Synthesis and characterization of new N-(4-(4-chloro-1H-imidazol-1-yl)-3- methoxyphenyl)amide/sulfonamide derivatives as possible antimicrobial and antitubercular agents

Article abstract of DOI:10.1016/j.ejmech.2013.11.002

In this paper we report the SAR studies of a series of N-(4-(4-chloro-1H- imidazol-1-yl)-3-methoxyphenyl)amide and N-(4-(4-chloro-1H-imidazol-1-yl)-3- methoxyphenyl)sulfonamide derivatives 6(a-o) and 7(a-o), were synthesized in good yields and characterized by ¹H NMR, ¹³C NMR and mass spectral analyses. The preparation of the key intermediate highlights an optimized palladium catalyzed (Pd₂(dba)₃/RuPhos) Buchwald cross-coupling of intermediate 2 and 3. The newly synthesized compounds were evaluated for their in vitro antibacterial activity against Staphylococcus aureus, (Gram-positive), Escherichia coli and Klebsiella pneumoniae (Gram-negative), antifungal activity against Candida albicans, Aspergillus flavus and Rhizopus sp. and antitubercular activity against Mycobacterium tuberculosis H37Rv, Mycobacterium smegmatis, Mycobacterium fortuitum and MDR-TB strains. The synthesized compounds displayed interesting antimicrobial activity. The compounds 7d, 7f, 7h and 7n displayed significant activity against Mycobacterium tuberculosis H37Rv strain.

Full text of DOI:10.1016/j.ejmech.2013.11.002

European Journal of Medicinal Chemistry 71 (2014) 354e365
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Original article
Synthesis and characterization of new N-(4-(4-chloro-1H-imidazol-1-
yl)-3-methoxyphenyl)amide/sulfonamide derivatives as possible
antimicrobial and antitubercular agents
,
Pakkath Karuvalam Ranjith a, Rajeesh Pakkath a, Karickal R. Haridas a
*
,
Suchetha N. Kumari b
a School of Chemical Sciences, Kannur University, Payyanur Campus, Edat P.O., 670327 Kannur, Kerala, India
b Department of Biochemistry, Justice K.S. Hegde Medical Academy, Deralakatte, India
a r t i c l e i n f o
a b s t r a c t
Article history:
In this paper we report the SAR studies of
a series of N-(4-(4-chloro-1H-imidazol-1-yl)-3-
Received 25 June 2013
Received in revised form
28 September 2013
Accepted 3 November 2013
Available online 10 November 2013
methoxyphenyl)amide and N-(4-(4-chloro-1H-imidazol-1-yl)-3-methoxyphenyl)sulfonamide de-
rivatives 6(aeo) and 7(aeo), were synthesized in good yields and characterized by 1H NMR, 13C NMR and
mass spectral analyses. The preparation of the key intermediate highlights an optimized palladium
catalyzed (Pd2(dba)3/RuPhos) Buchwald cross-coupling of intermediate 2 and 3. The newly synthesized
compounds were evaluated for their in vitro antibacterial activity against Staphylococcus aureus, (Gram-
positive), Escherichia coli and Klebsiella pneumoniae (Gram-negative), antifungal activity against Candida
albicans, Aspergillus flavus and Rhizopus sp. and antitubercular activity against Mycobacterium tubercu-
losis H37Rv, Mycobacterium smegmatis, Mycobacterium fortuitum and MDR-TB strains. The synthesized
compounds displayed interesting antimicrobial activity. The compounds 7d, 7f, 7h and 7n displayed
significant activity against Mycobacterium tuberculosis H37Rv strain.
Keywords:
Imidazole
Pd2(dba)3
RuPhos
Antimicrobial activity
Antimycobacterial activity
Ó 2013 Elsevier Masson SAS. All rights reserved.
1. Introduction
problem of MDR-TB has focused attention on developing new drugs
that are not only active against drug resistant TB, but also shorten
There are certain diseases that take a long time to develop; these
diseases are called chronic germ diseases. Tuberculosis is a specific
communicable disease caused by Mycobacterium tuberculosis. It
affects both the pulmonary and non pulmonary tissues. This disease
may be acute or chronic, general or local. These bacilli are micro-
scopic and were first discovered in 1882. Due to the heterogeneous
bacterial populations in the tuberculosis lesions and perhaps also to
insufficient host immunity, treatment with a combination of drugs
must be given for extended periods of time to prevent reactivation
of disease by persisting bacilli. Tuberculosis is a devastating
worldwide problem, whose control is complicated by a number of
confounding factors including development of multi-drug-resistant
(MDR) strains to commonly used drugs, substantially long course of
therapy, and lack of affordable cheap drugs in the cases involving
patients suffering due to MDR tuberculosis [1e3]. The increasing
the lengthy therapy [4]. In developing new TB drugs, it is crucial to
think about which target in the tubercle bacillus are good targets.
Several reviews on this topic are readily available [5,6]. Literature
review shows that imidazole based compounds were reported to
possess antimicrobial activities [7]. In recent years [8], the high
therapeutic properties of the imidazole related drugs have been
attracting the attention of medicinal chemists to synthesize a large
number of novel chemotherapeutic agents. Medicinal properties of
imidazole containing compounds include anticancer [9], antimi-
crobial [8,10e12], antioxidant [13,14], antiviral [15], antitubercular
[16] activities. Keeping in view of the overall statistics, there is an
urgent requirement of developing new drugs with a unique
structure and different mechanism of action than the existing drug.
The present study highlights the recently synthesized series of
imidazole derivatives possessing important biological activities. In
this communication, we describe the synthesis of N-(4-(4-chloro-
1H-imidazol-1-yl)-3-methoxyphenyl)amide, N-(4-(4-chloro-1H-
imidazol-1-yl)-3-methoxyphenyl)sulfonamide derivatives and
evaluation of their in vitro antibacterial activity against three
representative bacterial species viz., Staphylococcus aureus, (Gram-
* Corresponding author. Tel./fax: þ91 0497 2806402.
E-mail addresses: pkranjith@rediffmail.com (P.K. Ranjith), krharidas2001@
yahoo.com (K.R. Haridas).
0223-5234/$ e see front matter Ó 2013 Elsevier Masson SAS. All rights reserved.
http://dx.doi.org/10.1016/j.ejmech.2013.11.002

P.K. Ranjith et al. / European Journal of Medicinal Chemistry 71 (2014) 354e365
355
positive), Escherichia coli and Klebsiella pneumoniae (Gram-nega-
tive) using ciprofloxacin as reference and in vitro antifungal activity
against three representative fungal species viz., Candida albicans,
Aspergillus flavus and Rhizopus sp. using Amphotericin B as refer-
ence, In addition, the anti-tuberculosis activity against M. tuber-
culosis H37Rv ATCC 27294, and non-tubercular mycobacterial
(NTM) species like Mycobacterium smegmatis (MC2) ATCC 19420,
Mycobacterium fortuitum ATCC 19542 and MDR-TB strains were also
carried out.
As a part of our research work on the development of useful
synthetic molecules [17] and for new antitubercular agents [18] it
has been planned to introduce 4-chloro substituted imidazole
amides and sulfonamides. In this communication, we report the
synthesis of newly designed N-(4-(4-chloro-1H-imidazol-1-yl)-3-
temperature. Microwave assisted palladium catalyzed Buchwald
cross-coupling reactions were employed on the chloroimidazole,
(2) with 1-chloro-2-methoxy-4-nitrobenzene (3) in dioxane at
120 ꢀC. Palladium catalyst and different ligand combinations
(Table 1) were tried in this step to find an appropriate catalyst that
would enhance the coupling. Table 2 shows the different bases that
were explored in order to find an effective base that would enhance
the coupling yield. From the table it is clear that Cs2CO3 was found
to be an effective base among all the bases explored. Among the
solvents, dioxane (Table 3) was found to be a better choice and
Table 3 shows the effect of solvents on the cyclization reactions.
Surprisingly, Pd2(dba)3/RuPhos was found to give better conver-
sions to product compared to other catalytic systems. The key in-
termediate (5) which is formed by reducing intermediate (4) by
using NH4Cl in presence of Zinc powder in THF at ambient tem-
perature. The title compounds 6(aeo) were synthesized by
coupling the key intermediate 5 with different substituted phenyl
acids in presence of N-(3-dimethylaminopropyl)-N0-ethyl-
carbodiimide hydrochloride (EDC$HCl) and hydroxybenzotriazole
(HOBt) [19] in dichloromethane at ambient temperature. The title
compounds 7(aeo) were synthesized by coupling the key inter-
mediate 5 with different substituted phenyl sulfonyl chlorides in
presence of (EDC$HCl) and dimethylaminopyridine (DMAP) in
dichloromethane at ambient temperature. The newly synthesized
compounds were characterized by 1H NMR, 13C NMR and LCMS. The
formation of 4-chloroimidazole (2) was confirmed by its 1H NMR
spectrum where the disappearance of the doublet aromatic proton
methoxyphenyl)amide,
N-(4-(4-chloro-1H-imidazol-1-yl)-3-
methoxyphenyl)sulfonamide derivatives 6(aeo) and 7(aeo)
(Scheme 1) and evaluated these compounds for the antimicrobial
and antitubercular activities.
2. Results and discussion
2.1. Chemistry
The synthetic pathway that leads to the formation of the title
compounds 6(aeo) and 7(aeo) are sketched in Scheme 1. 4-
Chloroimidazole (2) was prepared by reacting simple imidazole
with sodium hypochlorite and sodium hydroxide at ambient
Cl
N
Cl
Cl
O
N
N
A
B
N
+
O
N
H
N
H
NO2
3
1
2
Cl
NO2
4
N
C
N
O
E
D
Cl
Cl
NH2
5
N
N
N
N
O
O
R
O
HN
HN
S
R
O
O
7(a-o)
6(a-o)
Scheme 1. (A) NaOH, NaOCl, ambient temperature (B) Pd2(dba)3/RuPhos, dioxane, microwave, Cs2CO3, 120 ꢀC (C) Zn, NH4Cl, THF, ambient temperature (D) RCOOH, EDCl, HOBt, TEA,
Dichloromethane, ambient temperature (E) RSO2Cl, EDCl, DMAP, dichloromethane, ambient temperature.

356
P.K. Ranjith et al. / European Journal of Medicinal Chemistry 71 (2014) 354e365
Table 1
Table 3
Effect of catalyst on the Buchwald coupling of 2 and 3.a
Effect of solvent on Buchwald coupling of 2 and 3.a
Entry
Ligand
% Yieldb
Entry
Solvent
% Yield
1
2
3
4
5
PPh3
Traces
Traces
25
45
60
1
2
3
4
5
Toluene
THF
DME
DMF
Dioxane
21
39
32
62
79
Xanthphos
X-Phos
S-Phos
RuPhos
a
a
Reaction conditions: Intermediate 2 (0.01 mol), Intermediate 3 (0.011 mol),
K3PO4 (0.02 mol), Pd2(dba)3 (5 mol %), Ligand (10 mol%), DMF. microwave irradiated
at 120 ꢀC for 30 min.
Reaction conditions: Intermediate 2 (0.01 mol), intermediate 3 (0.011 mol),
Cs2CO3 (0.02 mol), Pd2(dba)3 (5 mol %), RuPhos (10 mol%), solvent, microwave
irradiated at 120 ꢀC for 30 min.
b
Isolated yield after column purification.
derivatives with electron withdrawing group at the ring at the re-
gion 2 of the molecules were less active (6a, 6d, 6f, 6g, 6h and 6n).
On the other hand benzyl substituted sulfonamides (7b and 7k) at
the region 2 of the molecule showed less activity, which shows
aromatic ring which is directly attached to the sulfonamide group
are more active. Surprisingly electron donating substituent at the
region 2 reduces the activity (7e, 7m and 7o). For instance, after
methyl substitution at the region 2 the activity has been lowered
for compound 7i compared to compound 7d. Furthermore biolog-
ical results showed that the heterocyclic substitution at the region 2
of the molecule (7c and 7j) is slightly active. The SAR studies of the
synthesized molecules show that sulfonamide linkage at the region
2 of the molecule is more active than amide linkage at the region 2
and electron withdrawing substituent at the region 2 of the sul-
fonamide derivatives are more active. Electron donating substitu-
ent at the region 2 of the sulfonamide derivatives decreases the
activity.
peak at
d
7.21 ppm. The formation of intermediate 4 [20] was
confirmed by the disappearance of eNH peak at
d12.42 ppm and
was also evidenced by LCMS spectral data. The formation of the key
intermediate 5 was confirmed by its 1H NMR spectrum. In its
spectrum appearance of singlet (eNH2) peak at d 5.47 ppm and was
also evidenced by LCMS spectral data. The title compound forma-
tion was confirmed by its 1H NMR spectrum, where the absence of
NH2 proton at
d 5.47 ppm and was also evidenced by its LCMS
spectral data. The spectral data is discussed in experimental section
and the characterization data of 6(aeo) and 7(aeo) are tabulated in
Table 4.
2.2. Structure activity relationship
In this study we have mainly concentrated at the region 2 (Fig.1)
of the synthesized molecules. When we screened an in house
collection of compounds for antibacterial activity, sulfonamide
derivative (7l) was identified as a moderate inhibitor to the tested
organisms. Surprisingly the amide derivative (6l) showed less ac-
tivity against the tested organisms. In view of its novel structural
template we were interested to study further SAR of the related
class of compounds. Thus with compound 7l as the starting point,
we developed a novel series of imidazole derivatives and investi-
gated their biological actions as potential antimicrobial and anti-
tubercular agents. Lipophilicity of compounds plays a major part in
studying the biological activity of a compound [21,22]. These
properties are seen as an important parameter related to mem-
brane permeation in biological system. It has been well established
that halogenated and particularly CF3 substituted molecules have
got a significant place in modern medicinal chemistry [23,24]. The
eNH2 group of the key intermediate was coupled with different
carboxylic acids and sulfonyl chlorides which lead to the formation
of amide and sulfonamide respectively. Biological results indicate
that compound 7d, 7f and 7h displayed good activity and this might
be due to the presence of halogen and eCF3 group attached to the
aryl ring increases the lipophilic nature of the compound, there by
making the molecule more cell permeable. One of the other reasons
could be the sulfonamide group present in the molecule. The bio-
logical results indicated that the sulfonamide derivatives with
electron withdrawing group at the ring at the region 2 of the
molecules were more active (7a, 7d, 7f, 7g and 7h), where as amide
From the obtained results (Table 5), it has been noticed that
tested compounds exhibited moderate to good inhibition (4e
256 mg/mL in DMSO) against the tested two Gram-negative and one
Gram-positive bacteria except 6c, 6e, 6h, and 6m against S. aureus,
6e, 6g, 6i, 6n, 6o and 7e against E. coli and 6a, 6c, 6n and 7c against
K. pneumoniae. Someof the compoundsexhibitedsignificant activity
against S. aureus as exemplified by compounds 7a, 7b, 7d, 7f, 7g, 7h
and 7l. Surprisingly, the inhibitory activity of the compound 7b, 7d,
7fand 7h against S. aureus, exhibiting MIC value aboutone fold times
lower than the reference Ciprofloxacin. Similarly, the inhibitory ac-
tivity of the compound 7a, 7d and 7h against E. coli were found to be
same as that of reference. The inhibitory activity of the compounds
7d and 7f and 7h against Klebsiella pneumonia exhibiting MIC value
about one fold times and the compound 7b exhibiting MIC value
about two fold times lower than the reference Ciprofloxacin.
Investigation of antifungal screening data has shown that few of the
compounds produced considerable and varied results. It is apparent
from Table 5 compounds 6e, 6i, 6k and 6n failed to exert activity
against all the three pathogenic strains at MIC 256
and 6g against C. albicans (for which MIC was noticed at 128
and 6c, 6m and 7e against A. flavus (for which MIC was noticed at
128 g/ml). Thus against C. albicans compounds 7d, 7f and 7h and
mg/ml except 6b
mg/ml)
m
against A. flavus compound 7d showed equivalent potency in com-
parison with reference Amphotericin B, whilst all other compounds
exhibited MIC between 16 and 256
6c, 6e, 6g, 6i, 6k, 6m, 6n, 7c, 7e, 7g, 7i and 7o did not exert antifungal
activity against Rhizopus sp. up to 256 g/ml, interestingly com-
pounds 7d, 7f and 7h exhibited the same potency (MIC 16 g/ml)
mg/ml. Although compounds 6b,
m
Table 2
Effect of base on the Buchwald coupling of 2 and 3.a
m
compared to the reference drug. Further, the preliminary anti-
mycobacterial screening of the title compounds were carried out at
1, 10 and 100 mg/mL concentrations against three different TB strains
and also against MDR-TB strain. From the result, it was noticed that
thecompounds 6a, 6b, 6d, 6f, 6g, 6j, 6k, 7c, 7d, 7f, 7g, 7h, 7j, 7l and 7n
Entry
Base
% Yield
1
2
3
4
CH3COOK
Na2CO3
K2CO3
NR
NR
57
62
Cs2CO3
were active between 1 and 10
tuberculosis H37Rv strain. The active compounds from the pre-
liminary investigation were further subjected to second level of
mg/mL concentrations against M.
a
Reaction conditions: Intermediate 2 (0.01 mol), Intermediate 3 (0.011 mol), base
(0.02 mol), Pd2(dba)3 (5 mol%), RuPhos (10 mol%), DMF, microwave irradiated at
120 ꢀC for 30 min.

P.K. Ranjith et al. / European Journal of Medicinal Chemistry 71 (2014) 354e365
357
Table 4
Characterization data of synthesized compounds 6(aeo) and 7(aeo).
Compound
Structure
Mol. formula
M. wt
M.P. ꢀC
Yielda (%)
O
O
O
Cl
6a
C17H12Cl3N3O2
396.7
178e180
84
89
N
N
N
N
NH
Cl
Cl
Cl
O
6b
C19H15ClF3N3O2
409.8
164e166
NH
CF3
O
O
O
6c
C15H12ClN3O3
317.7
ND
85
80
N
N
N
N
N
NH
Cl
Cl
Cl
Cl
Cl
F
O
O
6d
C18H12ClF4N3O2
413.8
180e182
N
N
N
NH
CF3
O
O
O
6e
6f
C18H16ClN3O3
357.8
173e175
162e164
208e210
90
72
63
NH
O
O
CF3
C18H13ClF3N3O2
395.8
NH
Cl
NO2
O
O
6g
C17H12Cl2N4O4
407.2
N
N
N
NH
Cl
CF3
O
O
6h
6i
C18H11Cl2F4N3O2
448.2
182e184
68
62
N
NH
F
Cl
F
O
O
O
C18H14ClF2N3O3
393.8
ND
N
N
NH
F
Cl
O
O
S
6j
C15H12ClN3O2S
333.8
196e198
81
N
N
N
NH
Cl
Cl
H
N
6k
C20H17Cl2N3O2
402.3
ND
68
O
O
Cl
N
(continued on next page)

358
P.K. Ranjith et al. / European Journal of Medicinal Chemistry 71 (2014) 354e365
Table 4 (continued )
Compound
Structure
Mol. formula
M. wt
M.P. ꢀ
C
Yielda (%)
O
O
O
6l
C17H14ClN3O2
327.8
169e171
173e175
68
N
N
NH
N
N
Cl
Cl
O
O
6m
C19H18ClN3O4
387.8
85
NH
O
O
O
O
NO2
CN
6n
6o
C17H13ClN4O4
372.8
216e218
62
59
N
N
N
NH
Cl
H3C
O
C20H17ClN4O2
380.8
ND
N
N
NH
Cl
Cl
N
O
Cl
7a
7b
O
C16H12Cl3N3O3S
432.7
149e151
84
80
S
O
N
Cl
H
CF3
O
O
C18H15ClF3N3O3S
445.8
ND
S
NH
N
O
N
N
Cl
Cl
N
O
O
7c
O
S
C14H ClN3O4S
353.8
ND
ND
76
72
N
O
H
F
N
O
Cl
N
7d
C17H12ClF4N3O3S
449.8
O
S
CF3
N
O
H
O
O
7e
7f
C17H16ClN3O4S
393.8
ND
ND
82
70
S
O
N
O
NH
N
N
Cl
Cl
N
O
CF3
O
S
C17H13ClF3N3O3S
431.8
N
O
H

P.K. Ranjith et al. / European Journal of Medicinal Chemistry 71 (2014) 354e365
359
Table 4 (continued )
Compound
Structure
Mol. formula
M. wt
M.P. ꢀC
Yielda (%)
NO2
N
N
O
Cl
O
Cl
Cl
N
N
7g
7h
C16H12Cl2N4O5S
443.3
192e194
84
73
S
N
O
H
CF3
F
O
Cl
O
C17H11Cl2F4N3O3S
484.3
154e156
S
N
O
H
N
N
O
F
O
S
O
Cl
Cl
N
N
7i
7j
C18H14ClF4N3O4S
479.8
ND
70
68
N
O
CF3
H
O
S
O
S
C14H12ClN3O3S2
369.8
142e144
N
O
H
O
O
S
7k
7l
C19H17Cl2N3O3S
438.3
ND
62
66
N
O
Cl
N
NH
Cl
Cl
N
O
N
O
C16H14ClN3O3S
363.8
138e140
S
O
N
H
N
N
O
O
O
Cl
Cl
N
7m
7n
O
C18H18ClN3O5S
423.9
144e146
64
S
N
O
H
O
NO2
N
O
C16H13ClN4O5S
408.8
184e186
79
74
S
N
O
H
Cl
N
N
O
7o
C19H17ClN4O3S
416.9
ND
O
CN
S
O
N
CH3
H
a
Isolated yield after column chromatography.
testing. The compounds which were active at 100
m
g/mL concen-
concentrations. Similarly the target molecules 6g, 6j, 7e, 7f, 7h, 7j
and 7m displayed significant activity at 1.25 g/mL against M.
smegmatis (ATCC 19420). It is interesting to note that most of the
compounds showed either enhanced activity or activity in line with
the reference compound isoniazid against M. fortuitum (ATCC
19542). Further, the compounds 7d, 7f, 7h and 7n showed promising
tration were not taken for further studies. The second level testing
was carried out at concentrations 0.3125, 0.625, 1.25, 2.5, and 5 g/
mL. Amongst the tested compounds 7d, 7f, 7h and 7n are active at
0.625 g/mL concentrations against M. tuberculosis H37Rvstrain and
compounds 6f, 6g, 6n, 7b, 7e, 7j, 7k and 7m are active at 1.25 g/mL
m
m
m
m

360
P.K. Ranjith et al. / European Journal of Medicinal Chemistry 71 (2014) 354e365
non-tubercular mycobacterial (NTM) species by Resazurin Assay
Cl
Cl
method. Antibacterial and antifungal activities of the synthesized
compounds 6(aeo) and 7(aeo) were assessed in vitro against each
three-representative bacterial species viz., S. aureus, (Gram-posi-
tive), E. coli and K. pneumoniae (Gram-negative) and fungal species
viz., C. albicans, A. flavus and Rhizopus sp. by serial plate dilution
method. Ciprofloxacin and Amphotericin B were used as positive
controls for bacteria and fungi respectively while the solvent,
dimethylsulfoxide (DMSO) served as negative control. DMSO used
for the preparation of compounds did not show inhibition against
the tested organisms. Table 5 displays antimicrobial activity of final
compounds 6(aeo) and 7(aeo) in terms of minimum inhibitory
N
N
Re
gi
on
1
N
N
O
R
O
O
HN
concentrations (MIC in mg/ml). Based on the encouraging results
HN
from the antibacterial screening, title compounds were further
tested for their in vitro antimycobacterial activity against M.
tuberculosis H37Rv, M. smegmatis (ATCC 19420), M. fortuitum (ATCC
19542) and MDR-TB strains using isoniazid and rifampicin as
standards. The screening results of in vitro antimycobacterial ac-
tivity of the final compounds are tabulated in Table 6.
S
R
Re
gi
on
2
O
O
Fig. 1. Selected regions for the study.
activity against the MDR-TB strain at 6.25 mg/mL. These are just
initial screening results to check the antimicrobial potential, since
this is established and further work would be done to understand
their mechanism of action.
3. Conclusion
We herein report the successful synthesis of N-(4-(4-chloro-1H-
imidazol-1-yl)-3-methoxyphenyl)amide, N-(4-(4-chloro-1H-imi-
dazol-1-yl)-3-methoxyphenyl)sulfonamide derivatives 6(aeo) and
7(aeo). They have been characterized by spectral studies. The
2.3. Pharmacology
Antimycobacterial activity of the synthesized compounds 6(ae
o) and 7(aeo) were evaluated against M. tuberculosis-H37Rv and
Table 6
Table 5
Antitubercular activity data of the synthesized compounds 6(aeo) and 7(aeo).
Antimicrobial activity data of the synthesized compounds 6(aeo) and 7(aeo).
Preliminary in vitro screening results,
MIC ( g/mL)
Second level screening results,
Minimum inhibitory concentration (MIC in
Entry Bacterial strains
m
g/mL)a
Fungal strains
m
MIC (
MTB
5
m
g/mL)
Compound MTBa
MSb
MFc
%
MS
MF
MDR-TB
d
S. aureus E. coli K. pneumoniae C. albicans A. flavus Rhizopus sp.
6a
6b
6c
6d
6e
6f
10
10
>100
10
>100
1
10
>100
10
>100
10
>100
10
<90
10
10
e
e
25
>50
>50
>50
e
6a
6b
6c
6d
6e
6f
6g
6h
6i
128
128
>256
128
>256
128
128
>256
256
128
64
128
>256
256
256
8
64 >256
>256
128
>256
64
>256
32
128
128
256
256
>256
256
>256
>256
128
128
64
128
256
128
256
256
128
256
>256
256
64
256
256
128
>256
256
64
128
>256
>256
128
>256
64
>256
128
>256
32
>256
128
256
256
128
128
128
256
16
>256
16
256
16
256
128
128
64
128
64
10
10
>100
>100
1
<90 2.5
<90
90 10
10
e
256
64
5
128 >256
e
10
e
128
>256
64
64
256
64
0
e
e
90 1.25
90 1.25
<90 2.5
2.5
1.25
2.5
1.25 >50
1.25 >50
6g
1
1
10
>256
128
>256
128
128
256
128
64
6h
6i
6j
10
>100
1
10
10
1
>100
>100
10
e
25
>50
>50
25
<90
5
e
e
90 5.0
<90 2.5
1.25
2.5
10
2.5
6j
6k
6l
6k
6l
6m
6n
6o
7a
7b
7c
7d
10
10
>100
>100
10
10
10
10
10
10
1
>100
10
>100
>100
10
>100
10
>100
10
e
e
e
128
256
256
256
128
256
>100
>100
>100
>100
>100
>100
10
<90
5
e
25
0
e
e
6m
6n
6o
7a
7b
7c
7d
7e
7f
<90 1.25
2.5
1.25 >50
>256 >256
90 2.5
e
10
e
>50
>50
>50
25
>256
4
64
128
64
4
<90
90 1.25
<90
5
e
e
10
e
4
128
4
128
4
32
64
8
128
16
128
16
128
256
64
5
10
64 >256
128
8
256
8
64
8
1
95 0.625 10
10
6.25
4
>256
16
8
128
8
7e
7f
>100
1
10
10
90 1.25
95 0.625
<90 2.5
90 0.625
1.25
1.25 10
2.5
1.25 10
10
1.25
1.25 >50
6.25
25
6.25
25
1.25 >50
1
7g
7h
7i
10
1
>100
1
10
1
10
1
1
10
>100
10
e
7g
7h
7i
7j
7k
7l
7m
7n
7o
Cfn
Am B
8
4
64
128
128
8
256
128
64
128
4
128
64
64
64
128
128
128
4
32
8
32
256
128
128
256
64
<90
5
e
128
64
7j
90 1.25
90 1.25
7k
7l
>100
10
>100
1
10
10
1
1
10
50
10
>100
10
10
1
e
10
>50
128
128
128
256
64
<90
5
10
1.25
e
25
128
256
128
128
e
7m
7n
7o
Isoniazid
Rifampicin
90 1.25
90 0.625 10
1.25 >50
1.25 6.25
>100
<90 2.5
95 0.7
95 0.5
2.5
50
1.5
e
25
12.5
25
64
16
256
e
0.7
0.5
12.5
1.5
12.5
1.5
8
e
1.5
e
e
e
8
8
16
‘e’ Not detected.
a
a
MIC values were evaluated at concentration ranging between 4 and 256
m
g/mL.
Mycobacterium tuberculosis H37Rv.
Mycobacterium smegmatis (ATCC 19420).
Mycobacterium fortuitum (ATCC 19542).
b
c
The figures in the table show the MIC values in
inhibitory concentration, i.e., lowest concentration to completely inhibit bacterial
growth.
m
g/mL; MIC (
m
g/mL) ¼ minimum
d
Percentage of inhibition against M. tuberculosis H37Rv.

P.K. Ranjith et al. / European Journal of Medicinal Chemistry 71 (2014) 354e365
361
preparation of the key intermediate highlights an optimized
palladium catalyzed (Fig. 2) (Pd2(dba)3/RuPhos) Buchwald cross-
coupling of 4-chloroimidazole and 1-chloro-2-methoxy-4-
nitrobenzene. All the title compounds have been investigated for
their antibacterial and antimycobacterial activities, the investiga-
tion of antibacterial screening revealed that all the newly synthe-
to internal standard TMS. The signals are designated as follows: s,
singlet; d, doublet; t, triplet; m, multiplet.
4.2. Procedure for the preparation of 4-chloroimidazole (2)
Imidazole (10 g, 0.150 mol) and sodium hydroxide (29.4 g,
0.74 mol) were charged to the reaction flask containing water
(250 mL) and stirred vigorously for 15 min at ambient temperature.
Cooled the reaction mass to 10 ꢀC and charged sodium hypochlorite
(16.7 g, 0.225 mol) to the reaction mixture, during the addition
temperature was maintained at 10 ꢀC. Stirred the reaction mass for
6 h at ambient temperature, the reaction completion was moni-
tored by TLC. After the completion of the reaction cooled the re-
action mass to 10 ꢀC and slowly charged concentrated HCl solution
to bring the reaction pH to 6 to 7. Charged dichloromethane
(2 ꢁ 200 mL) and stirred for 10 min, separated the organic layer and
was washed with saturated brine solution. The organic layer was
dried over sodium sulfate and concentrated the dichloromethane
and the crude obtained was purified by column chromatography on
a silica gel (230e400 mesh) using ethyl acetate (10e35%) in pe-
troleum ether as eluant to afford 4-chloroimidazole.
sizes compounds showed moderate to good inhibition at 4e256 mg/
mL in DMSO. Compounds 7d, 7f and 7h exhibited comparatively
good activity against the tested bacterial strains. Further, the
compounds 7d, 7f, 7h and 7n displayed significant activity against
M. tuberculosis H37Rv strain. Furthermore, the target molecules 6g,
6j, 7e, 7f, 7h, 7j and 7m displayed significant activity at 1.25 mg/mL
against M. smegmatis (ATCC 19420). Similarly the compounds 7d,
7f, 7h and 7n showed substantial activity against the MDR-TB strain
at 6.25
mg/mL. The halogen and trifluoro substituted aromatic
compounds will improve the lipophilic nature of the compound at
the same time methyl or methoxy substituted compound would act
as an electron donors. In addition the presence of a sulfonamide
group would be the essential element for the enhanced activity of
the synthesized compounds. The above mentioned properties of
these pharmacophores would be responsible for the promising
activities of the title compounds. The scaffold synthesized in the
research work can be taken for further derivatization in order to
find the lead in these series.
Appearance: Pale yellow solid; Yield ¼ 52%; M.P. ¼ 118e119 ꢀC;
1H NMR (400 MHz, DMSO-d6)
d
ppm ¼ 7.09 (s, 1H, ArH), 7.39 (s, 1H,
ArH), 12.42 (s, 1H, NH); 13C NMR (300 MHz, DMSO-d6)
ppm ¼ 126.7, 128.2, 140.2; LC/MS (ESI-MS) m/z ¼ 103.6 (M þ 1).
d
4. Experimental
4.1. General
4.3. Procedure for the preparation of 4-chloro-1-(2-methoxy-4-
nitrophenyl)-1H-imidazole (4)
All reagents were purchased from Aldrich. Solvents used were
extra dried. Final purifications were carried out using Quad biotage
Flash purifier (A Dyax corp. Company). Microwave-assisted syn-
theses were performed in Biotage initiator. TLC experiments were
performed on alumina backed silica gel 40 F254 plates (Merck,
Darmstadt, Germany). The plates were illuminated under UV
(254 nm) and molesybidinic acid. All 1H and 13C NMR spectra were
4-Chloroimidazole (1.0 g, 0.01 mol), in dioxane (15 mL) was
added Pd2(dba)3 (5 mol%), RuPhos (10 mol%). The solution was
purged with nitrogen and stirred at room temperature for 5 min
and 1-chloro-2-methoxy-4-nitrobenzene (2.0 g, 0.011 mol), Cs2CO3
(0.02 mol), were added. The reaction mixture was again purged
with nitrogen and heated in the microwave at 120 ꢀC for 30 min.
Reaction was monitored by TLC. After the completion, reaction
mixture was cooled to room temperature and water was added to
the reaction mixture. It was then extracted with ethyl acetate
(25 mL ꢁ 2) and separated organic layer was dried over Na2SO4.
recorded on
a Bruker AM-300 (300.12 MHz) and AM-400
(400.13 MHz), Bruker Biospin Corp., Germany. Molecular weights
of unknown compounds were checked by LCMS 6200 series Agilent
Technology. Chemical shifts are reported in ppm (
d
) with reference
PCy2
PCy2
PCy2
OMe
i-Pr
i-Pr
i-PrO
OPr-i
MeO
i-Pr
RuPhos
SPhos
XPhos
PPh2
PPh2
O
P
Xantphos
Triphenylphosphine
Fig. 2. Structures of ligands used for the Buchwald coupling.

362
P.K. Ranjith et al. / European Journal of Medicinal Chemistry 71 (2014) 354e365
Organic layer was filtered and concentrated under vacuum, and the
residue was purified by flash column chromatography on silica gel.
Appearance: Off white solid; yield ¼ 79%; M.P. ¼ 251e252 ꢀC; 1H
4.5.3. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)furan-
2-carboxamide (6c)
Appearance: brown solid; 1H NMR (400 MHz, DMSO-d6)
NMR (400 MHz, DMSO-d6)
d
ppm ¼ 3.83 (s, 3H, CH3), 7.34 (d, 1H,
d
ppm ¼ 3.73 (s, 3H, CH3), 7.14 (d, 1H, ArH), 7.23 (d, 1H, ArH), 7.58 (s,
ArH), 7.48 (s,1H, ArH), 7.59 (d,1H, ArH), 7.72 (s, 1H, ArH), 7.83 (s,1H,
1H, ArH), 7.62 (t,1H, ArH), 7.75 (s,1H, ArH), 7.88 (s,1H, ArH), 7.96 (d,
ArH); 13C NMR (300 MHz, DMSO-d6)
125.9, 126.4. 127.6, 131.8, 136.4, 148.7, 152.3; LC/MS (ESI-MS) m/
z ¼ 254.7 (M þ 1).
d
ppm ¼ 55.9, 113.5, 117.8,
1H, ArH), 8.12 (d, 1H, ArH), 10.84 (s, 1H, NH); 13C NMR (300 MHz,
DMSO-d6)
d
ppm ¼ 54.7, 103.2, 110.9, 112.6, 114.8, 117.9, 120.9, 123.8,
124.7, 131.6, 139.5, 144.2, 148.5, 151.3, 164.6; LC/MS (ESI-MS) m/
z ¼ 319.0 (M þ 1).
4.4. Procedure for the preparation of 4-(4-chloro-1H-imidazol-1-
yl)-3-methoxy benzenamine (5)
4.5.4. N-((4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-3-
fluoro-5-trifluoromethyl) benzamide (6d)
The intermediate 4-chloro-1-(2-methoxy-4-nitrophenyl)-1H-
imidazole (1.0 g, 0.004 mol), NH4Cl (0.42 g, 0.008 mol) and Zinc
powder (0.25 g, 0.008 mol) in methanol (15 mL) were stirred at
ambient temperature and stirred for 12 h. Reaction completion was
monitored by TLC. After completion, reaction mass was filtered
through celite. The filtrate concentrated under reduced pressure.
The crude obtained was dissolved in ethyl acetate (25 mL) and the
organic layer was washed with water (2 ꢁ 20 mL). The organic layer
was dried over sodium sulfate and concentrated under reduced
pressure to afford (5) an off white solid. Appearance: Off white
Appearance: brown solid; M.P. ¼ 180e182 ꢀC; 1H NMR
(400 MHz, DMSO-d6)
d
ppm ¼ 3.85 (s, 3H, CH3), 7.44 (s, 1H, ArH),
7.49 (d, 2H, ArH), 7.55 (s,1H, ArH), 7.73 (s,1H, ArH), 7.88 (s,1H, ArH),
8.02 (s, 1H, ArH), 8.17 (s, 1H, ArH), 10.72 (s, 1H, NH); 13C NMR
(300 MHz, DMSO-d6)
119.0,120.9,122.2,123.8,124.7,131.6,134.6,137.5, 139.5,151.3,164.7,
d
ppm ¼ 54.7, 103.2, 112.6, 115.2, 116.2, 117.9,
165.9; LC/MS (ESI-MS) m/z ¼ 415.0 (M þ 1).
4.5.5. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-4-
methoxybenzamide (6e)
solid; M.P.
ppm ¼ 3.70 (s, 3H, CH3), 5.47 (s, 2H, NH2), 6.19 (d,1H, ArH), 6.38 (s,
1H, ArH), 6.99 (d, 1H, ArH), 7.32 (s, 1H, ArH), 7.64 (s, 1H, ArH); 13C
NMR (300 MHz, DMSO-d6)
¼
219e221 ꢀC; 1H NMR (400 MHz, DMSO-d6)
Appearance: gray solid; M.P. ¼ 173e175 ꢀC; 1H NMR (400 MHz,
d
DMSO-d6)
d
ppm ¼ 2.43 (s, 3H, CH3), 3.67 (s, 3H, CH3), 6.78 (s, 1H,
ArH), 6.88 (d, 1H, ArH), 6.99 (d, 1H, ArH), 7.41 (s, 1H, ArH), 7.50 (s,
d
ppm ¼ 54.7, 101.2, 101.7, 108.2, 113.2,
1H, ArH), 7.61 (d, 2H, ArH), 7.70 (s, 1H, ArH), 10.94 (s, 1H, NH); 13C
120.6, 124.2, 127.8, 132.9, 142.4, 146.8; LC/MS (ESI-MS) m/z ¼ 224.9
NMR (300 MHz, DMSO-d6)
117.9, 120.9, 123.8, 124.7, 125.6, 129.5, 131.6, 139.5, 151.3, 162.8,
d
ppm ¼ 54.7, 61.3, 103.2, 112.6, 115.2,
(M þ 1).
165.9; LC/MS (ESI-MS) m/z ¼ 358.9 (M þ 1).
4.5. General procedure for the preparation of compounds 6(aeo)
4.5.6. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-4-
(trifluoromethyl)benzamide (6f)
A mixture of phenyl acid (0.001 mol), EDCl (0.003 mol), HOBt
(0.002 mol), Triethylamine (0.006 mol) and dichloromethane
(5.0 mL) was stirred vigorously for 10 min at ambient temperature.
Then amine (5) (0.0022 mol) in dichloromethane was added
slowly to the reaction mixture. The reaction mass was stirred at
Appearance: off white solid; M.P. ¼ 162e164 ꢀC; 1H NMR
(400 MHz, DMSO-d6)
6.78 (d,1H, ArH), 7.12 (s,1H, ArH), 7.70 (s, 1H, ArH), 7.84 (s, 1H, ArH),
d
ppm ¼ 3.70 (s, 3H, CH3), 6.71 (d, 1H, ArH),
8.17 (d, 2H, ArH), 8.31 (d, 2H, ArH), 10.94 (s, 1H, NH); 13C NMR
ambient temperature for
4
h. The reaction completion was
(300 MHz, DMSO-d6)
124.3, 124.7, 128.2, 128.9, 131.6, 135.6, 137.6, 139.5, 151.3, 167.9; LC/
MS (ESI-MS) m/z ¼ 397.1 (M þ 1).
d
ppm ¼ 54.7, 103.2, 112.6, 117.9, 120.9, 123.8,
monitored by TLC. After completion, the reaction mass was diluted
with dichloromethane, washed with 10% NaHCO3 (10 mL), brine
solution. The organic layer was dried over anhydrous sodium
sulfate and concentrated under reduced pressure. The crude
product was purified on a Biotage parallel column purifier using
ethyl acetate: petroleum ether (3:1) as eluant to methanol:
methylene chloride (2e6%). The spectral data of compounds 6(ae
o) are given below.
4.5.7. 2-Chloro-N-(4-(4-chloro-1H-imidazol-1-yl)-3-
methoxyphenyl)-3-nitrobenzamide (6g)
Appearance: yellow solid; M.P.
(400 MHz, DMSO-d6)
¼
208e201 ꢀC; 1H NMR
d
ppm ¼ 3.91 (s, 3H, CH3), 7.06 (m, 3H, ArH),
7.21 (d,1H, ArH), 7.29 (d,1H, ArH), 7.37 (s, 1H, ArH), 7.51 (s,1H, ArH),
7.82 (s, 1H, ArH), 11.08 (s, 1H, NH); 13C NMR (300 MHz, DMSO-d6)
4.5.1. 2,4-Dichloro-N-(4-(4-chloro-1H-imidazol-1-yl)-3-
methoxyphenyl)benzamide (6a)
d
ppm ¼ 54.7, 103.2, 112.6, 117.9, 120.9, 123.8, 124.7, 126.4, 128.6,
129.1, 131.6, 136.0, 136.7, 139.5, 145.2, 151.3, 168.4; LC/MS (ESI-MS)
m/z ¼ 408.5 (M þ 1).
Appearance: off white solid; M.P. ¼ 178e180 ꢀC; 1H NMR
(400 MHz, DMSO-d6)
d
ppm ¼ 3.74 (s, 3H, CH3), 6.75 (d, 1H, ArH),
6.82 (d, 1H, ArH), 6.94 (s, 1H, ArH), 7.55 (s, 1H, ArH), 7.61 (s, 1H,
ArH), 7.77 (d, 1H, ArH), 7.98 (s, 1H, ArH), 8.05 (d, 1H, ArH), 11.01 (s,
4.5.8. 2-Chloro-N-(4-(4-chloro-1H-imidazol-1-yl)-3-
methoxyphenyl)-6-fluoro-3-(trifluoro methyl) benzamide (6h)
1H, NH); 13C NMR (300 MHz, DMSO-d6)
d
ppm ¼ 54.7, 103.2, 112.6,
Appearance: white solid; M.P. ¼182e184 ꢀC; 1H NMR (400 MHz,
117.9,120.9,123.8,124.7, 127.1,130.3,130.9,131.6, 134.2,136.8,139.5,
DMSO-d6)
d
ppm ¼ 3.87 (s, 3H, CH3), 7.09 (d, 1H, ArH), 7.18 (s, 1H,
151.3, 165.9; LC/MS (ESI-MS) m/z ¼ 397.8 (M þ 1).
ArH), 7.23 (d, 2H, ArH), 7.50 (d, 1H, ArH), 7.78 (s, 1H, ArH), 7.98 (s,
1H, ArH), 10.92 (s, 1H, NH); 13C NMR (300 MHz, DMSO-d6)
4.5.2. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-2-(3-
(trifluoromethyl)phenyl) acetamide (6b)
d
ppm ¼ 54.7, 103.2, 112.6, 113.6, 115.2, 117.9, 120.9, 121.6, 123.8,
124.7, 126.3, 127.9, 129.9, 131.6, 139.5, 151.3, 162.8, 165.9; LC/MS
(ESI-MS) m/z ¼ 449.7 (M þ 1).
Appearance: brown solid; M.P. ¼ 164e166 ꢀC; 1H NMR
(400 MHz, DMSO-d6)
d
ppm ¼ 3.28 (s, 2H, CH2), 3.85 (s, 3H, CH3),
7.44 (s,1H, ArH), 7.49 (d, 2H, ArH), 7.55 (s,1H, ArH), 7.73 (s,1H, ArH),
4.5.9. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-2,6-
difluoro-4-methoxy benzamide (6i)
7.88 (s, 1H, ArH), 7.92 (m, 3H, ArH), 10.72 (s, 1H, NH); 13C NMR
(300 MHz, DMSO-d6)
123.8, 124.1, 124.5, 124.7, 128.2, 129.1, 131.0, 131.6, 135.7, 137.2, 139.5,
d
ppm ¼ 38.2, 54.7, 103.2, 112.6, 117.9, 120.9,
Appearance: semisolid; 1H NMR (400 MHz, DMSO-d6)
ppm ¼ 2.56 (s, 3H, CH3), 3.67 (s, 3H, CH3), 6.80 (s, 1H, ArH), 7.11 (d,
d
151.3, 168.4; LC/MS (ESI-MS) m/z ¼ 410.7 (M þ 1).
1H, ArH), 7.48 (s, 1H, ArH), 7.59 (s, 1H, ArH), 7.64 (d, 2H, ArH), 7.82

P.K. Ranjith et al. / European Journal of Medicinal Chemistry 71 (2014) 354e365
363
(s, 1H, ArH), 11.08 (s, 1H, NH); 13C NMR (300 MHz, DMSO-d6)
4.6. General procedure for the preparation of 7(aeo)
d
ppm ¼ 54.7, 60.2, 94.6, 103.2, 107.4, 112.6, 117.9, 120.9, 123.8, 124.7,
131.6, 139.5, 151.3, 161.8, 165.2, 169.4; LC/MS (ESI-MS) m/z ¼ 395.1
(M þ 1).
The intermediate (5) (0.002 mol), EDCl (0.0032 mol), DMAP
(0.0028 mol) were stirred in dichloromethane (10 mL) at 0 ꢀC, and
the substituted sulfonyl chloride (0.002 mol) were dissolved in
(4 mL) of dichloromethane and charged to the reaction mixture and
stirred at ambient temperature for 6 h. The reaction completion
was monitored by TLC. After completion, the reaction mixture was
diluted with (10 mL) of dichloromethane, and was washed with 10%
NaHCO3 (10 mL). Separated the organic layer and was washed with
saturated brine solution (10 mL). The organic layer was dried over
sodium sulfate and concentrated the organic layer under reduced
pressure. The crude obtained was recrystallized in ethyl acetate/
hexane to afford compounds 7(aeo). The spectral data of com-
pounds 7(aeo) are given below.
4.5.10. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)
thiophene-2-carboxamide (6j)
Appearance: off white solid; M.P. ¼ 196e198 ꢀC; 1H NMR
(400 MHz, DMSO-d6)
d
ppm ¼ 3.81 (s, 3H, CH3), 7.23 (d, 1H, ArH),
7.37 (d, 1H, ArH), 7.47 (s, 1H, ArH), 7.51 (t, 1H, ArH), 7.69 (s, 1H, ArH),
7.82 (s, 1H, ArH), 7.89 (d, 1H, ArH), 8.05 (d, 1H, ArH), 10.41 (s, 1H,
NH); 13C NMR (300 MHz, DMSO-d6)
d
ppm ¼ 54.7, 103.2, 112.6,
117.9, 120.9, 123.8, 124.7, 129.3, 131.6, 134.4, 136.9, 138.5, 139.5,
151.3, 164.5; LC/MS (ESI-MS) m/z ¼ 335.2 (M þ 1).
4.5.11. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-1-(4-
chlorophenyl) cyclo propanecarboxamide (6k)
4.6.1. 2,4-Dichloro-N-(4-(4-chloro-1H-imidazol-1-yl)-3-
methoxyphenyl)benzene sulfonamide (7a)
Appearance: colorless oil; 1H NMR (400 MHz, DMSO-d6)
d
ppm ¼ 1.14 (t, 2H, CH2), 1.47 (t, 2H, CH2), 3.74 (s, 3H, CH3), 7.39 (d,
Appearance: white solid; M.P. ¼149e151 ꢀC; 1H NMR (400 MHz,
2H, ArH), 7.46 (d, 4H, ArH), 7.51 (s,1H, ArH), 7.77 (s,1H, ArH), 7.79 (s,
DMSO-d6)
d
ppm ¼ 3.73 (s, 3H, CH3), 6.01 (d, 1H, ArH), 6.22 (d, 1H,
1H, ArH), 10.99 (s, 1H, NH); 13C NMR (300 MHz, DMSO-d6)
ArH), 6.30 (s,1H, ArH), 7.43 (s,1H, ArH), 7.58 (s,1H, ArH), 7.69 (d,1H,
d
ppm ¼ 14.2, 28.6, 54.7, 103.2, 112.6, 117.9, 120.9, 123.8, 124.7, 125.4,
ArH), 7.92 (s, 1H, ArH), 8.10 (d, 1H, ArH), 8.34 (s, 1H, NH); 13C NMR
128.6, 130.2, 131.6, 139.5, 144.6, 151.3, 170.1; LC/MS (ESI-MS) m/
z ¼ 403.9 (M þ 1).
(300 MHz, DMSO-d6)
124.0, 127.9, 129.4, 130.0, 132.4, 134.2, 135.2, 138.7, 150.7; LC/MS
d
ppm ¼ 54.2, 102.1, 112.6, 117.4, 119.5, 123.2,
(ESI-MS) m/z ¼ 433.9 (M þ 1).
4.5.12. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)
benzamide (6l)
4.6.2. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-2-(3-
(trifluoromethyl)phenyl) methanesulfonamide (7b)
Appearance: white solid; M.P. ¼169e171 ꢀC; 1H NMR (400 MHz,
DMSO-d6)
d
ppm ¼ 3.74 (s, 3H, CH3), 6.72 (s, 1H, ArH), 6.86 (d, 1H,
Appearance: colorless oil; 1H NMR (400 MHz, DMSO-d6)
ArH), 7.06 (d, 1H, ArH), 7.32 (s, 1H, ArH), 7.47 (s, 1H, ArH), 7.65 (d,
d
ppm ¼ 3.24 (s, 2H, CH2), 3.80 (s, 3H, CH3), 6.85 (s,1H, ArH), 6.92 (d,
2H, ArH), 7.82 (s, 1H, ArH), 11.08 (s, 1H, NH); 13C NMR (300 MHz,
2H, ArH), 7.05 (s, 1H, ArH), 7.64 (s, 1H, ArH), 7.94 (s, 1H, ArH), 7.99
DMSO-d6)
d
ppm ¼ 54.7, 103.2, 112.6, 117.9, 120.9, 123.8, 124.7, 127.5,
(m, 3H, ArH), 8.38 (s, 1H, NH); 13C NMR (300 MHz, DMSO-d6)
129.4, 131.6, 132.9, 135.8, 139.5, 151.3, 166.1; LC/MS (ESI-MS) m/
z ¼ 329.2 (M þ 1).
d
ppm ¼ 37.6, 53.4, 102.8, 113.0, 118.4, 121.2, 122.6, 123.9, 124.2,
125.8, 127.9, 128.4, 131.0, 131.6, 134.2, 136.3, 138.4, 150.8; LC/MS
(ESI-MS) m/z ¼ 447.1 (M þ 1).
4.5.13. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-3,4-
dimethoxybenzamide (6m)
4.6.3. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)furan-
2-sulfonamide (7c)
Appearance: brown solid; M.P. ¼ 173e175 ꢀC; 1H NMR
(400 MHz, DMSO-d6)
d
ppm ¼ 2.51 (s, 6H, CH3), 3.69 (s, 3H, CH3),
Appearance: semisolid; 1H NMR (400 MHz, DMSO-d6)
6.83 (s, 1H, ArH), 6.94 (d, 1H, ArH), 7.01 (d, 1H, ArH), 7.48 (s, 1H,
ArH), 7.56 (s, 1H, ArH), 7.64 (d, 2H, ArH), 7.75 (s, 1H, ArH), 11.01 (s,
d
ppm ¼ 3.54 (s, 3H, CH3), 6.38 (d, 1H, ArH), 6.42 (d, 1H, ArH), 6.69
(s, 1H, ArH), 7.50 (t, 1H, ArH), 7.62 (s, 1H, ArH), 7.95 (s, 1H, ArH), 8.05
1H, NH); 13C NMR (300 MHz, DMSO-d6)
d
ppm ¼ 54.7, 63.2, 103.2,
(d, 1H, ArH), 8.35 (d, 1H, ArH), 8.74 (s, 1H, NH); 13C NMR (300 MHz,
112.6, 114.5,115.6, 117.9, 120.9,122.2,123.8, 124.7, 128.9, 131.6, 139.5,
DMSO-d6)
d
ppm ¼ 53.8, 102.8, 108.7, 111.6, 113.6, 116.8, 119.4, 122.8,
144.6, 151.3, 155.6, 166.8; LC/MS (ESI-MS) m/z ¼ 389.1 (M þ 1).
125.4, 133.6, 136.8, 146.4, 147.4, 149.8; LC/MS (ESI-MS) m/z ¼ 355.1
(M þ 1).
4.5.14. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-4-
nitrobenzamide (6n)
4.6.4. N-((4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-3-
fluoro-5-trifluoromethyl) benzene sulfonamide (7d)
Appearance: pale yellow solid; M.P. ¼ 216e218 ꢀC; 1H NMR
(400 MHz, DMSO-d6)
d
ppm ¼ 3.75 (s, 3H, CH3), 6.76 (d, 1H, ArH),
Appearance: semisolid; 1H NMR (400 MHz, DMSO-d6)
6.82 (d, 1H, ArH), 6.98 (s, 1H, ArH), 7.62 (s, 1H, ArH), 7.71 (s, 1H,
d
ppm ¼ 3.80 (s, 3H, CH3), 6.62 (s, 1H, ArH), 6.89 (d, 2H, ArH), 7.01 (s,
ArH), 8.00 (d, 2H, ArH), 8.10 (d, 2H, ArH), 11.07 (s, 1H, NH); 13C NMR
1H, ArH), 7.52 (s,1H, ArH), 7.93 (s,1H, ArH), 8.22 (s,1H, ArH), 8.29 (s,
(300 MHz, DMSO-d6)
123.8, 124.7, 126.8, 131.6, 139.5, 148.5, 151.3, 153.4, 166.9; LC/MS
d
ppm ¼ 54.7, 103.2, 112.6, 117.9, 120.9, 121.6,
1H, ArH), 9.03 (s, 1H, NH); 13C NMR (300 MHz, DMSO-d6)
d
ppm ¼ 53.8, 102.7, 113.4, 114.8, 116.8, 118.2, 119.1, 120.7, 122.8,
(ESI-MS) m/z ¼ 373.8 (M þ 1).
123.8, 126.1, 132.8, 135.2, 137.9, 140.6, 152.6, 159.4; LC/MS (ESI-MS)
m/z ¼ 451.3 (M þ 1).
4.5.15. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-3-(1-
cyanoethyl)benzamide (6o)
4.6.5. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-4-
methoxybenzenesulfonamide (7e)
Appearance: yellow oil; 1H NMR (400 MHz, DMSO-d6)
d
ppm ¼ 1.62 (s, 3H, CH3), 3.84 (s, 3H, CH3), 4.45 (m, 1H, CH), 7.41 (d,
Appearance: semisolid; 1H NMR (400 MHz, DMSO-d6)
1H, ArH), 7.52 (d, 1H, ArH), 7.59 (s, 1H, ArH), 7.62 (s, 1H, ArH), 7.83
(m, 1H, ArH), 7.96 (d, 2H, ArH), 7.99 (s, 1H, ArH), 8.05 (s, 1H, ArH),
d
ppm ¼ 2.30 (s, 3H, CH3), 3.54 (s, 3H, CH3), 6.38 (s,1H, ArH), 6.46 (d,
1H, ArH), 6.72 (d, 1H, ArH), 7.18 (s, 1H, ArH), 7.48 (s, 1H, ArH), 7.68
10.59 (s, 1H, NH); 13C NMR (300 MHz, DMSO-d6)
d
ppm ¼ 16.4, 25.8,
(d, 2H, ArH), 7.84 (s, 1H, ArH), 9.07 (s, 1H, NH); 13C NMR (300 MHz,
54.7, 103.2, 112.6, 117.9, 118.6, 120.9, 123.8, 124.7, 126.4, 128.4, 129.4,
130.4, 131.6, 133.5, 136.8, 139.5, 151.3, 168.5; LC/MS (ESI-MS) m/
z ¼ 381.9 (M þ 1).
DMSO-d6)
d
ppm ¼ 52.8, 60.1, 104.7, 113.4, 115.2, 118.3, 119.4, 123.8,
124.2, 127.4, 129.9, 134.7, 138.5, 156.4, 160.1; LC/MS (ESI-MS) m/
z ¼ 394.9 (M þ 1).

364
P.K. Ranjith et al. / European Journal of Medicinal Chemistry 71 (2014) 354e365
4.6.6. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-4-
(trifluoromethyl)benzene sulfonamide (7f)
6.57 (d, 1H, ArH), 6.89 (d, 1H, ArH), 7.21 (s, 1H, ArH), 7.37 (s, 1H,
ArH), 7.79 (d, 2H, ArH), 8.02 (s, 1H, ArH), 8.49 (s, 1H, NH); 13C NMR
Appearance: colorless oil; 1H NMR (400 MHz, DMSO-d6)
(300 MHz, DMSO-d6)
125.7, 126.9, 130.2, 132.5, 133.8, 136.8, 142.6, 153.9; LC/MS (ESI-MS)
d
ppm ¼ 46.8, 99.2, 109.7, 113.8, 119.6, 122.4,
d
ppm ¼ 3.84 (s, 3H, CH3), 6.82 (d, 1H, ArH), 6.94 (d, 1H, ArH), 6.99
(s, 1H, ArH), 7.12 (s, 1H, ArH), 7.42 (s, 1H, ArH), 8.64 (d, 2H, ArH),
m/z ¼ 364.9 (M þ 1).
8.92 (d, 2H, ArH), 9.35 (s, 1H, NH); 13C NMR (300 MHz, DMSO-d6)
d
ppm ¼ 53.4, 102.7, 113.4, 118.2, 121.4, 122.5, 124.3, 125.9, 128.2,
4.6.13. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-3,4-
dimethoxybenzene sulfonamide (7m)
130.4, 131.2, 136.3, 137.2, 142.3, 153.4; LC/MS (ESI-MS) m/z ¼ 432.9
(M þ 1).
Appearance: brown solid; M.P. ¼ 144e146 ꢀC; 1H NMR
(400 MHz, DMSO-d6)
d
ppm ¼ 2.35 (s, 6H, CH3), 3.48 (s, 3H, CH3),
4.6.7. 2-Chloro-N-(4-(4-chloro-1H-imidazol-1-yl)-3-
methoxyphenyl)-3-nitrobenzenesulfon amide (7g)
6.26 (s, 1H, ArH), 6.57 (d, 1H, ArH), 6.84 (d, 1H, ArH), 7.29 (s, 1H,
ArH), 7.74 (s, 1H, ArH), 7.89 (d, 2H, ArH), 8.01 (s, 1H, ArH), 8.64 (s,
Appearance: off white solid; M.P. ¼ 192e194 ꢀC; 1H NMR
1H, NH); 13C NMR (300 MHz, DMSO-d6)
d
ppm ¼ 49.4, 59.6, 99.8,
(400 MHz, DMSO-d6)
d
ppm ¼ 3.72 (s, 3H, CH3), 6.91 (m, 3H, ArH),
107.4, 111.5, 114.8, 118.6, 120.1, 121.5, 123.8, 126.9, 128.0, 135.6, 142.5,
7.01 (d,1H, ArH), 7.20 (d,1H, ArH), 7.24 (s,1H, ArH), 7.48 (s,1H, ArH),
146.9, 153.4, 157.3; LC/MS (ESI-MS) m/z ¼ 425.6 (M þ 1).
7.80 (s, 1H, ArH), 8.34 (s, 1H, NH); 13C NMR (300 MHz, DMSO-d6)
d
ppm ¼ 53.2, 102.4, 113.4, 116.8, 119.9, 122.4, 125.6, 126.9, 128.6,
4.6.14. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-4-
nitrobenzenesulfonamide (7n)
129.9, 133.4, 136.0, 137.4, 140.4, 146.2, 153.3; LC/MS (ESI-MS) m/
z ¼ 444.3 (M þ 1).
Appearance: yellow solid; M.P. ¼ 184e186 ꢀC; 1H NMR
(400 MHz, DMSO-d6)
d
ppm ¼ 2.69 (s, 3H, CH3), 5.98 (d, 1H, ArH),
4.6.8. 2-Chloro-N-(4-(4-chloro-1H-imidazol-1-yl)-3-
methoxyphenyl)-6-fluoro-3-(trifluoro methyl) benzene sulfonamide
(7h)
6.17 (d,1H, ArH), 6.49 (s,1H, ArH), 7.54 (s,1H, ArH), 7.99 (s, 1H, ArH),
8.14 (d, 2H, ArH), 8.21 (d, 2H, ArH), 9.21 (s, 1H, NH); 13C NMR
(300 MHz, DMSO-d6)
121.9, 125.6, 128.4, 133.6, 139.0, 147.6, 152.9, 156.7; LC/MS (ESI-MS)
d
ppm ¼ 45.6, 99.8, 108.6, 114.5, 117.9, 120.4,
Appearance: white solid; M.P. ¼154e156 ꢀC; 1H NMR (400 MHz,
DMSO-d6)
d
ppm ¼ 3.72 (s, 3H, CH3), 6.68 (d, 1H, ArH), 6.87 (s, 1H,
m/z ¼ 409.9 (M þ 1).
ArH), 6.99 (d, 2H, ArH), 7.46 (d, 1H, ArH), 7.70 (s, 1H, ArH), 7.82 (s,
1H, ArH), 8.39 (s, 1H, NH); 13C NMR (300 MHz, DMSO-d6)
4.6.15. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-3-(1-
cyanoethyl)benzene sulfonamide (7o)
d
ppm ¼ 50.7, 101.4, 110.7, 112.4, 115.9, 116.5, 120.1, 121.4, 123.6,
125.2, 126.3, 128.2, 129.4, 133.2, 142.8, 153.4, 161.5; LC/MS (ESI-MS)
Appearance: colorless oil; 1H NMR (400 MHz, DMSO-d6)
m/z ¼ 486.2 (M þ 1).
d
ppm ¼ 1.48 (s, 3H, CH3), 3.28 (s, 3H, CH3), 4.08 (m,1H, CH), 6.38 (d,
1H, ArH), 6.64 (d, 1H, ArH), 6.96 (s, 1H, ArH), 7.48 (s, 1H, ArH), 7.59
(m, 1H, ArH), 7.87 (d, 2H, ArH), 8.14 (s, 1H, ArH), 8.29 (s, 1H, ArH),
4.6.9. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-2,6-
difluoro-4-methoxybenzene sulfonamide (7i)
8.98 (s, 1H, NH); 13C NMR (300 MHz, DMSO-d6)
d
ppm ¼ 14.8, 24.8,
Appearance: semisolid; 1H NMR (400 MHz, DMSO-d6)
50.2, 98.7, 108.9, 116.4, 117.5, 119.5, 121.6, 125.9, 127.4, 129.0, 130.2,
132.6, 133.2, 134.7, 136.1, 140.2, 153.5; LC/MS (ESI-MS) m/z ¼ 418.2
(M þ 1).
d
ppm ¼ 2.62 (s, 3H, CH3), 3.75 (s, 3H, CH3), 6.24 (s,1H, ArH), 6.92 (d,
1H, ArH), 7.36 (s, 1H, ArH), 7.64 (s, 1H, ArH), 7.83 (d, 2H, ArH), 7.89
(s, 1H, ArH), 8.49 (s, 1H, NH); 13C NMR (300 MHz, DMSO-d6)
d
ppm ¼ 52.7, 64.3, 92.7, 102.9, 108.3, 113.4, 118.6, 121.4, 123.2, 126.4,
4.7. Antibacterial studies
133.4, 141.6, 153.4, 160.1, 163.4; LC/MS (ESI-MS) m/z ¼ 480.8
(M þ 1).
The synthesized compounds were screened for their antibac-
terial activity against one Gram positive and two Gram negative
bacterial species viz., S. aureus (ATCC-25923), E. coli (ATCC-25922)
and K. pneumoniae (ATCC-13883) bacterial strains by serial plate
dilution method [25,26]. Serial dilutions of the drug in Mueller-
Hinton broth were taken in tubes and their pH was adjusted to
5.0 using phosphate buffer. A standardized suspension of the test
bacterium was inoculated and incubated for 16e18 h at 37 ꢀC. The
minimum inhibitory concentration (MIC) was noted by seeing the
lowest concentration of the drug at which there was no visible
growth. A number of antimicrobial discs are placed on the agar for
the sole purpose of producing zone of inhibition in the bacterial
lawn. Twenty milliliters of agar media was poured into each Petri
dish. Excess of suspension was decanted and plates were dried by
placing in an incubator at 37 ꢀC for an hour. Using an agar punch,
wells were made on these seeded agar plates and minimum
inhibitory concentration of the test compounds in dimethylsulf-
oxide (DMSO) were added into each labeled well. A control was also
prepared for the plates in the same way using solvent DMSO. The
Petri dishes were prepared in triplicate and maintained at 37 ꢀC for
3e4 days. DMSO used for the preparation of compounds did not
show inhibition against the tested organisms. Antibacterial activity
was determined by measuring the diameter of the inhibition zone.
Activity of each compound was compared with ciprofloxacin as
4.6.10. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)
thiophene-2-sulfonamide (7j)
Appearance: brown solid; M.P. ¼ 142e144 ꢀC; 1H NMR
(400 MHz, DMSO-d6)
d
ppm ¼ 3.75 (s, 3H, CH3), 6.72 (d, 1H, ArH),
6.89 (d, 1H, ArH), 7.07 (s,1H, ArH), 7.48 (t,1H, ArH), 7.76 (s, 1H, ArH),
7.94 (s, 1H, ArH), 8.03 (d,1H, ArH), 8.17 (d,1H, ArH), 9.02 (s,1H, NH);
13C NMR (300 MHz, DMSO-d6)
d
ppm ¼ 53.8, 102.8, 112.6, 1184,
119.8, 124.9, 125.5, 130.2, 132.5, 133.5, 137.4, 138.9, 140.1, 151.8; LC/
MS (ESI-MS) m/z ¼ 371.0 (M þ 1).
4.6.11. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)-1-(4-
chlorophenyl)cyclo propane sulfonamide (7k)
Appearance: semisolid; 1H NMR (400 MHz, DMSO-d6)
d
ppm ¼ 1.63 (t, 2H, CH2), 1.82 (t, 2H, CH2), 3.95 (s, 3H, CH3), 6.67 (d,
2H, ArH), 6.89 (d, 4H, ArH), 7.17 (s,1H, ArH), 7.48 (s,1H, ArH), 7.87 (s,
1H, ArH), 8.56 (s, 1H, NH); 13C NMR (300 MHz, DMSO-d6)
d
ppm ¼ 13.5, 24.5, 42.9, 99.4, 108.6, 114.5, 119.7, 122.6, 124.1, 126.3,
127.4, 129.8, 133.8, 137.8, 140.6, 149.7; LC/MS (ESI-MS) m/z ¼ 439.5
(M þ 1).
4.6.12. N-(4-(4-Chloro-1H-imidazol-1-yl)-3-methoxyphenyl)
benzenesulfonamide (7l)
Appearance: off white solid; M.P. ¼ 138e140 ꢀC; 1H NMR
standard [27,28]. MIC (mg/mL) and corresponding results are sum-
(400 MHz, DMSO-d6)
d
ppm ¼ 3.25 (s, 3H, CH3), 6.25 (s, 1H, ArH),
marized in Table 5.

P.K. Ranjith et al. / European Journal of Medicinal Chemistry 71 (2014) 354e365
365
4.8. Antifungal studies
Acknowledgment
Newly prepared compounds were screened for their antifungal
activity against C. albicans, A. flavus and Rhizopus sp in DMSO by
serial plate dilution method [29,30]. Sabourands agar media was
Authors are thankful to Head of the Department of Biochem-
istry, Justice K. S. Hegde Medical Academy, to carry out biological
studies. They are also grateful to the Head, Chemistry Department
and School of Chemical Sciences for providing necessary laboratory
facilities for the research work and valuable support.
prepared by dissolving peptone (1 g), D-glucose (4 g) and agar (2 g)
in distilled water (100 mL) and adjusting the pH to 5.7. Normal
saline was used to make a suspension of spore of fungal stain for
lawning. A loopful of particular fungal strain was transferred to
3 mL saline to get a suspension of corresponding species. Twenty
milliliters of agar medis was poured into each Petri dish. Excess of
suspension was decanted and plates were dried by placing in
incubator at 37 ꢀC for 1 h. Using a punch, wells were made on these
seeded agar plates minimum inhibitory concentrations of the test
compounds in DMSO were added into each labeled well. A control
was also prepared for the plates in the same way using solvent
DMSO. The Petri dishes were prepared in triplicate and maintained
at 37 ꢀC for 3e4 days. DMSO used for the preparation of compounds
did not show inhibition against the tested organisms. Antifungal
activity was determined by measuring the diameter of the inhibi-
tion zone. Activity of each compound was compared with
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McFarland 2 standard with the same medium. From this, 50
mL of
this culture was added to 150 L of fresh medium in 96 well
m
microtitre plates. Stock solutions (2 mg/mL) of the test compounds
were prepared in dimethyl formamide (DMF). The compounds
were tested at 1, 10 and 100
second level testing was carried out at concentrations 0.3125,
0.625,1.25, 2.5, and 5 g/mL. Control tubes had the same volumes of
DMF without any substrate. Rifampicin and isoniazid were used as
the reference compounds. After incubation at 37 ꢀC for 7 days, 20
mg/mL concentrations. Further the
m
mL
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of 0.01% Resazurin (Sigma, St. Louis. MO, USA) in water was added
to each tube. Resazurin, a redox dye, is blue in the oxidized state
and turns pink when reduced by the growth of viable cells. The
control tubes showed a color change from blue to pink after 1 h at
37 ꢀC. Compounds which prevented the change of color of the dye
were considered to be inhibitory to M. tuberculosis and the corre-
sponding results are summarized in Table 6.
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