2-Methyl-4/5-nitroimidazole derivatives potentiated against sexually transmitted Trichomonas: Design, synthesis, biology and 3D-QSAR study

Article abstract of DOI:10.1016/j.ejmech.2016.09.006

Trichomoniasis is the most prevalent, non-viral sexually transmitted diseases (STD) caused by amitochondriate protozoan Trichomonas vaginalis. Increased resistance of T.?vaginalis to the marketed drug Metronidazole necessitates the development of newer chemical entities. A library of sixty 2-methyl-4/5-nitroimidazole derivatives was synthesized via nucleophilic ring opening reaction of epoxide and the efficacies against drug-susceptible and -resistant Trichomonas vaginalis were evaluated. All the molecules except two were found to be active against both susceptible and resistant strains with MICs ranging 8.55–336.70?μM and 28.80–1445.08?μM, respectively. Most of the compounds were remarkably more effective than the standard Metronidazole. This study analyzes the in?vitro and in?vivo activities of the new 5-nitroimidazoles, which were found to be safe against human cervical HeLa cells with good selectivity index. The exploration of SAR by the synthesis of four different prototypes and 3D-QSAR study has shown the importance of prototype 1 over other prototypes.

Full text of DOI:10.1016/j.ejmech.2016.09.006

European Journal of Medicinal Chemistry 124 (2016) 820e839
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Short communication
2-Methyl-4/5-nitroimidazole derivatives potentiated against sexually
transmitted Trichomonas: Design, synthesis, biology and 3D-QSAR
study*
,
Dhanaraju Mandalapu a, Bhavana Kushwaha b, Sonal Gupta a g, Nidhi Singh c,
Mahendra Shukla d, Jitendra Kumar e, Dilip K. Tanpula f, Satya N. Sankhwar h,
,
g
Jagdamba P. Maikhuri b, Mohammad I. Siddiqi c, Jawahar Lal d, Gopal Gupta b
,
Vishnu L. Sharma a
, g, *
a Medicinal & Process Chemistry Division, CSIR-Central Drug Research Institute, Sitapur Road, Lucknow, 226031, India
b Endocrinology Division, CSIR-Central Drug Research Institute, Sitapur Road, Lucknow, 226031, India
c Molecular and Structural Biology Division, CSIR-Central Drug Research Institute, Sitapur Road, Lucknow, 226031, India
d Pharmacokinetic & Metabolism Division, CSIR-Central Drug Research Institute, Sitapur Road, Lucknow, 226031, India
e Medicinal Chemistry, National Institute of Pharmaceutical Education and Research (NIPER), Raebareli, 229 010, India
f Department of Pharmaceutics, National Institute of Pharmaceutical Education and Research (NIPER), Raebareli, 229 010, India
g Academy of Scientific and Innovative Research (AcSIR), New Delhi, 110001, India
h Department of Urology, King George Medical University, Lucknow, 226003, India
a r t i c l e i n f o
a b s t r a c t
Article history:
Trichomoniasis is the most prevalent, non-viral sexually transmitted diseases (STD) caused by ami-
tochondriate protozoan Trichomonas vaginalis. Increased resistance of T. vaginalis to the marketed drug
Metronidazole necessitates the development of newer chemical entities. A library of sixty 2-methyl-4/
5-nitroimidazole derivatives was synthesized via nucleophilic ring opening reaction of epoxide and
the efficacies against drug-susceptible and -resistant Trichomonas vaginalis were evaluated. All the
molecules except two were found to be active against both susceptible and resistant strains with MICs
Received 10 May 2016
Received in revised form
1 September 2016
Accepted 2 September 2016
Available online 4 September 2016
ranging 8.55e336.70
mM and 28.80e1445.08 mM, respectively. Most of the compounds were
Keywords:
remarkably more effective than the standard Metronidazole. This study analyzes the in vitro and in vivo
activities of the new 5-nitroimidazoles, which were found to be safe against human cervical HeLa cells
with good selectivity index. The exploration of SAR by the synthesis of four different prototypes and
3D-QSAR study has shown the importance of prototype 1 over other prototypes.
© 2016 Elsevier Masson SAS. All rights reserved.
Anti-Trichomonas
Dithiocarbamate
4/5-Nitroimidazoles
Resistant Trichomonas
Hybridization
1. Introduction
STDs are insidious, diabolic and have an intense impact on
Abbreviations: STDs, sexually transmitted diseases; TV, Trichomonas vaginalis;
DTC, dithiocarbamate; SAR, structure activity relationship; MTZ, Metronidazole; NI,
nitroimidazoles; HeLa, epithelium cells; 3D-QSAR, 3D-quantitative structur-
eeactivity relationship; SAR, structureeactivity relationship; MIC, minimum
reproductive health of millions of men, women and infants
worldwide, which can't be overlooked [1,2]. More than 30 in-
fections have been identified to date that can be sexually trans-
mitted. Over 358 million new cases of STDs occur every year,
which include mostly the common curable STDs like gonorrhea,
syphilis, chlamydia and trichomoniasis [3]. Trichomoniasis caused
by Trichomonas vaginalis (TV) alone accounts for over half of the
new cases detected in men and women of reproductive age [4]
and thus is the most prevalent sexually transmitted protozoan
pathogen, the highest among of all the curable and non-viral STDs
inhibitory concentration; IC50, half maximal inhibitory concentration; CoMFA,
comparative molecular field analysis; PLS, partial least squares; LDH, lactate de-
hydrogenase; DMEM, dulbecco's modified eagle's medium; TLC, thin layer
chromatography.
*
CDRI Communication No. 9293.
* Corresponding author. Medicinal and Process Chemistry Division, CSIR-Central
Drug Research Institute, Sector 10, Jankipuram ext., Lucknow, Uttar Pradesh,
226031, India.
E-mail addresses: vl_sharma@cdri.res.in, vlscdri@gmail.com (V.L. Sharma).
http://dx.doi.org/10.1016/j.ejmech.2016.09.006
0223-5234/© 2016 Elsevier Masson SAS. All rights reserved.

D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
821
in the world. Since 2005, the incidence of TV has increased by
2. Results and discussion
11.5% and prevalence has increased by 22.2% [5]. TV, discovered by
Alfred Donn in 1836, is an amitochondrial, microaerotolerant
protozoan parasite of the human urogenital tract where it colo-
nizes and causes the disease [6]. Trichomoniasis in women is
frequently responsible for endometritis, vaginitis, pyosalpinx,
adnexitis, bacterial vaginosis and increased risk of pelvic inflam-
matory disease, cervical cancer, HIV transmission and birth
complications like infertility, preterm delivery, low birth weight
[7e9]. Men are often asymptomatic carriers which results in
persistent spread of over 50% of TV infections through hetero-
sexual contacts. Complications associated with TV infection in
men include urethral discharge, urethritis, dysuria, prostatitis,
epididymitis, lower abdominal pain, pruritis, infertility and
benign prostatic hyperplasia [10e12]. On the other hand, HIV-
infected men with Trichomoniasis have nearly 6-fold-higher HIV
concentrations in semen. Therefore, it would be quite rational to
conclude that controlling trichomoniasis can also considerably
reduce the incidence of new HIV infections [13].
2.1. Chemistry
The general procedure for the synthesis of the designed pro-
totypes has been illustrated in Schemes 1 and 2. In the first step, 2-
methyl-4(5)-nitroimidazole (1) was reacted with epichlorohydrin
in acidic conditions affording 1-chloro-3-(2-methyl-5-nitro-1H-
imidazol-1-yl)propan-2-ol (2) [39]. Whereas in basic conditions it
was
yielded
1-chloro-3-(2-methyl-4-nitro-1H-imidazol-1-yl)
propan-2-ol (51) [40]. Further these open chain chlorohydrins
compounds (2 and 51) were treated with aqueous NaOH to form
oxirane intermediates 2-methyl-5-nitro-1-(oxiran-2-ylmethyl)-
1H-imidazole (3) and 2-methyl-4-nitro-1-(oxiran-2-ylmethyl)-1H-
imidazole (52) in good yields. Furthermore, nucleophilic ring
opening of compounds 3 and 52 with different substituted-1-
carbodithioates in water:acetone (10:1) at 0 ꢀC for 2e4 h yields
2-hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)propyl
substituted carbodithioate/carbamodithioate (prototype 1; 4e24)
The US-FDA approved Metronidazole (MTZ) serves as the pri-
mary drug for treatment of infections with TV. However, drug
resistance against MTZ was reported as early as 1962 and the
increased prevalence of resistant infections in the 21st century is a
matter of concern, given that 2.5e10% of isolates are found resis-
tant, which make the situation grimmer [14,15]. Since 1997, the
incidence of resistance has increased by 17 fold and the treatment
typically relies on increased doses of MTZ [6]. The mechanism of
action of nitroimidazoles (NI) is assumed to be through the
reduction of the nitro group for hydrogenosomal function, which is
inhibited in refractory cases. Some other 5-NI class of drugs have
been currently used in treatment but cross-resistance to anaerobic
pathogen is a challenging problem with no universally successful
treatment [16]. The emergence of drug resistance along with a
declining pipeline of clinical agents warrants the development of
novel anti-trichomonal agents. Now a days, dithiocarbamate (DTC)
group has drawn a lot of attention due to its presence in various
biologically active compounds [17,18] utilized as microbicidal
spermicides [19e21], anesthetic [22], fungicidal [23,24], anti-HIV
[25], mono glyceride lipase inhibitors [26], anti-tumor [27], anti-
alcoholism [28] etc. Compounds having DTC groups along with
other functional groups are of massive interest due to more than
one pharmacophore [29e31].
and
2-hydroxy-3-(2-methyl-4-nitro-1H-imidazol-1-yl)propyl
substituted carbodithioate/carbamodithioate (prototype 3; 53e61)
respectively in good yields [41]. Where on nucleophilic ring
opening of oxirane intermediates
3 and 52 with different
substituted amines/imidazoles/triazoles in acetonitrile at 80 ꢀC for
overnight to form 1-(2-methyl-5-nitro-1H-imidazol-1-yl)-3-(sub-
stitutedamine)propan-2-ol (prototype 2; 25e50) and 1-(2-methyl-
4-nitro-1H-imidazol-1-yl)-3-(substitutedamine)propan-2-ol (pro-
totype 4; 62e65) respectively in good yields.
2.2. Biological evaluation
2.2.1. Anti-Trichomonas activity of synthesized compounds
The library of all the four prototypes (4e50 and 53e65, Table 1)
was evaluated for anti-Trichomonas activity in vitro against drug-
susceptible (ATCC 33592) and -resistant (ATCC 50143) strains of
T. vaginalis and for safety towards cervical epithelium cells (HeLa).
The anti-Trichomonas activity of the synthesized compounds (4e50
and 53e65, Table 1) demonstrated good to remarkable activity,
which was mostly better than MTZ, against both susceptible as well
as resistant strains of T. vaginalis. Interestingly, all the compounds
tested were found to be active against MTZ-susceptible strain at
MIC ranging from 8.55 to 336.70
mM and also against MTZ-resistant
The concept of hybridization is
a
rational approach of
strain at MIC 28.80e1445.08 M (except 55 and 63). Among the
m
conquering the drug resistance by introducing a new pharmaco-
phore in a biologically active molecule to get improved thera-
peutic potential [32e38]. Even though the 5-NIs have been in use
since long yet the true potential of this important drug class is still
not fully explored [16]. Numerous imidazole derivatives have been
reported showing the importance of nitro group [16,38]. In a
pursuit to develop novel hybrid molecules with enhanced anti-
Trichomonas activity especially against the resistant strains it was
found that the incorporation of the DTC group into an MTZ core
generally resulted in improved biological activity where the
modifications were carried out at terminal hydroxyl group of MTZ
(Fig. 1) [38]. However, in the present study we tried to incorporate
the DTC group while keeping the MTZ structure intact (Fig. 1).
In the present study several 4/5-nitroimidazole derived entities
have been screened against MTZ-susceptible and -resistant TV
in vitro and the most active structure was also tested in vivo against
the former. Fluorescence labelling of biological targets, safety
evaluation against cervical epithelium cells (HeLa) and 3D-QSAR
study data have been reported.
compounds evaluated for anti-Trichomonas activity against
MTZesusceptible strain, fourteen compounds (4, 6, 10e12, 16e18,
23, 24, 26, 29, 33 and 46) were up to 2.4 fold more active (MIC range
8.55e18.86 mM) than the standard MTZ (MIC 21.05 mM) while the
activity of nine compounds (5, 20, 25, 27, 30, 37, 40, 41 and 57) was
comparable to MTZ. Furthermore, forty six compounds (4e20,
22e41, 43e50 and 57) were up to 12.7 fold more active (MIC
28.80e344.35
most active compound (6) of this series demonstrated trichomo-
nacidal activity at MIC 8.55 and 37.10 M against MTZ-susceptible
mM) than the standard MTZ (MIC 365.50 mM). The
m
and -resistant strains of Trichomonas, respectively and was thus
2.4 and 9.8 fold more active than MTZ against these two strains.
2.2.2. Structure activity relationship (SAR) study
The anti-Trichomonas activity data of compounds (4e50 and
53e65) against MTZ-susceptible and -resistant strains, revealed
that the amine substituents -NR1R2 and nitro group position both
have been useful for the biological activity. To better understand
the substitution requirements for desirable activity four prototypes
(prototype 1, 4e24; prototype 2, 25e50; prototype 3, 53e61 and
prototype 4, 62e65) were synthesized.
Prototype 1 i.e., 2-hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-

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D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
Fig. 1. Structures of 5-nitroimidazole drugs and dithiocarbamate hybrid molecules with enhanced activities.
Scheme 1:. Synthesis of compounds (4ꢁ50). Reagents and Reaction Conditions: a) ( )-Epichlorohydrin, AlCl3, EtOAc, 0 ꢀC-rt, 24e26 h, 79% yield; b) Aq. NaOH, DCM, 2 h, 91% yield;
c) Substituted-1-carbodithioate, Water:Acetone (10:1), 0 ꢀC, 2e4 h, 68e91% yield; d) Substituted amines, Acetonitrile, 80 ꢀC, overnight, 40e85% yield.
yl)propyl substituted carbodithioate/carbamodithioate (4e24)
contained 2-methyl-5-nitro imidazole and DTC groups linked by a
2-hydroxy propyl chain. At -NR1R2 various amine substituents like
acyclic amine (20e22), cyclic amine (13e19) and piperazine (4e12,
23 and 24) were employed. Against MTZ-susceptible strain, in
acyclic amines the activity decreased with the increasing the alkyl
chain (22 > 21 > 20) while with cyclic amines the activity enhanced
as the ring size increased (34 < 35<40 < 37 ¼ 38 < 39) except in
case of piperidine (36). In case of piperazines alkyl/carboxy sub-
stitutions at N4 had activity better than MTZ where as in case of
aryl/hetero aryl substitution the activity pattern followed was
phenyl (6)>phenyl substituted with electron withdrawing groups
(10e12)>electron donating groups (7) followed by hetero aryl
substitution (8 and 9). the most desirable substituent at -NR1R2 was
found to be N4-phenylpiperazine (6). Against MTZ-resistant strain
among acyclic amine dimethyl (20)/diethyl (22) substituents were
more desirable than ethylmethyl substitution (21) and in cyclic
amine substitution at -NR1R2 with increasing ring size from
13 < 15<19. A further substitution on piperidine ring resulted in
increased activity (16e18) whereas a hetero atom substitution
decreased activity (14). These compounds (13e19) were 2.5e12.6
fold more active than MTZ. Alkyl/carboxy substitution at N4 of
piperazine had better activity than MTZ wherein aryl/hetero aryl
substitution the order of activity was 2-pyrimidyl (9)>phenyl (6)
>2-methoxyphenyl (7)>2-flurophenyl (10)>3-chlorophenyl (11)
>2,3-dichlorophenyl (12)>2-pyridyl (8). The most desirable sub-
stituent was 2-pyrimidyl (9) as it was 12.3 fold more active than
MTZ. In prototype 1 the essential substitution at -NR1R2 was aryl/
heteroaryl-substituted piperazine against both susceptible and
resistant strains. The SAR revealed that the loss of activity from

D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
823
Scheme 2:. Synthesis of compounds (53e65). Reagents and Reaction Conditions: a) ( )-Epichlorohydrin, K2CO3, 110 ꢀC, 30 min, 60% yield; b) Aq. NaOH, DCM, 2 h, 86% yield; c)
Substituted-1-carbodithioate, Water:Acetone (10:1), 0 ꢀC, 2e4 h, 70e84% yield; d) Substituted amines, Acetonitrile, 80 ꢀC, overnight, 55e72% yield.
susceptible to resistant strain in most of the compounds was much
lesser (1e8 times) than MTZ (17 times). In order to explore the
importance of DTC group, another prototype 2 i.e., 1-(2-methyl-5-
nitro-1H-imidazol-1-yl)-3-(substitutedamine)propan-2-ol
activity was considerably lost by 3e28 fold as compared their 5-
nitro analogues.
The SAR study suggested that prototype 1 was most desirable
which comprised of both DTC and 5-nitro groups for the anti-Tri-
chomonas activity better than MTZ against both susceptible and
resistant strains. Compound 6 (2-hydroxy-3-(2-methyl-5-nitro-1H-
imidazol-1-yl)propyl 4-phenylpiperazine-1-carbodithioate) was
taken for the further biological studies based on its activity profile
against both the strains tested. Safety data of all the synthesized
compounds suggested that all compounds were safe against
normal HeLa cells with higher SI values.
(25e50) was devoid of DTC group from prototype 1. It was syn-
thesized to observe the effect of DTC group. At -NR1R2 among cyclic
amines (34e40, 42 and 43) an increase in ring size (5-membered to
7-membered) enhanced the activity against susceptible strain
while a further substitution in piperidine ring (36) decreased the
activity (38, 39, 42 and 43) except 3-methyl substitution (37),
which was comparable. In piperazines at N4-position alkyl group
(26) was more desirable over ethoxycarbonyl (25) or aryl/hetero
aryl substitutions (27e33). Several azole groups (45e50) were also
substituted at -NR1R2 which resulted in decreased activity as
compared to MTZ except 1,2,3-triazole substitution (46). Against
MTZ-resistant strain with cyclic amine substitution at -NR1R2 the
activity pattern was to be similar as observed against susceptible
strain of T. vaginalis. Further an N4-heteroaryl/alkoxy carbonyl
substitution in piperazine (29, 30/25) was more favourable over
alkyl/aryl substitutions (26, 27, 28 and 31e33). Among the various
substituents attempted at -NR1R2 azoles were most promising
(44e50) of which 1,2,3-benzotriazole (50) and 1,2,5-triazoles (48)
found to be most desirable. In prototype 2 the required substitution
at -NR1R2 was azoles against both susceptible and resistant strains.
From the SAR study it was found that the loss of activity from
susceptible to resistant strain in all of the compounds was 1.6e8
fold only as compared to 17 times in MTZ. From the activity data it
was revealed that prototype 1 was more desirable for anti-Tricho-
monas activity in both susceptible and resistant strains. Against
susceptible strain twelve compounds of prototype 1 and only four
of prototype 2 were found to be more active than MTZ while against
resistant strain four compounds of prototype 1 and only two of
2.2.3. 3D-QSAR study
The reliability of CoMFA models is dependent on number of
factors such as alignment rules, orientation of the aligned com-
pounds, lattice shifting step size and probe atom type [42]. Mo-
lecular alignment was done through similarity based method
considering compound 6 as template. The resulting alignment of
whole dataset is shown in Fig. 2.
The leave-one-out partial least squares (PLS) analysis of the
reported model yielded cross-validated q2 value of 0.71 and non-
cross validated correlation coefficient r2 of 0.999. A significant
predictive r2 value of 0.654 was obtained for the test set molecules,
indicating a reasonably good predictive power for the untested
compounds. The experimental and predicted activity values for the
compounds of training and test set is given in Supplementary
Table 1. The results of CoMFA statistical analysis has been sum-
marized in the Supplementary Table 2. The plot of experimental
versus predicted values for CoMFA model is shown in
Supplementary Fig. 1. The contour maps derived from the CoMFA-
PLS model have permitted an understanding of the steric and
electrostatic requirements for ligand binding. The total field
contribution provided by electrostatic field is 49.7% and steric field
is 50.3% for CoMFA model. Most active compound 6 was embedded
in the CoMFA contour map (Fig. 3). The decrease in activity with
increase in alkyl chain length is supported by prominent yellow
contour near -NR1R2 substituent position as exemplified by com-
pound 20 > 21 > 22. The compounds 7 and 8 are also less active as
compared to compound 23 and 24 and their substituent also fall in
this yellow contour. The red contour in the vicinity of DTC group
favors electronegative substitution and the compounds 6, 10, 18, 26
and 46 are more active as compared to the compounds devoid of
prototype 2 were more active at MIC <50 mM.
To further explore the effect of position of 5-nitro group in
imidazole ring prototype 3 and 4 were synthesized with nitro
group at 4-position along with and without DTC group respectively.
The substituent at -NR1R2 were chosen according to the activity of
their 5-nitro equivalents. In prototype 3 i.e., DTC derivatives
(53e61) against susceptible strain the activity was lost by 1.6e8
fold and 4e20 fold against resistant strain as compared their 5-
nitro analogues. While in prototype 4 i.e., without DTC group
(62e65) against both the susceptible and resistant strains the

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D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
Table 1
Anti-Trichomonas activity and cytotoxicity data of synthesized compounds (4e50 and 53e65)a.
Selectivity index (IC50/MIC)
Compound -NR1R2
MTZ susceptible strainb MICc
14.98
(m
M) MTZ resistant straind MIC (
m (mM)
M) HeLae IC50
f
MTZ susceptible strain MTZ resistant strain
4
59.95
1609.11
107
26
5
20.93
83.78
>5000
>250
>60
6
7
8.55
37.10
55.43
>5000
>5000
>584
>185
>135
>90
27.71
8
9
29.62
29.55
148.10
29.55
2966.82
2044.91
100
69
20
69
10
11
12
14.23
17.16
15.97
56.94
68.68
3243.73
1076.92
1000.00
227
62
56
15
7
127.81
62
13
14
37.87
36.12
151.51
144.50
1342.42
4523.12
35
9
125
31
15
16
72.67
17.45
145.34
69.83
1404.06
608.93
19
35
9
8
17
18
17.45
14.40
69.83
28.80
1818.43
1315.66
104
91
26
45
19
20
21
22
34.91
20.55
24.55
37.65
69.83
82.23
393.08
75.30
410.61
>5000
11
>243
169
65
6
>61
10
4150.94
2457.83
32
23
24
15.58
17.55
31.17
70.22
1905.23
689
122
39
61
9

D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
825
Table 1 (continued )
Selectivity index (IC50/MIC)
Compound -NR1R2
MTZ susceptible strainb MICc
22.90
(
m
M) MTZ resistant straind MIC (
m
M) HeLae IC50
(m
M)
f
MTZ susceptible strain MTZ resistant strain
25
91.64
3671.55
4942.76
160
40
26
12.12
105.21
407
47
27
28
22.63
33.33
181.15
133.33
>5000
>220
>27
4389.33
131
33
29
30
18.06
22.50
72.25
90.05
1826.58
3927.95
101
174
25
43
31
32
33
43.03
131.92
18.86
344.35
329.81
150.96
>5000
1435.35
>5000
>116
10
>14
4
>265
>33
34
35
49.21
46.29
196.85
92.59
>5000
>5000
>102
>108
>25
>54
36
37
23.32
22.16
186.56
88.65
>5000
>5000
>217
>227
>26
>56
38
39
44.32
34.91
177.30
139.66
>5000
>113
>28
1430.16
40
10
40
22.16
44.32
>5000
>227
>113
41
42
21.51
55.39
172.17
443.26
3523.41
163
20
>5000
>90
>11
43
42.22
84.46
>5000
>119
>59
44
45
26.38
50.38
105.57
100.80
>5000
>192
>47
4354.83
86
43
46
12.38
99.20
>5000
>416
>50
(continued on next page)

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D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
Table 1 (continued )
Selectivity index (IC50/MIC)
Compound -NR1R2
MTZ susceptible strainb MICc
30.99
(m
M) MTZ resistant straind MIC (
m
M) HeLae IC50
(m
M)
f
MTZ susceptible strain MTZ resistant strain
47
99.20
4968.25
160
50
48
49
30.99
25.94
49.60
83.05
>5000
>161
>102
4528.23
4235.09
724.48
>5000
181
169
30
54
103
2
50
53
54
25.86
25.51
41.39
510.20
1340.48
134.04
>37
>3
55
56
124.68
119.90
Inactive
599.52
4331.67
2359.71
34
19
Inactive
4
57
58
22.69
296.91
>5000
>5000
>227
>22
>16
>4
221.72
1108.64
59
60
54.94
34.91
549.45
1736.26
2695.53
31
3
2
1396.64
105
61
62
28.08
561.79
>5000
>178
>9
120.77
1207.72
3623.18
30
3
63
64
336.70
144.50
Inactive
1445.08
>5000
>5000
>14
>34
Inactive
>3
65
99.20
21.05
992.06
365.49
>5000
>5000
>50
>5
MTZ
>238
>13
a
All the experiments were carried out in triplicate.
ATCC 33592 strain.
Minimum inhibitory concentration.
ATCC 50143 strain.
Human cervical cell line.
Inhibitory concentration killing 50% HeLa cells; MTZ ¼ Metronidazole.
b
c
d
e
f
this group. The blue contour near -NR1R2 substituent position fa-
vors the higher activity of compounds 18 and 46 than compounds
54 and 58 as observed. The large blue contour near nitroimidazole
ring favors the electropositive substitution which is supported by
the less activity of 4-nitro substituent at imidazole ring, lying in this
contour than 5-nitro substituent, away from it (Fig. 3).
The 3D-QSAR study carried out in the present study shed light
onto the regions of importance for steric and electrostatic contri-
bution. The reported model helps in the understanding of observed
variance in the activity and provides direction for structural

D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
827
possible dual mechanism of this prototype with DTC group made
prototype 1 more desirable scaffold for anti-Trichomonas activity
than others.
2.2.5. In vivo efficacy of compound 6
The most promising compound 6 with high in vitro activity and
absence of cytotoxicity against HeLa cells was screened for in vivo
anti-trichomoniasis activity using the mouse abscess assay. Sub-
cutaneous injections of live trichomonads resulted in a small pus-
tule of ~60 mm2 area on day-7 of injection (day-1 of treatment) in
experimental and control animals that grew to ~120 mm2 in area in
controls but was reduced to ~1e5 mm2 after 5-days of oral treat-
ment with compound-6 or MTZ (Fig. 5). Thereafter the growth of
abscess was exponential in controls and 7 days after the treatment
it was >100 mm2 in area in controls while it was further subdued to
~0.5e2 mm2 in treated animals. On the day of autopsy (i.e. the day
following seven days of treatment), the abscess was ~113 mm2 in
area in untreated controls, 1.57 mm2 in 50 mg/kg of MTZ-treated
group and 1.55 and 0.785 mm2 in 50 mg and 100 mg/kg of
compound-6 treated groups, respectively.
Fig. 2. Whole dataset aligned on the most active compound 6.
2.2.6. Pharmacokinetics study
A preliminary pharmacokinetic study involves monitoring drug
substance in blood plasma carried out for compound 6. The animals
tolerated the treatment as no peculiarities in the animals' behav-
iour were observed. The mean peak serum concentration
Cmax ¼ 35.2 2.0 ng/mL was achieved after 50 mg/kg oral dosing at
4.0 h. However, following oral administration, compound 6 could
be monitored in serum up to 10 h post dose. The pharmacokinetic
parameters were calculated using non compartmental approach
and the calculated pharmacokinetic parameters are shown in
Table 2. The volume of distribution (80.6 7.2 L/kg) is larger than
the total blood volume of rat (0.054 L/kg [48]) and systemic clear-
ance (16.3 1.8 L/h/kg) is higher than the total hepatic blood flow
in rats (2.9 L/h/kg [48]) indicating extra vascular distribution along
with the extra hepatic elimination of the compound.
Fig. 3. CoMFA steric and electrostatic contours displayed with most potent compound
6. The green areas in the figure indicate regions where steric bulks are well accomo-
dated with an increase in activity, whereas yellow areas indicate regions where steric
bulk is unfavourable. The red contours indicate regions where substitution with more
electronegative substituent will increase the activity, whereas the blue contour show
the reverse. (For interpretation of the references to colour in this figure legend, the
reader is referred to the web version of this article.)
requirement for compounds possessing better activity.
3. Conclusion
2.2.4. Plausible mode of action of active compound 6
A library of sixty 2-methyl-4/5-nitroimidazoles was designed
which demonstrated improved trichomonicidal activities against
MTZesusceptible and eresistant strains in vitro than the marketed
drug MTZ. Furthermore, these derivatives were also found to be
safe in cytotoxicity study against HeLa cells with good selectivity
index. The most active compound 6 demonstrated trichomonacidal
T. vaginalis is an anaerobic parasite that contains hydro-
genosomes (instead of mitochondria) to generate energy and pro-
duces molecular hydrogen, which maintains the redox balance. The
metabolic pathway of hydrogenosome is different from that found
in mitochondria and thus drugs intended for targeting hydro-
genosomes generally do not affect the host cells. Metronidazole,
FDA-approved drug for trichomoniasis management acts through
the hydrogenosomal pathway. The nitro group is reduced in the
hydrogenosome to produce cytotoxic nitro radicals liable for DNA
destruction of parasite. The 2-methyl-4/5-nitroimidazole de-
rivatives studied here also possibly act through the same pathway
due to the presence of NO2 group in the molecules [43,44].
Also the lack of glutathione makes T. vaginalis dependent on
cysteine to overcome redox stress, making them very susceptible to
sulfhydryl manipulating agents. The DTC compounds are known to
be sulfhydryl binding agents [45e47]. Compound 6 was evaluated
for its sulfhydryl binding ability due to the presence of DTC in its
structure. Fig. 4 indicates a considerable inhibition in free thiol
fluorescence of Trichomonas treated with compound 6. In the
control group the fluorescence intensities were visibly higher due
to the higher number of free sulfhydryl groups than that in com-
pound 6 treated. The diminished fluorescence indicates the inter-
activity at an MIC of 8.55 and 37.10 mM against MTZ-susceptible and
-resistant strains of Trichomonas respectively, which was 2.4 and
9.8 fold better than MTZ. To further explore the importance of 5-
nitro group the positional isomers 4-nitroimidazoles were also
synthesized and evaluated. The SAR study revealed that change in
the position of nitro group on imidazole ring from 5 to 4-position
drastically reduced the activity against resistant Trichomonas
which was a clear indication of the importance of the 5-nitro group.
Some activity of 4-nitro molecules against MTZesusceptible strain
could also be due to the presence of DTC group. The finding have
suggested that prototype 1 was more desirable over remaining
prototypes plausibly due to the presence of both DTC and 5-nitro
groups for better anti-Trichomonas activity against both the
strains (inhibition of hydrogenosomal function by nitro group and
sulfhydryl binding ability of DTC group, as also supported by sulf-
hydryl inhibition assay). The compound 6 was apparently nontoxic
in animal infection models and was found to be active in vivo too.
Preliminary pharmacokinetic study has shown good distribution
and systemic clearance of compound 6 in rats and thus could serve
as a novel lead molecule for the development of structurally
action of compound
6 with the sulfhydryls present over
Trichomonas further boosting its trichomonicidal mechanism. Even
though non-DTC compounds of the series were also active but

828
D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
Fig. 4. Fluorescent labelling of Trichomonas sulfhydryls: (i) Labelled with fluorometric thiol detector specifically binds with free sulfhydryls, (ii) Phase contrast image, (iii) Merged
image.
Fig. 5. Decrease of abscess size in subcutaneous abscess assay in mice model at days 1, 2, 5 and 7(autopsy day). Significant difference from infected-untreated animals is indicated as
**P < 0.01; ***P < 0.001.
diverse, next-generation 5-nitroimidazoles.
and are uncorrected. IR spectra (nmax in cmꢁ1) of the compounds
were recorded on Perkin Elmer FT-IR RX1 PC spectrophotometer. 1H
NMR spectra were recorded on Bruker Supercon Magnet Avance
DPX-200/DRX-300 spectrometers (operating at 400 and 100 MHz,
respectively, for 1H and 13C) in deuterated solvents with TMS as
4. Experimental section
4.1. Chemistry
internal reference (chemical shifts
d in ppm, J in Hz.). Electrospray
ionization mass spectra (ESI-MS) were recorded on Ion Ttrap LCQ
Advantage Max-IT (Thermo Electron Corporation). High-resolution
mass spectra (HRMS) were recorded on a 6520 Agilent Q Tof LC-MS/
MS (accurate mass). Elemental analyses were performed on a Carlo
Erba EA-1108 micro analyzer/Vario EL-III C, H, N analyzer. All
compounds were analyzed of C, H, N and the results obtained were
In general, all reagents and solvents were of commercial quality
and were used without further purification. Chromatography was
carried on silica gel (100e200 and 60e120 mesh). All reactions
were monitored by thin-layer chromatography (TLC) using F254
silica gel plates with fluorescence (Aldrich). Melting points were
determined in open capillary tubes on an electrically heated block

D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
829
Table 2
Reaction progress was monitored by TLC and after completion of
the reaction EtOAc (20 mL), excess water (50 mL) was added and
organic layer was separated, dried (anhyd. Na2SO4) and concen-
trated under reduced pressure. Crude product obtained was
recrystallized from EtOAc/hexane to get the final compound (4) in
Pharmacokinetic parameters of compound 6 after single 50 mg/
kg oral administration in male Sprague Dawley rats.a
Parameters
Compound 6
Cmax (ng/mL)
35.2 2.0
4.0 0.0
149.1 13.9
5.0 0.1b
16.3 1.8
80.6 7.2
75% yield as white solid. mp: 88e90 ꢀC; IR (KBr)
n
(cmꢁ1): 3339,
T
max (hr)
3110, 1740, 1540, 1360, 1215, 1150; 1H NMR (400 MHz, DMSO-d6):
AUClast (ng*hr/mL)
t1/2 (hr)
Cl (L/hr/kg)
Vss (L/kg)
d
8.02 (s, 1H), 5.61e5.60 (m, 1H), 4.49 (d/d, J ¼ 3.4 & 14.2 Hz, 1H),
4.25e3.98 (m, 8H), 3.58e3.51 (m, 5H), 3.39 (d/d, J ¼ 7.3 & 13.6 Hz,
1H), 2.45 (s, 3H), 1.20 (t, J ¼ 7.0 Hz, 3H); 13C (100 MHz, DMSO-d6):
Abbreviations: AUClast ¼ area under the concentration-time
curve up to last observation, Cmax ¼ peak serum concentration,
tmax ¼ time to Cmax, Vss ¼ steady-state volume of distribution,
Cl ¼ clearance, T1/2 ¼ elimination half-life.
d
195.8, 155.0, 152.3, 138.9, 133.3, 68.6, 61.5, 50.9, 42.9, 41.3, 15.0,
14.8; ESI-MS: m/z 418 (MþHþ); HRMS (ESI): m/z calculated for
C
15H23N5O5S2 þ Hþ (MþHþ): 418.1219. Found: 418.1219. Elemental
a
Each value represent the average of four rats.
MRT(mean residence time).
analysis (%) for C15H23N5O5S2: Calcd.: C, 43.15; H, 5.55; N, 16.77;
Found, C, 43.40; H, 5.90; N, 16.69.
b
The compounds 5e24 were synthesized using a procedure
similar to described for compound 4.
within 0.4% of calculated values. All final compounds were found
to have >95% purity.
4.1.4. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl 4-ethylpiperazine-1-carbodithioate (5)
4.1.1. Synthesis of ( )e1-chloro-3-(2-methyl-5-nitro-1H-imidazol-
1-yl)propan-2-ol (2)
The title compound (5) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.64 mmol) and so-
dium 4-ethylpiperazine-1-carbodithioate (3.27 mmol) in 70% yield
A mixture of 2-methyl-4/5-nitro-1H-imidazole (1, 39.37 mmol)
and anhydrous aluminium chloride (39.37 mmol) were dissolved in
ethylacetate (50 mL) at 0 ꢀC and stirred for 15 min then added
( )-epichlorohydrin (78.74 mmol) to the above reaction mixture
and contents were further stirred for 15e20 h. After completion of
reaction (as monitored by TLC) 30 mL of distilled water was added
and further continued the stirring for 30 min and stopped the re-
action. Then EtOAc (20 mL) and excess water (3 ꢂ 30 mL) was
added to the reaction mixture and organic layer was separated,
dried (anhyd. Na2SO4), concentrated under reduced pressure. The
crude obtained was further purified by column chromatography
over silica (60e120 mesh) with methanol/chloroform as eluent to
get the title compounds 2 in 79% yield as white solid. mp:
as semi solid IR (KBr)
n
(cmꢁ1): 3405, 3019, 1541, 1360, 1215, 1120;
1H NMR (400 MHz, CDCl3):
d
7.85 (s, 1H), 4.66e4.63 (m, 1H),
4.35e4.06 (m, 9H), 3.73e3.69 (m, 1H), 3.63e3.60 (m, 5H), 2.51 (s,
3H), 1.30e1.26 (t, J ¼ 7.1 Hz, 3H); 13C (100 MHz, CDCl3):
d 196.8,
151.7, 138.4, 132.6, 69.9, 61.9, 50.8, 42.8, 40.7, 14.7, 14.6; ESI-MS: m/z
374 (MþHþ); Elemental analysis (%) for C18H23ClN5O3S2: Calcd.: C,
47.41; H, 4.86; N, 15.36; Found, C, 47.31; H, 4.97; N, 15.39.
4.1.5. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl 4-phenylpiperazine-1-carbodithioate (6)
The title compound (6) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 2.18 mmol) and so-
dium 4-phenylpiperazine-1-carbodithioate (4.37 mmol) in 82%
84e86 ꢀC; IR (KBr)
NMR (400 MHz, CDCl3):
1H), 4.19e4.16 (m, 2H), 3.73e3.63 (m, 2H), 2.45 (s, 3H); 13C
n
(cmꢁ1): 3400, 3110, 1540, 1360, 1150, 771; 1H
7.72 (s, 1H), 4.92 (s, 1H), 4.63e4.60 (m,
d
yield as light yellow solid. mp: 110e112 ꢀC; IR (KBr) (cmꢁ1): 3400,
n
3112, 1560, 1545, 1361, 1217, 1140; 1H NMR (400 MHz, DMSO-d6):
8.02 (s, 1H), 7.26e7.22 (m, 2H), 6.96e6.94 (m, 2H), 6.81 (t,
(100 MHz, CDCl3):
d 151.9, 138.3, 132.2, 69.8, 49.7, 46.9, 14.4; ESI-
d
MS: m/z 220 (MþHþ).
J ¼ 7.2 Hz, 1H), 5.63e5.61 (m, 1H), 4.52 (d/d, J ¼ 3.5 & 14.2 Hz, 1H),
4.38 (bs, 2H), 4.23 (d/d, J ¼ 9.1 & 14.2 Hz, 1H), 4.11e4.00 (m, 3H),
3.57 (d/d, J ¼ 4.8 & 13.6 Hz, 1H), 3.40 (d/d, J ¼ 7.3 & 13.6 Hz, 1H),
4.1.2. Synthesis of ( )e2-methyl-5-nitro-1-(oxiran-2-ylmethyl)-
1H-imidazole (3)
3.34e3.28 (m, 4H), 2.46 (s, 3H); 13C (100 MHz, DMSO-d6):
d 195.3,
The title compound (3) was synthesized by dissolving com-
pound 2 (29.68 mmol) in dichlorometane (10 mL) and added
aqueous NaOH (29.68 mmol) at 0 ꢀC. Stirred the contents for
40e45 min and after completion of reaction (as monitored by TLC)
contents was extracted with DCM/water and organic layer was
separated, dried (anhyd. Na2SO4), concentrated under reduced
pressure. The crude obtained was recrystallized with EtOAc/hexane
to get the final compound (3) in 91% yield as white solid. mp:
152.3, 150.5, 138.9, 133.3, 129.5, 119.7, 115.9, 68.6, 50.9, 49.6, 48.0,
41.3, 14.8; ESI-MS: m/z 422 (MþHþ); HRMS (ESI): m/z calculated for
C
18H23N5O3S2 þ Hþ (MþHþ): 422.1321. Found: 422.1320. Elemental
analysis (%) for C18H23N5O3S2: Calcd.: C, 51.29; H, 5.50; N, 16.61;
Found, C, 51.11; H, 5.74; N, 16.69.
4.1.6. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl 4-(2-methoxyphenyl)piperazine-1-carbodithioate (7)
The title compound (7) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.96 mmol) and so-
113e115 ꢀC; IR (KBr)
(400 MHz, CDCl3):
n
(cmꢁ1): 3405, 3110, 1540, 1362, 1151; 1H NMR
d
7.92 (s, 1H), 4.85 (d/d, J ¼ 2.3 & 15.0 Hz, 1H),
4.19 (d/d, J ¼ 5.8 & 15.0 Hz, 1H), 3.37e3.33 (m, 1H), 2.85 (t,
dium
(3.93 mmol) in 80% yield as white solid. mp: 85e87 ꢀC; IR (KBr)
(cmꢁ1): 3400, 3120, 2995, 1562, 1550, 1361, 1216, 1145; 1H NMR
(400 MHz, DMSO-d6): 8.02 (s, 1H), 7.00e6.97 (m, 2H), 6.92e6.88
4-(2-methoxyphenyl)piperazine-1-carbodithioate
J ¼ 4.2 Hz, 1H), 2.50 (d/d, J ¼ 2.5 & 4.4 Hz, 1H), 2.47 (s, 3H); 13C
n
(100 MHz, CDCl3): d 151.4, 138.5,132.8, 50.3, 47.5, 45.1, 14.3; ESI-MS:
m/z 184 (MþHþ).
d
(m, 2H), 4.53 (d/d, J ¼ 3.5 & 14.2 Hz, 1H), 4.38e4.01 (m, 6H), 3.80 (s,
3H), 3.58 (d/d, J ¼ 4.8 & 13.6 Hz,1H), 3.41 (d/d, J ¼ 7.3 & 13.6 Hz,1H),
3.08e3.06 (m, 4H), 2.88e2.87 (m, 1H), 2.47 (s, 3H); 13C (100 MHz,
4.1.3. Synthesis of ( )eethyl 4-((2-hydroxy-3-(2-methyl-5-nitro-
1H-imidazol-1-yl)propylthio)carbonothioyl)piperazine-1-
carboxylate (4)
DMSO-d6):
d 195.4, 152.4, 152.3, 140.5, 138.9, 133.3, 123.6, 121.2,
To
carbodithioate (3.27 mmol) in water (20 mL) at 0 ꢀC was added
( )e2-methyl-5-nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3,
1.64 mmol) in acetone (2 mL) and contents were stirred for 2.5 h.
a
solution of sodium 4-(ethoxycarbonyl)piperazine-1-
118.9, 112.3, 68.6, 55.8, 51.3, 50.9, 50.1, 41.3, 14.8; ESI-MS: m/z 452
(MþHþ); HRMS (ESI): m/z calculated for C19H25N5O4S2 þ Hþ
(MþHþ): 452.1426. Found: 452.1427. Elemental analysis (%) for
C
19H25N5O4S2: Calcd.: C, 50.54; H, 5.58; N, 15.51; Found, C, 50.75; H,

830
D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
5.89; N, 15.43.
DMSO-d6): d 195.4, 152.4, 151.6, 138.9, 134.3, 133.3, 131.0, 118.7,
114.8, 113.8, 68.6, 50.9, 49.5, 47.2, 41.3, 14.8; ESI-MS: m/z 456
(MþHþ); HRMS (ESI): m/z calculated for C18H22ClN5O3S2 þ Hþ
(MþHþ): 456.0931. Found: 456.0949. Elemental analysis (%) for
4.1.7. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl 4-(pyridin-2-yl)piperazine-1-carbodithioate (8)
The title compound (8) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 2.24 mmol) and so-
dium 4-(pyridin-2-yl)piperazine-1-carbodithioate (4.48 mmol) in
C18H22ClN5O3S2: Calcd.: C, 47.41; H, 4.86; N, 15.36; Found, C, 47.31;
H, 4.97; N, 15.39.
77% yield as yellow solid. mp: 137e139 ꢀC; IR (KBr)
n
(cmꢁ1): 3399,
4.1.11. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl 4-(2,3-dichlorophenyl)piperazine-1-carbodithioate (12)
The title compound (12) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.53 mmol) and so-
dium 4-(3-chlorophenyl)piperazine-1-carbodithioate (3.06 mmol)
3115, 1560, 1545, 1356, 1215, 1146; 1H NMR (400 MHz, DMSO-d6):
8.14e8.13 (m, 1H), 8.02 (s, 1H), 7.59e7.55 (m, 1H), 6.82 (d,
d
J ¼ 8.6 Hz, 1H), 6.69e6.66 (m, 1H), 5.61 (d, J ¼ 5.8 Hz, 1H), 4.52 (d/d,
J ¼ 3.5 & 14.2 Hz, 1H), 4.26e4.02 (m, 6H), 3.67 (bs, 4H), 3.58 (d/d,
J ¼ 4.7 & 13.6 Hz,1H), 3.43e3.38 (m,1H), 2.46 (s, 3H); 13C (100 MHz,
in 85% yield as yellow solid. mp: 118e120 ꢀC; IR (KBr)
3400, 3119, 1590, 1542, 1370, 1216, 785; 1H NMR (400 MHz, DMSO-
d6):
n
(cmꢁ1):
DMSO-d6):
d 195.4, 158.6, 152.3, 148.0, 138.9, 138.1, 133.3, 113.7,
107.4, 68.6, 50.9, 49.6, 44.1, 41.3, 14.8; ESI-MS: m/z 440 (MþHþ);
HRMS (ESI): m/z calculated for C17H22N6O3S2 þ Hþ (MþHþ):
423.1273. Found: 423.1273. Elemental analysis (%) for
d
8.02 (s, 1H), 7.34e7.30 (m, 2H), 7.17 (d/d, J ¼ 2.6 & 6.9 Hz, 1H),
5.64e5.63 (m, 1H), 4.53 (d/d, J ¼ 3.5 & 14.2 Hz, 1H), 4.39 (bs, 2H),
4.23 (d/d, J ¼ 9.1 &14.2 Hz, 1H), 4.04e4.00 (m, 3H), 3.57 (d/d, J ¼ 4.8
& 13.6 Hz, 1H), 3.12e3.02 (m, 5H), 2.46 (s, 3H); 13C (100 MHz,
C
17H22N6O3S2: Calcd.: C, 48.32; H, 5.25; N,19.89; Found, C, 48.00; H,
5.54; N, 19.62.
DMSO-d6): d 195.9, 152.4, 150.5, 138.9, 133.3, 133.1, 128.9, 126.6,
125.4, 120.4, 68.6, 51.6, 50.9, 50.4, 45.0, 41.4, 14.8; ESI-MS: m/z 490
(MþHþ); HRMS (ESI): m/z calculated for C18H21Cl2N5O3S2 þ Hþ
(MþHþ): 490.0541. Found: 490.0538. Elemental analysis (%) for
4.1.8. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl 4-(pyrimidin-2-yl)piperazine-1-carbodithioate (9)
The title compound (9) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 2.18 mmol) and so-
dium 4-(pyrimidin-2-yl)piperazine-1-carbodithioate (4.37 mmol)
C18H21Cl2N5O3S2: Calcd.: C, 44.08; H, 4.32; N,14.28; Found, C, 44.47;
H, 4.41; N, 14.01.
in 85% yield as white solid. mp: 118e120 ꢀC; IR (KBr)
n
(cmꢁ1):
4.1.12. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl pyrrolidine-1-carbodithioate (13)
3406, 3111, 1562, 1540, 1356, 1215, 1151; 1H NMR (400 MHz, DMSO-
d6):
8.39 (d, J ¼ 4.7 Hz, 2H), 8.00 (s, 1H), 6.69 (t, J ¼ 4.7 Hz, 1H),
d
The title compound (13) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.09 mmol) and so-
dium pyrrolidine-1-carbodithioate (2.18 mmol) in 91% yield as
5.67e5.66 (m, 1H), 4.52 (d/d, J ¼ 3.4 & 14.2 Hz, 1H); 4.33e3.99 (m,
7H), 3.86 (bs, 4H), 3.39 (d/d, J ¼ 7.4 & 13.7 Hz, 1H); 2.45 (s, 3H); 13
C
(100 MHz, DMSO-d6):
d
195.6, 161.2, 158.4, 152.4, 138.9, 133.2, 111.1,
white solid. mp: 144e146 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3119, 1542,
68.6, 50.9, 49.6, 42.9, 41.2, 14.8; ESI-MS: m/z 424 (MþHþ); HRMS
(ESI): m/z calculated for C16H21N7O3S2 þ Hþ (MþHþ): 424.1226.
Found: 424.1224. Elemental analysis (%) for C16H21N7O3S2: Calcd.:
C, 45.38; H, 5.00; N, 23.15; Found, C, 45.09; H, 5.32; N, 23.45.
1362, 1215, 1134; 1H NMR (400 MHz, DMSO-d6):
d 8.00 (s, 1H),
5.63e5.61 (m, 1H), 4.49 (d/d, J ¼ 3.5 & 14.2 Hz,1H); 4.21 (q, J ¼ 9.1 &
14.1 Hz, 1H); 3.95 (bs, 1H), 3.76 (t, J ¼ 6.8 Hz, 2H); 3.63 (t, J ¼ 6.8 Hz,
2H); 3.33 (q, J ¼ 7.3 & 13.7 Hz, 1H); 2.44 (s, 3H), 2.05e1.98 (m, 2H),
1.94e1.87 (m, 2H); 13C (100 MHz, DMSO-d6):
d 191.0, 152.3, 138.9,
4.1.9. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl 4-(2-fluorophenyl)piperazine-1-carbodithioate (10)
133.2, 68.8, 55.6, 51.0, 40.7, 26.0, 24.1, 14.8; ESI-MS: m/z 331
(MþHþ); HRMS (ESI): m/z calculated for C12H18N4O3S2 þ Hþ
(MþHþ): 331.0899. Found: 331.0897. Elemental analysis (%) for
The title compound (10) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.85 mmol) and so-
dium 4-(2-fluorophenyl)piperazine-1-carbodithioate (3.71 mmol)
C
12H18N4O3S2: Calcd.: C, 43.62; H, 5.49; N, 16.96; Found, C, 43.79; H,
5.83; N, 16.75.
in 72% yield as yellow solid. mp: 110e112 ꢀC; IR (KBr)
n
(cmꢁ1):
3400, 3109, 1562, 1540, 1361, 1215, 1143, 1010; 1H NMR (400 MHz,
DMSO-d6): 8.02 (s, 1H), 7.19e7.00 (m, 4H), 5.62e5.61 (m, 1H), 4.52
4.1.13. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl morpholine-4-carbodithioate (14)
d
(d/d, J ¼ 3.5 & 14.2 Hz, 1H), 4.40 (bs, 2H), 4.23 (d/d, J ¼ 9.1 &14.2 Hz,
1H), 4.13e4.00 (m, 3H), 3.57 (d/d, J ¼ 4.8 & 13.6 Hz, 1H), 3.43e3.34
(m, 4H), 3.13e2.99 (m, 1H), 2.46 (s, 3H); 13C (100 MHz, DMSO-d6):
The title compound (14) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.63 mmol) and so-
dium morpholine-4-carbodithioate (3.27 mmol) in 84% yield as
d
195.6, 156.6, 154.1, 152.3, 139.3, 139.2, 138.9, 133.3, 125.3, 123.5,
white solid. mp: 160e162 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3122, 1550,
123.4, 120.0, 116.6, 116.4, 68.6, 51.4, 50.9, 50.1, 41.4, 14.8; ESI-MS: m/
z 440 (MþHþ); HRMS (ESI): m/z calculated for C18H22FN5O3S2 þ Hþ
(MþHþ): 440.1226. Found: 440.1221. Elemental analysis (%) for
1352, 1217, 1094; 1H NMR (400 MHz, DMSO-d6):
d 8.02 (s, 1H),
5.61e5.60 (m, 1H), 4.52 (d/d, J ¼ 3.4 & 14.2 Hz, 1H), 4.25e3.98 (m,
6H), 3.69e3.66 (m, 4H), 3.56 (d/d, J ¼ 4.7 & 13.6 Hz, 1H), 3.39 (d/d,
C
18H22FN5O3S2: Calcd.: C, 49.19; H, 5.05; N, 15.93; Found, C, 49.15;
J ¼ 7.3 & 13.7 Hz,1H), 2.46 (s, 3H); 13C (100 MHz, DMSO-d6):
d 195.8,
H, 5.42; N, 16.24.
152.3, 138.9, 133.3, 68.6, 66.0, 51.9, 50.9, 41.2, 14.8; ESI-MS: m/z 347
(MþHþ); HRMS (ESI): m/z calculated for C12H18N4O4S2 þ Hþ
(MþHþ): 347.0848. Found: 347.0846. Elemental analysis (%) for
4.1.10. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl 4-(3-chlorophenyl)piperazine-1-carbodithioate (11)
C12H18N4O4S2: Calcd.: C, 41.60; H, 5.24; N, 16.17; Found, C, 41.77; H,
The title compound (11) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 2.40 mmol) and so-
dium 4-(3-chlorophenyl)piperazine-1-carbodithioate (4.80 mmol)
5.58; N, 16.39.
4.1.14. ( )e2-Hydroxy-3-(5-methyl-2-nitro-1H-imidazol-1-yl)
propyl piperidine-1-carbodithioate (15)
in 76% yield as white solid. mp: 98e100 ꢀC; IR (KBr) (cmꢁ1): 3400,
n
3110, 1565, 1536, 1361, 1215, 780; 1H NMR (400 MHz, DMSO-d6):
The title compound (15) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.80 mmol) and so-
dium piperidine-4-carbodithioate (3.60 mmol) in 78% yield as
d
8.01 (s, 1H), 7.23 (t, J ¼ 8.1 Hz, 1H), 6.95e6.94 (m, 1H), 6.88 (d/d,
J ¼ 2.0 & 8.3 Hz, 1H), 6.81 (d/d, J ¼ 1.4 & 7.8 Hz, 1H), 5.64e5.63 (m,
1H), 4.52 (d/d, J ¼ 3.5 & 14.2 Hz, 1H), 4.26e4.00 (m, 6H), 3.57 (d/d,
J ¼ 4.8 & 13.7 Hz,1H), 3.43e3.35 (m, 5H), 2.46 (s, 3H); 13C (100 MHz,
white solid. mp: 143e145 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3125, 2995,
8.01 (s, 1H),
1543, 1362, 1215, 1135; 1H NMR (400 MHz, DMSO-d6):
d

D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
831
5.58e5.57 (m, 1H), 4.52 (d/d, J ¼ 3.4 & 14.2 Hz, 1H); 4.25e3.96 (m,
6H), 3.52 (d/d, J ¼ 5.0 & 13.6 Hz, 1H), 3.41e3.39 (m, 1H), 2.45 (s, 3H),
1365, 1215, 1143; 1H NMR (400 MHz, CDCl3):
d
7.87 (s, 1H),
4.63e4.61 (m,1H), 4.28e4.13 (m, 4H), 3.99e3.92 (m, 3H), 3.74e3.70
(m, 1H), 3.64e3.59 (m, 1H), 2.52 (s, 3H), 1.89e1.87 (m, 4H),
1.67e1.59 (m, 6H); 13C (100 MHz, DMSO-d6):
d 193.8, 152.3, 138.9,
133.3, 68.7, 53.0, 51.4, 50.9, 41.3, 26.2, 25.6, 24.0, 14.8; ESI-MS: m/z
345 (MþHþ); HRMS (ESI): m/z calculated for C13H20N4O3S2 þ Hþ
(MþHþ): 345.1055. Found: 345.1053. Elemental analysis (%) for
1.61e1.58 (m, 4H); 13C (100 MHz, CDCl3):
d 195.7, 151.7, 138.5, 132.7,
70.4, 56.4, 53.2, 50.9, 40.3, 27.2, 26.5, 26.4, 26.1, 14.7; ESI-MS: m/z
359 (MþHþ); HRMS (ESI): m/z calculated for C14H22N4O3S2 þ Hþ
(MþHþ): 359.1212. Found: 359.1212. Elemental analysis (%) for
C
13H20N4O3S2: Calcd.: C, 45.33; H, 5.85; N, 16.27; Found, C, 45.11; H,
6.09; N, 16.02.
C14H22N4O3S2: Calcd.: C, 46.91; H, 6.19; N, 15.63; Found, C, 46.99; H,
6.42; N, 15.59.
4.1.15. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl 3-methylpiperidine-1-carbodithioate (16)
4.1.19. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl dimethylcarbamodithioate (20)
The title compound (16) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 2.24 mmol) and so-
dium 3-methylpiperidine-1-carbodithioate (4.48 mmol) in 77%
The title compound (20) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 2.18 mmol) and so-
dium dimethylcarbamodithioate (4.37 mmol) in 68% yield as white
yield as white solid. mp: 99e101 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3113,
7.78 (s,
2990, 1535, 1362, 1215, 1144; 1H NMR (400 MHz, CDCl3):
d
solid. mp: 143e145 ꢀC; IR (KBr)
n
(cmꢁ1): 3401, 3111, 3010, 1540,
1H), 5.28 (bs, 1H); 4.61e4.48 (m, 3H), 4.23e4.19 (m, 2H), 3.68e3.55
(m, 2H), 3.21 (bs, 1H), 2.97e2.79 (m, 1H), 2.46 (s, 3H), 1.93e1.58 (m,
4H), 1.27e1.20 (m, 1H), 0.95e0.93 (m, 3H); 13C (100 MHz, CDCl3):
1365, 1215, 1135; 1H NMR (400 MHz, CDCl3):
d 7.88 (s, 1H),
4.64e4.61 (m,1H), 4.27e4.10 (m, 2H), 3.73e3.68 (m, 1H), 3.60e3.43
(m, 6H), 3.26e3.06 (m, 1H), 2.52 (s, 3H); 13C (100 MHz, CDCl3):
d
194.7, 151.6, 138.4,132.3, 69.9, 59.5, 57.6, 53.2, 50.8, 40.7, 32.7, 31.2,
d 196.6, 151.7, 138.5, 132.6, 70.2, 50.9, 45.9, 41.8, 41.0, 14.7; ESI-MS:
25.3, 18.7, 14.6; ESI-MS: m/z 359 (MþHþ); HRMS (ESI): m/z calcu-
lated for C14H22N4O3S2 þ Hþ (MþHþ): 359.1212. Found: 359.1200.
Elemental analysis (%) for C14H22N4O3S2: Calcd.: C, 46.91; H, 6.19; N,
15.63; Found, C, 46.70; H, 6.48; N, 15.31.
m/z 305 (MþHþ); HRMS (ESI): m/z calculated for
C10H16N4O3S2
þ
Hþ (MþHþ): 305.0742. Found: 305.0738.
Elemental analysis (%) for C10H16N4O3S2: Calcd.: C, 39.46; H, 5.30; N,
18.41; Found, C, 39.73; H, 5.69; N, 18.33.
4.1.16. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl 4-methylpiperidine-1-carbodithioate (17)
4.1.20. 2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)propyl
ethyl(methyl)carbamodithioate (21)
The title compound (17) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.64 mmol) and so-
dium 4-methylpiperidine-1-carbodithioate (3.27 mmol) in 81%
The title compound (21) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.42 mmol) and so-
dium dimethylcarbamodithioate (2.84 mmol) in 68% yield as white
yield as white solid. mp: 125e127 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3110,
8.01
solid. mp: 80e82 ꢀC; IR (KBr)
n
(cmꢁ1): 3405, 3110, 3012,1530,1360,
2995, 1542, 1358, 1216, 1150; 1H NMR (400 MHz, DMSO-d6):
d
1216, 1140; 1H NMR (400 MHz, CDCl3):
d 7.87 (s, 1H), 4.64e4.61 (m,
(s, 1H), 5.58e5.56 (m, 1H), 5.27 (bs, 1H), 4.51 (d/d, J ¼ 3.4 & 14.1 Hz,
2H), 4.21 (q, J ¼ 9.2 & 14.1 Hz, 1H), 3.97 (bs, 1H), 3.51 (d/d, J ¼ 5.0 &
13.6 Hz, 1H), 3.40e3.21 (m, 3H), 2.45 (s, 3H), 1.77e1.76 (m, 3H),
1.16e1.10 (m, 2H), 0.93e0.91 (m, 3H); 13C (100 MHz, DMSO-d6):
1H), 4.25e4.23 (m, 2H), 4.12e3.86 (m, 3H), 3.72e3.56 (m, 2H), 3.50
(s, 1H), 3.37 (s, 1H), 2.52 (s, 3H), 1.31e1.23 (m, 3H); 13C (100 MHz,
CDCl3):
d 195.4, 151.7, 138.5, 132.6, 70.2, 52.7, 50.9, 49.7, 43.5, 40.8,
39.2, 14.7, 12.2, 11.1; ESI-MS: m/z 319 (MþHþ); HRMS (ESI): m/z
calculated for C11H18N4O3S2 þ Hþ (MþHþ): 319.0899. Found:
319.0892. Elemental analysis (%) for C11H18N4O3S2: Calcd.: C, 41.49;
H, 5.70; N, 17.60; Found, C, 41.63; H, 5.96; N, 17.31.
d
194.0, 152.3, 138.9, 133.3, 68.7, 52.3, 50.9, 50.5, 41.4, 34.1, 33.7,
30.4, 21.5, 14.8; ESI-MS: m/z 359 (MþHþ); HRMS (ESI): m/z calcu-
lated for C14H22N4O3S2 þ Hþ (MþHþ): 359.1212. Found: 359.1201.
Elemental analysis (%) for C14H22N4O3S2: Calcd.: C, 46.91; H, 6.19; N,
15.63; Found, C, 47.12; H, 6.47; N, 15.78.
4.1.21. ( )e2-Hydroxy-3-(5-methyl-2-nitro-1H-imidazol-1-yl)
propyl diethylcarbamodithioate (22)
4.1.17. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl 4-benzylpiperidine-1-carbodithioate (18)
The title compound (22) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.82 mmol) and so-
dium diethylcarbamodithioate (3.64 mmol) in 71% yield as white
The title compound (18) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.80 mmol) and so-
dium 4-benzylpiperidine-1-carbodithioate (3.60 mmol) in 71%
solid. mp: 91e93 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3105 2995, 1538, 1357,
1215, 1147; 1H NMR (400 MHz, DMSO-d6):
d
8.01 (s, 1H), 5.58e5.57
yield as semi solid. IR (KBr)
n
(cmꢁ1): 3400, 3112, 2990, 1540, 1361,
(m, 1H), 4.51 (d/d, J ¼ 3.4 & 14.2 Hz, 1H), 4.21 (q, J ¼ 9.2 & 14.2 Hz,
1H), 3.99e3.93 (m, 3H), 3.78 (q, J ¼ 7.0 & 14.2 Hz, 2H), 3.50 (d/d,
J ¼ 5.2 & 13.7 Hz, 1H), 3.38 (d/d, J ¼ 7.0 & 13.7 Hz, 1H), 2.45 (s, 3H),
1.25 (t, J ¼ 7.0 Hz, 3H), 1.17 (t, J ¼ 7.0 Hz, 3H); 13C (100 MHz, DMSO-
1215, 1150; 1H NMR (400 MHz, CDCl3):
d
7.93 (s, 1H), 7.33e7.29 (m,
2H), 7.25e7.23 (m, 1H), 7.15 (d, J ¼ 6.8 Hz, 1H), 5.52e5.50 (m, 1H),
4.66e4.62 (m, 2H), 4.28e4.23 (m, 2H), 3.78e3.66 (m, 3H),
3.20e3.09 (m, 2H), 2.60e2.58 (m, 2H), 2.55 (s, 3H), 1.83e1.80 (m,
d6): d 194.0, 152.3, 138.9, 133.3, 68.6, 50.8, 49.7, 47.0, 41.2, 14.8, 12.8,
1H), 1.43e1.27 (m, 4H); 13C (100 MHz, CDCl3):
d
195.0, 151.7, 139.5,
11.7; ESI-MS: m/z 333 (MþHþ); HRMS (ESI): m/z calculated for
138.5,132.7, 129.0, 128.4, 126.2, 70.1, 50.9, 47.0, 42.4, 40.6, 37.9, 32.0,
C
12H20N4O3S2 þ Hþ (MþHþ): 333.1055. Found: 333.1044. Elemental
31.5, 14.7; ESI-MS: m/z 435 (MþHþ); HRMS (ESI): m/z calculated for
analysis (%) for C12H20N4O3S2: Calcd.: C, 43.35; H, 6.06; N, 16.85;
Found, C, 43.59; H, 6.35; N, 16.59.
C
20H26N4O3S2 þ Hþ (MþHþ): 435.1525. Found: 435.1517. Elemental
analysis (%) for C20H26N4O3S2: Calcd.: C, 55.28; H, 6.03; N, 12.89;
Found, C, 55.40; H, 6.40; N, 13.02.
4.1.22. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl 4-butylpiperazine-1-carbodithioate (23)
4.1.18. ( )e2-Hydroxy-3-(2-methyl-5-nitro-1H-imidazol-1-yl)
propyl azepane-1-carbodithioate (19)
The title compound (23) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.15 mmol) and so-
dium 4-butylpiperazine-1-carbodithioate (2.30 mmol) in 74% yield
The title compound (19) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 2.18 mmol) and so-
dium azepane-1-carbodithioate (4.37 mmol) in 76% yield as white
as white solid. mp: 73e75 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3109 1545,
8.01 (s, 1H),
5.60e5.58 (m, 1H), 4.51 (d/d, J ¼ 3.5 & 14.2 Hz, 1H), 4.25e4.19 (m,
1361, 1215, 1149; 1H NMR (400 MHz, DMSO-d6):
d
solid. mp: 114e116 ꢀC; IR (KBr)
n
(cmꢁ1): 3405, 3120, 2995, 1536,

832
D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
3H), 3.98e3.94 (m, 3H), 3.53 (d/d, J ¼ 4.8 & 13.7 Hz, 1H), 3.37 (q,
J ¼ 7.3 & 13.7 Hz, 1H), 2.45e2.43 (m, 7H), 2.30 (t, J ¼ 7.2 Hz, 2H),
1.46e1.38 (m, 2H), 1.34e1.25 (m, 2H), 0.88 (t, J ¼ 7.3 Hz, 3H); 13C
4.1.26. ( )e1-(2-Methyl-5-nitro-1H-imidazol-1-yl)-3-(4-
phenylpiperazin-1-yl)propan-2-ol (27)
The title compound (27) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.42 mmol) and 1-
phenylpiperazine (1.56 mmol) in 78% yield as white solid. mp:
(100 MHz, DMSO-d6):
d 195.0, 152.3, 138.9, 133.3, 68.6, 57.3, 52.6,
51.7, 50.9, 50.1, 41.3, 28.8, 20.4, 14.8, 14.3; ESI-MS: m/z 402 (MþHþ);
HRMS (ESI): m/z calculated for C15H23N5O5S2 þ Hþ (MþHþ):
402.1634. Found: 402.1625. Elemental analysis (%) for
78e80 ꢀC; IR (KBr)
NMR (400 MHz, CDCl3):
n
(cmꢁ1): 3400, 3115, 1570, 1541, 1361, 1146; 1H
d
7.96 (s, 1H), 7.30e7.26 (m, 2H), 6.94e6.87
C
15H23N5O5S2: Calcd.: C, 47.86; H, 6.78; N, 17.44; Found, C, 48.11; H,
(m, 3H), 4.63e4.60 (m, 1H), 4.11e4.07 (m, 2H), 3.36 (bs, 1H),
3.22e3.18 (m, 4H), 2.85e2.80 (m, 2H), 2.66e2.60 (m, 3H), 2.58 (s,
6.59; N, 17.12.
3H), 2.49e2.44 (m, 1H); 13C (100 MHz, CDCl3):
d 152.0, 151.0, 138.4,
133.1, 129.1, 120.0, 116.1, 66.7, 61.0, 53.3, 50.3, 49.1, 14.8; ESI-MS: m/z
345 (MþHþ); HRMS (ESI): m/z calculated for C17H23N5O3 þ Hþ
(MþHþ): 346.1879. Found: 346.1894. Elemental analysis (%) for
4.1.23. ( )etert-Butyl 4-((2-hydroxy-3-(2-methyl-5-nitro-1H-
imidazol-1-yl)propylthio)carbonothioyl)piperazine-1-carboxylate
(24)
C
17H23N5O3: Calcd.: C, 59.12; H, 6.71; N, 20.28; Found, C, 59.41; H,
The title compound (24) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.36 mmol) and so-
6.95; N, 20.00.
dium
(2.73 mmol) in 85% yield as white solid. mp: 83e85 ꢀC; IR (KBr)
(cmꢁ1): 3410, 3106, 1740, 1538, 1357, 1215, 1145; 1H NMR (400 MHz,
CDCl3): 7.86 (s, 1H), 4.68e4.61 (m, 1H), 4.24e4.09 (m, 4H),
4.01e3.95 (m, 3H), 3.75e3.70 (m, 1H), 3.63e3.56 (m, 5H), 2.51 (s,
3H), 1.47 (s, 9H); 13C (100 MHz, CDCl3):
196.7, 154.4, 151.7, 138.4,
4-(tert-butoxycarbonyl)piperazine-1-carbodithioate
n
4.1.27. ( )e1-(4-(2-Methoxyphenyl)piperazin-1-yl)-3-(2-methyl-
5-nitro-1H-imidazol-1-yl)propan-2-ol (28)
d
The title compound (28) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.74 mmol) and 1-(2-
methoxyphenyl)piperazine (1.91 mmol) in 74% yield as oil. IR (KBr)
d
132.6, 80.7, 70.0, 51.5, 50.8, 49.9, 42.3, 40.6, 28.3, 14.7; ESI-MS: m/z
446 (MþHþ); HRMS (ESI): m/z calculated for C17H27N5O5S2 þ Hþ
(MþHþ): 446.1532. Found: 446.1485. Elemental analysis (%) for
n
(cmꢁ1): 3400, 3120, 2995, 1562, 1546, 1360, 1153; 1H NMR
(400 MHz, CDCl3):
d
7.98 (s, 1H), 7.02 (d/d, J ¼ 4.5 & 7.9 Hz, 1H), 6.93
(d, J ¼ 4.0 Hz, 2H), 6.88 (d, J ¼ 7.9 Hz, 1H), 4.63e4.60 (m, 1H),
4.10e4.07 (m, 2H), 3.88 (s, 3H), 3.10e3.08 (m, 5H), 2.90e2.86 (m,
2H), 2.67e2.64 (m, 3H), 2.59 (s, 3H), 2.47e2.41 (m, 1H); 13C
C
17H27N5O5S2: Calcd.: C, 45.83; H, 6.11; N, 15.72; Found, C, 46.03; H,
6.44; N, 15.90.
(100 MHz, CDCl3):
d 152.1, 152.0, 140.9, 138.4, 133.1, 123.1, 120.9,
118.1, 111.2, 66.6, 61.0, 55.3, 53.4, 50.6, 50.4, 14.8; ESI-MS: m/z 376
(MþHþ); HRMS (ESI): m/z calculated for C18H25N5O4 þ Hþ (MþHþ):
376.1985. Found: 376.1984. Elemental analysis (%) for C18H25N5O4:
Calcd.: C, 57.59; H, 6.71; N, 18.65; Found, C, 57.70; H, 7.03; N, 18.53.
4.1.24. ( )eEthyl 4-(2-hydroxy-3-(2-methyl-5-nitro-1H-imidazol-
1-yl)propyl)piperazine-1-carboxylate (25)
To a solution of ( )e2-methyl-5-nitro-1-(oxiran-2-ylmethyl)-
1H-imidazole (3, 1.36 mmol) in acetonitrile (20 mL) was added
ethyl piperazine-1-carboxylate (1.50 mmol) and contents were
stirred at 80 ꢀC for overnight. Reaction progress was monitored by
TLC and after completion of the reaction acetonitrile was evapo-
rated. The crude obtained was extracted with EtOAc (20 mL), excess
water (50 mL) and organic layer was separated, dried (anhyd.
Na2SO4) and concentrated in vacuo to get the final compound (25)
4.1.28. ( )e1-(2-methyl-5-nitro-1H-imidazol-1-yl)-3-(4-(pyridin-
2-yl)piperazin-1-yl)propan-2-ol (29)
The title compound (29) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.42 mmol) and 1-
(pyridin-2-yl)piperazine (1.56 mmol) in 75% yield as white solid.
in 77% yield as semi solid. IR (KBr)
n
(cmꢁ1): 3400, 3110, 1742, 1543,
7.94 (s, 1H), 4.60 (d/d,
mp: 130e132 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3113, 1562, 1541, 1360,
1361, 1090; 1H NMR (400 MHz, CDCl3):
d
1151; 1H NMR (400 MHz, CDCl3):
d 8.21e8.19 (m, 1H), 7.99 (s, 1H),
J ¼ 6.4 & 18.12 Hz, 1H), 4.15e4.04 (m, 4H), 3.49e3.46 (m, 4H), 3.25
7.52e7.48 (m, 1H), 6.67e6.65 (m, 2H), 4.63e4.61 (m, 1H), 4.11e4.09
(m, 2H), 3.60e3.51 (m, 5H), 2.81e2.76 (m, 2H), 2.59e2.58 (m, 6H),
(bs, 1H), 2.62e2.53 (m, 6H), 2.43e2.40 (m, 3H), 1.26 (t, J ¼ 7.1 Hz,
3H); 13C (100 MHz, CDCl3):
d
155.4, 152.0, 138.4, 133.1, 66.8, 61.4,
2.45 (d/d, J ¼ 9.6 & 12.1 Hz,1H); 13C (100 MHz, CDCl3):
d 159.3,152.1,
61.1, 53.0, 50.2, 43.6, 14.7, 14.6; ESI-MS: m/z 341 (MþHþ); HRMS
(ESI): m/z calculated for C14H23N5O5 þ Hþ (MþHþ): 342.1777.
Found: 342.1770. Elemental analysis (%) for C14H23N5O5: Calcd.: C,
49.26; H, 6.79; N, 20.52; Found, C, 49.41; H, 7.02; N, 20.42.
The compounds 26e50 were synthesized using a procedure
similar to described for compound 25.
147.9, 138.3, 137.5, 133.1, 113.6, 107.2, 66.7, 61.1, 53.1, 50.3, 45.2, 14.8;
ESI-MS: m/z 347 (MþHþ); HRMS (ESI): m/z calculated for
C
16H22N6O3 þ Hþ (MþHþ): 347.1832. Found: 347.1824. Elemental
analysis (%) for C16H22N6O3: Calcd.: C, 55.48; H, 6.40; N, 24.26;
Found, C, 55.29; H, 6.78; N, 24.20.
4.1.29. ( )e1-(2-methyl-5-nitro-1H-imidazol-1-yl)-3-(4-
(pyrimidin-2-yl)piperazin-1-yl)propan-2-ol (30)
4.1.25. ( )e1-(4-Ethylpiperazin-1-yl)-3-(2-methyl-5-nitro-1H-
imidazol-1-yl)propan-2-ol (26)
The title compound (26) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 2.18 mmol) and 1-
The title compound (30) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.91 mmol) and 2-
(piperazin-1-yl)pyrimidine (2.10 mmol) in 79% yield as white solid.
ethylpiperazine (2.40 mmol) in 81% yield as semi solid. IR (KBr)
(cmꢁ1): 3400, 3115,1536,1361,1140; 1H NMR (400 MHz, DMSO-d6):
8.00 (s, 1H), 5.06e5.05 (m, 1H), 4.59 (d/d, J ¼ 2.8 & 14.1 Hz, 1H),
n
mp: 183e185 ꢀC; IR (KBr)
n
(cmꢁ1): 3401, 3110, 1565, 1550, 1355,
1150; 1H NMR (400 MHz, CDCl3):
d
8.31 (d, J ¼ 4.7 Hz, 2H), 7.97 (s,
d
1H), 6.51 (t, J ¼ 4.7 Hz, 1H), 4.63e4.60 (m, 1H), 4.10e4.07 (m, 2H),
4.05 (d/d, J ¼ 9.3 & 14.1 Hz, 1H), 3.90 (bs, 1H), 2.50e2.26 (m, 15H),
3.85e3.81 (m, 5H), 2.74e2.69 (m, 2H), 2.62e2.41 (m, 7H); 13C
0.98 (t, J ¼ 7.1 Hz, 3H); 13C (100 MHz, DMSO-d6):
d
152.6, 138.9,
(100 MHz, CDCl3): d 161.6, 157.7, 152.0, 138.4, 133.2, 110.1, 66.7, 61.0,
133.3, 67.1, 62.7, 53.9, 52.8, 52.1, 51.0, 14.8, 12.4; ESI-MS: m/z 298
(MþHþ); HRMS (ESI): m/z calculated for C13H23N5O3 þ Hþ (MþHþ):
298.1879. Found: 298.1898. Elemental analysis (%) for C13H23N5O3:
Calcd.: C, 52.51; H, 7.80; N, 23.55; Found, C, 52.79; H, 8.11; N, 23.19.
53.1, 50.2, 43.6, 14.8; ESI-MS: m/z 348 (MþHþ); HRMS (ESI): m/z
calculated for
C
15H21N7O3
þ
Hþ (MþHþ): 348.1784. Found:
348.1784. Elemental analysis (%) for C15H21N7O3: Calcd.: C, 51.86; H,
6.09; N, 28.23; Found, C, 52.06; H, 5.89; N, 28.53.

D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
833
4.1.30. ( )e1-(4-(2-Fluorophenyl)piperazin-1-yl)-3-(2-methyl-5-
nitro-1H-imidazol-1-yl)propan-2-ol (31)
4.1.34. ( )e1-(2-methyl-5-nitro-1H-imidazol-1-yl)-3-
morpholinopropan-2-ol (35)
The title compound (31) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.64 mmol) and 1-(2-
fluorophenyl)piperazine (1.80 mmol) in 71% yield as light yellow
The title compound (35) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.36 mmol) and
morpholine (1.50 mmol) in 76% yield as white solid. mp:
solid. mp: 73e75 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3111, 1563, 1551, 1362,
116e118 ꢀC; IR (KBr)
NMR (400 MHz, CDCl3): d 7.98 (s, 1H), 4.62e4.59 (m, 1H), 4.09e4.05
n
(cmꢁ1): 3400, 3120, 1550, 1350, 1104; 1H
1150; 1H NMR (400 MHz, CDCl3):
d
7.96 (s, 1H), 7.08e7.02 (m, 2H),
6.97e6.92 (m, 2H), 4.64e4.59 (m, 1H), 4.11e4.05 (m, 2H), 3.13e3.05
(m, 5H), 2.86e2.81 (m, 2H), 2.67e2.62 (m, 3H), 2.58 (s, 3H),
(m, 2H), 3.73e3.71 (m, 4H), 3.50e3.41 (m, 1H), 2.68e2.63 (m, 2H),
2.58 (bs, 4H), 2.49e2.45 (m, 2H), 2.40e2.34 (m, 1H); 13C (100 MHz,
2.48e2.42 (m, 1H); 13C (100 MHz, CDCl3):
d
156.9, 154.4, 152.0,
CDCl3): d 152.0, 138.3, 133.0, 66.8, 66.6, 61.6, 53.7, 50.3, 14.7; ESI-
139.8, 138.4, 133.1, 124.4, 122.7, 118.9, 116.2, 116.0, 66.7, 61.0, 53.3,
50.5, 46.1, 14.8; ESI-MS: m/z 364 (MþHþ); HRMS (ESI): m/z calcu-
lated for C17H22FN5O3 þ Hþ (MþHþ): 364.1785. Found: 364.1784.
Elemental analysis (%) for C17H22FN5O3: Calcd.: C, 56.19; H, 6.10; N,
19.27; Found, C, 56.01; H, 6.41; N, 19.60.
MS: m/z 271 (MþHþ); HRMS (ESI): m/z calculated for
C
11H18N4O4 þ Hþ (MþHþ): 271.1406. Found: 271.1404. Elemental
analysis (%) for C11H18N4O4: Calcd.: C, 48.88; H, 6.71; N, 20.73;
Found, C, 48.97; H, 6.99; N, 20.79.
4.1.35. ( )e1-(2-methyl-5-nitro-1H-imidazol-1-yl)-3-(piperidin-
1-yl)propan-2-ol (36)
4.1.31. ( )e1-(4-(3-Chlorophenyl)piperazin-1-yl)-3-(2-methyl-5-
nitro-1H-imidazol-1-yl)propan-2-ol (32)
The title compound (32) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.64 mmol) and 1-(3-
The title compound (36) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.91 mmol) and
piperidine (2.10 mmol) in 80% yield as white solid. mp: 115e117 ꢀC;
IR (KBr)
(400 MHz, CDCl3):
2H), 2.55 (bs, 5H), 2.47 (d/d, J ¼ 3.4 & 12.2 Hz, 1H), 2.33e2.25 (m,
n
(cmꢁ1): 3400, 3124, 3011, 1540, 1365, 1132; 1H NMR
chlorophenyl)piperazine (1.80 mmol) in 82% yield as oily. IR (KBr)
(cmꢁ1): 3400, 3114, 1560, 1553, 1363, 1154, 780; 1H NMR (400 MHz,
CDCl3):
7.94 (s, 1H), 7.16 (t, J ¼ 8.1 Hz, 1H), 6.87e6.76 (m, 3H),
4.63e4.60 (m, 1H), 4.08e4.05 (m, 2H), 3.20e3.14 (m, 4H), 3.03 (bs,
1H), 2.80e2.75 (m, 2H), 2.62e2.57 (m, 5H), 2.46e2.43 (m, 1H); 13
(100 MHz, CDCl3): 152.6, 152.0, 138.4, 134.9, 133.1, 130.0, 119.5,
n
d 7.93 (s, 1H), 4.56e4.53 (m, 1H), 4.05e3.98 (m,
d
3H), 1.55e1.41 (m, 6H); 13C (100 MHz, CDCl3):
d 152.0, 138.4, 133.0,
66.5, 61.6, 54.6, 50.5, 25.9, 24.0, 14.7; ESI-MS: m/z 269 (MþHþ);
HRMS (ESI): m/z calculated for C12H20N4O3 þ Hþ (MþHþ): 269.1614.
Found: 269.1598. Elemental analysis (%) for C12H20N4O3: Calcd.: C,
53.72; H, 7.51; N, 20.88; Found, C, 53.44; H, 7.87; N, 20.98.
C
d
115.8, 113.9, 66.8, 61.0, 53.1, 50.3, 48.7, 14.7; ESI-MS: m/z 380
(MþHþ); HRMS (ESI): m/z calculated for C17H22ClN5O3 þ Hþ
(MþHþ): 380.1489. Found: 380.1480. Elemental analysis (%) for
4.1.36. ( )e1-(2-methyl-5-nitro-1H-imidazol-1-yl)-3-(3-
methylpiperidin-1-yl)propan-2-ol (37)
C
17H22ClN5O3: Calcd.: C, 53.75; H, 5.84; N, 18.44; Found, C, 53.51; H,
6.11; N, 18.63.
The title compound (37) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.69 mmol) and 3-
methylpiperidine (1.86 mmol) in 74% yield as oil. IR (KBr)
(cmꢁ1): 3400, 3121, 2995, 1541, 1362, 1140; 1H NMR (400 MHz,
CDCl3): 7.97 (s, 1H), 4.58e4.55 (m, 1H), 4.06e4.00 (m, 2H),
n
4.1.32. ( )e1-(4-(2,3-Dichlorophenyl)piperazin-1-yl)-3-(2-methyl-
5-nitro-1H-imidazol-1-yl)propan-2-ol (33)
d
The title compound (33) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.36 mmol) and 1-
(2,3-dichlorophenyl)piperazine (1.50 mmol) in 79% yield as semi
2.86e2.79 (m, 1H), 2.69e2.66 (m, 1H), 2.58 (s, 3H), 2.52e2.47 (m,
1H), 2.31e2.25 (m, 2H), 1.96e1.92 (m, 1H), 1.68e1.57 (m, 5H),
0.93e0.85 (m, 4H); 13C (100 MHz, CDCl3):
d 152.0, 138.4, 133.1, 66.6,
solid. IR (KBr)
n
(cmꢁ1): 3400, 3120, 1594, 1546, 1366, 780; 1H NMR
66.5, 61.4, 61.2, 60.5, 55.5, 50.4, 32.6, 31.1, 25.5, 19.4, 14.7; ESI-MS:
(400 MHz, CDCl3):
d
7.95 (s, 1H), 7.18e7.13 (m, 2H), 6.95e6.93 (m,
m/z 283 (MþHþ); HRMS (ESI): m/z calculated for
1H), 4.65e4.59 (m, 1H), 4.09e4.06 (m, 2H), 3.76e3.75 (m, 1H),
3.05e3.00 (m, 5H), 2.86e2.81 (m, 2H), 2.67e2.63 (m, 2H), 2.57 (s,
C
13H22N4O3 þ Hþ (MþHþ): 283.1770. Found: 283.1757. Elemental
analysis (%) for C13H22N4O3: Calcd.: C, 55.30; H, 7.85; N, 19.84;
Found, C, 55.49; H, 8.14; N, 19.97.
3H), 2.49e2.41 (m, 1H); 13C (100 MHz, CDCl3):
d 152.0, 150.9, 138.4,
134.0,133.1,127.4,124.7,124.5,118.5, 66.7, 61.0, 53.3, 51.3, 50.3,14.8;
ESI-MS: m/z 414 (MþHþ); HRMS (ESI): m/z calculated for
4.1.37. ( )e1-(2-methyl-5-nitro-1H-imidazol-1-yl)-3-(4-
methylpiperidin-1-yl)propan-2-ol (38)
The title compound (38) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.91 mmol) and 4-
C
17H21Cl2N5O3 þ Hþ (MþHþ): 414.1100. Found: 414.1082. Elemental
analysis (%) for C17H21Cl2N5O3: Calcd.: C, 49.29; H, 5.11; N, 16.90;
Found, C, 49.47; H, 5.34; N, 16.66.
methylpiperidine (2.10 mmol) in 73% yield as oil. IR (KBr)
(cmꢁ1): 3400, 3110, 2990, 1544, 1365, 1150; 1H NMR (400 MHz,
CDCl3): 7.97 (s, 1H), 4.58e4.54 (m, 1H), 4.08e3.99 (m, 2H),
n
4.1.33. ( )e1-(2-methyl-5-nitro-1H-imidazol-1-yl)-3-(pyrrolidin-
1-yl)propan-2-ol (34)
d
2.91e2.89 (m, 1H), 2.77e2.74 (m, 1H), 2.58 (s, 3H), 2.54e2.49 (m,
2H), 2.35e2.28 (m, 2H), 2.02e1.96 (m, 1H), 1.65e1.63 (m, 2H),
1.41e1.36 (m, 1H), 1.27e1.25 (m, 1H), 1.15e1.12 (m, 1H), 0.93 (t,
The title compound (34) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.64 mmol) and pyr-
rolidine (1.80 mmol) in 83% yield as white solid. mp: 86e88 ꢀC; IR
J ¼ 6.5 Hz, 3H); 13C (100 MHz, CDCl3):
d 152.0, 138.3, 133.1, 66.6,
(KBr)
n
(cmꢁ1): 3400, 3124, 1546, 1361, 1130; 1H NMR (400 MHz,
61.3, 55.6, 52.6, 50.5, 34.1, 30.5, 21.7, 14.7; ESI-MS: m/z 283 (MþHþ);
CDCl3):
d
7.98 (s, 1H), 4.58 (d/d, J ¼ 2.2 & 14.0 Hz, 1H), 4.08 (d/d,
HRMS (ESI): m/z calculated for
C13H22N4O3
þ
Hþ (MþHþ):
J ¼ 8.3 & 14.0 Hz, 1H), 4.01e3.96 (m, 1H), 2.69e2.65 (m, 3H), 2.58 (s,
283.1770. Found: 283.1762. Elemental analysis (%) for C13H22N4O3:
Calcd.: C, 55.30; H, 7.85; N, 19.84; Found, C, 55.49; H, 8.13; N, 20.07.
3H), 2.54e2.50 (m, 3H), 1.80e1.77 (m, 4H); 13C (100 MHz, CDCl3):
d
152.0, 138.4, 133.1, 68.4, 59.2, 54.1, 50.4, 23.5, 14.7; ESI-MS: m/z
255 (MþHþ); HRMS (ESI): m/z calculated for C11H18N4O3 þ Hþ
4.1.38. ( )e1-(4-Benzylpiperidin-1-yl)-3-(2-methyl-5-nitro-1H-
imidazol-1-yl)propan-2-ol (39)
(MþHþ): 255.1457. Found: 255.1444. Elemental analysis (%) for
C
11H18N4O3: Calcd.: C, 51.96; H, 7.13; N, 22.03; Found, C, 52.09; H,
The title compound (39) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.42 mmol) and 4-
7.46; N, 22.21.

834
D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
benzylpiperidine (1.56 mmol) in 68% yield as white solid. mp:
134e136 ꢀC; IR (KBr) (cmꢁ1): 3400, 3115, 2998, 1545, 1360, 1150;
1H NMR (400 MHz, CDCl3):
7.98 (s, 1H), 7.31e7.27 (m, 2H),
7.22e7.19 (m, 1H), 7.16e7.14 (m, 2H), 4.56 (d/d, J ¼ 1.6 & 13.5 Hz,
1H); 4.08e3.99 (m, 2H), 2.92e2.89 (m, 1H), 2.78e2.76 (m, 1H),
2.58e2.49 (m, 7H), 2.33e2.26 (m, 2H), 1.99e1.92 (m, 1H), 1.68e1.67
(m, 2H),1.64e1.57 (m,1H),1.31e1.20 (m, 2H); 13C (100 MHz, CDCl3):
1H), 4.00e3.95 (m, 1H), 3.85e3.83 (m, 1H), 2.71 (d/d, J ¼ 4.6 &
14.3 Hz, 1H), 2.58e2.50 (m, 5H), 2.48e2.46 (m, 1H), 1.69e1.27 (m,
6H), 1.17e1.06 (m, 7H); ESI-MS: m/z 297 (MþHþ); HRMS (ESI): m/z
n
d
calculated for
C
14H24N4O3
þ
Hþ (MþHþ): 297.1927. Found:
297.1915. Elemental analysis (%) for C14H24N4O3: Calcd.: C, 56.74; H,
8.16; N, 18.90; Found, C, 56.37; H, 8.45; N, 19.09.
d
152.0, 140.4, 138.4, 133.2, 129.0, 128.2, 125.8, 66.6, 61.1, 55.5, 52.4,
4.1.43. ( )e1-(2-methyl-5-nitro-1H-imidazol-1-yl)-3-(4-nitro-1H-
imidazol-1-yl)propan-2-ol (44)
The title compound (44) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.64 mmol) and 4-
nitro-1H-imidazole (1.80 mmol) in 42% yield as yellow solid. mp:
50.4, 43.0, 37.6, 32.3, 32.1, 14.8; ESI-MS: m/z 359 (MþHþ); HRMS
(ESI): m/z calculated for C19H26N4O3 þ Hþ (MþHþ): 359.2083.
Found: 359.2080. Elemental analysis (%) for C19H26N4O3: Calcd.: C,
63.67; H, 7.31; N, 15.63; Found, C, 63.81; H, 7.53; N, 15.50.
113e115 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3110, 2996, 1542, 1362, 1150;
4.1.39. ( )e1-(Azepan-1-yl)-3-(2-methyl-5-nitro-1H-imidazol-1-
yl)propan-2-ol (40)
The title compound (40) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.74 mmol) and aze-
pane (1.92 mmol) in 80% yield as white solid. mp: 92e94 ꢀC; IR
1H NMR (400 MHz, CDCl3þDMSO-d6):
d 7.89 (s, 1H), 7.76 (s, 1H),
7.45 (s, 1H), 5.63e5.62 (m, 1H), 4.47e4.44 (m, 1H), 4.47e4.44 (m,
1H), 4.13e3.82 (m, 4H), 2.32 (s, 3H); ESI-MS: m/z 297 (MþHþ);
HRMS (ESI): m/z calculated for C10H12N6O5 þ Hþ (MþHþ): 297.0947.
Found: 297.0964. Elemental analysis (%) for C10H12N6O5: Calcd.: C,
40.54; H, 4.08; N, 28.37; Found, C, 40.62; H, 4.38; N, 28.17.
(KBr)
(400 MHz, CDCl3):
n
(cmꢁ1): 3400, 3122, 3011, 1542, 1364, 1147; 1H NMR
d
7.98 (s, 1H), 4.56 (d/d, J ¼ 2.1 & 14.0 Hz, 1H);
4.04 (d/d, J ¼ 8.2 & 14.0 Hz, 1H); 3.93e3.88 (m, 1H), 2.82e2.73 (m,
4.1.44. ( )e1-(2-methyl-4-nitro-1H-imidazol-1-yl)-3-(2-methyl-
5-nitro-1H-imidazol-1-yl)propan-2-ol (45)
3H), 2.66e2.61 (m, 2H), 2.59 (s, 3H), 2.35e2.30 (m, 1H), 1.70e1.61
(m, 8H); 13C (100 MHz, CDCl3):
d
152.0, 138.3, 133.1, 67.3, 60.8, 55.7,
The title compound (45) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.91 mmol) and 2-
methyl-4-nitro-1H-imidazole (2.10 mmol) in 52% yield as light
50.4, 28.4, 26.8, 14.8; ESI-MS: m/z 283 (MþHþ); HRMS (ESI): m/z
calculated for
C
13H22N4O3
þ
Hþ (MþHþ): 283.1770. Found:
283.1764. Elemental analysis (%) for C13H22N4O3: Calcd.: C, 55.30; H,
7.85; N, 19.84; Found, C, 55.04; H, 8.11; N, 19.55.
yellow solid. mp: 190e192 ꢀC; IR (KBr) (cmꢁ1): 3400, 3110, 2993,
n
1540, 1361, 1150; 1H NMR (400 MHz, CDCl3þDMSO-d6):
d 8.19 (s,
1H), 7.92 (s, 1H), 5.61e5.59 (m, 1H), 4.48e4.44 (m, 1H), 4.19e4.10
4.1.40. ( )e1-(4-(Furan-2-yl)piperazin-1-yl)-3-(2-methyl-5-nitro-
1H-imidazol-1-yl)propan-2-ol (41)
The title compound (41) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.36 mmol) and 1-
(furan-2-yl)piperazine (1.50 mmol) in 82% yield as semi solid. IR
(m, 2H), 4.01e3.96 (m, 2H), 2.46e2.41 (m, 3H), 2.35 (s, 3H); 13C
(100 MHz, CDCl3þDMSO-d6):
d 157.1, 150.6,150.5,143.6,137.9, 127.7,
73.9, 55.1, 54.2, 19.5, 18.0; ESI-MS: m/z 311 (MþHþ); HRMS (ESI): m/
z calculated for C11H14N6O5 þ Hþ (MþHþ): 311.1104. Found:
311.1095. Elemental analysis (%) for C11H14N6O5: Calcd.: C, 42.58; H,
4.55; N, 27.09; Found, C, 42.58; H, 4.55; N, 27.09.
(KBr)
CDCl3):
n
(cmꢁ1): 3400, 3121, 2995, 1550, 1360; 1H NMR (400 MHz,
d
7.91 (s, 1H), 7.47 (d, J ¼ 0.8 Hz, 1H), 6.97 (d, J ¼ 3.5 Hz, 1H),
6.48e6.46 (m, 1H), 4.65e4.62 (m, 1H), 4.11e4.00 (m, 2H), 3.78 (bs,
4.1.45. ( )e1-(2-methyl-5-nitro-1H-imidazol-1-yl)-3-(1H-1,2,3-
triazol-1-yl)propan-2-ol (46)
4H), 2.69e2.64 (m, 2H), 2.57e2.43 (m, 8H); 13C (100 MHz, CDCl3):
d
159.0, 152.0, 147.6, 143.8, 138.4, 133.0, 116.6, 111.3, 66.9, 61.2, 53.4,
Into a solution of ( )e2-methyl-5-nitro-1-(oxiran-2-ylmethyl)-
1H-imidazole (3, 1.91 mmol) in acetonitrile was added 1H-1,2,3-
triazole (2.10 mmol) and stirred the contents for 14 h. After
completion of the reaction, acetonitrile was evaporated and the
crude obtained was separated through column chromatography
using MeOH/CHCl3 as eluent and the final compound (46) came out
as first spot from column in 40% yield as white solid. mp:
50.4, 43.6,14.7; ESI-MS: m/z 335 (MþHþ); Elemental analysis (%) for
C
15H21N5O4: Calcd.: C, 53.72; H, 6.31; N, 20.88; Found, C, 53.60; H,
6.00; N, 20.51.
4.1.41. ( )e1-(2-methyl-5-nitro-1H-imidazol-1-yl)-3-(2-
methylpiperidin-1-yl)propan-2-ol (42)
The title compound (42) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 2.18 mmol) and 2-
methylpiperidine (2.39 mmol) in 60% yield as white solid. mp:
127e129 ꢀC; IR (KBr)
1150; 1H NMR (400 MHz, CDCl3):
1H), 4.98 (s, 1H), 4.69e4.65 (m, 2H), 4.53e4.50 (m, 2H), 4.11e4.05
n
(cmꢁ1): 3400, 3114, 2995, 1542, 1360, 1268,
7.82 (s, 1H), 7.74 (s, 1H), 7.65 (s,
d
85e87 ꢀC; IR (KBr)
NMR (400 MHz, CDCl3):
n
(cmꢁ1): 3400, 3110, 2995, 1544, 1364, 1150; 1H
(m, 1H), 2.45 (s, 3H); 13C (100 MHz, DMSO-d6):
d 152.5, 138.9, 133.5,
d
7.95 (s, 1H), 4.58e4.52 (m, 1H), 4.12e3.94
133.3, 126.2, 68.8, 53.1, 49.6, 14.7; ESI-MS: m/z 253 (MþHþ); HRMS
(ESI): m/z calculated for C9H12N6O3 þ Hþ (MþHþ): 253.1049.
Found: 253.1041. Elemental analysis (%) for C9H12N6O3: Calcd.: C,
42.86; H, 4.80; N, 33.32; Found, C, 42.72; H, 5.05; N, 33.11.
(m, 2H), 2.81e2.77 (m, 1H), 2.68e2.63 (m, 1H), 2.57 (s, 3H),
2.32e2.20 (m, 2H), 2.17e2.14 (m, 1H), 1.65e1.26 (m, 7H), 1.04e1.03
(m, 3H); 13C (100 MHz, CDCl3):
d 152.0, 138.4, 133.1, 68.0, 66.5, 57.7,
56.9, 55.5, 52.3, 50.7, 34.6, 33.1, 23.6, 21.6, 16.2, 14.7; ESI-MS: m/z
283 (MþHþ); HRMS (ESI): m/z calculated for C13H22N4O3 þ Hþ
(MþHþ): 283.1770. Found: 283.1761. Elemental analysis (%) for
4.1.46. ( )e1-(2-methyl-5-nitro-1H-imidazol-1-yl)-3-(1H-1,2,4-
triazol-1-yl)propan-2-ol (47)
C
13H22N4O3: Calcd.: C, 55.30; H, 7.85; N, 19.84; Found, C, 55.65; H,
The title compound (47) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.91 mmol) and 1H-
1,2,4-triazole (2.10 mmol) in 53% yield as white solid. mp:
7.47; N, 20.04.
4.1.42. ( )e1-(2,6-Dimethylpiperidin-1-yl)-3-(2-methyl-5-nitro-
1H-imidazol-1-yl)propan-2-ol (43)
140e142 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3120, 3011, 1545, 1360, 1268,
1150; 1H NMR (400 MHz, CDCl3):
d
8.14 (s, 1H), 7.88 (s, 1H), 7.84 (s,
The title compound (43) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.80 mmol) and 2,6-
dimethylpiperidine (1.98 mmol) in 40% yield as white solid. mp:
1H), 5.12 (bs, 1H), 4.68 (d/d, J ¼ 2.5 & 14.1 Hz, 1H), 4.57 (d/d, J ¼ 3.0
& 13.6 Hz,1H), 4.39e4.37 (m,1H), 4.28 (Q, J ¼ 7.1 &13.6 Hz,1H), 4.12
(d/d, J ¼ 9.1 & 14.1 Hz, 1H), 2.46 (s, 3H); 13C (100 MHz,
124e126 ꢀC; IR (KBr)
NMR (400 MHz, CDCl3):
n
(cmꢁ1): 3400, 3110, 1541, 1362, 1150; 1H
CDCl3þDMSO-d6):
d 151.9, 151.4, 144.5, 138.3, 132.7, 68.2, 52.8, 49.4,
d
7.97 (s, 1H), 4.54 (d/d, J ¼ 2.0 & 14.0 Hz,
14.4; ESI-MS: m/z 253 (MþHþ); HRMS (ESI): m/z calculated for

D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
835
C9H12N6O3 þ Hþ (MþHþ): 253.1049. Found: 253.1044. Elemental
4.1.51. ( )e2-methyl-4-nitro-1-(oxiran-2-ylmethyl)-1H-imidazole
(52)
analysis (%) for C9H12N6O3: Calcd.: C, 42.86; H, 4.80; N, 33.32;
Found, C, 42.99; H, 5.18; N, 33.61.
The title compound (52) was synthesized by dissolving com-
pound 51 (27.39 mmol) in dichlorometane (10 mL) and added
27.39 mmol of aqueous NaOH at 0 ꢀC. Stirred the contents for
45 min and after completion of reaction (as monitored by TLC)
contents was extracted with DCM/water and organic layer was
separated, dried (anhyd. Na2SO4), concentrated in vacuo to get the
final compound (52) in 86% yield as white solid. mp: 94e96 ꢀC; IR
4.1.47. ( )e1-(2-methyl-5-nitro-1H-imidazol-1-yl)-3-(2H-1,2,3-
triazol-2-yl)propan-2-ol (48)
The title compound was obtained through
a procedure
described for the synthesis of compound (46) and the final com-
pound (48) came out as second spot from column in 35% yield as
(KBr)
CDCl3):
n
(cmꢁ1): 3402, 3110, 1540, 1361, 1155; 1H NMR (400 MHz,
white solid. mp: 113e115 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3120, 2998,
1543, 1365, 1144; 1H NMR (400 MHz, CDCl3):
d 7.93 (s, 1H), 7.70 (s,
d
7.78 (s, 1H), 4.40 (d/d, J ¼ 2.4 & 15.1 Hz, 1H), 3.89 (d/d,
J ¼ 6.2 & 15.1 Hz,1H), 3.29e3.25 (m, 1H), 2.90 (t, J ¼ 4.1 Hz,1H), 2.53
2H), 4.75 (d/d, J ¼ 3.9 & 13.8 Hz, 1H), 4.68e4.59 (m, 2H), 4.51 (bs,
(d/d, J ¼ 2.5 & 4.4 Hz, 1H), 2.44 (s, 3H); 13C (100 MHz, CDCl3):
1H), 4.14 (d/d, J ¼ 9.1 & 14.2 Hz, 1H), 3.90 (bs, 1H), 2.49 (s, 3H); 13
C
d
146.5, 145.2,120.3, 49.9, 48.5, 44.9, 13.0; ESI-MS: m/z 184 (MþHþ).
The compounds 53e61 were synthesized using a procedure
(100 MHz, CDCl3þDMSO-d6):
d 156.8, 143.2, 139.2, 137.5, 73.8, 62.6,
54.6, 19.3; ESI-MS: m/z 253 (MþHþ); HRMS (ESI): m/z calculated for
C9H12N6O3 þ Hþ (MþHþ): 253.1049. Found: 253.1047. Elemental
analysis (%) for C9H12N6O3: Calcd.: C, 42.86; H, 4.80; N, 33.32;
Found, C, 42.99; H, 5.18; N, 33.61.
similar to described for compound 4.
4.1.52. ( )e2-Hydroxy-3-(2-methyl-4-nitro-1H-imidazol-1-yl)
propyl 4-(2,3-dichlorophenyl)piperazine-1-carbodithioate (53)
The title compound (53) was synthesized from ( )e2-methyl-4-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (52, 1.36 mmol) and
4.1.48. ( )e1-(1H-Benzo[d]imidazol-1-yl)-3-(2-methyl-5-nitro-
1H-imidazol-1-yl)propan-2-ol (49)
sodium
(2.73 mmol) in 84% yield as white solid. mp: 180e182 ꢀC; IR
(KBr)
(cmꢁ1): 3400, 3115, 1590, 1541, 1370, 1215, 780; 1H NMR
(400 MHz, DMSO-d6): 8.24 (s, 1H), 7.36e7.31 (m, 2H), 7.18 (d/d,
4-(2,3-dichlorophenyl)piperazine-1-carbodithioate
The title compound (49) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.91 mmol) and 1H-
benzo[d]imidazole (2.10 mmol) in 83% yield as white solid. mp:
n
d
198e200 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3124, 1620, 1543, 1360, 1260,
J ¼ 2.4 & 7.1 Hz, 1H), 5.66e5.65 (m, 1H), 4.40e4.13 (m, 5H),
4.06e3.96 (m, 2H), 3.56 (d/d, J ¼ 3.8 & 13.5 Hz, 1H), 3.36e3.34 (m,
1H), 3.12e3.09 (m, 4H), 2.37 (s, 3H); 13C (100 MHz, DMSO-d6):
1150; 1H NMR (400 MHz, DMSO-d6):
d
8.19 (s, 1H), 8.01 (s, 1H), 7.63
(d/d, J ¼ 7.9 & 15.3 Hz, 2H), 7.30e7.19 (m, 2H), 5.59e5.58 (m, 1H),
4.56e4.46 (m, 2H), 4.32e4.16 (m, 3H), 2.43 (s, 3H); 13C (100 MHz,
d
196.0, 150.5, 145.9, 145.6, 133.1, 128.9, 126.6, 125.5, 123.3, 120.4,
DMSO-d6):
d 152.5, 145.0, 143.7, 138.9, 134.5, 133.4, 122.7, 121.9,
68.6, 51.9, 50.9, 41.5, 13.3; ESI-MS: m/z 490 (MþHþ); HRMS (ESI): m/
z calculated for C18H21Cl2N5O3S2 þ Hþ (MþHþ): 490.0541. Found:
490.0555. Elemental analysis (%) for C18H21Cl2N5O3S2: Calcd.: C,
44.08; H, 4.32; N, 14.28; Found, C, 44.15; H, 4.21; N, 14.50.
119.8, 110.8, 68.8, 49.8, 48.4, 14.7; ESI-MS: m/z 302 (MþHþ); HRMS
(ESI): m/z calculated for C14H15N5O3 þ Hþ (MþHþ): 302.1253.
Found: 302.1251. Elemental analysis (%) for C14H15N5O3: Calcd.: C,
55.81; H, 5.02; N, 23.24; Found, C, 55.56; H, 5.39; N, 23.09.
4.1.53. ( )e2-Hydroxy-3-(2-methyl-4-nitro-1H-imidazol-1-yl)
propyl 4-ethylpiperazine-1-carbodithioate (54)
4.1.49. ( )e1-(1H-Benzo[d][1,2,3]triazol-1-yl)-3-(2-methyl-5-
nitro-1H-imidazol-1-yl)propan-2-ol (50)
The title compound (54) was synthesized from ( )e2-methyl-4-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (52, 1.64 mmol) and
sodium 4-ethylpiperazine-1-carbodithioate (3.27 mmol) in 72%
The title compound (50) was synthesized from ( )e2-methyl-5-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (3, 1.91 mmol) and 1H-
benzo[d][1,2,3]triazole (2.10 mmol) in 85% yield as white solid. mp:
yield as white solid. mp: 101e103 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3020,
8.22 (s, 1H),
173e175 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3120, 1620, 1540, 1362, 1260,
1544,1360, 1215, 1125; 1H NMR (400 MHz, DMSO-d6):
d
1146; 1H NMR (400 MHz, DMSO-d6):
d
8.05e8.03 (m, 2H),
5.64e5.63 (m, 1H), 4.23e4.16 (m, 3H), 3.99e3.94 (m, 4H),
3.55e3.51 (m, 1H), 3.33e3.28 (m, 1H), 2.46e2.43 (m, 4H),
2.37e2.36 (m, 5H), 1.01 (t, J ¼ 7.1 Hz, 3H); 13C (100 MHz, DMSO-d6):
7.88e7.86 (m, 1H), 7.59e7.55 (m, 1H), 7.43e7.39 (m, 1H), 4.93 (d/d,
J ¼ 4.1 & 14.3 Hz, 1H), 4.84e4.79 (m, 1H), 4.62e4.57 (m, 1H),
4.34e4.25 (m, 2H), 2.44 (s, 3H); 13C (100 MHz, DMSO-d6):
d 152.5,
d
195.1, 145.8, 145.6, 123.3, 68.6, 52.2, 51.9, 51.4, 50.2, 41.4, 13.3, 12.3;
ESI-MS: m/z 374 (MþHþ); HRMS (ESI): m/z calculated for
145.5, 138.8, 134.1, 133.1, 127.6, 124.3, 119.4, 111.4, 69.3, 51.6, 49.8,
14.7; ESI-MS: m/z 303 (MþHþ); HRMS (ESI): m/z calculated for
C
14H23N5O3S2 þ Hþ (MþHþ): 374.1321. Found: 374.1317. Elemental
C
13H14N6O3 þ Hþ (MþHþ): 303.1206. Found: 303.1194. Elemental
analysis (%) for C14H23N5O3S2: Calcd.: C, 45.02; H, 6.21; N, 18.75;
Found, C, 44.69; H, 6.54; N, 18.48.
analysis (%) for C13H14N6O3: Calcd.: C, 51.65; H, 4.67; N, 27.80;
Found, C, 51.81; H, 4.85; N, 27.97.
4.1.54. ( )e2-Hydroxy-3-(2-methyl-4-nitro-1H-imidazol-1-yl)
propyl 4-butylpiperazine-1-carbodithioate (55)
4.1.50. ( )e1-Chloro-3-(2-methyl-4-nitro-1H-imidazol-1-yl)
propan-2-ol (51)
The title compound (55) was synthesized from ( )e2-methyl-4-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (52, 1.64 mmol) and
sodium 4-butylpiperazine-1-carbodithioate (3.27 mmol) in 82%
Into
a
mixture
of
2-methyl-(4/5-nitro-1H-imidazole
(39.37 mmol) and potassium carbonate (3.93 mmol) was added
excess ( )-epichlorohydrin (20 mL) at rt. The reaction mixture was
refluxed at 110e115 ꢀC with stirring for 15 min. Then the reaction
mixture cooled to rt, poured over crushed ice in a beaker, and
stirred vigorously. Solid precipitated out and water was decanted.
Solid compound 51 was filtered off and recrystallized from ethanol
yield as white solid. mp: 83e85 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3100
8.22 (s, 1H),
1540, 1364, 1215, 1152; 1H NMR (400 MHz, DMSO-d6):
d
5.63e5.62 (m, 1H), 4.22e4.15 (m, 3H), 3.99e3.94 (m, 4H), 3.52 (d/d,
J ¼ 4.0 & 13.5 Hz,1H), 3.32e3.27 (m, 1H), 2.45e2.42 (m, 4H), 2.36 (s,
3H), 2.32e2.28 (m, 2H), 1.45e1.38 (m, 2H), 1.34e1.25 (m, 2H), 0.88
in 60% yield as white solid. mp: 154e156 ꢀC; IR (KBr)
3400, 3110, 1542, 1360, 1150, 775; 1H NMR (400 MHz, DMSO-d6):
8.21 (s, 1H), 5.78 (s, 1H), 4.17e4.14 (m, 1H), 3.98e3.93 (m, 2H),
n
(cmꢁ1):
(t, J ¼ 7.3 Hz, 3H); 13C (100 MHz, DMSO-d6):
d 195.1, 145.8, 145.6,
123.2, 68.6, 57.3, 52.6, 51.9, 50.2, 41.4, 28.8, 20.4, 14.3, 13.3; ESI-MS:
d
m/z 402 (MþHþ); HRMS (ESI): m/z calculated for
3.68e3.58 (m, 2H), 2.36 (s, 3H); 13C (100 MHz, DMSO-d6):
d
146.1,
C
16H27N5O3S2 þ Hþ (MþHþ): 402.1634. Found: 402.1634. Elemental
145.6, 123.0, 69.6, 50.2, 47.3, 13.2; ESI-MS: m/z 220 (MþHþ).
analysis (%) for C16H27N5O3S2: Calcd.: C, 47.86; H, 6.78; N, 17.44;

836
D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
Found, C, 47.96; H, 6.99; N, 17.41.
(MþHþ): 456.0931. Found: 456.0932. Elemental analysis (%) for
C
18H22ClN5O3S2: Calcd.: C, 47.41; H, 4.86; N, 15.36; Found, C, 47.70;
4.1.55. ( )eEthyl 4-((2-hydroxy-3-(2-methyl-4-nitro-1H-imidazol-
1-yl)propylthio)carbonothioyl)piperazine-1-carboxylate (56)
The title compound (56) was synthesized from ( )e2-methyl-4-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (52, 1.64 mmol) and
H, 4.99; N, 15.65.
4.1.59. ( )e2-Hydroxy-3-(2-methyl-4-nitro-1H-imidazol-1-yl)
propyl 3-methylpiperidine-1-carbodithioate (60)
sodium
(3.27 mmol) in 77% yield as white solid. mp: 92e94 ꢀC; IR (KBr)
(cmꢁ1): 3402, 3110,1742, 1540, 1360, 1215,1153; 1H NMR (400 MHz,
4-(ethoxycarbonyl)piperazine-1-carbodithioate
The title compound (60) was synthesized from ( )e2-methyl-4-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (52, 1.09 mmol) and
sodium 3-methylpiperidine-1-carbodithioate (2.18 mmol) in 76%
n
DMSO-d6):
d
8.23 (s, 1H), 5.66e5.64 (m, 1H), 4.32e3.94 (m, 10H),
yield as white solid. mp: 83e85 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3110,
3.52e3.51 (m, 5H), 2.36 (s, 3H),1.20 (t, J ¼ 7.0 Hz, 3H); 13C (100 MHz,
3011, 1540, 1358, 1215, 1150; 1H NMR (400 MHz, DMSO-d6):
d 8.22
DMSO-d6):
d
195.9, 155.0, 145.9, 145.6, 123.2, 68.5, 61.5, 51.9, 51.0,
(s, 1H), 5.62e5.60 (m, 1H), 5.09 (bs, 1H), 4.49e4.15 (m, 2H),
3.99e3.95 (m, 2H), 3.53e3.49 (m, 1H), 3.38 (d/d, J ¼ 7.0 & 14.0 Hz,
1H), 3.14e2.95 (m, 1H), 2.36 (s, 3H), 1.79e1.63 (m, 3H), 1.47e1.40
(m, 1H), 1.27e1.24 (m, 1H), 0.91e0.90 (m, 3H); 13C (100 MHz,
42.9, 41.4, 15.0, 13.3; ESI-MS: m/z 418 (MþHþ); HRMS (ESI): m/z
calculated for C15H23N5O5S2 þ Hþ (MþHþ): 418.1219. Found:
418.1216. Elemental analysis (%) for C15H23N5O5S2: Calcd.: C, 43.15;
H, 5.55; N, 16.77; Found, C, 43.25; H, 5.90; N, 16.32.
DMSO-d6):
d 194.1, 145.8, 145.6, 123.3, 68.7, 58.7, 51.9, 41.5, 32.4,
25.1, 19.2, 18.9, 13.3; ESI-MS: m/z 359 (MþHþ). Elemental analysis
(%) for C14H22N4O3S2: Calcd.: C, 46.91; H, 6.19; N, 15.63; Found, C,
46.74; H, 6.50; N, 15.28.
4.1.56. ( )e2-Hydroxy-3-(2-methyl-4-nitro-1H-imidazol-1-yl)
propyl 4-phenylpiperazine-1-carbodithioate (57)
The title compound (57) was synthesized from ( )e2-methyl-4-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (52, 1.64 mmol) and
sodium 4-phenylpiperazine-1-carbodithioate (3.27 mmol) in 82%
4.1.60. ( )etert-Butyl 4-((2-hydroxy-3-(2-methyl-4-nitro-1H-
imidazol-1-yl)propylthio)carbonothioyl)piperazine-1-carboxylate
(61)
The title compound (61) was synthesized from ( )e2-methyl-4-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (52, 1.36 mmol) and
yield as white solid. mp: 113e115 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3115,
8.23
1562, 1540, 1360, 1215, 1140; 1H NMR (400 MHz, DMSO-d6):
d
(s, 1H), 7.24 (d/d, J ¼ 7.3 & 8.6 Hz, 2H), 6.95 (d, J ¼ 7.9 Hz, 2H), 6.81
(d, J ¼ 7.2 Hz, 1H), 5.66e5.64 (m, 1H), 4.38 (bs, 2H), 4.20e3.95 (m,
5H), 3.56 (d/d, J ¼ 4.0 & 13.5 Hz, 1H), 3.36e3.28 (m, 5H), 2.37 (s,
sodium
(2.73 mmol) in 82% yield as white solid. mp: 144e146 ꢀC; IR
(KBr)
(cmꢁ1): 3410, 3100, 1745, 1541, 1365, 1215, 1142; 1H NMR
(400 MHz, DMSO-d6): 8.22 (s, 1H), 5.64e5.63 (m, 1H), 4.23e4.16
4-(tert-butoxycarbonyl)piperazine-1-carbodithioate
3H); 13C (100 MHz, DMSO-d6):
d
195.4, 150.4, 145.9, 145.6, 129.5,
n
123.3, 119.7, 115.9, 68.6, 51.9, 51.2, 49.8, 48.0, 41.4, 13.3; ESI-MS: m/z
422 (MþHþ); HRMS (ESI): m/z calculated for C18H23N5O3S2 þ Hþ
(MþHþ): 422.1321. Found: 422.1316. Elemental analysis (%) for
d
(m, 3H), 3.99e3.94 (m, 4H), 3.54 (d/d, J ¼ 3.9 & 13.5 Hz, 1H),
3.48e3.45 (m, 4H), 2.36 (s, 3H), 1.42 (s, 9H); 13C (100 MHz, DMSO-
C
18H23N5O3S2: Calcd.: C, 51.29; H, 5.50; N, 16.61; Found, C, 51.60; H,
d6): d 195.8, 154.1, 145.9, 145.6, 123.3, 79.8, 68.6, 51.9, 49.8, 41.4,
5.83; N, 16.33.
28.4, 13.3; ESI-MS: m/z 446 (MþHþ); HRMS (ESI): m/z calculated for
C
17H27N5O5S2 þ Hþ (MþHþ): 446.1532. Found: 446.1526. Elemental
4.1.57. ( )e2-Hydroxy-3-(2-methyl-4-nitro-1H-imidazol-1-yl)
propyl 4-(2-methoxyphenyl)piperazine-1-carbodithioate (58)
The title compound (58) was synthesized from ( )e2-methyl-4-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (52, 1.09 mmol) and
analysis (%) for C17H27N5O5S2: Calcd.: C, 45.83; H, 6.11; N, 15.72;
Found, C, 45.99; H, 6.42; N, 15.40.
The compounds 62e65 were synthesized using a procedure
similar to described for compound 25.
sodium
(2.18 mmol) in 80% yield as white solid. mp: 162e164 ꢀC; IR (KBr)
(cmꢁ1): 3400, 3120, 1560, 1552, 1355, 1215, 1147; 1H NMR
(400 MHz, DMSO-d6): 8.23 (s, 1H), 7.02e6.96 (m, 2H), 6.92e6.86
4-(2-methoxyphenyl)piperazine-1-carbodithioate
4.1.61. ( )e1-(4-(2,3-Dichlorophenyl)piperazin-1-yl)-3-(2-methyl-
4-nitro-1H-imidazol-1-yl)propan-2-ol (62)
n
d
The title compound (62) was synthesized from ( )e2-methyl-4-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (52, 1.91 mmol) and 1-
(2,3-dichlorophenyl)piperazine (2.10 mmol) in 70% yield as white
(m, 2H), 5.66e5.64 (m, 1H), 4.38e4.37 (m, 2H), 4.20e3.95 (m, 6H),
3.80 (s, 3H), 3.56 (d/d, J ¼ 3.7 & 13.4 Hz,1H), 3.08e3.05 (m, 4H), 2.37
(s, 3H); 13C (100 MHz, DMSO-d6):
d
195.5, 152.4, 145.8, 145.6, 140.4,
solid. mp: 164e166 ꢀC; IR (KBr)
n
(cmꢁ1): 3400, 3120, 1595, 1545,
8.25 (s, 1H), 7.33e7.29
123.6, 123.3, 121.2, 118.9, 112.3, 68.6, 55.8, 51.9, 50.1, 41.4, 13.3; ESI-
1364, 785; 1H NMR (400 MHz, DMSO-d6):
d
MS: m/z 452 (MþHþ); HRMS (ESI): m/z calculated for
(m, 2H), 7.13 (d/d, J ¼ 2.8 & 6.8 Hz, 1H), 5.12 (d, J ¼ 5.1 Hz, 1H), 4.15
C
19H25N5O4S2 þ Hþ (MþHþ): 452.1426. Found: 452.1432. Elemental
(d/d, J ¼ 2.7 & 13.8 Hz, 1H), 4.01e3.98 (m, 1H), 3.91 (d, J ¼ 7.9 &
analysis (%) for C19H25N5O4S2: Calcd.: C, 50.54; H, 5.58; N, 15.51;
Found, C, 50.70; H, 5.90; N, 15.30.
13.8 Hz, 1H), 2.99 (s, 4H), 2.65e2.58 (m, 4H), 2.44e2.37 (m, 5H); 13
C
(100 MHz, DMSO-d6): d 151.6, 146.1, 145.6, 133.1, 128.9, 126.4, 124.8,
123.3, 119.9, 67.2, 61.7, 53.8, 51.3, 13.3; ESI-MS: m/z 414 (MþHþ);
HRMS (ESI): m/z calculated for C17H21Cl2N5O3 þ Hþ (MþHþ):
414.1100. Found: 414.1101. Elemental analysis (%) for
4.1.58. ( )e2-Hydroxy-3-(2-methyl-4-nitro-1H-imidazol-1-yl)
propyl 4-(3-chlorophenyl)piperazine-1-carbodithioate (59)
The title compound (59) was synthesized from ( )e2-methyl-4-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (52, 1.91 mmol) and
C17H21Cl2N5O3: Calcd.: C, 49.29; H, 5.11; N, 16.90; Found, C, 49.02;
H, 5.44; N, 16.63.
sodium
(3.82 mmol) in 76% yield as white solid. mp: 118e120 ꢀC; IR (KBr)
(cmꢁ1): 3400, 3110, 1564, 1530, 1364, 1215, 790; 1H NMR
(400 MHz, DMSO-d6):
4-(3-chlorophenyl)piperazine-1-carbodithioate
4.1.62. ( )e1-(4-Ethylpiperazin-1-yl)-3-(2-methyl-4-nitro-1H-
imidazol-1-yl)propan-2-ol (63)
The title compound (63) was synthesized from ( )e2-methyl-4-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (52, 1.91 mmol) and 1-
n
d
8.24 (s, 1H), 7.24 (t, J ¼ 8.1 Hz, 1H),
6.96e6.95 (m, 1H), 6.89 (d/d, J ¼ 2.0 & 8.3 Hz, 1H), 6.81 (d/d, J ¼ 1.4
& 7.8 Hz, 1H), 5.67e5.65 (m, 1H), 4.36 (bs, 2H), 4.19e3.95 (m, 5H),
ethylpiperazine (2.10 mmol) in 66% yield as semi solid. IR (KBr)
n
3.56 (d/d, J ¼ 3.8 & 13.5 Hz, 1H), 3.38e3.36 (m, 5H), 2.36 (s, 3H); 13
C
(cmꢁ1): 3400, 3105, 1535, 1361, 1140; 1H NMR (400 MHz, DMSO-
(100 MHz, DMSO-d6):
d
195.5, 151.6, 145.9, 145.6, 134.3, 130.9, 123.3,
d6):
d
8.21 (s, 1H), 5.16 (bs, 1H), 4.10 (d/d, J ¼ 2.4 & 13.5 Hz, 1H),
118.7, 114.8, 113.8, 68.6, 51.9, 50.8, 47.1, 41.4, 13.3; ESI-MS: m/z 456
3.95e3.85 (m, 2H), 2.51e2.22 (m, 15H), 0.97 (t, J ¼ 7.1 Hz, 3H); 13
C
(MþHþ); HRMS (ESI): m/z calculated for C18H22ClN5O3S2 þ Hþ
(100 MHz, DMSO-d6):
d 146.0, 145.6, 123.3, 67.1, 61.8, 53.8, 52.8,

D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
837
52.1, 51.3, 13.3, 12.4; ESI-MS: m/z 298 (MþHþ); HRMS (ESI): m/z
bromide] assay. Exponentially growing HeLa cells were seeded into
96-well tissue culture plates at a density of 2 ꢂ 104 cells per well (in
triplicate) and were incubated in culture medium (DMEM with 10%
fetal calf serum) for 24 h at 37 ꢀC in a 5% CO2e95% air atmosphere.
After 24 h, the culture medium was replaced with fresh medium
containing dilutions of test compounds in experimental wells and
0.05% DMSO in culture medium in control wells. After incubation
calculated for
C13H23N5O3
þ
Hþ (MþHþ): 298.1879. Found:
298.1885. Elemental analysis (%) for C13H23N5O3: Calcd.: C, 52.51; H,
7.80; N, 23.55; Found, C, 52.70; H, 8.09; N, 23.33.
4.1.63. ( )e1-(2-methyl-4-nitro-1H-imidazol-1-yl)-3-(4-(pyridin-
2-yl)piperazin-1-yl)propan-2-ol (64)
The title compound (64) was synthesized from ( )e2-methyl-4-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (52, 1.91 mmol) and 1-
(pyridin-2-yl)piperazine (2.10 mmol) in 72% yield as semi solid. IR
for another 24 h, 5 ml of 5 mg/ml MTT solution in PBS [pH 7.4] was
added to each well. The formazan crystals formed inside the viable
cells were solubilized in DMSO, and the optical density at 540 nm
(OD540) was recorded in a microplate reader (Microquant; BioTek)
(Table 1).
(KBr)
(400 MHz, CDCl3):
n
(cmꢁ1): 3400, 3110, 1560, 1542, 1360, 1155; 1H NMR
d
8.18e8.16 (m, 1H), 7.86 (s, 1H), 7.51e7.46 (m,
1H), 6.65e6.62 (m, 2H), 4.12e4.07 (m, 2H), 3.88 (d/d, J ¼ 7.6 &
14.8 Hz, 1H), 3.55e3.52 (m, 4H), 2.75e2.70 (m, 2H), 2.57e2.54 (m,
2H), 2.48e2.38 (m, 5H); 13C (100 MHz, CDCl3):
d
159.3, 147.9, 146.2,
4.2.3. 3D-QSAR study
145.4, 137.6, 120.9, 113.7, 107.2, 66.1, 60.6, 53.1, 50.6, 45.2, 13.2; ESI-
QSAR model has been developed for the dataset of compounds,
all calculations were performed using sybyl 2.1 [49]. The sketch
module was used to draw the compounds and energy mini-
mizationwas done using the Powell method. The compounds were
assigned Tripos force field and Gasteiger-Huckel partial charges
with termination criterion of 0.05 kcal/mol for 1000 iterations. The
energy minimized conformation of most active compound 6 was
used as a template for alignment and all other molecules were
overlaid over it using surflex-Sim module [50]. Alignment of mol-
ecules is generated on the basis of morphological similarity func-
tion and fast poses generation technique. Similarity is function of
molecular shape, hydrogen bonding and electrostatic properties.
MS: m/z 347 (MþHþ); HRMS (ESI): m/z calculated for
C
16H22N6O3 þ Hþ (MþHþ): 347.1832. Found: 347.1822. Elemental
analysis (%) for C16H22N6O3: Calcd.: C, 55.48; H, 6.40; N, 24.26;
Found, C, 55.69; H, 6.72; N, 24.32.
4.1.64. ( )e1-(2-methyl-4-nitro-1H-imidazol-1-yl)-3-(1H-1,2,4-
triazol-1-yl)propan-2-ol (65)
The title compound (65) was synthesized from ( )e2-methyl-4-
nitro-1-(oxiran-2-ylmethyl)-1H-imidazole (52, 1.91 mmol) and 1H-
1,2,4-triazole (2.10 mmol) in 55% yield as white solid. mp:
148e150 ꢀC; IR (KBr) (cmꢁ1): 3400, 3120, 2996, 1543, 1360, 12682,
n
1150; 1H NMR (400 MHz, CDCl3þDMSO-d6):
d
8.02 (s, 1H), 7.77 (s,
The activity values (in mM unit) were transformed into log unit and
1H), 7.70 (s, 1H), 5.50 (s, 1H), 4.13 (d/d, J ¼ 4.1 & 13.5 Hz, 1H);
used as dependent variable in PLS analysis. The CoMFA descriptor
was calculated and used as independent variable in partial least
square regression analysis. CoMFA calculations were done using the
Tripos force field with a distance-dependent dielectric constant at
all interactions in a regularly spaced (2 Å) grid taking a sp3 carbon
atom as steric probe and aþ1 charge as electrostatic probe, cut off
was set to 30 kcal/mol [51]. The whole dataset was divided into two
randomly generated sub datasets composed of 52 compounds in
training set and 8 compounds in the test set. PLS method [42] was
used to correlate the CoMFA fields to observed biological activity
values. The cross-validation was performed using the leave-one-
out (LOO) method in which one compound is removed from the
dataset and its activity is predicted using the model derived from
the rest of the molecules in the dataset. Non-cross-validation was
performed to calculate conventional r2 using the same number of
components. It was used in the analysis of CoMFA result and the
prediction of activity of compounds through the model. For eval-
uation of predictive ability of model, predictive r2 for test set has
been calculated.
4.05e3.98 (m, 2H), 3.91e3.87 (m, 1H), 3.72e3.64 (m, 1H), 2.17 (s,
3H); 13C (100 MHz, CDCl3þDMSO-d6):
d 151.6, 145.9, 145.4, 144.5,
121.3, 68.2, 52.3, 50.0, 13.0; ESI-MS: m/z 253 (MþHþ); HRMS (ESI):
m/z calculated for C9H12N6O3 þ Hþ (MþHþ): 253.1049. Found:
253.1034. Elemental analysis (%) for C9H12N6O3: Calcd.: C, 42.86; H,
4.80; N, 33.32; Found, C, 42.98; H, 5.12; N, 33.55.
4.2. Biological materials and methods
4.2.1. Anti-Trichomonas activity
Trichomonas vaginalis parasites to be used in assays (MTZ-sus-
ceptible ATCC-33592 and MTZ-resistant ATCC-50143 strains) were
grown in TYM medium supplemented with 10% FCS, vitamin
mixture and 100 U/mL penicillin/streptomycin, at 37 ꢀC in 15 mL
tubes for one day, followed by regular subculturing, and were in the
log phase of growth. [20] The cultures routinely attained a con-
centration of 2 ꢂ 107 cells/mL in 48 h. Inoculums of 1 ꢂ 104 cells per
tube were used for maintenance of the culture. In vitro drug sus-
ceptibility and resistant assays were carried out using the standard
procedure. Stock solutions (100
prepared in DMSO. These stock solutions were serially diluted with
TYM medium to obtain concentration up to 0.1 g/mL in 48-well
mg/mL) of test compounds were
4.2.4. Fluorescence labeling of sulfhydryl groups on Trichomonas
vaginalis
m
plates. DMSO/TYM was used as vehicle in control wells. Parasites
(5 ꢂ 104 trophozoites/L) were added to these wells and incubated
anaerobically at 37 ꢀC. Cells were checked for viability at different
time intervals from 3 to 48 h under the microscope at 40ꢂ
magnification. The viability of the cells was determined by trypan
blue exclusion assay. Minimum concentration of the test agent at
which all cells were found dead in 48 h was considered as its MIC.
The experiment was repeated three times to confirm the MIC
(Table 1).
The effect of test compound on Trichomonas sulfhydryl groups
was examined and imaged by a method published earlier with
slight modification [46] using a fluorescence microscope, after
labelling with the fluorometric thiol detector using
a thiol
edetection assay kit (Cayman). Trichomonas vaginalis was treated
with the vehicle or the test compound at MIC and incubated for
24 h at 37 ꢀC. After incubation, trichomonads were pelleted at
700 ꢂ g for 10 min at 4 ꢀC and washed 2e3 times with PBS.
Thereafter 50
m
L fluorometric thiol detector (pre-diluted 100ꢂ with
dilution buffer), was added and incubated for 5 min in the dark. A
drop of this sample was taken on a microscope slide, covered with a
coverslip and imaged on a Nikon Eclipse 80i microscope equipped
with epifluoresence illumination, using the UV-1A filter. Exposure
times were the same for all samples.
4.2.2. Cytotoxicity assay
The cytotoxic effect of test compounds was evaluated in an
in vitro model of cervicovaginal epithelium (HeLa) cells line, using
the MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium

838
D. Mandalapu et al. / European Journal of Medicinal Chemistry 124 (2016) 820e839
4.2.5. In vivo anti-Trichomonas assay
acceptable accuracy and precision [FDA, Guidance for Industry:
Bioanalytical Method Validation [53].
All animal experiments were conducted in accordance and as
per the approval of the Institutional Animal Ethics Committee.
According to the modified method described by Escribano et al. [52]
the mice were housed in polypropylene cages and kept in uniform
husbandry conditions of temperature (25e26 ꢀC), relative humidity
(50e70%) and light/dark cycle (12/12 h). T. vaginalis were cultured
under partial anaerobic condition in TYM medium and on attaining
concentration of approximately 2 ꢂ 106 cells/mL (in ~48 h);
trichomonads were harvested from the culture by centrifugation at
250 ꢂg for 10 min and then re-suspended in sterile saline. Six-
week-old mice were inoculated subcutaneously with T. vaginalis
Acknowledgment
We acknowledge Ms. Tara Rawat (Senior Technical Officer) for
technical assistance and the Sophisticated Analytical Instrument
Facility (SAIF) for spectral data. We are grateful to the Council of
Scientific and Industrial Research (CSIR-India) (D.M., N.S., M.S.), and
the Indian Council of Medical Research (ICMR-India) (S.G., B.K.) for
research fellowships. This study was supported by the Department
of Health Research (DHR), ICMR, New Delhi, Government of India
(GAP 00155). The authors declare no competing financial interests.
(50
m
L of 2 ꢂ 106 organisms per mL) into the left hind flank. Five
groups were used for each experiment (n ¼ 3). The abscess/lesion
formation was determined by palpation 7 days after injection and
measured daily thereafter. Fine needle biopsy specimens were
taken from the lesion and examined microscopically to ensure
infection. Infected animals were then treated with compounds in
gum acacia solution (orally) with a dose of 50 mg and 100 mg per kg
and control animals were given gum acacia solution only. Daily for
7 days, abscess size measured longitudinally and the area calcu-
Appendix A. Supplementary data
Supplementary data related to this article can be found at http://
dx.doi.org/10.1016/j.ejmech.2016.09.006.
References
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p
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column (5
m
m, 50 ꢂ 4.6 mm id) preceded with a guard column
(5
mm, 20 ꢂ 4.0 mm, id) packed with the same material with mobile
phase [acetonitrile: aqueous ammonium acetate buffer (0.01 M;
pH, 4.5) (80:20, %v/v)] pumped at a flow rate of 0.6 mL/min under
isocratic condition. The mobile phase was degassed by ultra-
sonication for 15 min before use. LC-MS/MS system was equili-
brated for approximately 20 min before commencement of
analysis. Total analysis time was 3 min per sample. The mass
spectral analysis was performed in positive ionization mode at
5500 V using multiple reaction monitoring technique to monitor
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