Synthesis characterization and biological evaluation of some novel amino pyrazole derivatives

Article abstract of DOI:10.14233/ajchem.2018.21499

Amino pyrazole and their derivatives for their biological activities. Present work describes the synthesis of novel amino pyrazole derivatives and evaluation of their medicinal value. The reaction of 3,5-bis(trifluoromethyl) aniline with cyano acetic acid

Full text of DOI:10.14233/ajchem.2018.21499

Asian Journal of Chemistry; Vol. 30, No. 12 (2018), 2647-2651
A
SIAN
J
OURNAL OF HEMISTRY
C
https://doi.org/10.14233/ajchem.2018.21499
Synthesis Characterization and Biological Evaluation of Some Novel Amino Pyrazole Derivatives
1,*
2
3
NILAY SHAH , PINESHKUMAR N. PATEL and DENISH C. KARIA
1Department of Chemistry, Kadi Sarva Vishwavidyalaya, Gandhinagar-382 024, India
2Huntsman International India Pvt Ltd, Vadodara-391 440, India
3Department of Chemistry, Patel J.D.K. Davolwala Science College, Borsad-388 540, India
*Corresponding author: E-mail: nilayashah315@rediffmail.com
Received: 5 June 2018;
Accepted: 30 July 2018;
Published online: 31 October 2018;
AJC-19126
Amino pyrazole and their derivatives for their biological activities. Present work describes the synthesis of novel amino pyrazole derivatives
and evaluation of their medicinal value. The reaction of 3,5-bis(trifluoromethyl) aniline with cyano acetic acid in presence of ethylene
dichloride-hydrochloride produced N-[3,5-bis(trifluoromethyl)phenyl]-2-cyanoacetamide (1); this intermediate, upon further reaction
with dimethyl sulfide in presence of K2CO3 followed by reaction with methyl iodide was converted to N-[3,5-bis(trifluoromethyl)phenyl]-
2-cyano-3,3-bis(methylthio)acrylamide (2). The cyclization of 2 with hydrazine in isopropyl alcohol resulted in 3-amino-N-[3,5-
bis(trifluoromethyl)phenyl]-5-(methylthio)-1H-pyrazole-4-carboxamide (3) as main scaffold. This isolated scaffold finally reacted with
various derivatives of aldehyde followed by reduction with sodium borohydride to isolate target compounds AP-1 to AP-17. The structures
1
of the synthesized compounds were confirmed by mass, FT-IR and H NMR analysis. All the compounds were tested for potential
antifungal and antimicrobial activity. Out of 17 compounds AP-1, 3, 4, 7, 9, 10 and 11 compounds having good activity in antimicrobial
agent.
Keywords: Pyrazole, Amine derivatives, Carboxamide derivatives, Antimicrobial, Antifungal activity.
heterocyclic rings in medicinal chemistry. Pyrazole containing
pharmaco active agent acts as an important role in medicinal
chemistry [2]. In literature, several pyrazole derivatives are
acknowledged to possess antibacterial [3-6], antidiabetic [7],
anti-inflammatory [8,9], antifungal [10-13], antitubercular
[14-16] and antiviral [17-19].
Literature search revealed that the variation of the substi-
tuent on 3-amino position of the pyrazole could impressively
encouragement the biological activities [20-26]. It was hypothe-
sized that inclusion of various moieties possessing fungicidal
and bacterial properties into the backbone of a pyrazole ring
might enhance the antibacterial and fungicidal activities
of pyrazole analogues. Based on this hypothesis, 17 novel
substituted pyrazole derivatives were designed synthesized and
evaluated their antimicrobial potential.
INTRODUCTION
Originally, the name of pyrazole was identified as a class
of compounds by German chemist Ludwig in 1883. Classical
method for the synthesis of pyrrazole was developed by German
chemist Hans von Pechmann in 1898, involves reaction of
acetylene and diazomethane.
Pyrazole shows special characteristics, including high
efficiency, low toxicity and unique reaction mechanism. Owing
to these properties, pyrazole derivatives found many applica-
tions in the field of biology and chemistry, has attracted increa-
sing interest, occupied a unique place in field of medicinal
chemistry due to their wide spectrum of biological activities.
In the recent years, pyrazole derivatives have attracted
the attention of medicinal chemists due to their important
biological and chemotherapeutic importance. They are known
to exhibit a wide range of biological activities and act as CSRC
kinase inhibitors involved with ischemic brain pathology [1].
The recently achievement of pyrazole as cyclooxygenase-2
inhibitor (COX-2) has further highlight the importance of these
EXPERIMENTAL
Chemicals used in the present research work were
procured from Spectrochem, Sigma-Aldrich, CDH and Alfa-
Aesar. The purification of solvents was carried out as per pro-
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2648 Shah et al.
Asian J. Chem.
cedures reported in literature. Melting points of the synthesized
compounds were determined by applying open capillary method
using an electrothermal apparatus. The progress of reactions
and the purity of the products formed were checked by thin
layer chromatography (TLC) using silica gel plates and exa-
mined under ultraviolet lamp. The structures of synthesized
compounds were corroborated by using different spectral tech-
niques i.e., FT-IR, 1H NMR and mass spectra. The FT-IR spectra
were scanned on Shimazdu IR Affinity-I FT-IR spectro-
photometer in range of 4000-400 cm-1 using potassium bromide
(KBr) powder. The NMR spectra were recorded at 400 (1H
NMR), on a commercial Bruker Advance II instrument, in
deuterated dimethylsulphoxide-d6 and CDCl3 as solvent. The
chemical shift values were noted as δ ppm using tetramethyl-
silane as an internal standard.
In the present work, novel amino pyrazole derivatives were
prepared by following general reaction (Scheme-I). The N-
[3,5-bis(trifluoromethyl)phenyl]-2-cyanoacetamide was
prepared by reaction of 3,5-bis(trifluoromethyl)aniline and
cyanoacetic acid in presence of EDC·HCl in DMF solvent to
afford good yield of compound 1. The compound 1 on reaction
with dimethyl sulfide in presence of K2CO3 followed by reaction
with methyl iodide in DMF solvent, was converted to N-[3,5-
bis(trifluoromethyl)phenyl]-2-cyano-3,3-bis(methylthio)-
acrylamide (2). The cyclization of 2 using hydrazine in IPA
solvent resulted in 3-amino-N-(3,5-bis(trifluoromethyl)-
phenyl)-5-(methylthio)-1H-pyrazole-4-carboxamide (3) as
main scaffold. Reaction of 3 with various substituted aromatic
aldehyde followed by reduction with NaBH4 produced various
derivatives of amino pyrazole AP(1-17). All the synthesized
compounds were tested for antifungal and antibacterial activity.
Preparation of N-[3,5-bis(trifluoromethyl)phenyl]-2-
cyanoacetamide (1): Cyanoacetic acid (16.51 g, 192.11 mmol)
and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydro-
chloride (EDC·HCl) (40.67 g, 261.97 mmol) are dissolved in
DMF (170 mL) at 25-35 °C, 3,5-bis(trifluoromethyl)aniline
(40 g, 174.64 mmol) was added in different lots within 60 min.
The resulted reaction mixture was stirred for 120 min. The
progress of the reaction was monitored by TLC by using ethyl
acetate:cyclohexane (5:5) as a mobile phase.After completion
of the reaction, the reaction mixture was dump in water.
Precipitated crude material was filtrated out and washed with
water. This crude product was purified using diethyl ether to
get pure intermediate N-(3,5-bis(trifluoromethyl)phenyl)-2-
cyanoacetamide (1) (41.38 g, 80 % yield) as a off white colour
solid.
Preparation of N-[3,5-bis(trifluoromethyl)phenyl]-2-
cyano-3,3-bis(methylthio)acrylamide (2): To a stirred solu-
tion of N-[3,5-bis(trifluoromethyl)phenyl]-2-cyanoacetamide
(1) (41 g, 178.9 mmol) in DMF (150 mL), anhydrous potassium
carbonate (30.86 g, 223.67 mmol) was added and the reaction
mixture was stirred for 120 min at 25-35 °C. After 120 min
carbon disulfide (27.42 g, 357.8 mmol) was added in the
reaction mass and stirred for another 120 min. Then the reaction
mass was gradually cooled to 0-5 °C and methyl iodide (50.79
g, 357.8 mmol) was added within 30 min, the reaction mass
warm to 25-35 °C and stirred it at same temperature for 180
min. The reaction progress was monitored by TLC by using
ethyl acetate:cyclohexane (5:5) as a mobile phase.After comp-
letion of reaction, the mixture was poured into water (700 mL)
and stirred for 30 min. The precipitated solid material was
filtered, washed with water and dried to afford N-[3,5-bis-
(trifluoromethyl)phenyl]-2-cyano-3,3-bis(methylthio)-
acrylamide (2) (50.14 g, 70 % yield) as off-white to yellow
coloured solid.
Preparation of 3-amino-N-[3,5-bis(trifluoromethyl)-
phenyl]-5-(methylthio)-1H-pyrazole-4-carboxamide (3): To
a stirred solution of N-[3,5-bis(trifluoromethyl)phenyl]-2-
cyano-3,3-bis(methylthio)acrylamide (2) (50.0 g, 124.99
mmol) in IPA (200 mL), hydrazine hydrate (12.51 g, 249.99
mmol) was added and reaction mass was heated to reflux
temperature for 240 min. The progress of the reaction was
monitored by TLC by using methanol:MDC (0.5:9.5) as a
mobile phase. After completion of reaction, the reaction
mixture was cooled to 25-35 °C and water (400 mL) was added.
The reaction mixture was stirred for 60 min at same tempe-
rature. The solid precipitated was filtered, washed with water.
the wet material dried and crystallization in IPA to afford 3-
amino-N-[3,5-bis(trifluoromethyl)phenyl]-5-(methylthio)-1H-
pyrazole-4-carboxamide (3) (28.22 g, 60 % yield) as a off-
white to yellow coloured solid.
Preparation of 3-(aryl amino)-N-[3,5-bis(trifluoro-
methyl)-phenyl]-5-(methylthio)-1H-pyrazole-4-carboxa-
mide (AP-1 to AP-17): The mixture of 3-amino-N-[3,5-bis-
(trifluoromethyl)phenyl]-5-(methylthio)-1H-pyrazole-4-
carboxamide (3) (1.30 mmol), substituted aromatic aldehyde
(1.42 mmol) and catalytic amount of CH3COOH in IPA (10
mL) was refluxed for 120-180 min. The reaction progress was
monitored by TLC by using methanol:MDC (0.5:9.5) as a
mobile phase. After completion of the reaction, sodium boro-
hydride (1.42 mmol) was added in lot wise manner into the
reaction mixture within 30 min at 25-35 °C. The reaction
N NH
N NH
S
Ar
O
N
S
NC
O
H2N
S
S
H
CN
NH2
HN
(c)
(d)
O
NH
(a)
(b)
NH
O
NH
F3C
CF3
F3C
CF3
F3C
CF3
F3C
CF3
F3C
CF3
(1)
(2)
AP-1 to AP-17
(3)
a) Cyanoaceticacid, EDC·HCl, DCM, RT 1 h; (b) i. CS2, K2CO3, DMF, 25-35 °C: ii. CH3I, 0-10 °C to 25-35 °C; (c) NH2NH2,
IPA, Reflux 240 min (d) i ArCHO, cat. acetic acid, IPA, reflux 120-180 min: ii sodium borohydride, IPA, RT 60 min.
Scheme-I: General synthesis

Vol. 30, No. 12 (2018)
Synthesis Characterization and Biological Evaluation of Some Novel Amino Pyrazole Derivatives 2649
mixture was then stirred for additionally 60 min at 25-35 °C.
The progress of the reduction was monitored by TLC by using
methanol:MDC (0.5:9.5) as a mobile phase. After completion
of the reaction, the mass was neutralized with CH3COOH and
solvent was distilled out under reduced pressure. The crude
material was dissolved in dichloromethane and washed with
water. The solvent was distilled out under reduced pressure
and the product was crystallized from IPA to give pure 3-(aryl-
amino)-N-[3,5-bis(trifluoromethyl)phenyl]-5-(methylthio)-
1H-pyrazole-4-carboxamide (AP-1 to AP-17) as a white to
off white coloured compound.
N-[3,5-bis(Trifluoromethyl)phenyl]-3-(4-chlorobenzyl-
amino)-5-(methylthio)-1H-pyrazole-4-carboxamide (AP-
3): Yield: 51.40 %, m.f. C20H15N4OSF6Cl; m.p. 199-203 ºC;
m.w. 508.06. 1H NMR (400 MHz, DMSO-d6) δ ppm: 2.57 (s,
3H), 4.49-4.47 (d, J = 7.2 Hz, 2H), 7.29-7.37 (m, 4H), 7.54 (s,
1H), 7.95 (s, 1H), 8.22 (m, 2H), 9.61 (s, 1H), 12.51 (s, 1H) ppm;
MS: m/z 508.8 (M+H)+. IR(KBr, νmax, cm-1):3329.14 (N-H amine),
1660.71 (-CONH-), 1276.88 (C-N amine), 1128.36 (C-F), 812.03
(C-Cl). Elemental analysis (%) Found (calcd.): C 47.21 (47.21),
H 2.97 (2.97), N 11.01 (11.01), O 3.14 (3.14).
N-[3,5-bis(Trifluoromethyl)phenyl]-3-(2-bromo-6-
fluorobenzylamino)-5-(methylthio)-1H-pyrazole-4-carbox-
amide (AP-4):Yield: 60.64 %, m.f. C20H14N4OSF7Br; m.p. 225-
229 ºC; m.w. 570.00. 1H NMR (400 MHz, DMSO-d6) δ ppm:
2.56 (s, 3H), 4.59-4.60 (d, J = 4.8 Hz, 2H), 6.69 (s, 1H), 7.16-
7.20 (m, 1H), 7.29-7.30 (m, 1H), 7.45-7.47 (d, J = 7.8 Hz,
1H), 7.54 (s, 1H), 8.18 (s, 1H), 9.63 (s, 1H), 12.82 (s, 1H)
ppm; MS: m/z 570.8 (M+H)+. IR (KBr, νmax, cm-1): 3570.24
(N-H amine), 1653 (-CONH-), 1278.81 (C-N amine), 1130.29
(C-F), 678.94 (C-Br). Elemental analysis (%) Found (calcd.):
C 42.05 (42.05), H 2.46 (2.47), N 9.81 (9.81), O 2.80 (2.80).
N-[3,5-bis(Trifluoromethyl)phenyl]-3-(4-hydroxybenzyl-
amino)-5-(methylthio)-1H-pyrazole-4-carboxamide (AP-
5):Yield: 70.53 %, m.f. C20H16N4O2SF6; m.p. 235-238 ºC; m.w.
490.09. 1H NMR (400 MHz, DMSO-d6) δ ppm: 2.53 (s, 3H),
4.31-4.32 (d, J = 7.2 Hz, 2H), 6.71-6.74 (m, 3H), 7.15-7.18
(m, 2H), 7.29-7.30 (m, 1H), 7.56 (s, 1H), 8.16 (s, 1H), 9.19 (s,
1H), 9.58 (s, 1H), 12.22 (s, 1H) ppm; MS: m/z 490.9 (M+H)+.
IR (KBr, νmax, cm-1): 3292.49 (N-H amine), 1664.57 (-CONH-),
1377.17 (-O-H), 1282.66 (C-N amine), 1124.5 (C-F). Elemental
analysis (%) Found (calcd.): C 48.98 (48.98), H 3.28 (3.29), N
11.41 (11.42), O 6.51 (6.52).
Spectral data
3-(Benzylamino)-N-[3,5-bis(trifluoromethyl)phenyl]-5-
(methylthio)-1H-pyrazole-4-carboxamide (AP-1): Yield:
89.11 %; m.f. C20H16N4OSF6; m.p. 217-221 ºC; m.w. 474.09.
1H NMR (400 MHz, DMSO-d6) δ ppm: 2.57 (s, 3H), 4.49-4.47
(d, J = 7.2 Hz, 2H), 7.25-7.37 (m, 6H), 7.52 (s, 1H), 8.18-8.20
(m, 2H), 9.62 (s, 1H), 12.51 (s, 1H) ppm; MS: m/z 474.8 (M+H)+.
IR (KBr, νmax, cm-1): 3344.57 (N-H amine), 1645.28 (-CONH-),
1284.59 (C-N amine), 1124.5 (C-F). Elemental analysis (%)
Found (calcd.): C 50.62 (50.63), H 3.40 (3.40), N 11.82 (11.81).
N-[3,5-Bis(trifluoromethyl)phenyl]-3-(3,4-dimethoxy-
benzylamino)-5-(methylthio)-1H-pyrazole-4-carboxamide
(AP-2):Yield: 68.31 %, m.f. C22H20N4O3SF6; m.p. 205-208 ºC;
m.w. 534.12. 1H NMR (400 MHz, CDCl3) δ ppm: 2.57 (s, 3H),
3.86 (s, 3H), 3.88 (s, 3H), 4.40-4.42 (d, J = 6.8 Hz, 2H), 6.84-6.94
(m, 4H), 7.26-7.33 (m, 1H), 7.58 (s, 1H), 8.10 (s, 1H), 9.46 (s, 1H),
12.51 (s, 1H) ppm; MS: m/z 534.9 (M+H). IR (KBr, νmax, cm-1):
3356.14 (N-H amine), 1658.78 (-CONH-), 1278.81 (C-N amine),
1246.02 (-C-O-, ether), 1128.36 (C-F). Elemental analysis (%)
Found (calcd.): C 49.44 (49.44), H 3.77 (3.77), 10.47 (10.48),
O 8.98 (8.98).
TABLE-1
ANTIBACTERIAL AND ANTIFUNGAL ACTIVITY, MINIMUM INHIBITORY CONCENTRATION (µg/mL)
Antibacterial activity
P. aeruginosa S. aureus
Antifungal activity
Code
No.
Ar
E. coli
MTCC 443
S. pyogenus C. albicans
A. niger
A. clavatus
MTCC 1688
MTCC 96
125
125
62.5
250
500
100
100
125
500
100
62.5
250
250
250
500
250
250
0.25
250
50
MTCC 442
125
100
250
500
500
250
250
250
250
125
100
250
100
250
500
500
100
0.5
MTCC 227 MTCC 282
MTCC 1323
> 1000
500
AP-1
AP-2
AP-3
AP-4
AP-5
AP-6
AP-7
AP-8
Phenyl
100
125
100
62.5
100
250
200
250
62.5
100
125
250
100
250
125
250
100
0.05
100
50
50
> 1000
> 1000
250
1000
1000
500
250
250
500
1000
250
500
500
500
1000
1000
> 1000
–
> 1000
500
3,4-Dimethoxy phenyl
4-Chloro phenyl
2-Fluoro-6-bromo phenyl
4-Hydroxy phenyl
4-N,N Dimethyl phenyl
4-Pyridine
4-Methyl phenyl
2-Bromo phenyl
4-Bromo phenyl
2-Methyl phenyl
4-Methoxy phenyl
2-Chloro phenyl
4-Fluoro phenyl
3,4-Fluoro phenyl
Thiophene
250
250
100
250
500
100
250
125
32.5
100
125
125
100
250
250
125
1
500
1000
1000
> 1000
250
1000
> 1000
250
500
500
> 1000
1000
> 1000
> 1000
500
1000
250
500
500
> 1000
–
–
–
> 1000
1000
> 1000
1000
500
1000
250
500
500
> 1000
–
–
–
AP-9
AP-10
AP-11
AP-12
AP-13
AP-14
AP-15
AP-16
AP-17
Gentamycine
Ampicillin
Chloramphenicol
Ciprofloxacin
Norfloxacin
Nystatin
2-Hydroxy phenyl
100
50
100
50
–
–
25
10
–
–
25
50
50
–
–
–
100
100
–
–
100
100
10
10
10
–
–
–
–
–
100
500
Greseofulvin
–
–

2650 Shah et al.
Asian J. Chem.
N-[3,5-bis(Trifluoromethyl)phenyl]-3-(4-(dimethyl-
ental analysis (%) Found (calcd.): C 51.64 (51.64), H 3.70
(3.71), N 23.33 (23.34), O 3.28 (3.28).
amino)benzylamino)-5-(methylthio)-1H-pyrazole-4-
carboxamide (AP-6):Yield: 74.26 %, m.f. C22H21N5OSF6; m.p.
N-[3,5-bis(Trifluoromethyl)phenyl]-3-(4-methoxy-
benzylamino)-5-(methylthio)-1H-pyrazole-4-carboxamide
(AP-12): Yield: 73.14 %, m.f. C21H18N4O2SF6; m.p. 210-214
ºC; m.w. 504.11. 1H NMR (400 MHz, DMSO-d6) δ ppm: 2.35
(s, 3H), 3.82 (s, 3H), 2.52 (s, 3H), 4.34-4.35 (d, J = 6.8 Hz, 2H),
6.85-6.87 (d, J = 7.2 Hz, 2H), 7.25-7.27 (d, J = 7.2 Hz, 2H),
7.75 (s, 1H), 8.12-8.15 (m, 2H), 9.58 (s, 1H), 12.20 (s, 1H).
1
215-220 ºC; m.w. 517.14. H NMR (400 MHz, DMSO-d6) δ
ppm: 2.53 (s,3H), 3.09 (s, 6H), 4.33-4.34 (d, J = 6.8 Hz,2H),
6.71-6.74 (m, 2H), 7.05-7.10 (m, 2H), 7.65 (s,1H), 8.15 (s,1H),
9.15 (s,1H), 9.58 (s,1H), 12.22 (s,1H) ppm; MS: m/z 490.9
(M+H)+. IR (KBr, νmax, cm-1): 3295.56 (N-H amine), 1665.32
(-CONH-), 1377.17 (C-N amine), 1124.5 (C-F). Elemental anal-
ysis (%) Found (calcd.): C 51.06 (51.06), H 4.09 (4.09), N 13.53
(13.53), O 3.09 (3.09).
-1
MS: m/z 504.9 (M+H)+. IR(KBr,νmax,cm ):3291.12 (N-H amine),
1663.45 (-CONH-), 1281.75, (C-N amine), 1123.5 (C-F). Elem-
ental analysis (%) Found (calcd.): C 50.01 (50.00), H 3.60 (3.60),
N 11.11 (11.11), O 6.34 (6.34).
N-[3,5-bis(Trifluoromethyl)phenyl]-5-(methylthio)-3-
(pyridin-4-ylmethylamino)-1H-pyrazole-4-carboxamide
(AP-7):Yield: 67.90 %, m.f. C19H15N5OSF6; m.p. 226-229 ºC;
m.w. 475.09. 1H NMR (400 MHz, DMSO-d6) δ ppm: 2.58 (s,
3H), 4.51-4.53 (d, J = 7.2 Hz, 2H), 7.35-7.39 (m, 2H), 7.81 (s,
1H), 8.22-8.34 (m, 2H), 8.52-8.55 (m, 2H), 9.75 (s, 1H), 12.52
(s, 1H); MS: m/z 475.9 (M+H)+. IR (KBr, νmax, cm-1): 3332.25
(N-H amine), 1665.75 (-CONH-), 1278.88 (C-N amine), 1123.42
(C-F). Elemental analysis (%) Found (calcd.): C 48.01 (48.00),
H 3.18 (3.18), N 14.73 (14.73), O 3.37 (3.37).
N-[3,5-bis(Trifluoromethyl)phenyl]-3-(4-methyl-
benzylamino)-5-(methylthio)-1H-pyrazole-4-carboxamide
(AP-8): Yield: 64.52 %, m.f. C21H18N4OSF6; m.p. 245-249 ºC;
m.w. 488.11. 1H NMR (400 MHz, DMSO-d6) δ ppm: 2.35 (s,
3H), 2.52 (s, 3H), 4.34-4.35 (d, J= 6.8 Hz, 2H), 7.12-7.16 (m, 4H),
7.78 (s, 1H), 8.12-8.15 (m, 2H), 9.59 (s, 1H), 12.20 (s, 1H). MS:
m/z 489.9 (M+H)+. IR (KBr, νmax, cm-1): 3290.29 (N-H amine),
1663.51 (-CONH-), 1281.65 (C-N amine), 1123.5 (C-F). Elem-
ental analysis (%) Found (calcd.): C 51.64 (51.64), H 3.71
(3.71), N 23.33 (23.34), O 3.28 (3.28).
N-[3,5-bis(Trifluoromethyl)phenyl]-3-(2-bromobenzyl-
amino)-5-(methylthio)-1H-pyrazole-4-carboxamide (AP-
9): Yield: 55.66 %, m.f. C20H15N4OSBrF6; m.p. 281-284 ºC;
m.w. 552.01. 1H NMR (400 MHz, DMSO-d6) δ ppm: 2.53 (s,
3H), 4.32-4.34 (d, J = 7.2 Hz, 2H), 7.12-7.15 (m, 2H), 7.19-7.22
(m, 2H), 7.75 (s, 1H), 8.11-8.13 (m, 2H), 9.56 (s, 1H), 12.19
(s, 1H). MS: m/z 452.9 (M+H)+. IR (KBr, νmax, cm-1): 3571.24
(N-H amine), 16532.52 (-CONH-), 1277.81 (C-N amine), 1131.19
(C-F), 679.91 (C-Br). Elemental analysis (%) Found (calcd.):
C 43.41 (43.41), H 2.73 (2.73), N 10.13 (10.13), O 2.88 (2.89).
N-[3,5-bis(Trifluoromethyl)phenyl]-3-(4-bromobenzyl-
amino)-5-(methylthio)-1H-pyrazole-4-carboxamide (AP-
10): Yield: 64.70 %, m.f. C20H15N4OSBrF6; m.p. 271-274 ºC;
m.w. 552.01. 1H NMR (400 MHz, DMSO-d6) δ ppm: 2.56 (s,
3H), 4.74.49 (d, J = 7.2 Hz, 2H), 7.30-7.36 (m, 4H), 7.53 (s, 1H),
7.94 (s, 1H), 8.22 (m, 2H), 9.62 (s, 1H), 12.51 (s, 1H). MS: m/z
452.9 (M+H)+. IR (KBr, νmax, cm-1): 3329.14 (N-H amine), 1661.12
(-CONH-), 1276.88 (C-N amine), 1127.86 (C-F), 678.15 (C-Br).
Elemental analysis (%) Found (calcd.): C 43.41 (43.41), H 2.72
(2.73), N 10.13 (10.13), O 2.88 (2.89).
N-[3,5-bis(Trifluoromethyl)phenyl]-3-(2-chlorobenzyl-
amino)-5-(methylthio)-1H-pyrazole-4-carboxamide (AP-
13): Yield: 65.76 %, m.f. C20H15N4OSClF6; m.p. 202-205 ºC;
m.w. 508.06. 1H NMR (400 MHz, DMSO-d6) δ ppm: 2.53 (s,
3H), 4.32-4.34 (d, J = 7.2 Hz, 2H), 7.11-7.15 (m, 2H), 7.19-
7.21 (m, 2H), 7.75 (s, 1H), 8.11-8.13 (m, 2H), 9.56 (s, 1H),
12.19 (s, 1H). MS: m/z 5089 (M+H)+. IR (KBr, νmax, cm-1):
3571.24 (N-H amine), 16532.52 (-CONH-), 1277.81 (C-N amine),
1131.19 (C-F), 679.91 (C-Br), 812.03 (C-Cl). Elemental
analysis (%) Found (calcd.): C 47.21 (47.21), H 2.97 (2.97),
N 11.01 (11.01), O 3.15 (3.14).
N-[3,5-bis(Trifluoromethyl)phenyl]-3-(4-fluorobenzyl-
amino)-5-(methylthio)-1H-pyrazole-4-carboxamide (AP-
14): Yield: 60.87 %, m.f. C20H15N4OSF7; m.p. 244-247 ºC;
m.w. 492.09. 1H NMR (400 MHz, DMSO-d6) δ ppm: 2.56 (s,
3H), 4.49-4.47 (d, J= 7.2 Hz, 2H), 7.32-7.41 (m, 4H), 7.55 (s, 1H),
7.95 (s, 1H), 8.12-8.15 (m, 2H), 9.61 (s, 1H), 12.51 (s, 1H).
MS: m/z 492.8 (M+H)+. IR (KBr, νmax, cm-1): 3329.14 (N-H amine),
1660.71 (-CONH-), 1276.88 (C-N amine), 1130.36 (C-F). Elem-
ental analysis (%) Found (calcd.): C 48.78 (48.78), H 3.07
(3.07), N 11.38 (11.38), O 3.26 (3.25).
N-[3,5-bis(Trifluoromethyl)phenyl]-3-(3,4-difluoro-
benzylamino)-5-(methylthio)-1H-pyrazole-4-carboxamide
(AP-15): Yield: 59.48 %, m.f. C20H14N4OSF8; m.p. 239-243
ºC; m.w. 510.08. 1H NMR (400 MHz, DMSO-d6) δ ppm: 2.56
(s, 3H), 4.49-4.47 (d, J = 7.2 Hz, 2H), 6.75 (m, 1H), 7.15-7.21
(m, 2H), 7.55 (s, 1H), 7.75 (s, 1H), 8.11-8.14 (m, 2H), 9.63 (s, 1H),
12.52 (s, 1H). MS: m/z 510.8 (M+H)+. IR (KBr, νmax, cm-1):
3329.14 (N-H amine), 1661.52 (-CONH-), 1276.88 (C-N amine),
1131.25 (C-F). Elemental analysis (%) Found (calcd.): C 47.05
(47.06), H 2.77 (2.76), N 10.98 (10.98), O 3.12 (3.13).
N-[3,5-bis(Trifluoromethyl)phenyl]-5-(methylthio)-3-
(thiophen-3-ylmethylamino)-1H-pyrazole-4-carboxamide
(AP-16): Yield: 65.60 %, m.f. C18H14N4OS2F6; m.p. 210-215
ºC; m.w. 480.05. 1H NMR (400 MHz, DMSO-d6) δ ppm: 2.34
(s, 3H), 2.53 (s, 3H), 4.34-4.36 (d, J = 6.8 Hz, 2H), 6.74-6.76 (m,
2H), 7.59 (s, 1H), 7.75 (s, 1H), 8.12-8.14 (m, 2H), 9.60 (s, 1H),
12.22 (s, 1H). MS: m/z 480.9 (M+H)+. IR (KBr, νmax, cm-1): 3291.29
(N-H amine), 1662.81 (-CONH-), 1280.65 (C-N amine), 1123.5
(C-F). Elemental analysis (%) Found (calcd.): C 45.01 (45.00),
H 2.94 (2.94), N 11.67 (11.66), O 3.33 (3.33).
N-[3,5-bis(Trifluoromethyl)phenyl]-3-(2-methylbenzyl-
amino)-5-(methylthio)-1H-pyrazole-4-carboxamide (AP-
11): Yield: 65.31 %, m.f. C21H18N4OSF6; m.p. 251-253 ºC;
m.w. 488.11. 1H NMR (400 MHz, DMSO-d6) δ ppm: 2.34 (s,
3H), 2.52 (s, 3H), 4.33-4.35 (d, J= 6.8 Hz, 2H), 7.12-7.16 (m, 4H),
7.79 (s, 1H), 8.11-8.13 (m, 2H), 9.59 (s, 1H), 12.20 (s, 1H).
MS: m/z 489.9 (M+H)+. IR(KBr, νmax,cm-1):3290.29 (N-H amine),
1662.81 (-CONH-), 1281.65 (C-N amine), 1123.5 (C-F). Elem-
N-[3,5-bis(Trifluoromethyl)phenyl]-3-(2-hydroxy-
benzylamino)-5-(methylthio)-1H-pyrazole-4-carboxamide
(AP-17): Yield: 66.61 %, m.f. C20H16N4O2SF6; m.p. 241-244
ºC; m.w. 490.09. 1H NMR (400 MHz, DMSO-d6) δ ppm: 2.53
(s, 3H), 4.31-4.32 (d, J = 7.2 Hz, 2H), 6.71-6.77 (m, 4H), 77.56

Vol. 30, No. 12 (2018)
Synthesis Characterization and Biological Evaluation of Some Novel Amino Pyrazole Derivatives 2651
(s, 1H), 8.11-8.13 (m, 2H), 9.58 (s, 1H), 9.89 (s, 1H), 12.22 (s,
1H). MS: m/z 490.9 (M+H)+. IR (KBr, νmax, cm-1): 3292.49
(N-H amine), 1664.57 (-CONH-), 1376.89 (-O-H), 1281.56 (C-N
amine), 1124.5 (C-F). Elemental analysis (%) Found (calcd.):
C 48.98 (48.98), H 3.29 (3.29), N 11.41 (11.42), O 6.52 (6.54).
Biological evaluation: All manufacturing compounds
were tested for their in vitro antifungal and antibacterial activity.
For evaluation of antibacterial activity, the representative strains
of Gram-negative bacteria (P. aeruginosa, E. coli) and Gram-
positive bacteria (S. pyogenus, S. aureus) are used. For testing
antifungal activity A. clavatus, A. niger and C. albicans, were
used.All standard medicine was procured from Institute of Micro
Care Laboratory, Surat, India. For testing antifungal activity
greseofulvin & nystatin standard were used while for antibac-
terial activity The ampicillin, chloramphenicol, gentamycin,
ciprofloxacin and norfloxacin standard were used for the
comparison. The minimum inhibitory concentration (MIC) was
prominent as the minimum concentration of the test element,
which completely inhibits the growth of microorganism i.e.
100 % transparency.
ACKNOWLEDGEMENTS
The authors are thankful toVaibhav Laboratory,Ahmedabad,
India for extending their support for instrumental analyses.
CONFLICT OF INTEREST
The authors declare that there is no conflict of interests
regarding the publication of this article.
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