Synthesis and antimicrobial activity of some heterocyclic compounds bearing benzimidazole and pyrazoline motifs

Article abstract of DOI:10.1007/s00044-017-2040-5

Abstract: A series of 1-(3-(1H-benzoimidazol-2-yl)-5-aryl-4-5dihydro-1H-pyrazol-1-yl)-2-(napthalene-1-yloxy)ethanones (5a–l) are synthesized and evaluated their antimicrobial activity against gram positive (S. aureus and S. pyogenes), gram negative bacteria (E. coli and P. aeruginosa), and strains of fungi (C. albicans, A. niger, and A. clavatus). Compounds were characterized by spectroscopic techniques such as ¹H NMR, ¹³C NMR, IR, and mass spectroscopy. The newly synthesized compounds 5b, 5i and 5j, 5k showed significant antimicrobial activity against tested microorganisms. Graphical abstract: [InlineMediaObject not available: see fulltext.].

Full text of DOI:10.1007/s00044-017-2040-5

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-017-2040-5
ORIGINAL RESEARCH
Synthesis and antimicrobial activity of some heterocyclic
compounds bearing benzimidazole and pyrazoline motifs
1 ●
1 ●
1
N. C. Desai Darshan Pandya Darshita Vaja
Received: 22 April 2017 / Accepted: 16 August 2017
©
Springer Science+Business Media, LLC 2017
Abstract A series of 1-(3-(1H-benzoimidazol-2-yl)-5-aryl-
-5dihydro-1H-pyrazol-1-yl)-2-(napthalene-1-yloxy)etha-
Introduction
4
nones (5a–l) are synthesized and evaluated their anti-
microbial activity against gram positive (S. aureus and S.
pyogenes), gram negative bacteria (E. coli and P. aerugi-
nosa), and strains of fungi (C. albicans, A. niger, and A.
clavatus). Compounds were characterized by spectroscopic
Bacteria and fungi have developed resistance strains against
currently available antimicrobial agents and therefore it is
essential for medicinal chemists to design and synthesize
novel antimicrobial agents having less toxicity and more
potent effects in much lesser time. In continuation to this,
chemists have successfully synthesized effective agents
based on heterocyclic compounds. The shining examples
are furamizole, nasapadil, tazobactam, and cefatrizine.
Benzimidazoles have various types of pharmacological
effects, including antimicrobial (Sekar et al. 2016), anthel-
matics (Mckellar and Scott 1990), and antiprolifretive
1
13
techniques such as H NMR, C NMR, IR, and mass
spectroscopy. The newly synthesized compounds 5b, 5i and
5
j, 5k showed significant antimicrobial activity against
tested microorganisms.
Graphical abstract
(Garuti et al. 2000). Numerous examples show that benzi-
midazole and its derivatives play an important role in
development of antimicrobial agents. Benzimidazole deri-
vatives have been synthesized by the condensation of o-
phenylenediamine with acids, their nitriles, imidates and
orthoesters (Alaqeel 2017).
Our research group has previously synthesized benzi-
midazole derivatives and we have received some exiting
antimicrobial results (Desai et al. 2014a, b). Therefore, we
have focused on benzimidazole-based pyrazoline deriva-
tives which possess diverse chemical structures. These
hybrid structures may be useful for the development of
antimicrobial agents. The development of efficient pre-
paration of benzimidazole-based pyrazoline played a key
role in modern organic synthesis. The pyrazoline scaffold
displays important biological activities such as antioxidant
●
●
Keywords Pyrazoline Benzimidazole Antimicrobial
●
●
activity Antibacterial activity Antifungal activity
Electronic supplementary material The online version of this article
doi:10.1007/s00044-017-2040-5) contains supplementary material,
which is available to authorized users.
(
(Padmaja et al. 2011), analgesic (Gawad et al. 2012), anti-
*
N. C. Desai
dnisheeth@rediffmail.com
inflammatory (Kumar et al. 2015), anti-infective (Desai
et al. 2014a, b), anti-HIV (Fernandez et al. 2014), antiviral
1
Department of Chemistry, Division of Medicinal Chemistry, UGC
NON-SAP & DST-FIST Sponsored Department, Mahatma Gandhi
Campus, Maharaja Krishnakumar Sinhji Bhavnagar University,
Bhavnagar 364002, India
(
Ouyang et al. 2008), antidepressant (Kaplancikli et al.
010), antitumor (Lesyk et al. 2012), and antitubercular
(Pathak et al. 2012, Khunt et al. 2012). Mebendazole
2

Med Chem Res
Fig. 1 Benzimidazole and
pyrazoline containing marketed
drugs
[
[
Formula (I)] (Ingle and Magar 2011) and ibipinabant
Formula (II)] (Desai et al. 2013) both are well known drugs
available in the market (Fig. 1). In the present paper, we
have clubbed benzimidazole and pyrazoline moieties in one
molecular structure for the synthesis of more potential
antimicrobial agents. We have synthesized a series of 1-(3-
(
1H-benzoimidazol-2-yl)-5-aryl-4-5dihydro-1H-pyrazol-1-
yl)-2-(napthalene-1-yloxy)ethanones (5a–l). The structures
of targeted compounds were characterized on the basis of
1
3
1
C nuclear magnetic resonance (NMR), H NMR, infrared
IR), and mass spectroscopy. These derivatives exhibited
(
antimicrobial activity on various strains of bacteria and
fungi.
Scheme 1 Synthetic pathway of compounds (5a–l)
hydrate was refluxed in ethanol to yield intermediate N-
amino-2-napthyloxyacetamide (3). In the final step, inter-
mediate (3) and 1-(1H-benzoimidazol-2-yl)-3-arylprop-2en-
Experimental
Materials and methods
1-ones (4a–l) were refluxed in acetic acid and cyclised to
furnished final compounds (5a–l)(Scheme 1).
For determination of melting point open capillary method
was used. Thin layer chromatography (TLC) on silica gel
plates was used for reaction monitoring. Percentage of C, H,
and N was checked by a Perkin-Elmer 2400 CHN analyzer.
IR spectra of all compounds were recorded on a Shimadzu
IR Prestige-21 (CE) Fourier transform infrared spectro-
Synthesis of ethyl 2-naphthyloxyacetate (2), N-amino-2-
napthyloxyacetamide (3) and 1-(1H-benzoimidazol-2-yl)-3-
arylprop-2-en-1-ones (4a–l)
−
1
photometer in KBr; the frequencies were reported in cm
.
Compound ethyl-2-naphthyloxyacetate (2) and N-amino-2-
napthyloxyacetamide (3) were prepared according to the
method of (Rokade and Dongare 2010; Kumar et al. 2012).
1
H NMR spectra were carried out on Varian Gemini 400
1
3
MHz and C NMR spectra on Varian Mercury 400, 100
MHz in this dimethyl sulfoxide (DMSO)-d as a used sol-
6
Similarly
1-(1H-benzoimidazol-2-yl)-3-arylprop-2-en-1-
1
vent, and tetramethylsilane used as a internal standard. H
ones were also prepared (Behera et al. 2016).
data were given in multiplicity (s, singlet; d, doublet; t,
triplet; m, multiple) and chemical shifts were interpreting in
δ ppm. Mass spectroscopic data were scanned on a Shi-
madzu LCMS 2010 spectrometer. Büchi Rota vapor was
used for the distillation.
Synthesis of 1-(3-(1H-benzoimidazol-2-yl)-5-aryl-4-
5dihydro-1H-pyrazol-1-yl)-2-(napthalen-1-yloxy)ethanones
(
5)
Chemistry
A mixture of 1-(1H-benzoimidazol-2-yl)-3-phenylprop-2-
en-1-one (4) (0.001 mol) and compound (3) (0.002 mol)
were taken in 20 ml glacial acetic acid and refluxed at
130 °C for a period of 10 h. The mixture was concentrated
under vacuum and diluted with ice cold water. On com-
pletion of the reaction, purity of compounds were checked
by TLC using hexane-ethyl acetate (8:2 v/v) as mobile
The synthesized compounds (5a–l) were prepared in four
steps. Compound (2) was synthesized from a mixture of α-
napthol, ethylchloro acetate, and refluxed in water bath. Dry
acetone used as a solvent and anhydrous K CO used as a
2
3
catalyst. In second step, compound (2) and hydrazine

Med Chem Res
phase and developed in an iodine chamber. All compounds
134.9 (2C, C and C benzimidazole ring), 132.4 (1C, C
8 9
aromatic ring), 128.6 (1C, C aromatic ring), 128.3 (1C, C
3
6
4
(
5a–l) of this series were prepared using the same method.
aromatic ring), 128.0 (1C, C5 aromatic ring), 127.3
(1C, C naphthalene ring), 126.2 (2C, C aromatic ring and
1
-(3-(1H-benzoimidazol-2-yl)-5-phenyl-4-5dihydro-1H-
pyrazol-1-yl)-2-(napthalen-1-yloxy)ethanone (5a) Off
white (MeOH) (yield 64%) mp 219–222 °C; IR
5
3
C6 naphthalene ring), 126.9 (1C, C3 naphthalene ring),
125.5 (1C, C naphthalene ring), 123.8 (1C, C naphthalene
7
8
KBr, cm− ): 3442 (N–H stretching, secondary amine),
060 (C–H stretching, aromatic ring), 2928 (C–H stretch-
ing, –CH group), 1680 (C=O stretching, aromatic ketone),
1
ring), 123.2 (2C, C and C benzimidazole ring), 120.7 (1C,
5 6
C naphthalene rig), 115.9 (2C, C and C benzimidazole
5 7 4
(
3
ring), 107.8 (1C, C naphthalene ring), 67.9 (1C, –OCH –),
2
2
2
1
500 (–C=N stretching aromatic ring), 1457 (C=C
61.6 (1C, C pyrazoline ring), 39.0 (1C, C pyrazoline
4 5
ring); MS (m/z): 480.1 (M ); anal. calcd. for
+
stretching, aromatic ring), 1230, 1120 (C–O–C stretching);
1
H NMR (400 MHz, DMSO-d ): δ = 12.73 (s, 1H, –NH),
(C H ClN O ): C, 69.92; H, 4.40; N, 11.65%; found: C,
6
28 21
4 2
6
1
1
–
.54–8.51 (m, 16H, Ar–H), 5.23 (d, JAC = 3.09 Hz, JBC
=
=
69.98; H, 4.48; N, 11.75%.
1.08 Hz, 1H, >CH–H ), 4.92 (d, JAB = 17.41 Hz, JBC
C
1.02 Hz, 1H, C -H pyrazoline H ), 4.74 (s, 2H,
Physical constant and characterization 1-(3-(1H-benzoimi-
dazol-2-yl)-5-(2-hydroxyphenyl-4-5dihydro-1H-pyrazol-1-
yl)-2-(napthalen-1-yloxy)ethanone (5c) Yellowish white
(MeOH) (yield 66%) mp 144–147 °C; IR (KBr, cm ):
3444 (N–H stretching, secondary amine), 3390 (O–H
stretching), 3065 (C–H stretching, aromatic ring), 2925
(C–H stretching, –CH2 group), 1681 (C=O stretching,
aromatic ketone), 1508 (–C=N stretching aromatic ring),
5
B
O–CH –), 3.64 (d, J = 17.48 Hz, JAC = 3.07 Hz, 1H,
2
AB
3
1
C -H pyrazoline H ); C NMR (100 MHz, DMSO-d ): δ
=
4
A
6
−1
169.7 (>C=O), 156.4 (1C, C naphthalene ring), 155.1
1
(1C, C3 pyrazoline ring), 151.7 (1C, C2 benzimidazole
ring), 141.1 (1C, C aromatic ring), 134.4 (2C, C and C
9
1
8
benzimidazole ring), 134.8 (1C, C naphthalene ring), 134.7
9
(
1C, C10 naphthalene ring), 128.3 (1C, C and C aromatic
3 5
ring), 127.1 (1C, C5 naphthalene ring), 126.0 (1C, C6
1452 (C=C stretching, aromatic ring), 1232, 1124 (C–O–C
1
naphthalene ring), 126.4 (1C, C naphthalene ring), 126.6
stretching); H NMR (400 MHz, DMSO-d ): δ = 12.81 (s,
3
6
(
1C, C aromatic ring), 126.7 (2C, C and C aromatic ring),
1H, –NH), 6.45–8.40 (m, 15H, Ar–H), 5.32 (s, 1H, –OH),
4
2
6
1
25.0 (1C, C naphthalene ring), 123.8 (1C, C naphthalene
7 8
5.25 (d, JAC = 3.11 Hz, JBC = 11.04 Hz, 1H, >CH–HC),
ring), 123.1 (2C, C and C benzimidazole ring), 120.7 (1C,
4.75 (s, 2H, –O–CH –), 3.74 (d, J = 17.40 Hz, JBC =
2 AB
6
5
C naphthalene ring), 115.6 (2C, C and C benzimidazole
11.11 Hz, 1H, C -H pyrazoline H ), 3.25 (d, J = 17.40
Hz, JAC = 3.04 Hz, 1H, C -H pyrazoline H ); C NMR
4 A
4
7
4
5 B AB
1
3
ring), 107.0 (1C, C2 naphthalene ring), 67.7 (1C,
O–CH –), 66.3 (1C, C pyrazoline ring), 39.0 (1C, C
–
(100 MHz, DMSO-d ): δ = 169.3 (1C, >C=O), 156.7 (1C,
2
5
4
6
+
pyrazoline ring); MS (m/z): 446.02 (M ); anal. calcd. for
C naphthalene ring), 155.1 (1C, C pyrazoline ring), 154.3
1
3
(
C H N O ): C, 75.32; H, 4.97; N, 12.55%; found: C,
(1C, C aromatic ring), 151.8 (1C, C benzimidazole ring),
2 2
2
8
22
4
2
7
5.40; H, 5.10; N, 12.62%.
134.4 (2C, C and C benzimidazole ring), 134.0 (1C, C
8 9 9
naphthalene ring), 134.7 (1C, C10 naphthalene ring), 130.1
(1C, C aromatic ring), 128.4 (1C, C aromatic ring), 127.9
Physical constant and characterization 1-(3-(1H-benzoimi-
dazol-2-yl)-5-(2-chlorophenyl-4-5dihydro-1H-pyrazol-1-
yl)-2-(napthalen-1-yloxy)ethanone (5b) Brown solid
1
4
(1C, C naphthalene ring), 126.8 (1C, C naphthalene ring),
4
6
126.7 (1C, C aromatic ring), 126.0 (1C, C naphthalene
2
3
−1
(
MeOH) (yield 70%) mp 195–197 °C; IR (KBr, cm ):
440 (N–H stretching, secondary amine), 3063 (C–H
ring), 125.4 (1C, C naphthalene ring), 123.4 (2C, C and
7 5
C benzimidazole ring), 121.4 (1C, C aromatic ring), 120.4
6 3
3
stretching, aromatic ring), 2923 (C–H stretching, –CH2
group), 1683 (C=O stretching, aromatic ketone), 1504
(1C, C naphthalene ring), 115.4 (2C, C and C benzimi-
4 4 7
dazole), 107.1 (1C, C2 naphthalene ring), 67.3 (1C,
(
–C=N stretching aromatic ring), 1456 (C=C stretching,
–OCH –), 66.8 (1C, C pyrazoline ring), 39.4 (1C, C
4
pyrazoline ring); MS (m/z): 462.7 (M ); anal. calcd. for
(C H N O ): C, 72.71; H, 4.79; N, 12.11%; found: C,
28 22 4 3
2
5
+
aromatic ring), 1231, 1122 (C–O–C stretching), 895 (C–Cl
stretching); H NMR (400 MHz, DMSO-d ): δ = 12.85 (s,
1
6
1
H, –NH), 6.42–8.42 (m, 15H, Ar–H), 5.21 (d, JAC = 3.10
Hz, JBC = 11.05 Hz, 1H, >CH–HC), 4.74 (s, 2H,
O–CH –), 3.70 (d, JAB = 17.42 Hz, JBC = 11.09 Hz, 1H,
72.80; H, 4.81; N, 12.15%.
–
Physical constant and characterization 1-(3-(1H-benzoimi-
dazol-2-yl)-5-(3-hydroxyphenyl-4-5dihydro-1H-pyrazol-1-
yl)-2-(napthalen-1-yloxy)ethanone (5d) Yellow (MeOH)
(yield 69%) mp 224–227 °C; IR (KBr, cm ): 3448 (N–H
stretching, secondary amine), 3395 (O–H stretching), 3069
(C–H stretching, aromatic ring), 2929 (C–H stretching,
–CH2 group), 1686 (C=O stretching, aromatic ketone),
2
C -H pyrazoline H ), 3.22 (d, J = 17.43 Hz, J = 3.05
Hz, 1H, C -H pyrazoline H ); C NMR (100 MHz,
DMSO-d ): δ = 169.3 (>C=O), 156.1 (1C, C naphthalene
ring), 155.7 (1C, C pyrazoline ring), 151.4 (1C, C ben-
zimidazole ring), 138.4 (1C, C aromatic ring), 134.1 (1C,
C naphthalene ring), 134.2 (1C, C naphthalene ring),
5
B
AB
AC
1
3
4
A
−1
6
1
3
2
1
9
10

Med Chem Res
1
510 (–C=N stretching aromatic ring), 1455 (C=C
(1C, C pyrazoline ring), 39.7 (1C, C pyrazoline ring);
MS (m/z): 462.9 (M ); anal. calcd. for (C H N O ):
28 22 4 3
C, 72.71; H, 4.79; N, 12.11%; Found: C, 72.80; H, 4.88;
N-12.19%.
5
4
+
stretching, aromatic ring), 1235, 1126 (C–O–C stretching);
1
H NMR (400 MHz, DMSO-d ): δ = 12.77 (s, 1H, –NH),
6
6
.48–8.49 (m, 15H, Ar–H), 5.38 (s, 1H, –OH), 5.20 (d, JAC
=
3.13 Hz, JBC = 11.04 Hz, 1H, >CH–H ), 3.78 (d, JAB
=
C
1
7.41 Hz, JBC = 11.12 Hz, 1H, C -H pyrazoline H ), 4.80
Physical constant and characterization 1-(3-(1H-benzoimi-
5
B
(
1
s, 2H, –O–CH –), 3.29 (d, J = 17.43 Hz, JAC = 3.01 Hz,
dazol-2-yl)-5-(4-hydroxy-3-methoxyphenyl-4-5dihydro-
2
AB
3
1
H, C -H pyrazoline H ); C NMR (100 MHz, DMSO-
1H-pyrazol-1-yl)-2-(napthalen-1-yloxy)ethanone
(5f)
4
A
d ): δ = 169.3 (1C, >C=O), 156.0 (1C, C naphthalene
Brown (MeOH) (yield 65%) mp 182–185 °C; IR (KBr,
cm ): 3452 (N–H stretching, secondary amine), 3400
(O–H stretching), 3075 (C–H stretching, aromatic ring),
6
1
−1
ring), 155.3 (1C, C pyrazoline ring), 151.6 (1C, C ben-
3
2
zimidazole ring), 142.8 (1C, C aromatic ring), 134.9 (2C,
1
C and C benzimidazole ring), 134.6 (1C, C naphthalene
2930 (C–H stretching, –CH group), 2820 (C–H stretching,
8
9
9
2
ring), 134.5 (1C, C10 naphthalene ring), 127.0 (1C, C5
–OCH group), 1689 (C=O stretching, aromatic ketone),
3
naphthalene ring), 126.9 (1C, C naphthalene ring), 126.8
1506 (–C=N stretching aromatic ring), 1459 (C=C
6
(
1
1C, C naphthalene ring), 125.0 (1C, C naphthalene ring),
stretching, aromatic ring), 1231, 1129 (C–O–C stretching);
3
7
1
23.8 (2C, C and C benzimidazole ring), 123.2 (1C, C
H NMR (400 MHz, DMSO-d ): δ = 12.70 (s, 1H, –NH),
5
6
8
6
naphthalene ring), 120.7 (1C, C naphthalene ring), 119.1
6.49–8.46 (m, 14H, Ar–H), 5.35 (s, 1H, –OH), 5.26 (d, JAC
4
(
1C, C aromatic ring), 115.0 (2C, C and C benzimidazole
= 3.19 Hz, JBC = 11.09 Hz, 1H, >CH–H ), 4.86 (s, 2H,
2
4
7
C
ring), 113.0 (1C, C aromatic ring), 112.4 (1C, C aromatic
–O–CH –), 3.85 (s, 3H, –OCH ), 3.78 (d, J = 17.46 Hz,
4
6
2
3
AB
ring), 107.4 (1C, C naphthalene ring), 67.0 (1C, –OCH –),
JBC = 11.17 Hz, 1H, C -H pyrazoline H ), 3.26 (d, J
=
C
2
2
5
B
AB
1
3
6
6.4 (1C, C pyrazoline ring), 39.0 (1C, C pyrazoline
17.49 Hz, JAC = 3.01 Hz, 1H, C -H pyrazoline H );
5
4
4
A
+
ring); MS (m/z): 462.7 (M ); anal. calcd. for (C H N O ):
NMR (100 MHz, DMSO-d ): δ = 169.0 (1C, >C=O),
2
8
22
4
3
6
C, 72.71; H, 4.79; N, 12.11%; found: C, 72.81; H, 4.84; N,
2.19%.
156.7 (1C, C naphthalene ring), 155.7 (1C, C pyrazoline
1
3
1
ring), 151.7 (1C, C benzimidazole ring), 147.0 (1C, C
2
3
1
aromatic ring), 146.0 (1C, C aromatic ring), 134.4 (1C, C
4
Physical constant and characterization 1-(3-(1H-benzoimi-
dazol-2-yl)-5-(4-hydroxy-4-5dihydro-1H-pyrazol-1-yl)-2-
aromatic ring), 139.0 (2C, C and C benzimidazole ring),
8 9
134.2 (1C, C naphthalene ring), 134.7 (1C, C naphtha-
9
10
(
6
napthalen-1-yloxy)ethanone (5e) Buff (MeOH) (yield
1%) mp 168–171 °C; IR (KBr, cm−1): 3449 (N–H
stretching, secondary amine), 3397 (O–H stretching), 3070
C–H stretching, aromatic ring), 2926 (C–H stretching,
lene ring), 127.0 (1C, C naphthalene ring), (2C, C and C
5 2 6
aromatic ring), 126.7 (1C, C naphthalene ring), 126.4 (1C,
6
C3 naphthalene ring), 127.0 (1C, C7 naphthalene ring),
123.8 (2C, C and C benzimidazole ring), 123.4 (1C, C
8
(
5
6
–
CH2 group), 1685 (C=O stretching, aromatic ketone),
naphthalene ring), 120.9 (1C, C naphthalene ring), 115.8
4
1
509 (–C=N stretching aromatic ring), 1457 (C=C
(2C, C and C benzimidazole ring), 119.0 (1C, C aromatic
7
4
6
stretching, aromatic ring), 1238, 1127 (C–O–C stretching);
ring), 115.7 (1C, C aromatic ring), 110.7 (1C, C aromatic
3 2
ring), 107.7 (1C, C naphthalene ring), 67.0 (1C, –OCH –),
2 2
1
H NMR (400 MHz, DMSO-d ): δ = 12.74 (s, 1H, –NH),
6
6
=
.44–8.42 (m, 15H, Ar–H), 5.35 (s, 1H, –OH), 5.23 (d, JAC
66.0 (1C, C pyrazoline ring), 56.7 (1C, –OCH ) 39.0 (1C,
5 3
C pyrazoline ring); MS (m/z): 492.5 (M ); anal. calcd. for
4
+
3.14 Hz, JBC = 11.02 Hz, 1H, >CH–H ), 4.85 (s, 2H,
C
–
O–CH –), 3.74 (d, JAB = 17.42 Hz, JBC = 11.11 Hz, 1H,
(C H N O ): C, 70.72; H, 4.91; N, 11.38%; found: C,
29 24 4 4
2
C -H pyrazoline H ), 3.25 (d, J = 17.45 Hz, J = 3.00
70.82; H, 4.95; N, 11.45%.
5
B
AB
AC
1
3
Hz, 1H, C -H pyrazoline H ); C NMR (100 MHz,
4
A
DMSO-d ): δ = 169.2 (1C, >C=O), 156. 5 (1C, C aro-
Physical constant and characterization 1-(3-(1H-benzoimi-
dazol-2-yl)-5-(2-nitrophenyl-4-5dihydro-1H-pyrazol-1-yl)-
2-(napthalen-1-yloxy)ethanone (5g) Dark yellow (MeOH)
(yield 60%) mp 141–143 °C; IR (KBr, cm ): 3454 (N–H
stretching, secondary amine), 3076 (C–H stretching, aro-
matic ring), 2932 (C–H stretching, –CH2 group), 1691
(C=O stretching, aromatic ketone), 1535 (N=O stretching,
aromatic ring), 1503 (–C=N stretching aromatic ring), 1463
6
4
matic ring), 156.2 (1C, C naphthalene ring), 155.4 (1C, C
1
3
pyrazoline ring), 151.9 (1C, C benzimidazole ring), 134.8
2
−1
(
1C, C aromatic ring), 134.2 (2C, C and C benzimidazole
1
8
9
ring), 134.9 (1C, C naphthalene ring), 134.7 (1C, C
9
10
naphthalene ring), 127.0 (2C, C and C aromatic ring),
2
6
1
27.5 (1C, C naphthalene ring), 126.3 (1C, C naphthalene
5 6
ring), 126.0 (1C, C3 naphthalene ring), 125.4 (1C, C7
naphthalene ring), 123.4 (2C, C and C benzimidazole
(C=C stretching, aromatic ring), 1230, 1130 (C–O–C
5
6
1
ring), 123.0 (1C, C8 naphthalene ring), 120.1 (1C, C4
naphthalene ring), 115.9 (2C, C and C benzimidazole
stretching); H NMR (400 MHz, DMSO-d ): δ = 12.89 (s,
6
1H, –NH), 6.48–8.49 (m, 15H, Ar–H), 5.52 (d, JAC = 3.21
Hz, JBC = 11.06 Hz, 1H, >CH–HC), 4.78 (s, 2H,
–O–CH –), 3.75 (d, J = 17.49 Hz, JBC = 11.19 Hz, 1H,
7
4
ring), 115.0 (2C, C3 and C5 aromatic ring), 107.1
1C, C2 naphthalene ring), 67.7 (1C, –OCH –), 66.0
(
2
2
AB

Med Chem Res
C -H pyrazoline H ), 3.26 (d, J = 17.52 Hz, JAC = 3.05
Physical constant and characterization 1-(3-(1H-benzoimi-
dazol-2-yl)-5-(4-nitrophenyl-4-5dihydro-1H-pyrazol-1-yl)-
2(napthalen-1-yloxy)ethanone (5i) Light orange (MeOH)
(yield 62%) mp 150–152 °C; IR (KBr, cm ): 3457 (N–H
stretching, secondary amine), 3077 (C–H stretching, aro-
matic ring), 2928 (C–H stretching, –CH2 group), 1693
(C=O stretching, aromatic ketone), 1525 (N=O stretching,
aromatic ring), 1511 (–C=N stretching aromatic ring), 1466
5
B
AB
3
1
Hz, 1H, C -H pyrazoline H ); C (100 MHz, DMSO-d6):
4
A
δ = 169.0 (1C, >C=O), 156.7 (1C, C naphthalene ring),
1
−1
1
55.7 (1C, C pyrazoline ring), 151.7 (1C, C benzimida-
3
2
zole ring), 147.0 (1C, C aromatic ring), 137.0 (1C, C
6
1
aromatic ring), 134.9 (2C, C and C benzimidazole ring),
8
9
1
34.3 (1C, C naphthalene ring), 134.1 (1C, C naphtha-
9 10
lene ring), 134.0 (1C, C aromatic ring), 127.4 (1C, C
3
2
aromatic ring), 127.3 (2C, C naphthalene ring and C2
(C=C stretching, aromatic ring), 1240, 1139 (C–O–C
5
1
aromatic ring), 127.0 (1C, C aromatic ring), 126.7 (1C, C6
stretching); H NMR (400 MHz, DMSO-d ): δ = 12.83 (s,
4
6
naphthalene ring), 126.4 (1C, C naphthalene ring), 125.0
1H, –NH), 6.49–8.44 (m, 15H, Ar–H), 5.58 (d, JAC = 3.23
Hz, JBC = 11.07 Hz, 1H, >CH–HC), 4.72 (s, 2H,
–O–CH –), 3.75 (d, J = 17.58 Hz, JBC = 11.13 Hz, 1H,
3
(
1C, C naphthalene ring), 124.0 (1C, C aromatic ring),
7 5
1
23.7 (2C, C and C benzimidazole ring), 123.1 (1C, C
5 6 8
2
AB
naphthalene ring), 120.0 (1C, C naphthalene ring), 115.0
C -H pyrazoline H ), 3.25 (d, J = 17.52 Hz, JAC = 2.99
Hz, 1H, C -H pyrazoline H ); C (100 MHz, DMSO-d6):
4 A
4
5 B AB
3
1
(
2C, C and C benzimidazole ring), 107.9 (1C, C naph-
7
4
2
thalene ring), 67.4 (1C, –OCH –), 61.0 (1C, C pyrazoline
δ = 169.1 (1C, >C=O), 156.0 (1C, C naphthalene ring),
2
5
1
+
ring), 38.0 (1C, C pyrazoline ring); MS (m/z): 491.2 (M );
155.0 (1C, C pyrazoline ring), 151.0 (1C, C benzimida-
4
3
2
anal. calcd. for (C H N O ): C, 68.42; H, 4.31; N,
zole ring), 147.4 (1C, C aromatic ring), 145.0 (1C, C
1 4
2
8
21
5
4
1
4.25%; found: C, 68.51; H, 4.41; N, 14.33%.
aromatic ring), 134.7 (2C, C and C benzimidazole ring),
8 9
1
34.3 (1C, C naphthalene ring), 134.2 (1C, C naphtha-
9 10
lene ring), (2C, C and C aromatic ring), 127.0 (1C, C
5
2
6
Physical constant and characterization 1-(3-(1H-benzoimi-
dazol-2-yl)-5-(3-nitrophenyl-4-5dihydro-1H-pyrazol-1-yl)-
naphthalene ring), 126.4 (1C, C naphthalene ring), 126.2
6
(1C, C naphthalene ring), 125.0 (1C, C naphthalene ring),
2
7
2
-(napthalen-1-yloxy)ethanone (5h) Yellowish orange
123.7 (2C, C and C benzimidazole ring), 123.4 (1C, C
5 6 8
naphthalene ring), 123.5 (2C, C and C aromatic ring),
2 6
123.2 (2C, C and C aromatic ring), 120.0 (1C, C naph-
3 5 4
−1
(
MeOH) (yield 68%) mp 154–156 °C; IR (KBr, cm ):
458 (N–H stretching, secondary amine), 3078 (C–H
3
stretching, aromatic ring), 2933 (C–H stretching, –CH2
group), 1690 (C=O stretching, aromatic ketone), 1530
thalene ring), 115.2 (2C, C and C benzimidazole ring),
7 4
107.0, (1C, C naphthalene ring), 67.7 (1C, –OCH –), 66.4
2
2
(
N=O stretching, aromatic ring), 1507 (–C=N stretching
(1C, C pyrazoline ring), 39.2 (1C, C pyrazoline ring); MS
5 4
+
aromatic ring), 1468 (C=C stretching, aromatic ring), 1234,
1
(m/z): 491.9 (M ); anal. calcd. for (C H N O ): C, 68.42;
2
8 21 5 4
1
136 (C–O–C stretching); H NMR (400 MHz, DMSO-d ):
H, 4.31; N, 14.25%; found: C, 68.49; H, 4.40; N, 14.34%.
6
δ = 12.80 (s, 1H, –NH), 6.45–8.45 (m, 15H, Ar–H), 5.50
d, JAC = 3.18 Hz, JBC = 11.02 Hz, 1H, >CH–H ), 4.78 (s,
(
Physical constant and characterization 1-(3-(1H-benzoimi-
dazol-2-yl)-5-(4-methylphenyl-4-5dihydro-1H-pyrazol-1-
C
2
1
3
H, –O–CH –), 3.72 (d, J = 17.56 Hz, JBC = 11.15 Hz,
2 AB
H, C -H pyrazoline H ), 3.20 (d, J = 17.54 Hz, JAC
=
yl)-2-(napthalen-1-yloxy)ethanone
(5j) Pale
yellow
5
B
AB
3
1
−1
.00 Hz, 1H, C -H pyrazoline H ); C (100 MHz, DMSO-
(MeOH) (yield 60%) mp 190–192 °C; IR (KBr, cm ):
3453 (N–H stretching, secondary amine), 3079 (C–H
stretching, aromatic ring), 2930 (C–H stretching, –CH2
4
A
d ): δ = 169.3 (1C, >C=O), (1C, C aromatic ring), 156.0
6
4
(
1C, C naphthalene ring), 155.3 (1C, C pyrazoline ring),
1
3
1
51.1 (1C, C benzimidazole ring), 147.1 (1C, C aromatic
group), 2889 (C–H stretching, –CH group), 1694 (C=O
2
3
3
ring), 144.0 (1C, C aromatic ring), 134.7 (2C, C and C
9
stretching, aromatic ketone), 1512 (–C=N stretching aro-
1
8
benzimidazole ring), 134.6 (1C, C naphthalene ring), 134.5
matic ring), 1471 (C=C stretching, aromatic ring), 1239,
9
1
(
1C, C10 naphthalene ring), 133.4 (1C, C aromatic ring),
1141 (C–O–C stretching); H NMR (400 MHz, DMSO-d ):
6
6
1
29.4 (1C, C aromatic ring), 127.1 (1C, C naphthalene
δ = 12.89 (s, 1H, –NH), 6.48–8.48 (m, 15H, Ar–H), 5.60
5
5
ring), 126.6 (1C, C6 naphthalene ring), 126.0 (1C, C3
(d, JAC = 3.20 Hz, JBC = 11.01 Hz, 1H, >CH–H ), 4.75 (s,
C
naphthalene ring), 125.1 (1C, C naphthalene ring), 123.7
2H, –O–CH –), 3.78 (d, J = 17.54 Hz, JBC = 11.14 Hz,
7
2
AB
(
1C, C naphthalene ring), 123.2 (2C, C and C benzimi-
1H, C -H pyrazoline H ), 3.20 (d, J = 17.57 Hz, JAC =
8
5
6
5 B AB
1
3
dazole ring), 121.2 (1C, C aromatic ring), 120.7 (1C, C
3.06 Hz, 1H, C -H pyrazoline H ), 2.40 (s, 3H, –CH );
C
5
4
4
A
3
naphthalene ring), 107.0 (1C, C naphthalene ring), 115.8
(100 MHz, DMSO-d ): δ = 169.7 (1C, >C=O), 156.0 (1C,
2
6
(
2C, C and C benzimidazole ring), 67.6 (1C, –OCH –),
C naphthalene ring), 155.8 (1C, C pyrazoline ring), 151.0
7
4
2
1
3
6
5.7 (1C, C pyrazoline ring), 39.1 (1C, C pyrazoline
(1C, C benzimidazole ring), 138.4 (1C, C aromatic ring),
2 1
(1C, C aromatic ring), 134.8 (2C, C and C benzimidazole
4 8 9
5
4
+
ring); MS (m/z): 491.5 (M ); anal. calcd. for (C H N O ):
2
8
21
5
4
C, 68.42; H, 4.31; N, 14.25%; found: C, 68.50; H, 4.38; N,
4.31%.
ring), 134.8 (1C, C naphthalene ring), 134.2 (1C, C
9 10
naphthalene ring), 128.4 (2C, C and C aromatic ring),
3 5
1

Med Chem Res
1
1
27.4 (1C, C naphthalene ring), 126.7 (1C, C naphthalene
1247, 1133 (C–O–C stretching); H NMR (400 MHz,
5
6
ring), 126.5 (1C, C3 naphthalene ring), 125.4 (1C, C7
naphthalene ring), 125.2 (2C, C and C aromatic ring),
DMSO-d ): δ = 12.85 (s, 1H, –NH), 6.50–8.47 (m, 15H,
6
Ar–H), 5.63 (d, JAC = 3.24 Hz, JBC = 11.03 Hz, 1H,
>CH–H ), 4.79 (s, 2H, –O–CH –), 3.81 (d, J = 17.61
3
5
1
23.4 (2C, C and C benzimidazole ring), 123.1(1C, C
5 6 8
C
2
AB
naphthalene ring), 120.4 (1C, C naphthalene ring), 115.1
Hz, JBC = 11.20 Hz, 1H, C -H pyrazoline H ), 3.26 (d, J
4
5 B AB
(
2C, C and C benzimidazole ring), 107.2 (1C, C naph-
= 17.53 Hz, JAC = 3.07 Hz, 1H, C -H pyrazoline H ), 3.08
4 A
7
4
2
1
3
thalene ring), 67.1 (1C, –OCH –), 66.7 (1C, C pyrazoline
(s, 6H, –N (CH3)2); C (100 MHz, DMSO-d ): δ = 169.3
2
5
6
ring), 39.9 (1C, C pyrazoline ring), 21.4 (1C, –CH ); MS
(1C, >C=O), 156.2 (1C, C naphthalene ring), 155.2 (1C,
4
3
1
+
(
m/z): 460.7 (M ); anal. calcd. for (C H N O ): C, 75.63;
C pyrazoline ring), 151.1 (1C, C benzimidazole ring),
2
9
24
4
2
3
2
H, 5.25; N, 12.17%; found: C, 75.74; H, 5.36; N, 12.26%.
149.2 (1C, C aromatic ring), 134.5 (2C, C and C ben-
4 8 9
zimidazole ring), 134.8 (1C, C9 naphthalene ring), 134.9
Physical constant and characterization 1-(3-(1H-benzoimi-
dazol-2-yl)-5-(4-methoxyphenyl-4-5dihydro-1H-pyrazol-1-
yl)-2-(napthalen-1-yloxy)ethanone (5k) Brown (MeOH)
(1C, C10 naphthalene ring), 131.5 (1C, C aromatic ring),
1
129.3 (2C, C and C aromatic ring), 129.6 (2C, C and C
6
2
6
2
aromatic ring), 127.5 (1C, C naphthalene ring), 127.7 (1C,
7
(
yield 65%) mp 242–244 °C; IR (KBr, cm−1): 3454 (N–H
C5 naphthalene ring), 126.4 (1C, C6 naphthalene ring),
126.1 (1C, C naphthalene ring), 125.5 (1C, C aromatic
stretching, secondary amine), 3080 (C–H stretching, aro-
matic ring), 2927 (C–H stretching, –CH2 group), 2888
3
7
ring), 123.3 (2C, C and C benzimidazole ring), 123.0 (1C,
5
6
(
C–H stretching, –OCH group), 1695 (C=O stretching,
C8 naphthalene ring), 120.1 (1C, C4 naphthalene ring),
115.5 (2C, C and C benzimidazole ring), 112.5 (2C, C
3
and C aromatic ring), 107.5 (1C, C naphthalene ring),
5 2
3
aromatic ketone), 1514 (–C=N stretching aromatic ring),
468 (C=C stretching, aromatic ring), 1245, 1138 (C–O–C
7
4
1
1
stretching); H NMR (400 MHz, DMSO-d ): δ = 12.85 (s,
67.1 (1C, –OCH –), 66.7 (1C, C pyrazoline ring), 41.7
2 5
6
1
H, –NH), 6.43–8.38 (m, 15H, Ar–H), 5.62 (d, JAC = 3.26
Hz, JBC = 11.05 Hz, 1H, >CH–HC), 4.83 (s, 2H,
O–CH –), 3.89 (s, 3H, –OCH ), 3.58 (d, J = 17.62 Hz,
(2C, –CH ) 39.4 (1C, C pyrazoline ring); MS (m/z): 489.2
3 4
+
(M ); anal. calcd. for (C H N O ): C, 73.60; H, 5.56; N,
30
27 5 2
–
14.31%; found: C, 73.71; H, 5.61; N, 14.38%.
2
3
AB
JBC = 11.18 Hz, 1H, C -H pyrazoline H ), 3.12 (d, J =
5
B
AB
1
3
1
7.50 Hz, JAC = 3.10 Hz, 1H, C -H pyrazoline H );
C
4
A
(
100 MHz, DMSO-d ,): δ = 169.6 (1C, >C=O), 158.4 (1C,
Biological evaluation
6
C aromatic ring), 156.4 (1C, C naphthalene ring), 155.1
4
1
(
1C, C3 pyrazoline ring), 151.8 (1C, C2 benzimidazole
Antimicrobial screening assay
ring), 147.1 (1C, C aromatic ring), (1C, C aromatic ring),
3
1
1
34.0 (2C, C and C benzimidazole ring), 134.8 (1C, C
9
1-(3-(1H-benzoimidazol-2-yl)-5-aryl-4-5dihydro-1H-pyr-
azol-1-yl)-2-(napthalen-1-yloxy)ethanones (5a–l) were
screened for their antibacterial activity against Escherichia
coli (MTCC-442), Pseudomonas aeruginosa (MTCC-441),
Staphylococcus aureus (MTCC-96), and Streptococcus
pyogenes (MTCC-443). MICs of the titled compounds were
compared with ampicillin (for bacteria) and griseofulvin
(for fungi) was standards and the results are displayed in
Table 1. Antifungal activity was screened against three
fungi Candida albicans (MTCC-227), Aspergillus niger
(MTCC-282) and Aspergillus clavatus (MTCC-1323).
Titled compounds were screened in six sets against bacteria
and fungi. The MIC of titled compounds was determined as
per the National Committee for Clinical Laboratory Stan-
dards protocol using Mueller-Hinton Broth (Becton-Dick-
inson, USA) dilution method (Rattan 2000).
8
9
naphthalene ring), 134.5 (1C, C10 naphthalene ring), 127.0
(
1C, C aromatic ring), 127.1 (1C, C naphthalene ring),
5 5
1
26.1 (1C, C naphthalene ring), 126.0 (1C, C aromatic
6 6
ring), 126.0 (1C, C3 naphthalene ring), 125.7 (1C, C7
naphthalene ring), 123.7 (1C, C8 naphthalene ring), 123.4
(
2C, C and C benzimidazole ring), 120.4 (1C, C naph-
5 6 4
thalene ring), 115.1 (2C, C and C benzimidazole ring),
7
4
1
14.4 (1C, C aromatic ring), 107.3 (1C, C naphthalene
3 2
ring), 67.4 (1C, –OCH –), 66.4 (1C, C pyrazoline ring),
2
5
5
4
5
5.1 (1C, –OCH ), 39.3 (1C, C pyrazoline ring); MS (m/z):
3 4
+
76.5 (M ); anal. calcd. for (C H N O ): C, 73.09; H,
.08; N, 11.76%; found: C, 73.14, H, 5.11; N, 11.85%.
2
9 24 4 3
Physical constant and characterization 1-(3-(1H-benzoimi-
dazol-2-yl)-5-(4-(dimethylamino)phenyl)-4-5dihydro-1H-
pyrazol-1-yl)-2-(napthalen-1-yloxy)ethanone (5l) Brown-
ish yellow (MeOH) (yield 63%) mp 170–172 °C; IR (KBr,
Antibacterial activity
−1
cm ): 3458 (N–H stretching, secondary amine), 3086
C–H stretching, aromatic ring), 2925 (C–H stretching,
CH group), 2886 (C–H stretching, –CH group), 1690
(
–
The data of compounds 5a–l are displayed in Table 1. The
data of antibacterial activity clearly showed that compound
2
3
(
C=O stretching, aromatic ketone), 1515 (–C=N stretching
5i (-4-NO ) exhibited very good activity (MIC = 25 μg/ml)
2
aromatic ring), 1473 (–C=C stretching, aromatic ring),
against E. coil, S. aureus, and S. pyogenes and showed

Med Chem Res
Table 1 Antibacterial and antifungal activity of compounds (5a–l)
Interpretation of data was reported in the experimental
Sr. no. –R
Minimum bactericidal
Minimum fungicidal
) in concentrations
(MIC ) in µg/ml
section. Infrared spectrum of compound 5h showed
stretching vibration at 3458 cm indicating the presence of
−1
concentrations (MIC
B
µg/ml
F
N–H stretching of secondary amines. The absorption band
−
1
E. c. P. a. S. a. S. p. C. a. A. n. A. c.
at 3078 cm indicated the presence of Ar–H stretching
−1
vibration. Stretching at 2933 cm had proved the presence
5a
5b
5c
5d
5e
5f
–H
250 250 200 250
100
100 100
500 500
100 100
100 >1000
500 100
500 500
of –CH group in compound 5h. The absorption band at
2
-2-Cl
-2-OH
-3-OH
-4-OH
-3-
50 50 100 12.5 500
−1
1
690 cm showed the presence of a >C=O stretching
100 100 100 100
500 500 500 100
500 250 100 100
250 250 250 500
100
500
100
100
−1
vibration. Absorption bands at 1507, 1468, and 1530 cm
showed the presence of >C=N, >C=C<, and –N=O–
stretching of the aromatic ring. Stretching at 1136 and 1234
−1
cm showed the presence of C–O–C bending vibrations.
OCH
OH
3
-4-
1
The H NMR spectra of final compound 5h showed that
protons attached to C-22, gave singlet at δ = 4.78
5
5
5
5
5
5
g
h
i
-2-NO
-3-NO
-4-NO
2
2
2
500 250 500 500
500 500 250 500
500
500
250
500
100
100
100 >1000
1000 >1000
100 250
(
–O–CH –). In pyrazoline ring one proton showed chemical
2
shift at δ = 5.50 (>CH–H ) as a doublet, one proton of
C
25
100 500 500 500
50 50 100 50
12.5 50
25
pyrazoline H and pyrazoline H gave doublet of doublet at
B
A
j
-4-CH
3
50
50
>100
δ = 3.72 and 3.20. Secondary amine displayed chemical
shift at δ = 12.80 as a singlet while the protons of phenyl
ring furnished multiple signals at δ = 6.45–8.45 (m, 15H,
Ar–H) (Fig. 2).
k
l
-4-OCH
3
25
-4-N
250 250 500 500
500 500
(
3 2
CH )
Ampicillin
100 100 250 100
–
–
–
1
3
Looking to the C NMR spectra, the chemical shifts of
Griseofulvin
–
–
–
–
500
100 100
the final compound 5h have carbons that varied from δ =
E.c. Escherichia coli (MTCC-442), P.a. Pseudomonas aeruginosa
MTCC-441), S.a. Staphylococcus aureus (MTCC-96), S.p. Strepto-
169.3–39.1 ppm. Carbon of ketone (>C=O) group has
(
chemical shift at δ = 169.3. The carbon of –OCH group at
2
coccus pyogenes (MTCC-443), C.a. Candida albicans (MTCC-227),
A.n. Asperginus niger (MTCC-282), A.c. Asperginus clavatus (MTCC-
C-22 attached to the ketone group has a chemical shift value
at δ = 67.6. The carbons of pyrazoline ring, C-9, C-10, and
C-11 showed chemical shifts at δ = 155.3, 39.1, and 65.7,
respectively. The benzimidazole carbons C-12 showed peak
at 151.1 ppm, C-15, C-20 appeared at 134.0 ppm. Similarly
C-16, C-19 exhibited chemical shifts at 115.8, C-17 while
C-18 showed at 123.7 ppm. The carbons of naphthalene
ring, C-24, C-26, C-27, and C-29 appeared at 156.0, 123.7,
1
323)
excellent activity (MIC = 12.5 μg/ml) against P. aerugi-
nosa. Compound 5k (-4-OCH ), showed good activity
3
(
MIC = 50 μg/ml) against E. Coil, P. aeruginosa, and S.
pyogenes. The remaining compounds of the series pos-
sessed moderate antibacterial activity against responsible
bacterial strains.
Antifungal activity
Antifungal activity was performed using C. albicans, A.
niger, and A. clavatus at various concentrations and MIC
values are displayed in Table 1. Synthesized compounds
were diluted to 1000 µg/ml concentration, as a stock solu-
tion. According to the screening results it was indicated
that, Compounds 5j and 5k exhibited good antifungal
activity against A. niger at MIC = 50 μg/ml and compound
5
k possessed very good activity against A. clavatus at MIC
=
25 μg/ml. Other derivatives showed moderate activity
against responsible fungal strains.
Results and discussion
Characterization of newly synthesized compounds was
carried out by standard spectroscopic methods.
Fig. 2 Carbon enumerations of compound 5h

Med Chem Res
1
25.1, 126.0, and 127.1. Carbons of C-25 and C-30
exhibited peaks at 134.7, 134.4 while C-31, C-32, and C-
3 appeared at 120.6, 126.6, and 107.0. The nitro group in
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the phenyl ring gave a chemical shift at δ = 147.1.
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The titled compounds were screened for their in vitro
antibacterial and antifungal activities. It is clearly concluded
from Table 1 that structural and electronic variety of the
targeted compounds affected their biological activities. On
the basis of results of biological activity we have concluded
that para nitro and para chloro are the most distinctive
derivatives in the present study because of their prominent
in vitro antibacterial potency. For antifungal activity it is
proved that para position of methoxy and methyl group
showed most incremental antifungal activity. SAR studies
revealed that para position of substituent is essential for
potential antimicrobial activity.
6
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Acknowledgements The authors are thankful to the University
Grants Commission (UGC), New Delhi, and Department of Science
and Technology (DST), New Delhi, for financial support under the
NON-SAP and DST-FIST programs respectively. N. C. Desai is
highly thankful to the UGC, New Delhi for providing a UGC-BSR
one-time grant (2012).
Compliance with ethical standards
Pathak RB, Chovatia PT, Parekh HH (2012) Synthesis, antitubercular
and antimicrobial evaluation of 3-(4-chlorophenyl)-4-substituted
pyrazole derivatives. Bioorg Med Chem Lett 22:5129–5133
Conflict of interest The authors declare that they have no competing
interests.

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