Synthesis and in vitro antimicrobial evaluation of novel fluorine-containing 3-benzofuran-2-yl-5-phenyl-4,5-dihydro-1H-pyrazoles and 3-benzofuran-2-yl-5-phenyl-4,5-dihydro-isoxazoles

Article abstract of DOI:10.1007/s00044-013-0735-9

In the present study, some novel fluorine-containing heterocycles incorporating benzofuran with dihydropyrazoles and dihydroisoxazoles have been synthesized and evaluated for their in vitro antibacterial and antifungal activities. 2-Acetylbenzofuran on treatment with fluorinated aldehydes afforded corresponding fluorine-containing 1-benzofuran-2-yl-3-phenyl-prop-2-en-1-ones (chalcones 5a-g). The cyclocondensation of chalcones (5a-g) with hydrazine hydrate under basic conditions resulted in formation of corresponding novel fluorine-containing 3-benzofuran-2yl-5-phenyl-4,5-dihydro-1H-pyrazoles (6a-g). Similar reaction with hydroxylamine hydrochloride yielded 3-benzofuran-2yl-5- phenyl-4,5-dihydro-isoxazoles (7a-g). All the synthesized compounds have been characterized on the basis of analytical and spectral data, and were screened for their antibacterial and antifungal activities. Some of the synthesized compounds showed good antibacterial and antifungal activities.

Full text of DOI:10.1007/s00044-013-0735-9

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-013-0735-9
ORIGINAL RESEARCH
Synthesis and in vitro antimicrobial evaluation of novel fluorine-
containing 3-benzofuran-2-yl-5-phenyl-4,5-dihydro-1H-pyrazoles
and 3-benzofuran-2-yl-5-phenyl-4,5-dihydro-isoxazoles
•
Tejpal Singh Chundawat Nutan Sharma
•
Sunita Bhagat
Received: 15 March 2013 / Accepted: 17 August 2013
ꢀ Springer Science+Business Media New York 2013
Abstract In the present study, some novel fluorine-con-
taining heterocycles incorporating benzofuran with dihydro-
pyrazoles and dihydroisoxazoles have been synthesized and
evaluated for their in vitro antibacterial and antifungal activ-
ities. 2-Acetylbenzofuran on treatment with fluorinated alde-
hydes afforded corresponding fluorine-containing 1-benzofuran-
2-yl-3-phenyl-prop-2-en-1-ones (chalcones 5a–g). The cy-
clocondensation of chalcones (5a–g) with hydrazine hydrate
under basic conditions resulted in formation of corresponding
novel fluorine-containing 3-benzofuran-2yl-5-phenyl-4,5-
dihydro-1H-pyrazoles (6a–g). Similar reaction with hydrox-
ylamine hydrochloride yielded 3-benzofuran-2yl-5-phenyl-
4,5-dihydro-isoxazoles (7a–g). All the synthesized com-
pounds have been characterized on the basis of analytical and
spectral data, and were screened for their antibacterial and
antifungal activities. Some of the synthesized compounds
showed good antibacterial and antifungal activities.
pharmacological agents (Engler et al., 1996; Dai et al.,
1998; Diyasena et al., 1985) as it represent a very impor-
tant heterocyclic pharmacophore (Corey, 1973). Several
benzofuran ring systems bearing various substituents at the
C-2 position are widely distributed in nature, e.g. ailan-
thoidol, a neolignan derivative, has been reported to have
antiviral, antioxidant and antifungal activities (Fuganti and
Serra, 1998). A number of compounds synthesized from
2-acetylbenzofurans possess antimicrobial, antitumor, anti-
inflammatory, fungicidal activity and are used for treat-
ment of cardiac arrhythmias (Basawaraj et al., 2001; Rida
et al., 2006; Ujjinamatada et al., 2006; Wachi et al., 1978;
Singh et al., 2005; Cho et al., 2004; Druzgala and Milner,
2002; Dawood et al., 2006).
On the other hand, dihydropyrazoles and dihydroisox-
azoles are important heterocyclic compounds demonstrated
to be versatile building blocks in organic synthesis (Bansal
et al., 2001; Mana et al., 1992; Teresa and Mello, 2005)
and possess remarkable pharma applications. Dihydropy-
razoles are important five-membered aza-heterocycles,
which are present in a wide range of bioactive compounds
with anti-inflammatory (Nasr and Said, 2003), antidepres-
sant (Palaska et al., 2001; Gokhan et al., 2003), hypoten-
sive (Turan-Zitouni et al., 2000) trypanocidal (Du et al.,
2002), anticancer (Havrylyuk et al., 2009; Shaharyar et al.,
2010), antibacterial and antiviral activities (Abdel-Wahab
et al., 2008). Similarly, dihydroisoxazoles also possess a
broad spectrum of biological activities such as antibiotic,
antitumour, insecticidal, antifungal etc. (Huisgen, 1963;
Caramella and Gruenanger, 1984).
Keywords Benzofuran Á Claisen-Schmidt condensation Á
Dihydropyrazole Á Dihydroisoxazole Á Antimicrobial
Introduction
Widespread interest in the chemistry of benzofuran in a
large number of natural products has attracted attention due
to their biological activities and potential applications as
T. S. Chundawat Á N. Sharma Á S. Bhagat (&)
Organic Synthesis Research Laboratory,
Department of Chemistry, A. R. S. D. College,
University of Delhi, New Delhi 110021, India
e-mail: sunitabhagat28@gmail.com
Moreover incorporation of fluorine in a heterocyclic
system may increase biological half life of molecules by
impeding oxidative metabolism and can increase bioabsorp-
tion by lipophilic effects (Purser et al., 2008; Smart, 2001).
The participation of fluorine in electrostatic interactions is
T. S. Chundawat
e-mail: chundawatchem@yahoo.co.in
123

Med Chem Res
widely accepted and contributes to the enhanced binding
affinity of organofluorine compounds for the enzyme’s active
site (Rowley et al., 2001).
NMR spectraofcompound(5a–g), (6a–g) and (7a–g) showed
doublet of two protons (7.50–7.80 ppm) and triplet of two
protons at (7.25–7.45 ppm) to confirm aromatic protons of
benzofuran ring, A singlet at (7.00–7.20 ppm) confirmed the
C-3 proton of benzofuran ring. The aromatic protons of
fluorine-containing ring were observed in the region
6.90–7.30 ppm. The formation of pyrazole (6a–g) and isox-
azole (7a–g) was confirmed by peaks in the region 4.90–5.55
(t), 3.40–3.85 (dd) and at 2.28–3.20 (dd).
Considering the significance of fluorine incorporation in
heterocycles and taking an overview on the biological
activities and commercial uses of different natural and
synthetic two-substituted benzofurans, in this study the
synthesis of some new fluorine-containing heterocyclic
systems using benzofuran as basic moiety and coupling it
with other bioactive nuclei viz. dihydropyrazole and di-
hydroisoxazole and evaluation of their possible antibacte-
rial and antifungal activities were aimed.
Biology
Antibacterial activity
Results and discussion
Newly synthesized 1-benzofuran-2-yl-3-phenyl-prop-2-en-
1-ones (5a–g), 3-benzofuran-2-yl-5-phenyl-4,5-dihydro-
1H-pyrazoles (6a–g) and 3-benzofuran-2-yl-5-phenyl-4,5-
dihydro-isoxazoles (7a–g) were evaluated for in vitro against
the Gram-positive bacteria S. aureus, B. subtilis, S. pneu-
moniae, S. pyogenes, the Gram-negative bacteria E. coli, P.
aeruginosa, S. typhi. For antibacterial activity ampicillin was
used as a standard control drug. Minimum inhibitory con-
centration (MIC) in lg/ml values are defined in Table 2.
Twenty-one synthesized compounds were tested for
antibacterial activity by microbroth dilution method using
nutrient Muller Hinton Broth culture medium (MHB) (Car-
son et al., 1995; Tarpay et al., 1980; Riesselman et al., 2000).
The results revealed that majority of the synthesized com-
pounds showed varying degrees of inhibition against the
tested microorganisms. By comparing the compounds from
(5a–g), (6a–g), and (7a–g) against S. aureus and B. subtillis,
5c, 5g, 6f, 6g, 7a, 7b, 7c, 7d show better antibacterial activity
then the reference sample ampicillin, while 5a, 5b, 5e, 5g, 7b
and 7c show similar activity against E. coli, S. typhi, P.
aeruginosa and S pneumoniae. Compound 5d show best
activity 62.5 lg/ml against S. typhi. Against S. pyogenes 5e,
6a and 6f show similar antibacterial activity with reference
drug.
Chemistry
In this present work, a series of 14 new fluorinated novel
heterocyclic systems containing benzofuran with pyrazoles
and isoxazoles were synthesized. 2-Acetylbenzofuran (3)
was prepared by the reaction of 2-hydroxybenzaldehyde (1)
and 1-chloropropanone (2), according to method described
in the literature (Paizs et al., 2003). The Claisen-Schmidt
condensation of 2-acetylbenzofuran (3) and fluorinated
benzaldehydes (4a–g) in ethanol in presence of diethyl
amine yielded 1-benzofuran-2-yl-3-phenyl-prop-2-en-1-one
(5a–g). Further reaction of 5a–g with hydrazine hydrate in
ethanol yielded 3-benzofuran-2-yl-5-phenyl-4,5-dihydro-
1H-pyrazoles (6a–g). Similar reaction of (5a–g) with
hydroxylamine hydrochloride and sodium acetate using
ethanol afforded 3-benzofuran-2-yl-5-phenyl-4,5-dihydro-
isoxazoles (7a–g). The synthetic route for target compounds
(6) and (7) is mentioned in Scheme 1.
The physical characterization for synthesized compound
(5a–g), (6a–g) and (7a–g) are given in Table 1. All reactions
were monitored by TLC (silica gel, aluminium sheet,
Merck). All melting points were taken on Electro-thermal IA
9000 series digital melting point apparatus. Elemental
analysis was obtained on GmbH Vario EL V300 elemental
analyser. The structure of all synthesized compounds was
Antifungal activity
1
confirmed by elemental analysis, EI-MS, IR, H NMR and
13C NMR spectral data. Mass spectra of all compounds
showed [M?1] peak corresponding to their molecular ion
peak. IR spectra of compound (5a–g) showed C=O bands in
the region 1,685–1,660 cm-1. The NH and C=N bands of
compound (6a–g) observed at 3,400–3,200 cm-1 and
1,625–1,610 cm-1, respectively. The C–O–C peaks of
compound (5a–g), (6a–g) and (7a–g) showed at 1,260–
1,220 cm-1 regions. The 1H NMR were recorded on
400 MHz using TMS as an internal standard. The 13C NMR
was recorded at 100 MHz using TMS as an internal standard.
Newly synthesized 1-(benzofuran-2-yl)-3-(phenyl)-prop-2-
en-1-ones (5a–g), 3-benzofuran-2-yl-5-phenyl-4,5-dihydro-
1H-pyrazoles (6a–g) and 3-benzofuran-2-yl-5-phenyl-4,5-
dihydro-isoxazoles (7a–g) were evaluated for in vitro
activity against the fungi C. albicans, A. niger, A. clavatus.
For antifungal activity greseofulvin was used as a standard
control drug. Minimum inhibitory concentration (MIC) in
lg/ml values are defined in Table 3. Twenty-one synthe-
sized compounds were tested for antifungal activity by mi-
crobroth dilution method. The results revealed that majority
of the synthesized compounds showed varying degrees of
1
Chemical shift (d) values are given in parts per million. H
123

Med Chem Res
Scheme 1 Synthetic route of
3-(benzofuran-2-yl)-5-phenyl-
4,5-dihydro-1H-pyrazoles and
3-(benzofuran-2-yl)-5-phenyl-
4,5-dihydro-isoxazoles
Table 1 Physical characterization of synthesized compounds by conventional method
N
N
R
NH
O
O
O
O
O
6a-g
5a-g
7a-g
R
R
Compd.
R
m.p. (ꢁC)
Molecular formula
Conventional synthesis
Time (h)
Yield (%)
5a
5b
5c
5d
5e
5f
4-F
106–108
120–122
130–132
122–124
140–142
122–124
160–162
144–146
120–122
112–114
160–162
152–154
146–148
208–210
160–162
138–140
156–158
176–178
182–184
140–142
188–190
C
17H11FO2
4
88
85
80
86
82
80
81
72
75
69
71
70
78
76
77
75
71
79
69
73
76
2-F,4-F
C17H10F2O2
C17H10F2O2
4.5
4.5
4
2-F,5-F
2-F,6-F
3-F,4-F
2-CF3
4-CF3
4-F
C
17H10F2O2
C17H10F2O2
C18H11F3O2
C18H11F3O2
4.5
5
5g
6a
6b
6c
6d
6e
6f
5
C
17H13FN2O
5
2-F,4-F
2-F,5-F
2-F,6-F
3-F,4-F
2-CF3
4-CF3
4-F
C17H12F2N2O
C17H12F2N2O
5.5
5.5
5
C
17H12F2N2O
C17H12F2N2O
C18H13F3N2O
C18H13F3N2O
6
5.5
6
6g
7a
7b
7c
7d
7e
7f
C
17H12FNO2
6.5
6
2-F,4-F
2-F,5-F
2-F,6-F
3-F,4-F
2-CF3
4-CF3
C17H11F2NO2
C17H11F2NO2
6
C
17H11F2NO2
6.5
6
C17H11F2NO2
C18H12F3NO2
C18H12F3NO2
7
7g
7
123

Med Chem Res
Table 2 In vitro antibacterial activity measured by (MICs) in lg/ml of (5a–g), (6a–g) and (7a–g)
Cd.
R
Gram-positive bacteria
Gram-negative bacteria
S. aureus
ATCC 25923
B. subtilis
MTCC 441
S. pneumoniae
MTCC 1936
S. pyogenes
ATCC 19615
E. coli
ATCC 25922
P. aeruginosa
ATCC 7853
S. typhi
MTCC 98
5a
5b
5c
5d
5e
5f
4-F
200
250
100
100
250
250
200
250
250
500
200
250
100
125
200
100
500
250
200
250
125
250
500
250
200
250
200
200
100
200
250
200
250
200
250
500
125
250
125
100
250
200
200
250
100
125
200
125
200
250
250
200
200
125
500
250
200
250
250
200
125
500
250
250
125
100
200
250
250
100
100
250
200
100
250
500
200
500
100
125
200
125
500
200
200
250
125
100
250
100
250
125
200
250
100
250
200
250
200
250
100
250
125
125
100
250
200
250
250
100
100
125
200
250
100
200
250
250
250
250
200
250
200
250
250
250
200
250
250
250
500
–
200
125
125
62.5
250
200
200
250
200
200
250
200
250
500
200
100
250
500
200
200
125
100
2-F,4-F
2-F,5-F
2-F,6-F
3-F,4-F
2-CF3
5g
6a
6b
6c
6d
6e
6f
4-CF3
4-F
2-F,4-F
2-F,5-F
2-F,6-F
3-F,4-F
2-CF3
6g
7a
7b
7c
7d
7e
7f
4-CF3
4-F
2-F,4-F
2-F,5-F
2-F,6-F
3-F,4-F
2-CF3
7g
4-CF3
Ampicilin
MIC minimum inhibition concentration in lg/ml
Table 3 In vitro antifungal
Compound
R
C. albicans
A. niger
A. clavatus
activity measured by (MFCs) in
lg/ml of (5a–g), (6a–g) and
(7a–g)
5a
4-F
500
250
1,000
1,000
500
1,000
1,000
1,000
500
5b
2-F,4-F
2-F,5-F
2-F,6-F
3-F,4-F
2-CF3
4-CF3
4-F
5c
5d
5e
5f
1,000
1,000
500
1,000
1,000
250
1,000
500
[1,000
[1,000
500
5g
6a
6b
6c
6d
6e
6f
250
250
1,000
500
[1,000
250
2-F,4-F
2-F,5-F
2-F,6-F
3-F,4-F
2-CF3
4-CF3
4-F
250
250
[1,000
250
[1,000
500
1,000
500
250
500
500
[1,000
500
[1,000
500
6g
7a
7b
7c
7d
7e
1,000
1,000
[1,000
250
500
500
2-F,4-F
2-F,5-F
2-F,6-F
3-F,4-F
[1,000
[1,000
500
[1,000
[1,000
1,000
[1,000
1,000
[1,000
[1,000
123

Med Chem Res
Table 3 continued
Compound
R
C. albicans
A. niger
A. clavatus
7f
2-CF3
500
250
500
[1,000
[1,000
–
[1,000
[1,000
100
7g
4-CF3
MFC minimum fungicidal
concentration in lg/ml
Greseofulvin
inhibition against the tested microorganisms. By comparing
the compounds from (5a–g), (6a–g), and (7a–g), compounds
5b, 6c, 7c and 7g show better activity then reference drug
greseofulvin against C. albicans, while compounds 5a, 5e,
6a, 6f and 7f show similar activity against C. albicans. Most
of the synthesized compounds showed weak antifungal
activity against A. niger and A. clavatus.
determined on Electro-thermal IA 9000 series digital melt-
ing point apparatus and are uncorrected. Elemental analysis
was obtained on GmbH Vario EL V300 elemental analyser.
IR spectra were recorded in KBr on a Perkin Elmer Spectrum
RX-1 FT-IR spectrophotometer. The EI-MS spectra were
1
recorded on a waters LC–MS spectrometer. The H NMR
spectra were recorded in CDCl3 and DMSO-d6 solution on a
on Jeol JNM-ECX400P at 400 MHz using TMS as internal
standard. The 13C NMR spectra were recorded in CDCl3 and
DMSO-d6 solution on Jeol JNM-ECX400P at 100 MHz.
Conclusion
1
Splitting patterns in H NMR are indicated as follows: (s),
It can be concluded that the Claisen-Schmidt condensation
of 2-acetylbenzofuran (3) and fluorinated benzaldehydes
(4) gives good yield of 1-benzofuran-2-yl-3-phenyl-prop-2-
en-1-one (5a–g). Further cyclisation reaction of 1-benzo-
furan-2-yl-3-phenyl-prop-2-en-1-one (5a–g) with hydra-
zine hydrate gives 3-benzofuran-2-yl-5-phenyl-4, 5-dihydro-
1H-pyrazoles (6a–g) and with hydroxylamine hydrochloride
gives 3-benzofuran-2-yl-5-phenyl-4, 5-dihydro-isoxazoles
(7a–g). Synthesized compounds were characterized by their
physical and analytical data, and their microbiological screen-
ing evaluates the antibacterial and antifungal activities which
are shown in Tables 2 and 3. Compounds 5c, 5g, 6f, 6g, 7a, 7b,
7c, 7d show better antibacterial activity against S. aureus and B.
subtillis. While, 5a, 5b, 5e, 5g, 7b and 7c show similar activity
against E. coli, S. typhi, P. aeruginosa and S. pneumoniae.
Compound 5d shows best activity 62.5 lg/ml against S. typhi.
Against S. pyogenes 5e, 6a and 6f show similar antibacterial
activity with reference drug ampicllin. For antifungal activity
compounds 5b, 6c, 7c and 7g show better activity than refer-
ence drug greseofulvin against C. albicans. While compounds
5a, 5e, 6a, 6f and 7f show similar activity against C. albicans.
Fluorine substitution is commonly used in medicinal chemistry
to improve lipophilicity, metabolic stability, bioavailability and
protein–ligand interactions. The observations of activity pro-
mote further development of fluorine-containing compounds as
antibacterial and antifungal agents.
singlet; (d), doublet; (t), triplet; (m), multiplet. Chemical
shift (d) values are given in ppm (parts per million). All
chemicals and reagents used were purchased from com-
mercial suppliers and were of analytical grade.
Reagents and solvents
Salicylaldehyde, 1-chloropropanone (chloroacetone) and
other fluorinated benzaldehydes were products procured
from Sigma Aldrich or Fluka. All solvents were purified
and dried by standard methods. 2-Acetylbenzofuran was
prepared according to the reported procedures.
General procedure for the synthesis of compounds
Synthesis of 1-Benzofuran-2-yl-3-phenyl-prop-2-
en-1-ones (5a–g)
A mixture of 2-acetylbenzofuran (0.0062 mol), fluorinated-
benzaldehyde (0.0068 mol) and diethylamine (1.2 ml)
were taken in ethanol (10 ml). The resulting reaction
mixture was refluxed for 4–5 h. Reaction was monitored by
TLC. After completion of reaction, the reaction mixture
was concentrated under reduced pressure, washed with
water and extracted with ethyl acetate (15 ml 9 3 times),
organic layer was dried over sodium sulphate and con-
centrated under reduced pressure. The obtained residues
were purified by column chromatography using silica
100–200 mesh-size by ethylacetate: hexane (5 %) mixture
as an eluent which afforded 1-benzofuran-2-yl-3-phenyl-
prop-2-en-1-ones (5a–g) in good yields.
Experimental
Materials and methods
Analytical methods
1-Benzofuran-2yl-3-(4-fluorophenyl)-prop-2-en-1-one (5a) M.p.:
106–108 ꢁC, yield:88 %, IR(cm-1, KBr): 3080 (C=C–H),
1660 (C=O), 1608 (C–C=O), 1222, 1100 (C–F), 938. H
The purity of the compound was checked on silica-gel-
coated aluminum plates (Merck). All melting points were
1
123

Med Chem Res
NMR (d ppm, CDCl3, 400 MHz): 7.91 (d, Jtrans
=
(d, Jtrans = 15.38 Hz, 1H), 7.67 (d, J = 8.05 Hz, 1H), 7.60
(1H,s), 7.56 (d, J = 8.79 Hz, 1H), 7.49–7.42 (m, 3H),
7.36–7.33(m, 1H), 7.27 (t, J = 8.05 Hz, 1H), 7.14 (t,
J = 8.05 Hz, 1H). 13C NMR (d ppm, CDCl3, 100 MHz):
179.21, 155.79, 150.40, 149.32, 142.11, 131.84, 128.43,
125.19, 124.03, 123.30, 121.91, 118.00, 117.83, 116.70,
113.49, 112.44. MS (m/z): 285.06 (M?1). Anal. Calc. for
C17H10F2O2, calculated (found) C: 71.83 (71.79), H: 3.55
(3.52).
15.38 Hz, 1H), 7.74–7.61 (m, 6H), 7.54 (s, 1H), 7.50 (t,
J = 7.32 Hz, 1H), 7.32 (t, J = 7.32 Hz, 1H), 7.13 (d, J =
7.32 Hz, 1H). 13C NMR (d ppm, CDCl3, 100 MHz): 179.50,
165.46, 162.95, 155.73, 143.25, 130.64, 130.55, 128.61, 128.26,
124.09, 123.94, 123.50, 123.24, 120.74, 116.26, 116.17, 112.41,
MS (m/z): 267.07 (M?1). Anal. Calc. for C17H11FO2, calculated
(found) C: 76.68 (76.65), H: 4.16 (4.14).
1-Benzofuran-2yl-3-(2,4-difluorophenyl)-prop-2-en-1-one
(5b) M.p.: 120–122 ꢁC, yield:85 %, IR (cm-1, KBr):
3107 (C=C–H), 1660.35 (C=O), 1612 (C–C=O), 1089 (C–
F). 1H NMR (d ppm, CDCl3, 400 MHz): 7.91 (d,
Jtrans = 16.11 Hz 1H), 7.68–7.55 (m, 4m), 7.43 (t,
J = 7.32 Hz, 1H), 7.26 (t, J = 8.05 Hz, 1H), 6.91–6.82
(m, 3H). 13C NMR (d ppm, CDCl3, 100 MHz): 179.48,
165.45, 162.97, 161.00, 155.81, 136.24, 131.15, 128.38,
127.19, 123.98, 123.29, 123.12, 119.00, 116.12, 113.52,
112.27, 105.06, MS (m/z): 285.06 (M?1). Anal. Calc. for
C17H10F2O2, calculated (found) C: 71.83 (71.79), H: 3.55
(3.52).
1-Benzofuran-2yl-3-(2-trifluoromethyl phenyl)-prop-2-en-
1-one (5f) M.p.: 122–124 ꢁC, yield: 80 %, IR (cm-1
KBr): 3076.54 (C=C–H), 1669.34 (C=O), 1612.86 (C–
,
1
C=O), 1152.79, 1139.68(C–F). H NMR (d ppm, CDCl3,
400 MHz): 8.23 (d, Jtrans = 15.38 Hz, 1H), 7.83 (d,
J = 8.05 Hz, 1H), 7.67 (d, J = 8.05 Hz, 2H), 7.60 (s, 1H),
7.55 (d, J = 8.05 Hz, 2H), 7.48–7.41 (m, 3H) 7.26 (t,
J = 7.32 Hz, 1H) 13C NMR (d ppm, CDCl3, 100 MHz):
179.27, 155.82, 139.89, 133.80, 132.09, 129.92, 128.43,
128.01, 127.18, 126.27, 125.45, 124.02, 123.34, 122.41,
119.00, 113.70, 112.45. MS (m/z): 317.07 (M?1). Anal.
Calc. for C18H11F3O2, calculated (found) C: 68.36 (68.33),
H: 3.51 (3.49).
1-Benzofuran-2yl-3-(2,5-difluorophenyl)-prop-2-en-1-one
(5c) M.p.: 130–132 ꢁC, yield:80 %, IR (cm-1, KBr):
3068(C=C–H), 1669.77 (C=O), 1617 (C–C=O), H NMR
1
1-Benzofuran-2yl-3-(4-trifluoromethyl phenyl)-prop-2-en-
(d ppm, CDCl3, 400 MHz): 7.91 (d, Jtrans = 16.11 Hz,
1H), 7.68 (d, J = 7.32 Hz, 1H), 7.61–7.56 (m, 3H), 7.43 (t,
J = 8.05 Hz, 1H), 7.27 (t, J = 7.32 Hz, 1H), 7.10–7.00
(m, 3H). 13C NMR (d ppm, CDCl3, 100 MHz): 179.26,
159.99, 158.96, 155.87, 153.38, 135.86, 128.50, 127.17,
124.40, 124.04, 123.34, 118.42, 117.57, 115.27, 115.03,
113.76, 112.50. MS (m/z): 285.06 (M?1). Anal. Calc. for
C17H10F2O2, calculated (found) C: 71.83 (71.79), H: 3.55
(3.52).
1-one (5g) M.p.: 160–162 ꢁC, yield: 81 %, IR (cm-1
,
KBr): 3033.34 (C=C–H), 1664.80 (C=O), 1611.03 (C–
C=O), 1129.11 (C–F). 1H NMR (d ppm, CDCl3,
400 MHz): 7.88 (d, Jtrans = 15.38 Hz, 1H), 7.74 (d,
J = 8.05 Hz, 2H), 7.68 (d, J = 8.05 Hz, 1H), 7.64–7.56
(m, 5H), 7.45 (t, J = 7.32 Hz, 1H), 7.28 (t, J = 8.05 Hz,
1H). 13C NMR (d ppm, CDCl3, 100 MHz): 178.21, 155.22,
138.11, 134.61, 131.99, 130.02, 129.21, 127.91, 127.68,
127.67, 126.11, 125.12, 122.94, 123.01, 118.76, 112.02,
113.15. MS (m/z): 317.07 (M?1). Anal. Calc. for
C18H11F3O2, calculated (found) C: 68.36 (68.33), H: 3.51
(3.49).
1-Benzofuran-2yl-3-(2,6-difluorophenyl)-prop-2-en-1-one
(5d) M.p.: 122–124 ꢁC, yield:86 %, IR (cm-1, KBr):
3020 (C=C–H), 1664.70 (C=O), 1606 (C–C=O). H NMR
1
(d ppm, CDCl3, 400 MHz): 7.96 (d, Jtrans = 16.11 Hz,
1H), 7.78 (d, J = 16.11 Hz, 1H), 7.67 (d, J = 8.05 Hz,
1H), 7.60 (s, 1H), 7.56(d, J = 8.05 Hz, 2H), 7.42 (t,
J = 7.32 Hz, 1H), 7.27 (t, J = 8.05 Hz, 1H), 6.92 (t,
J = 8.79 Hz, 2H). 13C NMR (CDCl3, 100 MHz): 179.70,
163.33, 160.62, 160.62, 155.91, 131.67, 130.41, 128.43,
127.19, 126.49, 123.32, 113.83, 112.55, 112.07, 111.82.
MS (m/z): 285.06 (M?1). Anal. Calc. for C17H10F2O2,
calculated (found) C: 71.83 (71.79), H: 3.55 (3.52).
Synthesis of 3-Benzofuran-2-yl-5-phenyl-4,5-
dihydro-1H-pyrazoles (6a–g)
A mixture of 1-Benzofuran-2-yl-3-phenyl-prop-2-en-1-one
(5a–g) (0.00052 mol), hydrazine hydrate (0.00010 mol)
were taken in ethanol (5 ml). The resulting reaction mix-
ture was refluxed for 5–6 h. Reaction was monitored by
TLC. After completion of reaction, the reaction mixture
was concentrated under reduced pressure, washed with
water and extracted with ethyl acetate (10 ml 9 3 times),
organic layer was dried using sodium sulphate and con-
centrated under reduced pressure. The obtained residues
were purified by column chromatography using silica
100–200 mesh-size by ethylacetate: hexane (18 %) mixture
1-Benzofuran-2yl-3-(3,4-difluorophenyl)-prop-2-en-1-one
(5e) M.p.: 140–142 ꢁC, yield: 82 %, IR (cm-1, KBr):
3075(C=C–H), 1660.90 (C=O), 1615(C–C=O), 1137,
1042 (C–F). 1H NMR (d ppm, CDCl3, 400 MHz): 7.77
123

Med Chem Res
as eluent which afforded 3-benzofuran-2-yl-5-phenyl-4,
102.75, 29.68, MS (m/z): 299.09(M?1). Anal. Calc. for
C17H12F2N2O, calculated (found) C: 68.45 (68.42), H: 4.05
(4.01), N: 9.39 (9.36).
5-dihydro-1H-pyrazoles (6a–g) in good yields.
3-Benzofuran-2-yl-5-(4-fluorophenyl)-4,5-dihydro-1H-pyr-
azoles (6a) M.p.: 144–146 ꢁC, yield: 72 %, IR (cm-1
KBr): 3408.28 (=NH), 1627.42 (C=N), 1263.23 (C–O–C).
1H NMR (d ppm, CDCl3, 400 MHz): 7.67–7.23 (m, 6H),
7.07 (t, J = 8.05 Hz, 1H), 6.97 (d, J = 7.32 Hz, 2H), 6.83
,
3-Benzofuran-2-yl-5-(3,4-difluorophenyl)-4,5-dihydro-1H-
pyrazoles (6e) M.p.: 152–154 ꢁC, yield: 70 %, IR (cm-1
,
KBr): 3272.34(=NH), 1634.23 (C=N), 1224.11 (C–O–C).
1H NMR (d ppm, CDCl3, 400 MHz): 7.71–7.50 (m, 4H),
7.45–7.30 (m, 2H), 7.11–6.92 (m, 2H), 6.77 (s, 1H), 4.60 (t,
J = 7.32, 1H), 4.21 (dd, Jgem = 16.84 Hz, J = 7.32 Hz,
1H), 3.65 (dd, Jgem = 16.84 Hz, J = 6.59 Hz, 1H), 13C
NMR (d ppm, CDCl3, 100 MHz): 159.23, 154.90, 148.98,
142.76, 137.95, 132.50, 128.42, 127.94, 125.12, 124.29,
122.11, 112.01, 106.92, 58.41, 39.20, MS (m/
z):299.09(M?1). Anal. Calc. for C17H12F2N2O, calculated
(found) C: 68.45 (68.42), H: 4.05 (4.01), N: 9.39 (9.36).
(s, 1H), 5.30 (t, J = 9.52 Hz, 1H), 3.56 (dd, Jgem
=
15.82 Hz, 1H), 3.30 (dd, Jgem = 15.84 Hz, 1H). 13C NMR
(d ppm, CDCl3, 100 MHz): 156.00, 154.36, 143.33,
130.52, 128.12, 127.56, 127.48, 126.24, 123.29, 122.12,
116.08, 112.40, 111.51, 102.89, 47.00, 29.67. MS (m/z):
281.10 (M?1). Anal. Calc. for C17H13FN2O, calculated
(found) C: 72.85 (72.81), H: 4.67 (4.64), N: 9.99 (9.97).
3-Benzofuran-2-yl-5-(2,4-difluorophenyl)-4,5-dihydro-1H-
pyrazoles (6b) M.p.: 120–122 ꢁC, yield: 75 %. IR (cm-1
,
3-Benzofuran-2-yl-5-(2-trifluoromethylphenyl)-4,5-dihy-
dro-1H-pyrazoles (6f) M.p.: 146–148 ꢁC, yield: 78 %,
IR (cm-1, KBr): 3307.74(=NH), 1605.76 (C=N), 1451.09,
1315.25, 1270.38 (C–O–C). 1H NMR (d ppm, CDCl3,
400 MHz): 7.76 (d, J = 8.05 Hz, 1H), 7.60 (d, J = 8.05 Hz,
1H), 7.52–7.44 (m, 3H), 7.33 (t, J = 8.05 Hz, 1H), 7.24 (t,
J = 8.05 Hz, 1H), 7.18–7.14 (m, 2H), 6.75 (s, 1H), 5.34 (t,
J = 10.25 Hz, 1H), 3.53 (dd, Jgem = 16.84 Hz, J =
10.98 Hz, 1H), 2.93 (dd, Jgem = 16.11 Hz, J = 9.52 Hz,
1H). 13C NMR (d ppm, CDCl3, 100 MHz): 155.85, 150.99,
145.34, 138.40, 133.76, 128.87, 129.65, 129.07, 128.36,
126.26, 125.84, 124.03, 122.06, 111.80, 105.97, 60.40,
45.18, MS (m/z): 331.09(M?1). Anal. Calc. for
C18H13F3N2O, calculated (found) C: 65.45, (65.40), H: 3.97
(3.94), N: 8.48 (8.46).
KBr): 3410.29(=NH), 1633.13(C=N), 1267.45(C–O–C).
1H NMR (d ppm, CDCl3, 400 MHz): 7.62–7.53 (m, 3H),
7.41 (t, J = 8.05 Hz, 1H), 7.28 (t, J = 7.32 Hz, 1H),
7.25–7.10 (m, 3H), 6.90 (s, 1H), 4.91 (t, J = 9.58 Hz, 1H),
3.41 (dd, Jgem = 16.84 Hz, 1H), 2.98 (dd, Jgem
=
16.84 Hz, 1H). 13C NMR (d ppm, CDCl3, 100 MHz):
157.23, 154.11, 141.99, 129.55, 128.29, 128.18, 126.75,
126.57, 122.45, 114.11, 107.42, 53.22, 31.52, MS (m/z):
299.09(M?1). Anal. Calc. for C17H12F2N2O, calculated
(found) C: 68.45 (68.42), H: 4.05 (4.01), N: 9.39 (9.36).
3-Benzofuran-2-yl-5-(2,5-difluorophenyl)-4,5-dihydro-1H-
pyrazoles (6c) M.p: 112–114 ꢁC, yield: 69 %, IR (cm-1
,
KBr): 3435.96 (=NH), 1640.30 (C=N), 1259.53 (C–O–C).
1H NMR (d ppm, CDCl3, 400 MHz): 7.57 (d, J = 8.79 Hz,
2H), 7.52 (d, J = 8.05 Hz, 2H), 7.33 (t, J = 8.05 Hz, 2H),
7.10–7.01 (m, 2H), 6.85 (s, 1H), 5.26 (t, J = 10.25 Hz,
1H), 3.59 (dd, Jgem = 16.11 Hz, J = 10.98 Hz, 1H,dd),
3.01 (dd, Jgem = 16.11 Hz, J = 10.25 Hz, 1H), 13C NMR
(d ppm, CDCl3, 100 MHz): 155.05, 149.22, 142.90,
128.18, 125.10, 123,12, 121.29, 116.33, 114.99, 113.86,
111.50, 106.29, 57.36, 39.65. MS (m/z): 299.09(M?1).
Anal. Calc. for C17H12F2N2O, calculated (found) C: 68.45
(68.42), H: 4.05 (4.01), N: 9.39 (9.36).
3-Benzofuran-2-yl-5-(4-trifluoromethylphenyl)-4,5-dihydro-
1H-pyrazoles (6g) M.p.: 208–210 ꢁC, yield: 76 %, IR
(cm-1, KBr): 3267.77 (=NH), 1618.01 (C=N), 1258.66 (C–
1
O–C). H NMR (d ppm, CDCl3, 400 MHz): 7.56 (d, J =
8.79 Hz, 2H), 7.50 (d, J = 8.05 Hz, 2H), 7.45 (d, J =
8.05 Hz, 2H), 7.25 (t, J = 8.05 Hz, 1H), 7.16 (d, J =
7.32 Hz, 2H), 6.77 (s, 1H), 4.99 (t, J = 10.98 Hz, 1H), 3.50
(dd, Jgem = 16.11 Hz, J = 10.98 Hz, 1H), 3.00 (dd, Jgem
=
16.11 Hz, J = 9.52 Hz, 1H). 13C NMR (d ppm, CDCl3,
100 MHz): 155.10, 149.26, 145.69, 143.00, 128.20, 126.83,
125.87, 125.57, 123.28, 121.32, 111.52, 106.41, 63.72, 41.26.
MS (m/z): 331.09 (M?1). Anal. Calc. for C18H13F3N2O,
calculated (found) C: 65.45, (65.40), H: 3.97 (3.94), N: 8.48
(8.46).
3-Benzofuran-2-yl-5-(2,6-difluorophenyl)-4,5-dihydro-1H-
pyrazoles (6d) M.p.: 164–166 ꢁC, yield: 71 %, IR (cm-1
KBr): 3283.35(=NH), 1593.16 (C=N), 1469.12, 1216.12
,
1
(C–O–C). H NMR (d ppm, CDCl3, 400 MHz): 7.68–7.57
(m, 3H), 7.41 (t, J = 8.05 Hz, 1H), 7.30 (t, J = 7.32 Hz,
1H), 7.18–6.99 (m, 3H), 6.88(s, 1H), 5.60 (t, J = 9.52 Hz,
3-Benzofuran-2-yl-5-phenyl-4,5-dihydro-isoxazoles (7a–g)
1H), 3.71 (dd, Jgem = 16.12 Hz, 1H), 3.40 (dd, Jgem
=
16.11 Hz, 1H), 13C NMR (d ppm, CDCl3, 100 MHz):
162.92, 160.99, 154.30, 153.24, 129.34, 127.98, 125.96,
123.49, 122.63, 121.92, 121.08, 111.75, 110.96, 108.10,
A mixture of 1-benzofuran-2-yl-3-phenyl-prop-2-en-1-one
(5a–g) (0.00052 mol), hydroxylamine hydrochloride
(0.00010 mol) in basic medium using sodium acetate
123

Med Chem Res
3-Benzofuran-2-yl-5-(2,6-difluorophenyl)-4,5-dihydro-is-
(0.0014 mol) were taken in ethanol (5 ml). The resulting
reaction mixture was refluxed for 5–7 h. Reaction was
monitored by TLC. After completion of reaction, the
reaction mixture was concentrated under reduced pressure,
washed with water and extracted with ethyl acetate
(10 ml 9 3 times), organic layer was dried by sodium
sulphate and concentrated under reduced pressure. The
obtained residues were purified by column chromatography
using silica 100–200 mesh-size by ethylacetate : hexane
(18 %) mixture as eluent which afforded 3-benzofuran-2-
yl-5-phenyl-4,5-dihydro-isoxazoles (7a–g) in good yields.
oxazoles (7d) M.p.: 176–178 ꢁC, yield: 79 %, IR (cm-1
,
KBr): 1592.11 (C=N), 1467.32 (N–O), 1256.79 (C–O–C),
1H NMR (d ppm, DMSO-d6, 400 MHz): 7.61 (d,
J = 8.05 Hz, 1H), 7.50 (d, J = 8.79 Hz, 1H), 7.30 (t, J =
7.32 Hz, 1H), 7.25–7.19 (m, 3H), 6.92 (t, J = 8.79 Hz,
2H), 4.72 (t, J = 7.32 Hz, 1H), 3.25 (dd, Jgem = 12.45 Hz,
J = 6.59 Hz, 1H), 3.18 (dd, Jgem = 12.45 Hz, J =
8.79 Hz, 1H), 13C NMR (d ppm, DMSO-d6, 100 MHz):
162.54, 160.36, 154.16, 152.15, 146.44, 129.25, 127.58,
125.23, 123.15, 121.42, 116.78, 111.07, 105.25, 54.97,
27.32, MS (m/z): 300.07(M?1). Anal. Calc. for
C17H11F2NO2, calculated (found) C: 68.23 (68.20), H: 3.70
(3.68), N: 4.68 (4.66).
3-Benzofuran-2-yl-5-(4-fluorophenyl)-4,5-dihydro-isoxaz-
oles (7a) M.p.: 160–162 ꢁC, yield: 77 %, IR (cm-1
,
KBr): 1622.34 (C=N), 1498.31 (N–O), 1229.56 (C–O–C).
1H NMR (d ppm, CDCl3, 400 MHz): 7.53–7.40 (m, 2H),
7.35–7.25 (m, 3H), 7.10–6.92 (m, 3H) 6.54 (s, 1H), 4.47 (t,
J = 9.52 Hz, 1H), 2.51 (dd, Jgem = 13.18 Hz, 1H), 2.19
(dd, Jgem = 13.19 Hz, 1H). 13C NMR (d ppm, CDCl3,
100 MHz): 163.37, 159.37, 154.25, 151.62, 137.75,
129.14, 128.83, 128.73, 126.26, 124.06, 123.95, 115.54,
112.19, 110.61, 68.51, 29.67. MS (m/z): 282.08 (M?1).
Anal. Calc. for C17H12FNO2, calculated (found) C: 72.59
(72.55), H: 4.30 (4.26), N: 4.98 (4.95).
3-Benzofuran-2-yl-5-(3,4-difluorophenyl)-4,5-dihydro-is-
oxazoles (7e) M.p.: 182–184 ꢁC, yield: 69 %, IR (cm-1
,
1
KBr): 1630.75 (C=N), 1386.64,. H NMR (d ppm, CDCl3,
400 MHz): 7.55 (d, J = 8.05 Hz, 1H), 7.48 (t,
J = 8.79 Hz, 1H), 7.40 (t, J = 7.32 Hz, 1H), 7.34–7.28
(m, 2H), 7.15–7.08 (m, 2H), 6.92 (s, 1H), 4.52–4.46 (m,
1H), 3.39 (dd, Jgem = 13.91 Hz, J = 8.05 Hz, 1H), 3.02
(dd, Jgem = 16.11 Hz, J = 5.86 Hz, 1H). 13C NMR
(d ppm, CDCl3, 100 MHz): 162.14, 154.89, 150.80,
148.76, 137.74, 127.66, 126.56, 125.85, 123.37, 121.54,
117.22, 114.78, 111.38, 107.10, 63.06, 30.22, MS (m/z):
300.07(M?1). Anal. Calc. for C17H11F2NO2, calculated
(found) C: 68.23 (68.20), H: 3.70 (3.68), N: 4.68 (4.66).
3-Benzofuran-2-yl-5-(2,4-difluorophenyl)-4,5-dihydro-is-
oxazoles (7b) M.p.: 138–140 ꢁC, yield: 75 %. IR (cm-1
,
KBr): 1618.34 (C=N), 1503.78 (N–O), 1258.47 (C–O–C).
1H NMR (d ppm, CDCl3, 400 MHz): 7.57–7.46 (m, 4H),
7.32 (t, J = 7.32 Hz, 1H), 6.99 (s, 1H), 6.86–6.78 (m, 2H),
4.79 (dd, J = 8.79 Hz, 1H), 3.54 (dd, Jgem = 13.18 Hz,
J = 8.79 Hz, 1H), 3.04 (dd, Jgem = 13.91 Hz, J =
5.13 Hz, 1H). 13C NMR (d ppm, Acetone-d6, 100 MHz):
162.46, 155.91, 152.94, 148.00, 132.71, 128.83, 126.27,
123.90, 122.39, 112.02, 107.65, 103.81, 57.84, 29.99, MS
(m/z): 300.07(M?1). Anal. Calc. for C17H11F2NO2, cal-
culated (found) C: 68.23 (68.20), H: 3.70 (3.68), N: 4.68
(4.66).
3-Benzofuran-2-yl-5-(2-trifluoromethylphenyl)-4,5-dihy-
dro-isoxazoles (7f) M.p.: 140–142 ꢁC, yield: 73 %, IR
(cm-1, KBr): 1609.85 (C=N), 1384.24, 1350.82, 1314.40
1
(C–O–C). H NMR (d ppm, CDCl3, 400 MHz): 7.83 (d,
J = 8.05 Hz, 1H), 7.77 (d, J = 8.05 Hz, 1H), 7.65–7.57
(m, 2H), 7.47 (t, J = 7.32 Hz, 1H), 7.39 (t, J = 8.05 Hz,
1H), 7.29 (t, J = 7.32 Hz, 1H), 7.26–7.15(m, 1H), 6.86 (s,
1H), 5.06 (t, J = 8.79 Hz, 1H), 3.57 (dd, Jgem = 13.18 Hz,
J = 10.25 Hz, 1H), 2.98 (dd, Jgem = 13.91 Hz, 1H). 13C
NMR (d ppm, Acetone-d6, 100 MHz): 155.84, 155.02,
153.18, 147.70, 136.07, 133.53, 132.79, 129.61, 129.08,
126.66, 125.94, 122.35, 113.96, 111.86, 107.29, 60.74,
29.99. MS (m/z): 332.08 (M?1). Anal. Calc. for
C18H12F3NO2, calculated (found) C: 65.26, (65.21), H:
3.65 (3.61), N: 4.23 (4.21).
3-Benzofuran-2-yl-5-(2,5-difluorophenyl)-4,5-dihydro-is-
oxazoles (7c) M.p: 156–158 ꢁC, yield: 71 %, IR (cm-1
,
KBr): 1622.32 (C=N), 1496.05 (N–O), 1256.62 (C–O–C).
1H NMR (d ppm, CDCl3, 400 MHz): 7.50 (d,
J = 8.05 Hz, 1H), 7.42 (d, J = 8.05 Hz, 1H), 7.33–7.26
(m, 2H), 6.96 (s, 1H), 6.92–6.84 (m, 3H), 4.73 (dd,
J = 9.52 Hz, 1H), 3.44 (dd, Jgem = 13.91 Hz, J =
8.79 Hz, 1H), 2.96 (dd, Jgem = 13.91 Hz, J = 5.13 Hz,
1H). 13C NMR (d ppm, Acetone-d6, 100 MHz): 155.05,
149.22, 142.90, 128.18, 125.10, 123.12, 121.29, 116.33,
114.99, 113.86, 111.50, 106.29, 57.36, 39.65. MS (m/z):
300.07(M?1). Anal. Calc. for C17H11F2NO2, calculated
(found) C: 68.23 (68.20), H: 3.70 (3.68), N: 4.68 (4.66).
3-Benzofuran-2-yl-5-(4-trifluoromethylphenyl)-4,5-dihydro-
isoxazoles (7g) M.p.: 188–190 ꢁC, yield: 76 %, IR (cm-1
,
KBr): 1617.85 (C=N), 1454.52 (N–O), 1331.29, 1118.22.
1H NMR (d ppm, DMSO-d6, 400 MHz): 7.58–7.50 (m,
6H), 7.30 (t, J = 7.32 Hz, 1H), 7.21 (t, J = 7.32 Hz, 1H),
7.06 (s, 1H), 4.35 (t, J = 7.32 Hz, 1H), 3.08 (dd,
Jgem = 13.18 Hz, J = 7.32 Hz, 1H), 2.94 (dd, Jgem
=
12.45 Hz, J = 8.05 Hz, 1H). 13C NMR (d ppm, DMSO-d6,
123

Med Chem Res
100 MHz): 154.38, 151.91, 146.35, 129.01, 128.45,
125.48, 124.99, 123.18, 121.57, 111.14, 106.57, 64.24,
29.46. MS (m/z): 332.08(M?1). Anal. Calc. for
C18H12F3NO2, calculated (found) C: 65.26, (65.21), H:
3.65 (3.61), N: 4.23 (4.21).
The control tube containing no antibiotic is immediately
sub cultured (before inoculation) by spreading a loopful
evenly over a quarter of plate of medium suitable for the
growth of the test organism and put for incubation at 37 ꢁC
overnight. The tubes are then incubated overnight. The
MIC of the control organism is read to check the accuracy
of the drug concentrations. The lowest concentration
inhibiting growth of the organism is recorded as the MIC.
The amount of growth from the control tube before incu-
bation (which represents the original inoculums) is
compared.
Biological assays
Materials
All clinically standard strains Gram-positive bacteria S.
aureus, B. subtilis, S. pneumoniae, S. pyogenes, the Gram-
negative bacteria E. coli, P. aeruginosa, S. typhi; and the
fungi C. albicans, A. niger, A. clavatus were used for
screening of antibacterial and antifungal activities were
procured from Institute of Microbial Technology, Chan-
digarh. All necessary controls like: drug control, vehicle
control, agar control, organism control, known antibacterial
drugs control were used. All MTCC cultures were tested
against above mentioned known and unknown drugs.
Muller Hinton Broth (MBH) was used as nutrient medium
to grow and dilute the drug suspension for the test bacteria.
Inoculum size for test strain was adjusted to 108 Cfu
(colony forming unit) per millilitre by comparing the tur-
bidity. DMSO was used as diluents/vehicle to get desired
concentration of drugs to test upon standard bacterial
strains.
Reading result
The highest dilution showing at least 99 % inhibition zone
is taken as MIC. The result of this is much affected by the
size of the inoculums. The test mixture should contain
108 organism/ml.
Acknowledgments The authors thank to Department of Science &
Technology (DST), New Delhi and University Grants Commission
(UGC) for providing financial support. We gratefully acknowledge
USIC, University of Delhi for providing analytical support.
References
Abdel-Wahab BF, Abdel-Aziz HA, Ahmed EM (2008) Convenient
synthesis and antimicrobial activity of new 3-substituted
5-(benzofuran-2-yl)-pyrazole derivatives. Arch Pharm Chem
Life Sci 341:734–739
Antibacterial and antifungal activity
Bansal E, Srivastava VK, Kumar A (2001) Synthesis and antiinflamma-
tory activity of 1-acetyl-5-substituted aryl-3-(b-aminonaphthyl)-2-
pyrazolinesand b-(substitutedaminoethyl)amidonaphthalenes. Eur
J Med Chem 36:81–92
Basawaraj R, Yadav B, Sangapure SS (2001) Synthesis of some 1H-
pyrazolines bearing benzofuran as biologically active agents.
Indian J Heterocycl Chem 11:31–34
Caramella P, Gruenanger P (1984) In: Padwa A (Ed) 1,3-Dipolar
cycloaddition chemistry, vol 1, Wiley, New York, p 337
Carson CF, Hammer KA, Riley TV (1995) Broth micro-dilution
method for determining the susceptibility of Escherichia coli and
Staphylococcus aureusto the essencial oil of Melaleuca alterni-
folia (tea tree oil). Microbios 82:181–185
Cho JU, Kim CJ, Lee HB, Lim CH (2004) Patent Korea KR
2004064795 (CA: 145, 182279)
Corey EJ (1973) In: ApSimon J (ed) The Total Synthesis of Natural
Products vol. 1. Wiley, New York, p 81
Dai JR, Hallock YF, Cardellina JH, Boyd M (1998) HIV-inhibitory
and cytotoxic oligostillbenes from the leaves of Hopea malibato.
J Nat Prod 61:351–353
Dawood KM, Abdel-Gawad H, Rageb EA, Ellithey M, Mohamed HA
(2006) Synthesis, anticonvulsant, and anti-inflammatory evalu-
ation of some new benzotriazole and benzofuran-based hetero-
cycles. Bioorg Med Chem 14:3672–3680
‘Broth dilution method’ was used for minimum inhibition
concentration (MIC) of synthesized compounds against
bacterial and fungal strains. It is one of the non-automated
in vitro bacterial susceptibility tests. This classic method
yields a quantitative result for the amount of antimicrobial
agents that is needed to inhibit growth of specific micro-
organisms. It is carried out in tubes.
•
•
Macrodillution method in tubes.
Microdillution format using plastic trays.
Serial dilutions of synthesized compounds in DMSO
were prepared for primary and secondary screening. Each
synthesized drug was diluted obtaining 2,000 lg/ml con-
centration, as a stock solution.
Primary screen In primary screening 1,000, 500, and
250 lg/ml concentrations of the synthesized drugs were
taken. The active synthesized drugs found in this primary
screening were further tested in a second set of dilution
against all microorganisms.
Diyasena MNC, Sotheeswaran S, Surendrakumar S, Balasubramanian
S, Bokel M, Karus WJ (1985) Balanocarpol, a new polyphenol
from Balanocarpus zeylanicus (trimen) and Hopea jucunda
Secondary screen The drugs found active in primary
screening were similarly diluted to obtain 200, 100, 50, 25,
12.5, and 6.250 lg/ml concentrations.
(Thw.) (Dipterocarpaceae).
1807–1809
J
Chem Soc Perkin Trans 1:
123

Med Chem Res
Druzgala P, Milner PG (2002) Novel enantiomeric compounds for
treatment of cardiac arrhythmias and methods of use. US Patent
Appl Publ 2002193428 (CA: 138, 39179)
Du X, Guo C, Hansell E, Doyle PS, Caffrey CR, Holler TP,
McKerrow JH, Cohen FE (2002) Synthesis and structure–
activity relationship study of potent trypanocidal thio semicar-
bazone inhibitors of the trypanosomal cysteine protease cruzain.
J Med Chem 45:2695–2707
Engler TA, LaTessa KO, Iyengar R, Chai W, Agrios K (1996)
Stereoselective syntheses of substituted pterocarpans with anti-
HIV activity, and 5-aza-/5-thia-pterocarpan and 2-aryl-2,3-
dihydrobenzofuran analogues. Bioorg Med Chem 4:1755–1769
Fuganti C, Serra S (1998) A new approach to 2-aryl-7-alkoxy-
benzofurans: synthesis of ailanthoidol, a natural neolignan.
Tetrahedron Lett 39:5609–5610
Purser S, Moore PR, Swallow S, Gouverneur V (2008) Fluorine in
medicinal chemistry. Chem Soc Rev 37:320–330
Rida SM, EI-Hawash SAM, Fahmy HTY, Hazzaa AA, EI-Meligy MMM
(2006) Synthesis of novel benzofuran and related benzimidazole
derivatives for evaluation of in vitro anti-HIV-1, anticancer and
antimicrobial activities. Arch Pharm Res 29:826–833
Riesselman MH, Hazen KC, Cutler JE (2000) Determination of
antifungal MICs by a rapid susceptibility assay. J Clin Microbiol
38:333–340
Rowley M, Hallett DJ, Goodacre S, Moyes C, Crawforth J, Sparey TJ,
Patel S, Marwood R, Patel S, Thomas S, Hitzel L, Connor DO,
Szeto N, Castro JL, Hutson PH, Macleod AM (2001) 3-(4-
Fluoropiperidin-3-yl)-2-phenylindoles as high affinity, selective,
and orally bioavailable h5-HT2Areceptor antagonists. J Med
Chem 44:1603–1614
Gokhan N, Yeilada A, Uc¸ar G, Erol K, Bilgin AA (2003) 1-N-
thiocarbamoyl-3-phenyl-5-thienyl-2-pyrazolines.
Shaharyar M, Abdullah MM, Bakht MA, Majeed J (2010) Pyrazoline
bearing benzimidazoles: search for anticancer agent. Eur J Med
Chem 45:114–119
Singh DV, Mishra AR, Mishra RM, Pandey AK, Singh CR, Dwivedi
AK (2005) Synthesis and fungicidal activity of benzofuran
incorporated substituted pyrimidines. Indian J Heterocycl Chem
14:319–322
Substituted
synthesis and evaluation as mao inhibitors. Arch Pharm
336:362–371
Havrylyuk D, Zimenkovsky B, Vasylenko O, Zaprutko L, Gzella A,
Lesyk R (2009) Synthesis of novel thiazolone based compounds
containing pyrazoline moiety and evaluation of their anticancer
activity. Eur J Med Chem 44:1396–1404
Huisgen R (1963) 1,3-Dipolar cycloadditions. Angew Chem Int Ed
2:565–598
Mana F, Chimenti F, Bolasco A, Cenicola ML, Parrillo MDC, Rossi
F, Marmo E (1992) Anti-inflammatory, analgesic and antipyretic
N-acetyl-2-pyrazolines and dihydrothieno coumarines. Eur J
Med Chem 27:633–639
Nasr MNA, Said SA (2003) Novel 3,3a,4,5,6,7-hexahydroindazole
and arylthiazolyl pyrazoline derivatives as anti-inflammatory
agent. Arch Pharm 336:551–559
Paizs C, Tosa M, Majdik C, Moldovan P, Novak L, Kolonits P,
Marcovivi A, Irimie F, Poppe L (2003) Optically active
1-(benzofuran-2-il)ethanols and ethane-1,2-diols by enantiotopic
selective bioreductions. Tetrahedron Asym 14:1495–1501
Palaska E, Aytemir M, Uzbay IT, Erol E (2001) Synthesis and
antidepressant activities of some 3,5-diphenyl-2-pyrazolines. Eur
J Med Chem 36:539–543
Smart BE (2001) Fluorine substutuent effects (on bioactivity).
J Fluorine Chem 109:3–11
Tarpay MM, Welch DF, Marks MI (1980) Antimicrobial suscepti-
bility testing of Streptococcus pneumoniae by micro-broth
dilution. Antimicrob Agents Chemother 18:579–581
Teresa MVD, Mello PE (2005) Review article: recent advances on the
synthesis and reactivity of isaxazoles. Current Org Chem
9:925–958
Turan-Zitouni G, Chevallet P, Kilic¸ FS, Erol K (2000) Synthesis of some
thiazolyl-pyrazoline derivatives and preliminary investigation of
their hypotensive activity. Eur J Med Chem 35:635–641
Ujjinamatada RK, Appala RS, Agasimundin YS (2006) Synthesis and
antimicrobial activity of new benzofuranyl-1,3-benzoxazines
and 1,3-benzoxazin-2-ones. J Heterocycl Chem 43:437–441
Wachi S, Takagi K, Menichi G, Hubert-Habart M (1978) Research on
potential antitumor agents. Methods for preparing hydropyrim-
idines from coumarins. Bull Soc Chim Fr 5–6:230–233
123