3225 and
3101 (m, NeH stretch), 1651 (s, C]N stretch), 1597 (s, C]N stretch),
1551 (s, NeH bend), 1319 and 1157 (s, SO2 stretch); 1H NMR (DMSO-
(DMSO-d6, 300 MHz):
d 9.87 (s, ex, 1H, NH/SH), 9.36 (s, ex, 1H, NH/
d6, 300 MHz):
d
9.85 (s, ex,1H, NH/SH), 9.29 (s, ex,1H, NH/SH), 8.89 (s,
SH), 8.91 (s, 1H, pyrazole C5eH), 8.13 (d, 2H, J ¼ 8.7 Hz, Ar), 7.97 (d,
1H, pyrazole C5eH), 8.11 (d, 2H, J ¼ 8.4 Hz, Ar), 7.96 (d, 2H, J ¼ 8.4 Hz,
2H, J ¼ 8.7 Hz, Ar), 7.66e7.68 (m, 4H, Ar), 7.46 (s, ex, 2H, SO2NH2);
Ar), 7.45e7.72 (m, 7H, SO2NH2, Ar); 13C NMR (DMSO-d6, 75.5 MHz):
13C NMR (DMSO-d6, 75.5 MHz):
d 193.8, 148.9, 142.5, 141.3, 131.7,
d
194.2, 149.7, 141.4, 132.2, 129.8, 128.9, 128.7, 128.4, 127.8, 126.4,
131.4, 130.5, 129.9, 127.8, 126.3, 122.3, 119.0; DART MS m/z 437.01
118.9; DART MS m/z 359.08 (M þ H)þ, C16H14N4O2S2Hþ calcd. 359.07.
(M þ H)þ, C16H13BrN4O2S2Hþ calcd. 436.98.
4.6.2. 1-[4-(Aminosulfonyl)phenyl]-3-(4-methylphenyl)-1H-
pyrazole-4-carbothioamide (11b)
4.6.7. 1-[4-(Aminosulfonyl)phenyl]-3-(2-thienyl)-1H-pyrazole-4-
carbothioamide (11h)
Yield 80%; m.p. 222e225 ꢂC; IR (KBr, cmꢀ1): 3310, 3232 and
3101 (m, NeH stretch), 1659 (s, C]N stretch), 1597 (s, C]N
stretch),1551 (s, NeH bend),1327 and 1157 (s, SO2 stretch); 1H NMR
Yield 79%; m.p. 207e209 ꢂC; IR (KBr, cmꢀ1): 3441, 3340, 3256
and 3124 (m, NeH stretch), 1628 (s, C]N stretch), 1597 (s, C]N
stretch), 1535 (s, NeH bend), 1350 and 1165 (s, SO2 stretch); 1H
(DMSO-d6, 300 MHz):
d
9.84 (s, ex, 1H, NH/SH), 9.25 (s, ex, 1H, NH/
NMR (DMSO-d6, 300 MHz): d 10.03 (s, ex, 1H, NH/SH), 9.56 (s, ex,
SH), 8.87 (s, 1H, pyrazole C5eH), 8.12 (d, 2H, J ¼ 8.4 Hz, Ar), 7.95 (d,
2H, J ¼ 8.4 Hz, Ar), 7.62 (d, 2H, J ¼ 7.8 Hz, Ar), 7.45 (s, ex, 2H,
SO2NH2), 7.26 (d, 2H, J ¼ 7.8 Hz, Ar), 2.35 (s, 3H, CH3); 13C NMR
1H, NH/SH), 8.89 (s, 1H, pyrazole C5eH), 8.09 (d, 2H, J ¼ 8.7 Hz, Ar),
7.96 (d, 2H, J ¼ 8.7 Hz, Ar), 7.60e7.62 (m, 2H, thienyl), 7.47 (s, ex, 2H,
SO2NH2), 7.13e7.16 (m, 1H, thienyl); 13C NMR (DMSO-d6,
(DMSO-d6, 75.5 MHz):
d
193.4, 149.6, 142.4, 138.3, 129.8, 129.3,
75.5 MHz): d 194.0, 144.0, 142.4, 141.1, 133.8, 129.7, 128.0, 127.9,
128.3, 127.8, 126.3, 118.8, 21.3 (CH3); DART MS m/z 373.11 (M þ H)þ,
127.5, 127.3, 125.9, 118.8; DART MS m/z 365.05 (M þ H)þ,
C17H16N4O2S2Hþ calcd. 373.08.
C14H12N4O2S3Hþ calcd. 365.02.
4.6.3. 1-[4-(Aminosulfonyl)phenyl]-3-(4-methoxyphenyl)-1H-
pyrazole-4-carbothioamide (11c)
4.7. Antimicrobial assay
Yield 93%; m.p. 203e205 ꢂC; IR (KBr, cmꢀ1): 3325, 3248 and
3109 (m, NeH stretch),1651 (s, C]N stretch),1597 (s, C]N stretch),
1551 (s, NeH bend),1342 and 1165 (s, SO2 stretch); 1H NMR (DMSO-
4.7.1. In vitro antibacterial assay
The antibacterial activity of newly synthesized compounds was
evaluated by agar well diffusion method [41]. All the microbial
cultures were adjusted to 0.5 McFarland standard, which is visually
d6, 300 MHz): d 9.85 (s, ex, 1H, NH/SH), 9.26 (s, ex, 1H, NH/SH), 8.85
(s, 1H, pyrazole C5eH), 8.11 (d, 2H, J ¼ 9.0 Hz, Ar), 7.95 (d, 2H,
J ¼ 9.0 Hz, Ar), 7.66 (d, 2H, J ¼ 8.7 Hz, Ar), 7.46 (s, ex, 2H, SO2NH2),
7.02 (d, 2H, J ¼ 8.7 Hz, Ar), 3.79 (s, 3H, OCH3); 13C NMR (DMSO-d6,
comparable to
a
microbial suspension of approximately
1.5 ꢃ108 cfu/mL [42,45]. 20 mL of Mueller Hinton agar medium was
poured into each Petri plate and the agar plates were swabbed with
75.5 MHz):
d
194.3, 159.9, 149.7, 142.1, 141.4, 129.8, 127.8, 125.9,
100
adsorption. Using sterile cork borer of 8 mm diameter, wells were
bored into seeded agar plates and these were loaded with a 100
mL inocula of each test bacterium and kept for 15 min for
124.4, 118.8, 114.2, 55.6 (OCH3); DART MS m/z 389.10 (M þ H)þ,
C17H16N4O3S2Hþ calcd. 389.08.
mL
volume with concentration of 4.0 mg/mL of each compound
reconstituted in dimethylsulphoxide (DMSO). All the plates were
incubated at 37 ꢂC for 24 h. Antibacterial activity of 15 newly
synthesized compounds was evaluated by measuring the zone of
growth inhibition against the test bacteria with zone reader (Hia-
ntibiotic zone scale). DMSO was used as a negative control whereas
ciprofloxacin was used as a positive control. The experiments were
performed in triplicates. The antibacterial activity of the
compounds was compared with ciprofloxacin as standard.
Minimum Inhibitory Concentration (MIC) of newly synthesized
compounds against tested bacteria was determined using macro-
dilution tube method as recommended by NCCLS [42,43]. MIC is the
lowest concentration of an antimicrobial compound that will
inhibit the visible growth of a microorganism after overnight
incubation. In this method, various test concentrations of newly
4.6.4. 1-[4-(Aminosulfonyl)phenyl]-3-(4-fluorophenyl)-1H-
pyrazole-4-carbothioamide (11d)
Yield 91%; m.p. 230e232 ꢂC; IR (KBr, cmꢀ1): 3433, 3286 and
3148 (m, NeH stretch), 1636 (s, C]N stretch), 1597 (s, C]N
stretch), 1543 (s, NeH bend), 1342 and 1157 (s, SO2 stretch); 1H
NMR (DMSO-d6, 300 MHz): d 9.87 (s, ex, 1H, NH/SH), 9.34 (s, ex, 1H,
NH/SH), 8.91 (s, 1H, pyrazole C5eH), 8.13 (d, 2H, J ¼ 8.7 Hz, Ar), 7.97
(d, 2H, J ¼ 8.7 Hz, Ar), 7.75 (dd, 2H, 4JHF ¼ 5.7 Hz, 3JHH ¼ 8.7 Hz, Ar),
7.46 (s, ex, 2H, SO2NH2), 7.31 (t, 2H, J ¼ 8.7 Hz, Ar); 13C NMR (DMSO-
1
d6, 75.5 MHz): 194.2, 162.5 (d, JCF ¼ 248.2 Hz), 149.7, 141.9, 141.4,
3
130.8 (d, JCF ¼ 8.3 Hz), 129.6, 128.3, 127.9, 125.6, 119.2, 115.6 (d,
2JCF ¼ 21.9 Hz); DART MS m/z 377.09 (M þ H)þ, C16H13FN4O2S2Hþ
calcd. 377.06.
4.6.5. 1-[4-(Aminosulfonyl)phenyl]-3-(4-chlorophenyl)-1H-
pyrazole-4-carbothioamide (11e)
synthesized compounds were prepared from 128 to 0.25
sterile tubes No. 1e10. 100 L sterile Mueller Hinton Broth (MHB)
was poured in each sterile tube followed by addition of 200 L test
compound in tube 1. Two fold serial dilutions were carried out from
mg/mL in
m
Yield 94%; m.p. 216e219 ꢂC; IR (KBr, cmꢀ1): 3572, 3441, 3340
and 3148 (m, NeH stretch), 1643 (s, C]N stretch), 1597 (s, C]N
m

1432
P.K. Sharma et al. / European Journal of Medicinal Chemistry 46 (2011) 1425e1432
[9] A.K. Tewari, P. Srivastava, V.P. Singh, A. Singh, R.K. Goel, C.G. Mohan, Chem.
Pharm. Bull. 58 (2010) 634e638.
tube 1 to tube 10 and excess broth (100
last tube No. 10. To each tube, 100
m
m
L) was discarded from the
L of standard inoculum
[10] G. Szabo, J. Fischer, A. Kis-Varga, K. Gyires, J. Med. Chem. 51 (2008) 142e147.
[11] N. Benaamane, B. Nedjar-Kolli, Y. Bentarzi, L. Hammal, A. Geronikaki,
P. Eleftheriou, A. Langunin, Bioorg. Med. Chem. 6 (2008) 3059e3066.
[12] O. Rosati, M. Curini, M.C. Marcatullio, A. Macchiarulo, M. Perfumi, L. Mattioli,
F. Rismondo, G. Cravotto, Bioorg. Med. Chem. 15 (2007) 3463e3473.
[13] E. Palaske, M. Aytemir, I.T. Uzbay, D. Erol, Eur. J. Med. Chem. 36 (2001)
539e543.
[14] P.Y. Rajendra, R.A. Lakshmana, L. Prasoona, K. Murali, K.P. Ravi, Bioorg. Med.
Chem. Lett. 15 (2005) 5030e5034.
[15] Z. Ozdemir, B. Kandilici, B. Gumusel, U. Calis, A. Bilgin, Eur. J. Med. Chem. 42
(2007) 373e379.
(1.5 ꢃ108 cfu/mL) was added. Ciprofloxacin was used as control.
Turbidity was observed after incubating the inoculated tubes at
37 ꢂC for 24 h.
4.7.2. In vitro antifungal assay
The antifungal activity of newly synthesized compounds was
evaluated by poisoned food method [44]. The molds were grown on
Saburaud Dextrose Agar (SDA) at 25 ꢂC for 7 days and used as
inocula. 15 mL of molten SDA (45 ꢂC) was poisoned by the addition
[16] O. Ruhogluo, Z. Ozdemir, U. Calis, B. Gumusel, A. Bilgin, Arzneim.-Forsch. 55
(2005) 431e436.
of 100 mL volume of each compound having concentration of
ꢀ
[17] A. Sener, R. Kasımogullari, M.K. Sener, I. Bildirici, Y. Akcamur, J. Heterocycl.
4.0 mg/mL, reconstituted in DMSO, poured into a sterile Petri plate
and allowed to solidify at room temperature. The solidified
poisoned agar plates were inoculated at the centre with fungal
plugs (8 mm diameter), obtained from the actively growing colony
and incubated at 25 ꢂC for 7 days. DMSO was used as a negative
control whereas fluconazole was used as a positive control. The
experiments were performed in triplicates. Diameter of the fungal
colonies was measured and expressed as percent mycelial inhibi-
tion determined by applying the following formula:
Chem. 39 (2002) 869.
[18] G.A. Wachter, R.W. Hartmann, T. Sergejew, G.L. Grun, D. Ledergerber, J. Med.
Chem. 39 (1996) 834e841.
[19] R. Sridhra, P.T. Perumal, S. Etti, G. Shanmugam, M.N. Ponnuswamy,
V.R. Prabavathy, N. Mathivanan, Bioorg. Med. Chem. Lett. 14 (2004)
6035e6040.
[20] A.A. Bekhit, H.T.Y. Fahmy, Sh.A.F. Rostom, A.M. Baraka, Eur. J. Med. Chem. 38
(2003) 27e36.
[21] A.A. Bekhit, H.T.Y. Fahmy, Arch. Pharm. Pharm. Med. Chem. 336 (2003)
111e118.
[22] A.A. Bekhit, H.M.A. Ashour, Y.S. Abdel-Chany, A.El-Din A. Bekhit, A.M. Baraka,
Eur. J. Med. Chem. 43 (2008) 456e463.
[23] A.A. Bekhit, H.M.A. Ashour, A.A. Guemei, Arch. Pharm. Chem. Life Sci. 338
(2005) 167e174.
[24] P.K. Sharma, S. Kumar, P. Kumar, P. Kaushik, D. Kaushik, Y. Dhingra, K.R. Aneja,
Eur. J. Med. Chem. 45 (2010) 2650e2655.
[25] A.A. Bekhit, H.M.A. Ashour, A.El-Din A. Bekhit, H.M. Abdel-Rahman,
S.A. Bekhit, J. Enzyme Inhib. Med. Chem. 24 (2009) 296e309.
[26] S. Wang, J. Yan, J. Wang, J. Chen, T. Zhang, Y. Zhao, M. Xue, Eur. J. Med. Chem.
45 (2010) 2663e2670.
Inhibition of mycelial growth % ¼ (dc ꢀ dt)/dc ꢃ 100
where dc ¼ average diameter of fungal colony in negative
control plates; dt ¼ average diameter of fungal colony in experi-
mental plates.
[27] N. Lakshminarayana, Y.R. Prasad, L. Gharat, A. Thomas, P. Ravikumar,
S. Narayanan, C.V. Srinivasan, B. Gopalan, Eur. J. Med. Chem. 44 (2009)
3147e3157.
Acknowledgements
[28] Zhong-Cheng Song, Gao-Yuan Ma, Peng-Cheng Lv, Huan-Qiu Li, Zhu-
Ping Xiao, Hai-Liang Zhu, Eur. J. Med. Chem. 44 (2009) 3903e3908.
[29] Guo-Xiang Li, Zai-Qun Liu, Xu-Yang Luo, Eur. J. Med. Chem. 45 (2010)
1821e1827.
[30] R. Chawla, U. Sahoo, A. Arora, P.C. Sharma, V. Radhakrishanan, Acta Pol.
Pharm. 67 (2010) 55e61.
[31] V. Klimesova, M. Svoboda, K. Waisser, J. Kaustova, V. Buchta, K. Kralova, Eur. J.
Med. Chem. 34 (1999) 433e440.
[32] O. Morgenstern, H. Wanka, I. Roser, A. Steveling, B. Kuttler, Bioorg. Med.
Chem. 12 (2004) 1071e1089.
Defence Research and Development Organization (DRDO), New
Delhi is thankfully acknowledged for financial support in the form
of a research project. Authors (NC and PK) are grateful to the
Council of Scientific and Industrial Research (CSIR), New Delhi for
the award of senior and junior research fellowship respectively. The
authors are thankful to Sophisticated Analytical Instrument Facility,
Central Drug Research Institute, Lucknow for Mass spectra.
[33] T. Tojo, G.W. Spears, K. Tsuji, H. Nishimura, T. Ogino, N. Seki, A. Sugiyama,
M. Matsuo, Bioorg. Med. Chem. Lett. 24 (2002) 27e30.
[34] S.H. Krawczyk, T.E. Renau, M.R. Nassiri, A.C. Westerman, L.L. Wotring,
J.C. Drach, L.B. Townsend, J. Med. Chem. 38 (1995) 4115e4119.
[35] A. Vilsmeier, A. Haack, Ber. Dtsch. Chem. Ges. 60b (1927) 119e122.
[36] M.K. Bratenko, V.A. Chornous, M.V. Vovk, Russ. J. Org. Chem. 37 (2001)
552e555.
References
[1] T.J. Sultivan, J.J. Truglio, M.E. Boyne, P. Novichenok, X. Zhang, C.F. Stratton,
H.J. Li, T. Kaur, A. Amin, F. Johnson, R.A. Stayden, C. Kisker, P.J. Tonge, ACS
Chem. Biol. 1 (2006) 43e53.
[2] X.H. Liu, P. Cui, B.A. Song, P.S. Bhadury, H.L. Zhu, S.F. Wang, Bioorg. Med. Chem.
16 (2008) 4075e4082.
[37] M.K. Bratenko, V.A. Chornous, M.V. Vovk, Chem. Heterocycl. Compd. 37 (2001)
467e469.
[3] H. Foks, D. Pancechowska-Ksepko, A. Kedzia, Z. Zwolska, M. Janowiec,
E. Augustynowicz-Kopec, Il Farmaco 60 (2005) 513e517.
[4] A.M. Gilbert, A. Failli, J. Shumsky, Y. Yang, A. Severin, G. Singh, W. Hu,
D. Keeney, P.J. Petersen, A.H. Katz, J. Med. Chem. 49 (2006) 6027e6036.
[5] A.H. Shamroukh, M.E.A. Zaki, E.M.H. Morsy, F.M. Abdel-Motti, F.M.E. Abdel-
Megeid, Arch. Pharm. Chem. Life Sci. 340 (2007) 345e351.
[6] O. Prakash, R. Kumar, V. Parkash, Eur. J. Med. Chem. 43 (2008) 435e440.
[7] O. Prakash, R. Pundeer, P. Ranjan, K. Pannu, Y. Dhingra, K.R. Aneja, Indian.
J. Chem. 48B (2009) 563e568.
[8] I.V. Magedov, M. Manpadi, S. Van slambrouck, W.F.A. Steelant, E. Rozhkova,
N.M. Przheval’skii, S. Rogelj, A. Kornienko, J. Med. Chem. 50 (2007) 5183e5192.
[38] Jiun-Jie Shie, Jim-Min Fang, J. Org. Chem. 68 (2003) 1158e1160.
[39] Y. Saito, K. Umezawa, Bioorg. Med. Chem. Lett. 7 (1997) 861e864.
[40] A.E.S. Fairfull, J.K. Lowe, D.A. Peak, J. Chem. Soc. (1952) 742.
[41] I. Ahmad, A.J. Beg, J. Ethnopharmacol. 74 (2001) 113e123.
[42] J.M. Andrews, J. Antimicrob. Chemother. 48 (Suppl. 1) (2001) 5e16.
[43] NCCLS, Method for Dilution Antimicrobial Susceptibility Test for Bacteria that
Grow Aerobically; Approved Standards, fifth ed. National Committee for
Clinical Laboratory Standards, Villanova, PA, 2000.
[44] S.K.S. Al-Burtamani, M.O. Fatope, R.G. Marwah, A.K. Onifade, S.H. Al-Saidi,
J. Ethnopharmacol. 96 (2005) 107e112.
[45] J. McFarland, J. Am. Med. Assoc. 14 (1907) 1176e1178.