Ketene dithioacetal mediated synthesis of 1,3,4,5-tetrasubstituted pyrazole derivatives and their biological evaluation

Article abstract of DOI:10.1080/10426507.2019.1565760

Ketene dithioacetal mediated chemo- and regioselective synthesis of a series of novel 1,3,4,5-tetrasubstituted pyrazole derivatives (4a-l) integrated with a bioactive indole nucleus was achieved by reacting substituted 2-(1-methyl-1H-indole-3-carbonyl)-3,

Full text of DOI:10.1080/10426507.2019.1565760

Phosphorus, Sulfur, and Silicon and the Related Elements
ISSN: 1042-6507 (Print) 1563-5325 (Online) Journal homepage: https://www.tandfonline.com/loi/gpss20
Ketene dithioacetal mediated synthesis of 1,3,4,5-
tetrasubstituted pyrazole derivatives and their
biological evaluation
Pravin S. Bhale, Babasaheb P. Bandgar, Sakharam B. Dongare, Sadanand N.
Shringare, Dnyaneshwar M. Sirsat & Hemant V. Chavan
To cite this article: Pravin S. Bhale, Babasaheb P. Bandgar, Sakharam B. Dongare, Sadanand
N. Shringare, Dnyaneshwar M. Sirsat & Hemant V. Chavan (2019): Ketene dithioacetal mediated
synthesis of 1,3,4,5-tetrasubstituted pyrazole derivatives and their biological evaluation,
Phosphorus, Sulfur, and Silicon and the Related Elements, DOI: 10.1080/10426507.2019.1565760
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PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
https://doi.org/10.1080/10426507.2019.1565760
Ketene dithioacetal mediated synthesis of 1,3,4,5-tetrasubstituted pyrazole
derivatives and their biological evaluation
Pravin S. Bhalea,b, Babasaheb P. Bandgara, Sakharam B. Dongarea, Sadanand N. Shringarea, Dnyaneshwar M.
Sirsatc, and Hemant V. Chavand
b
aMedicinal Chemistry Research Laboratory, School of Chemical Sciences, Solapur University, Solapur, Maharashtra, India; Department of
c
Chemistry, Yeshwantrao Chavan Mahavidyalaya, Tuljapur, Dist-Osmanabad, Maharashtra, India; Department of Chemistry, A. R. A. C. S.
d
College, Vaibhavwadi, Dist-Sindhudurg, Maharashtra, India; Department of Chemistry, A. S. P. College, Devrukh, Dist-Ratnagiri,
Maharashtra, India
ABSTRACT
ARTICLE HISTORY
Received 9 June 2018
Accepted 30 December 2018
Ketene dithioacetal mediated chemo- and regioselective synthesis of a series of novel 1,3,4,5-tetra-
substituted pyrazole derivatives (4a-l) integrated with a bioactive indole nucleus was achieved by
reacting substituted 2-(1-methyl-1H-indole-3-carbonyl)-3,3-bis-(methylthio)-acrylonitrile (2) and sub-
stituted phenyl hydrazine hydrochloride (3) in the presence of a catalytic amount of anhydrous
KEYWORDS
a-Aroylketene dithioacetal;
anti-inflammatory; antioxi-
dant; breast
1
K2CO3 under reflux conditions. The structures were ascertained by H NMR, NOESY, 13C NMR, FT-
IR, and HRMS data. In vitro cytotoxicity evaluation of the synthesized compounds against MCF 7
(breast carcinoma) and normal Vero (monkey kidney) cell lines revealed that the compound 5-(5-
Bromo-1-methyl-1H-indol-3-yl)-1-(4-cyano-phenyl)-3-methylsulfanyl-1H-pyrazole-4-carbonitrile (4k)
showed significant cytotoxicity against MCF 7 (GI50 ¼ 15.6 mM) with low cytotoxicity against nor-
mal Vero cell line. Most of the synthesized compounds were also found to possess excellent anti-
inflammatory and antioxidant (DPPH, NO, H2O2 and SOR) potential.
cancer; pyrazole
GRAPHICAL ABSTRACT
Introduction
have been screened to evaluate their selective cytotoxic potential.
In particular, indoles with 5- or 6-membered heterocyclic sys-
tems in the 3-position have gained considerable interest due to
their significant anti-cancer activity.[3] Some drugs containing
indole and pyrazole heterocycles, such as Ruxolitinib 1,[4]
Crizotinib 2,[4] indomethacin 3,[5] celecoxib 4,[6] have created
some hope for the life of cancer patients (Figure 1).
Cancer is one of the most severe clinical problems and among
the leading causes of death worldwide. The number of deaths
due to cancer alone is more than those caused by AIDS, mal-
aria, and tuberculosis combined,[1] by 2030, there will be 27 mil-
lion people with cancer and 17 million deaths annually.[2]
Numerous compounds, both synthetic and naturally derived,
ꢀ
CONTACT Hemant V. Chavan
Maharashtra, India.
hemantchavan.sus@rediffmail.com
Department of Chemistry, A. S. P. College, Devrukh, Dist-Ratnagiri-415 804,
Color versions of one or more of the figures in the article can be found online at www.tandfonline.com/gpss.
Supplemental data for this article can be accessed on the publisher’s website.
ß 2019 Taylor & Francis Group, LLC

2
P. S. BHALE ET AL.
CN
H N
N
2
N
N
N
Cl
O
NH
N
N
F
N
1
2
Cl
HN
CF
3
O
N
N
O
N
Cl
COOH
H NO S
2
2
3
4
Figure 1. Indole and pyrazole heterocycle containing drug molecules.
Recently, some indole-pyrazole hybrid molecules reported formation of desired product 4 over 5. To carry out distinc-
by Singh et al. were found to be effective inhibitors of tumour
promoting activities in an average concentration range of
2.0–3.2 lM, when tested against 60 human cancer cell lines.[7]
Zhang synthesized a series of novel 3-(1H-indole-3-yl)-1H-
pyrazole-5-carbohydrazide derivatives and evaluated for their
cytotoxic activity against four human cancer cell lines and one
of the synthesized compounds was found to arrest the cell
cycle at S phase when analyzed by the flow cytometry
method.[8] Therefore, it would be of interest to combine both
the indole functionality and pyrazole into one molecule.
Inspired by these observations and in continuation of our
enduring research programme on the development of novel
anticancer and anti-inflammatory agents,[9] herein we have
reported library of 1,3,4,5-tetrasubstituted pyrazole derivatives
(4a-l) integrated with indole nucleus as potent anti-breast can-
cer, anti-inflammatory and antioxidant agents (Scheme 1).
tion between plausible regioisomers 4 and 6, the representa-
tive compound 4h was analyzed by 2D NMR (NOESY)
spectroscopy in CDCl3. The full NOESY and partial NOESY
results are presented in Figure 2.
In 2D NOESY experiment, the weak NOE between -OMe of
ring A vs aromatic proton of ring B and strong NOE of CH of
ring A with CH of ring B suggested that the aromatic ring B is
attached to N1 nitrogen of pyrazole i.e. compound 4h (Figure 2).
Anticancer activity
All the synthesized 1,3,4,5-tetrasubstituted pyrazole deriva-
tives (4a-l) were evaluated for their in vitro cytotoxic poten-
cies in human breast cancer cell line MCF-7 by employing
the sulforhodamine B (SRB) assay method.[11] Adriamycin is
one of the most efficient anticancer drug is employed as ref-
erence standard. Three parameters such as GI50, TGI and
LC50 were determined during the screening process and the
results are summarized in Table S1 (Supplemental
Materials). Among the compounds screened, compound 4k
(5-(5-Bromo-1-methyl-1H-indol-3-yl)-1-(4-cyano-phenyl)-3-
methylsulfanyl-1H-pyrazole-4-carbonitrile) exhibited signifi-
cant cytotoxicity (GI50 = 15.6 mM) against the MCF-7 cell
line, whereas compounds 4j, 4c, 4h and 4f exhibited moder-
ate cytotoxicity (GI50 = 47.0–71.6 mM). On the other hand,
rest of the compounds showed weak cytotoxic potential
against MCF-7 cell line. A comparison of the TGI concen-
trations of the compounds with adriamycin was also done.
Most of the compounds unveiled weak activity against the
MCF-7 cell line. The LC50 concentrations of the compounds
were also appraised to get an indication of the cytotoxic
effects of these compounds against the MCF-7 cell line. As
like adriamycin (LC50 >100 mM), the compounds synthe-
sized showed weak activity (LC50 >100 mM).
Results and discussion
Chemistry
In the present study, the synthesis of the desired 1,3,4,5-tet-
rasubstituted pyrazole derivatives (4a-l) has been achieved
by chemo and regioselective cyclization of substituted 2-(1-
methyl-1H-indole-3-carbonyl)-3,3-bis(methylthio)acryloni-
trile (2) and substituted phenyl hydrazine hydrochloride (3)
in the presence of anhydrous K2CO3 (3 eq.) under reflux
conditions in ethanol (Scheme 1). The starting material for
the synthesis of title compounds, namely 2-(1-methyl-1H-
indole-3-carbonyl)-3,3-bis(methylthio)acrylonitrile (2), was
synthesized in good yield from the reaction of substituted 3-
(1-methyl-1H-indol-3-yl)-3-oxopropanenitrile (1) with car-
bon disulfide and dimethyl sulfate in presence of sodium
tert-butoxide.[10] The products were purified by column
chromatography using silica gel mesh size, 100–200 and elu-
tion with 10% ethyl acetate in hexane. The structures of tar-
A major disadvantage in the progress of anticancer drug
development is most of the anticancer drugs affect the normal
cell growth. Therefore, we have ensured the selectivity by
1
get molecules were ascertained by IR, H NMR, 13C NMR
and HRMS data. The CN stretching band at 2219 cmꢁ1 in
the IR spectrum confirms the chemoselective cyclization and in vitro screening against the normal Vero (Monkey, Kidney)

PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
3
ppm
2
S
N
N
B
CN
O
3
4
5
6
7
8
A
N
4h
7.0
6.0
5.0
4.0
3.0
2.0
ppm
(a)
ppm
6.4
ppm
3.2
3.4
6.8
7.2
3.6
3.8
4.0
7.6
4.2
7.2
6.8
6.4
7.6
7.2
6.8
(c)
6.4
ppm
ppm
(b)
Figure 2. (a) Full NOESY Spectrum; (b) Partial NOESY: aliphatic vs aromatic; (c) Partial NOESY: aromatic vs aromatic region (500 MHz, CDCl3).
cell line.[12] All the compounds subjected for the cytotoxicity with almost every type of biomolecules found in living cell
screening against normal Vero cell line surprisingly exhibited and may deviate the cells from its normal physiological
functions.[13] Taking into the account of multifactorial char-
very low cytotoxicity (GI50 >100mM, TGI >100mM and LC50
>100mM) compared to standard drug Adriamycin (GI50
=
acter of oxidative stress; involved in many pathological
states, al the synthesized 1,3,4,5-tetrasubstituted pyrazole
derivatives (4a-l) were evaluated for their scavenging activity
against a variety of reactive oxygen and nitrogen radicals
such as 2,2-diphenyl-2-picrylhydrazyl (DPPH), nitric oxide
(NO), superoxide (SOR) and peroxide (H2O2).[14] Free rad-
ical scavenging activity was estimated in terms of percent
inhibition and results are depicted in Table S2
(Supplemental Materials). Most of the compounds displayed
0.03mM, TGI = 10mM and LC50 >100mM). A structure activity
relationship (SAR) study revealed that increase in activity was
observed with the introduction of electron withdrawing groups
at R3 and R1 position whereas, a decrease in activity was
observed with electron donating groups.
Anti-inflammatory activity
Protein denaturation is a very well recognised cause of good to excellent scavenging activity against DPPH, NO,
inflammation. In the present study, in vitro anti-inflamma- SOR and H2O2 radicals compared to the ascorbic acid as a
tory effect of synthesized 1,3,4,5-tetrasubstituted pyrazole reference standard (Figure S1, Supplemental Materials).
derivatives (4a-l) was also evaluated against denaturation of
egg albumin and results are summarized in Table S2
(Supplemental Materials). Compound 4e showed excellent
inhibition (93.80%) compared to the standard drug diclofe-
nac sodium (90.21%) at 1mM concentration. All other com-
pounds showed good to moderate inhibition of heat induced
albumin denaturation (47.23–71.08%).
Compounds except 4b, 4f and 4j, all other compounds
exhibited excellent DPPH radical scavenging activity (71.
59–44.18%) compared to the ascorbic acid (44.18%).
Compounds except 4c and 4k, all other compounds dis-
played excellent NO radical scavenging activity (85.71–48.
57%) compared to ascorbic acid (42.63%). Compounds 4j,
4a, 4f and 4l were found to be excellent SOR radical scav-
engers (90.24–74.50%) compared to ascorbic acid (74.07%),
however rest of the compounds were moderate SOR scav-
engers (66.66–15.68%). Compounds 4b, 4f, 4j, 4l, 4c and 4i
Antioxidant activity
Reactive oxygen species (ROS) plays key role in the patho- were found to possess significant H2O2 scavenging activity
physiological mechanisms and they reacts indiscriminately (69.72–47.19) as compared to the ascorbic acid (47.17%).

4
P. S. BHALE ET AL.
S
R1
O
2
O
R1
S
i
CN
CN
R2
N
N
R2
1
R3
NH-NH2
ii
3
R1
R1
H2N
O
R3
NH
R3
O
N
HN
S
S
N
CN
NC
N
R2
R2
R3
S
S
N
R1
R1
O
N
R3
R1
N
N
N
N
S
CN
R2
CN
N
NH2
N
R2
R2
N
R3
5 (Not Formed)
6 (Not Formed)
4a-l
4a = R1 = R2 = R3 = H
4g = R1 = Br, R2 = R3 = H
4b = R1 = R3 = H, R2 = CH3
4c = R1 = Br, R2 = R3 = H
4h = R1 = OCH3, R2 = H, R3 = CH3
4i = R1 = R2 = H, R3 = CN
4d = R1 = OCH3, R2 = R3 = H
4e = R1 = R2 = H, R3 = CH3
4f = R1 = H, R2 = R3 = CH3
4j = R1 = H, R2 = CH3, R3 = CN
4k = R1 = Br, R2 = H, R3 = CN
4l = R1 = OCH3, R2 = H, R3 = CN
Scheme 1. Chemo- and regioselective cyclization for the synthesis of 1,3,4,5-tetrasubstituted pyrazole derivatives. Reagents and conditions: i) Sodium tert-butox-
ide, CS2, Dimethyl sulfate, THF; ii) K2CO3, Ethanol, Reflux, 3h.
However, all other compounds were moderate H2O2 radical spots were visualized under UV lamp (254 nm). Melting
point of compounds was determined with digital thermom-
eter and was uncorrected. The IR spectra were performed
on Infrared FT-IR Spectrometer, Nicolet iS10; Thermo
Electron Scientific, USA and values were represented in
cmꢁ1. The mass spectra were confirmed on Shimadzu
LCMS-2010 EV. 1H NMR spectra were run on 400 MHz
FT-NMR, Bruker AVIII, Switzerland, using CDCl3/DMSO-
d6 solvent and chemical shift values recorded in parts per
million on d scale. Coupling constants (J) are referred in
Hertz (Hz). The Supplemental Materials contains sample
scavengers (42.57–17.32%).
Experimental
General methods
All the chemicals and reagents used in experiment were of
analytical grade purchased from Sigma Aldrich, Germany
and purified if required by standard technique. All the
reactions were supervised by thin–layer Chromatography
(TLC), which was performed on aluminum sheet pre-
1H NMR and HRMS spectra for products
4
coated with silica gel, kiesel gel 60 F254 (Merck) and the (Figures S2–S21).

PHOSPHORUS, SULFUR, AND SILICON AND THE RELATED ELEMENTS
5
General procedure for the preparation of 5-(1-methyl-1H-
indol-3-yl)-3-(methylthio)-1-phenyl-1H-pyrazole-4-carboni-
trile derivatives (4):
A mixture of substituted 2-(1-methyl-1H-indole-3-carbonyl)-
3,3-bis(methylthio)acrylonitrile 2 (302 mg, 1.0 mmol) and
substituted phenyl hydrazine hydrochloride 2 (144 mg,
124.90, 115.91(CN), 113.33, 109.23, 105.92, 103.42, 99.07, 55.
43(OCH3), 32.09(N-CH3), 12.92(S-CH3); HRMS m/z calcd
for C21H18N4OS 374.1201, found 375.1268 (M þ H).
5-(1-methyl-1H-indol-3-yl)-3-(methylthio)-1-p-tolyl-1H-
pyrazole-4-carbonitrile (4e): Light brown solid; Yield: 84%;
M.P.: 184-186 ꢂC; IR (KBr cmꢁ1): 2932 (CH), 2216 (CN),
1
1 mmole) in ethanol (10 ml) in the presence of catalytic 1612 (C ¼ C), 1562; H NMR (CDCl3, 400 MHz): d = 7.35
amount of anhydrous K2CO3 was refluxed for 3 h. The reac-
tion mixture was cooled and poured in ice cold water. The
faint brownish solid obtained was filtered, washed with
water and recrystallized from ethanol to obtain pure com-
pound 4 (Yield: 86%).
(d, J= 8.0 Hz, 2H), 7.31-7.25 (m, 2H), 7.23 (d, J= 6.8 Hz,
1H), 7.09 (d, J= 8.4 Hz, 2H), 7.05-6.97 (m, 2H), 3.86 (s, 3H),
2.70 (s, 3H), 2.33 (s, 3H); 13C NMR (CDCl3, 75 MHz): d =
151.67, 144.66, 138.11, 137.07, 136.93, 130.10, 125.04,
124.19, 122.67, 120.76, 120.24, 114.24(CN), 109.71, 101.53,
93.34, 33.32(N-CH3), 21.10(Ar-CH3), 14.83(S-CH3); HRMS
m/z calcd for C21H18N4S 358.1252, found 359.1307 (M þ H).
5-(1,2-dimethyl-1H-indol-3-yl)-3-(methylthio)-1-p-tolyl-
1H-pyrazole-4-carbonitrile (4f): Light brown solid; Yield:
87%; M.P.: 180-182 ꢂC; IR (KBr cmꢁ1): 2939 (CH), 2222
(CN), 1612 (C ¼ C), 1581, 1560; 1H NMR (CDCl3,
400 MHz): d = 7.77 (d, J= 8.0 Hz, 1H), 7.64-7.57 (m, 3H),
7.48-7.42 (m, 3H), 7.27 (d, J= 6.6 Hz, 1H), 3.86 (s, 3H,
NCH3), 2.99 (s, 3H), 2.70 (s, 3H, SCH3), 2.50 (s, 3H, Ar-
CH3); 13C NMR (CDCl3, 75 MHz): d = 150.33, 140.43,
138.10, 135.07, 136.73, 130.00, 128.04, 126.21, 125.00,
121.46, 121.01, 119.04, 115.01(CN), 109.31, 103.22, 97.22,
31.12(N-CH3), 21.34(Ar-CH3), 13.93(S-CH3), 11.02 (Ar-
CH3); HRMS m/z calcd for C22H20N4S 372.1409, found
371.2001 (M-H).
Spectral data of synthesized compounds
5-(1-methyl-1H-indol-3-yl)-3-(methylthio)-1-phenyl-
1H-pyrazole-4-carbonitrile (4a): Light brown solid; Yield:
86%; M.P.: 164-166 ꢂC; IR (KBr cmꢁ1): 2930 (CH), 2219
(CN), 1614 (C ¼ C), 1593, 1570; 1H NMR (CDCl3,
400 MHz): d = 7.44-7.40 (m, 2H), 7.39-7.53 (m, 1H), 7.34-
7.32 (m, 1H), 7.31-7.28 (m, 3H), 7.27-7.21 (m, 1H), 6.99-
6.96 (m, 2H), 3.86 (s, 3H, NCH3), 2.72 (s, 3H, SCH3); 13C
NMR (CDCl3, 75 MHz): d = 150.10, 142.33, 136.13, 135.10,
130.00, 129.10, 128.12, 127.19, 124.17, 121.76, 120.32,
119.24, 117.01(CN), 110.13, 105.02, 97.66, 32.12(N-CH3),
13.11(S-CH3); HRMS m/z calcd for C20H16N4S 344.1096,
found 345.1162 (M þ H).
5-(1,2-dimethyl-1H-indol-3-yl)-3-(methylthio)-1-phenyl-
1H-pyrazole-4-carbonitrile (4b): Light brown solid; Yield:
83%; M.P.: 170-172 ꢂC; IR (KBr cmꢁ1): 2972 (CH), 2224
(CN), 1616 (C ¼ C), 1593, 1576; 1H NMR (CDCl3,
400 MHz): d = 7.73 (d, J ¼ 8.0 Hz, 1H), 7.62-7.58 (m, 4H),
7.50 (d, J= 6.8 Hz, 1H), 7.45-7.42 (m, 2H), 7.27 (d, J=
6.8 Hz, 1H), 3.84 (s, 3H, NCH3), 2.96 (s, 3H), 2.72 (s, 3H,
SCH3); 13C NMR (CDCl3, 75 MHz): d = 151.21, 142.41,
139.41, 138.23, 136.00, 130.11, 128.91, 128.19, 126.65,
125.11, 121.50, 120.24, 115.60(CN), 109.33, 105.08, 97.66,
31.89(N-CH3), 14.17(S-CH3), 11.03(Ar-CH3); HRMS m/z
calcd for C21H18N4S 358.1252, found 359.2001 (M þ H).
5-(5-bromo-1-methyl-1H-indol-3-yl)-3-(methylthio)-
1-phenyl-1H-pyrazole-4-carbonitrile (4c): Light brown
solid; Yield: 83%; M.P.: 176-178 ꢂC; IR (KBr cmꢁ1): 2934
(CH), 2227(CN), 1603 (C ¼ C), 1583; 1H NMR (CDCl3,
400 MHz): d = 7.70 (s, 1H), 7.64 (m, 3H), 7.55 (d, J= 8.0 Hz,
2H), 7.40-7.32 (m, 3H), 3.87 (s, 3H, NCH3), 2.68 (s, 3H,
SCH3); 13C NMR (CDCl3, 75 MHz): d = 150.33, 139.65,
137.45, 133.23, 130.03, 129.31, 128.19, 126.05, 125.91,
124.00, 123.94, 122.50, 115.21 (CN), 110.33, 105.24, 96.07,
31.99 (N-CH3), 13.92 (S-CH3); HRMS m/z calcd for
C20H1581BrN4S 424.0180, found 425.0101 (M þ H) (81Br).
5-(5-methoxy-1-methyl-1H-indol-3-yl)-3-(methylthio)-1-
phenyl-1H-pyrazole-4-carbonitrile (4d): Light brown solid;
Yield: 86%; M.P.: 178-180 ꢂC; IR (KBr cmꢁ1): 2994 (CH),
2216 (CN), 1621 (C ¼ C), 1595, 1565; 1H NMR (CDCl3,
400 MHz): d = 7.47-7.42 (m, 2H), 7.40 (s, 1H), 7.35-7.28 (m,
3H), 7.23 (d, J= 8.8 Hz, 1H), 6.85 (dd, J= 8.8 Hz, 2.4 Hz,
1H), 6.29 (d, J= 2.4 Hz, 1H), 3.84 (s, 3H), 3.50 (s, 3H), 2.72
(s, 3H); 13C NMR (CDCl3, 75 MHz): d = 154.21, 142.43,
5-(5-bromo-1-methyl-1H-indol-3-yl)-3-(methylthio)-
1-p-tolyl-1H-pyrazole-4-carbonitrile (4g): Light brown
solid; Yield: 88%; M.P.: 176-178 ꢂC; IR (KBr cmꢁ1): 2942
(CH), 2210 (CN), 1605 (C ¼ C), 1585, 1559; 1H NMR
(CDCl3, 400 MHz): d = 7.84 (s, 1H), 7.65 (d, J= 6.8 Hz, 1H),
7.51 (d, J= 8.0 Hz, 2H), 7.40 (d, J= 8.0 Hz, 2H), 7.29 (m,
2H), 3.89 (s, 3H, NCH3), 2.73 (s, 3H, SCH3), 2.48 (s, 3H,Ar-
CH3); 13C NMR (CDCl3, 75 MHz): d = 149.03, 140.11,
136.10, 135.07, 130.73, 130.00, 129.21, 126.31, 126.00,
125.21, 123.51, 121.04, 114.81(CN), 110.31, 109.12, 96.32,
32.03(N-CH3), 21.23(Ar-CH3), 12.93(S-CH3); HRMS m/z
calcd for C21H1781BrN4S 438.0337, found 439.0307
(M þ H) (81Br).
5-(5-methoxy-1-methyl-1H-indol-3-yl)-3-(methylthio)-1-
p-tolyl-1H-pyrazole-4-carbonitrile (4h): Light brown solid;
Yield: 86%; M.P.: 178-180 ꢂC; IR (KBr cmꢁ1): 2935 (CH),
2221 (CN), 1620 (C ¼ C), 1560; 1H NMR (CDCl3,
400 MHz): d = 7.38 (s, 1H), 7.33 (dd, J= 6.4 Hz, 2.0 Hz, 2H),
7.21 (d, J= 8.8 Hz, 1H), 7.12 (d, J= 8.0 Hz, 2H), 6.85 (dd, J=
8.8 Hz, 2.4 Hz, 1H), 6.34 (d, J ¼ 2.4 Hz, 1H), 3.83 (s, 3H),
3.52 (s, 3H), 2.71 (s, 3H), 2.34 (s, 3H); 13C NMR (75 MHz,
CDCl3): d = 154.73, 151.75, 144.93, 138.10, 137.38, 132.08,
130.39, 129.71, 125.21, 124.20, 114.39(CN), 113.68, 110.58,
101.20, 101.08, 92.89, 55.34(OCH3), 33.50(N-CH3),
21.07(Ar-CH3), 14.82(S-CH3); HRMS m/z calcd for
C22H20N4OS 388.1358, found 389.1410 (M þ H).
1-(4-cyanophenyl)-5-(1-methyl-1H-indol-3-yl)-3-
(methylthio)-1H-pyrazole-4-carbonitrile (4i): Light brown
solid; Yield: 84%; M.P.: 258-260 ꢂC; IR (KBr cmꢁ1): 2927
(CH), 2221 (CN), 1605 (C ¼ C), 1584, 1560; 1H NMR
139.22, 136.23, 130.05, 129.21, 129.00, 128.05, 125.21, (CDCl3, 400 MHz): d = 7.60-7.55 (m, 2H), 7.49 (s, 1H), 7.40

6
P. S. BHALE ET AL.
(d, J= 8.4 Hz, 2H), 7.39-7.25 (m, 1H), 7.01-6.97 (m, 1H), activity. As the structures of synthesized compounds are
6.83 (d, J= 8.0 Hz, 2H), 3.92 (s, 3H), 2.72 (s, 3H); 13C NMR analogues to coxib family, most of the compounds found to
(75 MHz, CDCl3): d = 153.22, 145.20, 142.76, 137.17, 133.04, possess excellent anti-inflammatory and antioxidant (DPPH,
130.22, 124.70, 124.02, 123.17, 121.26, 119.69, 117.92(CN), NO, SOR and H2O2) potential. The compound 5-(1,2-
Dimethyl-1H-indol-3-yl)-3-methylsulfanyl-1-phenyl-1H-pyr-
azole-4-carbonitrile (4e) exhibited excellent anti-inflamma-
tory activity compared to diclofenac sodium. These results
suggest the cogent use of these compounds for the design
and development of novel anti-cancer and anti-inflamma-
tory agents.
113.60(CN), 111.19, 110.17, 100.81, 94.49, 33.49 N-CH3),
14.41(S-CH3); HRMS m/z calcd for C21H15N5S 369.1048,
found 370.1104 (M þ H).
1-(4-cyanophenyl)-5-(1,2-dimethyl-1H-indol-3-yl)-
3-(methylthio)-1H-pyrazole-4-carbonitrile
(4j):
Light
brown solid; Yield: 82%; M.P.: 158-160 ꢂC; IR (KBr cmꢁ1):
1
2937 (CH), 2225 (CN), 1609 (C ¼ C), 1580, 1567; H NMR
(CDCl3, 400 MHz): d = 7.87 (d, J= 8.0 Hz, 2H), 7.70 (d, J=
8.4 Hz, 1H), 7.62 (d, J= 8.0 Hz, 2H), 7.50-743 (m, 2H), 7.21
(d, J= 6.4 Hz, 1H), 3.85 (s, 3H, NCH3), 3.01 (s, 3H), 2.71 (s,
3H, SCH3); 13C NMR (75 MHz, CDCl3): d = 150.12, 143.44,
142.21, 137.23, 135.04, 129.22, 126.10, 121.80, 121.17,
119.69, 118.43(CN), 114.53(CN), 112.09, 110.07, 105.12,
99.99, 31.12(N-CH3), 13.31(S-CH3), 11.09(Ar-CH3); HRMS
m/z calcd for C22H17N5S 383.1205, found 384.1704 (M þ H).
5-(5-bromo-1-methyl-1H-indol-3-yl)-1-(4-cyanophenyl)-
Acknowledgements
Authors express thanks to Tata Memorial Centre, Advanced Centre for
Treatment Research and Education in Cancer (ACTREC), Kharghar,
Navi Mumbai-410210 for conducting the in vitro anticancer screening
and Dr. Sandip Patil, Birnale College of Pharmacy, Sangli, India for
anti-oxidant and anti-inflammatory activity determinations.
References
3-(methylthio)-1H-pyrazole-4-carbonitrile
(4k):
Light
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brown solid; Yield: 87%; M.P.: 240-242 ꢂC; IR (KBr cmꢁ1):
2941 (CH), 2220 (CN), 1602 (C ¼ C), 1583, 1560; 1H
NMR (CDCl3, 400 MHz): d = 7.96 (s, 1H), 7.89 (d, J=
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2929 (CH), 2226 (CN), 2217 (CN), 1621 (C ¼ C), 1605,
1
1583; H NMR (CDCl3, 400 MHz): d = 7.61-7.57 (m, 4H),
7.44 (s, 1H), 7.25 (s, 1H), 6.90 (d, J= 6.8 Hz, 1H), 6.24 (d, J=
6.8 Hz, 1H), 3.88 (s, 3H), 3.52 (s, 3H), 2.72 (s, 3H); 13C
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55.78(OCH3), 32.02(N-CH3), 12.71(S-CH3); HRMS m/z
calcd for C22H17N5OS 399.1154, found 398.1599 (M-H).
Conclusion
In conclusion, ketene dithioacetal mediated chemo- and
regioselective synthesis of novel 1,3,4,5-tetrasubstituted pyra-
zole derivatives (4a-l) was achieved and structural investiga-
tions of regioisomers was accomplished by using 2D NMR
(NOESY). All the synthesized compounds were in vitro eval-
uated for their anti-inflammatory, antioxidant and cytotoxic
potential against breast carcinoma (MCF-7). Among the
compounds under investigation, 5-(5-Bromo-1-methyl-1H-
indol-3-yl)-1-(4-cyano-phenyl)-3-methylsulfanyl-1H-pyra-
zole-4-carbonitrile (4k) exhibited significant antitumor activ-
ities. The introduction of electron withdrawing group at p-
position of phenyl ring of aryl pyrazole leads to increase in

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