1-[(4′-Chlorophenyl) carbonyl-4-(aryl) thiosemicarbazide derivatives as potent urease inhibitors: Synthesis, in vitro and in silico studies

Article abstract of DOI:10.1016/j.bioorg.2018.05.017

A series of 1-[(4′-chlorophenyl)carbonyl-4-(aryl)thiosemicarbazide derivatives 1–25 was synthesized and characterized by spectroscopic techniques such as EI-MS and ¹H NMR. All compounds were screened for urease inhibitory activity in vitro and demonstrated excellent inhibitory activity in the range of IC₅₀ = 0.32 ± 0.01–25.13 ± 0.13 μM as compared to the standard thiourea (IC₅₀ = 21.25 ± 0.13 μM). Amongst the potent analogs, compounds 3 (IC₅₀ = 2.31 ± 0.01 μM), 6 (IC₅₀ = 2.14 ± 0.04 μM), 10 (IC₅₀ = 1.14 ± 0.06 μM), 20 (IC₅₀ = 2.15 ± 0.05 μM), and 25 (IC₅₀ = 0.32 ± 0.01 μM) are many folds more active than the standard. Structure-activity relationship (SAR) was rationalized by looking at the effect of diversely substituted aryl ring on inhibitory potential which predicted that regardless of the nature of substituents, their positions on aryl ring is worth important for the potent activity. Furthermore, to verify these interpretations, in silico study was performed on all compounds and a good correlation was perceived between the biological evaluation and docking study of compounds.

Full text of DOI:10.1016/j.bioorg.2018.05.017

BioorganicChemistry79(2018)363–371
Contents lists available at ScienceDirect
Bioorganic Chemistry
journal homepage: www.elsevier.com/locate/bioorg
1-[(4′-Chlorophenyl) carbonyl-4-(aryl) thiosemicarbazide derivatives as
potent urease inhibitors: Synthesis, in vitro and in silico studies
⁎
Basharat Alia, Khalid Mohammed Khana,d, , Uzma Salara, Kanwala, Safdar Hussainb,
Muhammad Ashrafb, Muhammad Riazc, Abdul Wadoodc, Muhammad Tahad, Shahnaz Perveene
a
H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan
Department of Chemistry, The Islamia University of Bahawalpur, Bahawalpur 63100, Pakistan
Department of Biochemistry, Computational Medicinal Chemistry Laboratory, UCSS, Abdul Wali Khan University, Mardan, Pakistan
Department of Clinical Pharmacy, Institute for Research and Medical Consultations (IRMC), Imam Abdulrahman Bin Faisal University, P.O. Box 1982, Dammam 31441,
b
c
d
Saudi Arabia
e
PCSIR Laboratories Com, Karachi, Shahrah-e-Dr. SalimuzzamanSiddiqui, Karachi 75280, Pakistan
A R T I C L E I N F O
A B S T R A C T
Keywords:
Synthesis
A series of 1-[(4′-chlorophenyl)carbonyl-4-(aryl)thiosemicarbazide derivatives 1–25 was synthesized and
characterized by spectroscopic techniques such as EI-MS and 1H NMR. All compounds were screened for urease
inhibitory activity in vitro and demonstrated excellent inhibitory activity in the range of
Thiosemicarbazide
Urease inhibitory activity
In vitro
Structure-activity relationship
In silico
IC50 = 0.32
Amongst the potent analogs, compounds
(IC50 = 1.14 0.06 μM), 20 (IC50 = 2.15
0.01–25.13
0.13 μM as compared to the standard thiourea (IC50 = 21.25
(IC50 = 2.31 0.01 μM), (IC50 = 2.14
0.05 μM), and 25 (IC50 = 0.32
0.13 μM).
3
6
0.04 μM), 10
0.01 μM) are many folds more
active than the standard. Structure-activity relationship (SAR) was rationalized by looking at the effect of di-
versely substituted aryl ring on inhibitory potential which predicted that regardless of the nature of substituents,
their positions on aryl ring is worth important for the potent activity. Furthermore, to verify these interpreta-
tions, in silico study was performed on all compounds and a good correlation was perceived between the bio-
logical evaluation and docking study of compounds.
1. Introduction
derivatives of thiocarbamic acid. They are not only transition com-
pounds for the synthesis of various bioactive heterocycles such as
Urease (urea amidohydrolase, EC3.5.1.5) is a well-known nickel
containing metalloenzyme which was isolated from Jack beans
(Canavalia ensiformis) as the first crystalline enzyme, in 1926, by
Summer, [1,2]. Urease enzyme catalyzes the hydrolysis of urea into
ammonia and carbamate. The carbamate then spontaneously hydro-
lyses, at physiological pH, to form bicarbonate and a second molecule
of ammonia [3]. The produced ammonia neutralizes the stomach acid
and create a suitable pH environment for the survival and colonization
of urease-producing Helicobacter pylori. H. pylori colonization leads to
numerous health complications in humans as they destroys mucosal
membrane and causes gastric ulcers, urinary, and gastrointestinal tract
infections [4,5]. Hyperactivity of urease enzyme can also induce some
other complications such as development of kidney stones, pyelone-
phritis, hepatic coma etc. As the urease enzyme plays a key role in such
clinically important complications, it is necessary to regulate urease
activity with the help of inhibitors [6].
triazoles, triazepine, oxadiazoles, thiadiazoles, thiazole, thiadiazine,
thiadiazepine, pyrazoles, and tetrazoles [7–16] but also a biologically
potent scaffold. They are reported to have antiamebal [17,18], anti-
fungal [19], and antiproliferative [20] activities. They are also ex-
hibited antimalrial [21], antiviral [22], and antinociceptive activities
[23]. Their widest use is found in treatment of various microbial in-
fections, particularly p-acetamidobenzaldehyde thiosemicarbazone
under trade name thiacetazone (tibon) has been used for more than
50 years against Tubercular mycobacterium [24].
Previously, we have discovered several sulfur and nitrogen con-
taining potent urease inhibitors such as Schiff bases of thiazoles [25],
substituted 4-thiazolidinones [26], thiobarbituric acid derivatives [27],
and 1,3,4-oxazole-2(3H)-thiones [28]. In addition to that, we have also
reported thiosemicarbazones as potent urease inhibitors where we
evaluated a diverse variety of thiosemicarabazones hybrid with dif-
ferent pharmacophores such as benzophenones, benzofuran, and isatin
for their urease inhibitory potential [29–31]. In that study, we found a
Thiosemicarbazides (NH2-NH-CSNH2) are the simplest hydrazine
⁎
Corresponding author at: H.E.J. Research Institute of Chemistry, International Center for Chemical and Biological Sciences, University of Karachi, Karachi 75270, Pakistan.
E-mail address: khalid.khan@iccs.edu (K.M. Khan).
https://doi.org/10.1016/j.bioorg.2018.05.017
Received 17 March 2018; Received in revised form 12 May 2018; Accepted 20 May 2018
Availableonline23May2018
0045-2068/©2018ElsevierInc.Allrightsreserved.

B. Ali et al.
BioorganicChemistry79(2018)363–371
Fig. 1. Rationale of the current study.
number of chloro substituted derivatives as significant urease in-
hibitors, so we intended to further explore chloro group containing
thiosemicarbazone derivatives. For that purpose, we synthesized a
series of 1-[(4′-chlorophenyl)carbonyl-4-(aryl)thiosemicarbazide deri-
vatives 1–25 in which all synthesized analogs have the 4-chlorophenyl
moiety as constant structural part but in addition to that we also used a
variety of chloro group/s bearing phenyl isothiocyanate in the synthesis
in order to install chloro group/s on other half of the molecule (aryl
part) (Fig. 1).
(IC50 = 2.15
0.05 μM), and 25 (IC50 = 0.32
0.01 μM) were
found to be many folds more potent than the standard thiourea.
2.3. Structure-activity relationship (SAR)
Indeed, the inhibitory potential demonstrated by the compounds
1–25 is the cordial participation of the all structural motifs of the
molecule (Fig. 1). But it is also a fact that the some structural features
plays important role in the inhibitory activity. In the synthesized li-
brary, the varying part is only the aryl part (R). So, a limited structure-
activity relationship (SAR) was established by comparing the effect of
nature and positions of substituents on N4 aryl moiety of thiosemi-
carbazide derivatives 1–25 on urease inhibitory activity.
2. Results and discussion
2.1. Chemistry
Thiosemicarbazide derivative 1 (IC50 = 8.14
substituted N4 aryl moiety, was found to be more than two-fold better
active than the standard thiourea (IC50 = 21 0.11 µM). Which
0.05 µM) with un-
4-Chlorophenyl hydrazide was reacted with various substituted
phenyl isothiocyanates in the presence of ethanol to get our desired
thiosemicarbazide derivatives 1–25 (Scheme 1). The reaction mixture
was refluxed at 80 °C for 20–30 min and monitored through TLC (silica
gel GF-254). The synthesized compounds 1–25 were characterized by
various spectroscopic techniques such as EI-MS and 1H NMR. Com-
pounds 3, 10, 14, and 17 are new derivatives while rest of the com-
pounds are previously known [32–36].
showed that this compound interacted more efficiently with active site
of enzyme. However, incorporation of a variety of groups on N4 aryl
ring leads to a varying degree of inhibitory potential as discussed in the
following part.
Incorporation of bromo substituents on two different positions of N4
aryl ring demonstrated a huge difference in the inhibitory activity as in
compounds 2 (IC50 = 23.59
0.11 µM) with 2″-bromo group and 3
2.2. Urease inhibitory activity
(IC50 = 2.31 0.01 µM) with 3″-bromo group. It shows that 3″-bromo
group in compound 3 is playing an important role in the inhibitory
potential. Activities of compounds 2 and 3 can be compared with chloro
In continuation of our previous studies on the identification of po-
tent urease inhibitors, further thiosemicarbazide derivatives 1–25 were
synthesized and screened for urease inhibitory potential. It is worth
mentioning that all compounds were showed excellent inhibitory ac-
substituted
derivatives
on
same
positions
such
as
4
(IC50 = 9.23
0.05 µM) and 5 (IC50 = 21.69
0.11 µM), a reverse
inhibitory attribute was observed. 2″-Chloro substituted compound 4
showed more inhibitory potential than 3″-chloro substituted compound
5. Which revealed that the chloro group is more appropriate at 2″-po-
sition to better interact with the active site. While compound 6
tivity in the range of IC50 = 0.32
pared to the standard thiourea (IC50 = 21.25
number of compounds including
(IC50 = 2.14 0.04 μM), 10
0.01–25.13
0.13 μM as com-
0.13 μM) (Table 1). A
3
(IC50 = 2.31
0.01 μM),
6
20
(IC50 = 1.14
0.06 μM),
(IC50 = 2.14
0.04 µM) having chloro at 4″-position (para to
Scheme 1. Synthesis of 1-[(4′-chlorophenyl)
carbonyl-4-(aryl)thiosemicarbazide derivatives
1–25.
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B. Ali et al.
BioorganicChemistry79(2018)363–371
Table 1
In vitro urease inhibitory activity of thiosemicarbazide derivatives 1–25.
Comp.
Structure
IC50
8.14
SEMa
Comp.
Structure
IC50
SEMa
0.09
1
0.05
14
13.15
2
23.59
0.11
15
21.13
0.09
3
4
2.31
9.23
0.01
0.05
16
17
17.92
8.26
0.11
0.07
5
6
7
21.69
2.14
0.11
0.04
0.11
18
19
20
7.43
15.64
2.15
0.06
0.05
0.05
17.98
8
13.17
0.03
21
17.31
0.08
9
19.45
1.14
0.09
0.06
22
23
15.26
8.63
0.06
0.03
10
11
12
13
21.13
25.13
8.21
0.06
0.13
0.04
24
25
12.17
0.32
0.06
0.01
0.13
Standard = Thioureac
21.25
SEMa (Standard error of the mean); Thioureac (Standard for urease inhibitory activity).
thiosemicarbazide) showed even far better inhibitory activity as com-
pared to compounds 4 and 5. The above activity attribute demonstrated
that the 3″-position (meta to thiosemicarbazide) is appropriate for
bromo but less appropriate for chloro group.
activities as compared to the standard thiourea (IC50 = 21
0.11 µM).
Activity of compound 4 (IC50 = 9.23
with derivatives (IC50 = 17.98
(IC50 = 13.17 0.03 µM) in which incorporation of second chloro
0.05 µM) can be correlated
7
0.11 µM)
and
8
Incorporation of dichloro substituents as in compounds
7
9
group at 3″- and 5″-positions (meta to thiosemicarbazide), respectively,
brought decline in the inhibitory activity. Which showed the negative
involvement of 3″- and 5″-positions (meta to thiosemicarbazide) in the
(IC50 = 17.98
(IC50 = 19.45
0.11 µM),
8
(IC50 = 13.17
0.03 µM), and
0.09 µM), showed closed but potent inhibitory
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B. Ali et al.
BioorganicChemistry79(2018)363–371
Fig. 2. (A). Superposition of co-crystallized and docked conformations of the reference ligand. Red native co-crystallized ligand and green docked ligand. (B).
Mapping between the hydrophobic and polar parts of compound 6 and the reference ligand i.e., acetohydroxamic acid.
inhibitory activity. This can further confirmed by the comparison of the
activities of compounds (IC50 = 2.14 0.04 µM) and
(IC50 = 19.45 0.09 µM), in which incorporation of second chloro at
more potent than the standard thiourea (IC50 = 21
of compound 23 (IC50 = 8.63 0.03 µM) can also be compared with
closely similar analog 24 (IC50 = 12.17 0.06 µM) having 4″-ethoxy
0.11 µM). Activity
6
9
3″-positions (meta to thiosemicarbazide) leads to diminished inhibitory
activity. However, incorporation of electron donating methyl group at
instead of 4″-methoxy, a decline in the inhibitory potential observed on
increasing chain length.
2″-position in compound 10 (IC50 = 1.14
0.06 µM) gave even more
It can be extracted out from the limited SAR studies that the nature
of the substituents is not really make difference in the activity, all
substituents are equally important for the activity but their positions on
aryl part are responsible for the variations in the inhibitory potential.
However, to verify these interpretations and to rationalize the binding
interactions of compounds with the active site of enzyme, in silico study
was performed on all compounds. A plausible description is following.
potent activity than compound 6 which apparently showed that the
inductively electron donating group played positive role in the in-
hibitory potential.
Fluoro substituted compounds 11 (IC50 = 21.13
12 (IC50 = 25.13 0.13 µM) bearing fluoro at 2″- and 3″-positions,
respectively, showed almost closed but comparable inhibitory activity
to standard. Comparison of activities of compounds 11 and 12 with
structurally similar analogs 4 and 5 revealed that fluoro group is less
actively participating in the inhibitory potential as compared to chloro.
However, the positional effect is same as previously observed for chloro
groups. Activity of compound 12 can also be compared with 17
0.06 µM) and
2.4. Docking studies
To predict the binding interactions, molecular docking of the syn-
thesized derivatives 1–25 was carried out with the crystal structure of
urease via MOE software. For all compounds, the most favorable
docking conformations were observed inside the active site with proper
orientation. The active site consists of both the hydrophobic and hy-
drophilic amino acids.
The hydrophobic part was composed of Ala366, 170, Leu319,
Lys169, Cys322, and Met 637 while hydrophilic amino acids included
Arg339, Glu166, 223, Asp494, His323, 324, and Asp224, 363. The two
Ni ions also played a vital role by linking the key amino acid and li-
gands. It has been observed that almost all conformations of all ligands
showed interactions with key residues inside the pocket. The most
promising docked conformation of each compound was further eval-
uated for binding mode. The docked poses were ranked by the scores
from the GBVI/WSA binding free energy calculation. Detailed docking
results are listed in Table 2 (see SI).
The MOE dock predicted conformation of reference ligand i.e.,
acetohydroxamic acid is shown in Fig. 2A with superposition of X-ray
crystallographic structure in active sites of target urease enzyme. The
root-mean square deviation (RMSD) value between the predicted dock
conformation and X-ray crystallographic structure is equal to 0.87,
suggesting that MOE dock protocol has a high docking reliability in
reproducing the experimentally observed binding mode for urease in-
hibitors. The MOE dock program and the parameter set could be ex-
tended accordingly to search the urease binding conformations for
other inhibitors. From Fig. 2B, it was also observed that our docked
confirmations showed good mapping on the active site of the enzyme
with the reference inhibitor, although our synthesized derivatives have
diverse chemical structures. In Fig. 2B very good mapping was observed
between the hydrophobic and polar parts of compound 6 and the re-
ference ligand i.e., acetohydroxamic acid.
(IC50 = 8.26
0.07 µM) having an additional inductively electron
donating methyl group at 2″-position, and showed three-folds better
inhibitory potential. The effect is same as observed in case of compound
10. Difluoro substituted analogs 13 (IC50 = 8.21
0.04 µM) and 14
(IC50 = 13.15 0.09 µM) were found to be more potent than the
mono fluoro analogs 11 and 12. Their more potency might be due to
more fluoro groups available to interact with the active site of enzyme.
Amongst the compounds bearing trifluoromethyl group, compound
16 (IC50 = 17.92
showed superior activity than 15 (IC50 = 21.13
stituted at 2″-position. Another compound 18 (IC50 = 7.43
0.11 µM) having trifluoromethyl at 3″-position
0.09 µM) sub-
0.06 µM)
having strong electron withdrawing nitro group showed three-times
more inhibitory potential than standard thiourea. Unfortunately, its
positional effect is unjudged due to lacking of analogs having nitro at
different positions.
Amongst the di-methyl substituted potent analogs 19
(IC50 = 15.64
0.05 µM) and 20 (IC50 = 2.15
0.05 µM), the 3″,5″-
disubstituted derivative 20 showed eight-folds increased activity than the
2″,6″-disubstituted derivative 19. The less potential of compound 19
might be due to the presence of dimethyl groups closed to the thiose-
micarbazide moiety which may create steric hinderance to strongly bind
to the active site as compound 20. However, amongst the methoxy
substituted thiosemicarbazide derivatives 21–23, compound 23
(IC50 = 8.63
0.03 µM) having methoxy at 4″-position showed su-
perior inhibitory activity than compound 21 (IC50 = 17.31
with 2″-methoxy followed by compound 22 (IC50 = 25.26
with 3″-methoxy. Which showed that the 3″-position is less favourable
for the methoxy group and compound 25 (IC50 = 0.32 0.01 µM) is
the best example of 2″,4″-dimethoxy substituted analog showing the
combine effect of positions-2″ and -4″. In addition to that compound 25
was found to be the most potent analog of the series and sixty six-times
0.08 µM)
0.06 µM)
The analysis of the binding mode of the most favorite docked con-
formations revealed that all ligands interacted well over the active site
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B. Ali et al.
BioorganicChemistry79(2018)363–371
Fig. 3. Three dimensional interactions of compounds 20, 3, 6, 25, 10, and 18 with active site residues of urease. Ligands are shown in brown color, key residues of the
active site are shown in stick mode, hydrogen bonding and other interaction are shown in dark color dotted lines. (A) Hydrogen bonding and polar interaction of
compound 20 with the active site residues (B) 3D interactions network of compound 3 (C) 3D interactions network of compound 6 (D) 3D interaction of compound 25
(E) 3D binding mode of compound 10 (F) 3D binding mode of compound 18.
cavity through NH, O, C]O, S, X (halogens), and pi (π) system. The
binding mode of the ligands with the active site residues showed that
almost all ligands tightly engaged the backbone of the enzyme using
hydrogen bonds, polar bonds, arene-arene, and arene-cation interac-
tions. The synthesized compounds have different active electrons rich
groups and almost all the ligands showed similar pattern of binding
inside the active site. In halogens substituted derivatives, for different
groups and positions a gradually altered potential was observed.
Among mono ortho substituted halogen derivatives such as compounds
2, 4, and 11, Cl substituted compound 4 showed best potential followed
by F (compound 11), and Br (compound 2). However, in case of meta
substituted derivatives such as 3, 5, and 12, best potential was observed
for Br containing derivative 3, followed by Cl (compound 5), and F
(compound 12) (Table 2, see SI). Similarly, a correlated best potential
was observed for both Br (compound 3) and Cl (compound 6) sub-
stituted derivatives at meta and para positions, respectively (Fig. 3B and
C). All the di-substituted halogen derivatives including 7, 8, 9, 13, and
14 have shown intermediary potential as compared to mono-sub-
stituted derivatives (Table 2, see SI). Among other compounds, deri-
vatives 10, 20, and 25 with electrons donating inductive groups
showed favorable in silico inhibition owing to the positions of their
attachment. 3D interaction of some favorable inhibitors are shown in
Fig. 3. Fig. 3A presents the 3D binding mode of compound 20, a deri-
vative with two electron donating methyl groups. The figure reflects
that methyl groups are not involved in bonding directly, however, they
may enhance the polarizability of the molecule by their electron do-
nating inductive effect resulting in a good interaction pattern. π-Elec-
trons system of chlorobenzene moiety in compound accomplished
arene-arene bonding with His324 and the carbonyl oxygen (C]O) and
sulfur (C]S) are bonded to Lys169 and Ala170, respectively, via H-
acceptor bonding. The NH group of the hydrazine moiety of compound
is located at a distance of H-donor contact with Cys322. Compounds 3
and 6 having meta-bromo and para-chloro substitutions, respectively,
were found to be as interactive as compared 20. The π-electrons system
at both ends and almost all the active groups (C]O, C]S, NH) in
compound 3 were found interactive resulting in a good binding mode as
shown in Fig. 3B. π-Electrons system of chloro and bromobenzene
moieties at the two ends in the compound accomplished π-H bonding
with Ala366 and Ala170, respectively. The carbonyl oxygen (C]O) and
sulfur (C]S) are bonded to Cys322 and Lys169, respectively, via H-
acceptor bonding. The NH group of the hydrazine moiety of compound
is located to form an H-donor bond with Glu166. The docking mode of
compound 6 depicted the inhibition of catalytic activities of the enzyme
slightly in a different way by performing three H-donor interactions
with Glu166, Lys169, and Glu223 (Fig. 3C). Regarding binding mode,
compound 3 offered better potential in this in silico study as compared
to compound 20 and 6 which seems to be in a while contrast to their
biological activities. However, the docking scores calculated for these
compounds showing the overall stability of the predicted possible
complexes (Table 2, see SI), are in good agreement with their biological
activities. Like compound 6, compound 25, the dimethoxy (OMe)
substituted compound, the ever best derivative also showed moderate
inhibition mode regarding number of interactions as illustrated in
Fig. 3D. However, the high energies calculated for the bonds formed
and good docking score may favor the enhanced inhibitory activity of
this compound. The carbonyl sulfur (C]S) is bonded to Lys169 and
Glu166 via H-acceptor bonding. The NH group of the hydrazine moiety
of compound is located at a distance of H-donor contact with Cys322.
Compound 10, the second most active compound, presented a very
good inhibition mode in accordance to its biological activity (Fig. 3E). It
was observed that both substituted groups Me and Cl were not involved
in interactions with the active site residues directly, however, they may
enhance the polarizability of the molecule by their electron donating
inductive effect resulting in a good interaction mode. The carbonyl
sulfur (C]S) is bonded to His324 by forming an H-acceptor bond. The
Cl group of the compound is located at a distance of H-donor contact
with Met318. Two H-donor contacts were also observed between
Cys322 and the compound.
Similarly, nitro substituted derivative 18 also presented better re-
sults. The nitro group (NO2) was observed active by interacting with
Arg339 as depicted in Fig. 3F. An additional hydrogen bond was also
observed between carbonyl sulfur of the ligand and Ala366.
The docking results complemented well the experimental results
based on the multiple interactions of ligands with key residues of the
urease enzyme and the docking scores calculated. The docking pose of
almost all potent compounds computationally inhibited the catalytic
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BioorganicChemistry79(2018)363–371
activities of the urease by binding firmly through strong hydrogen
bonding, hydrophobic, and polar interactions with key residues.
δH 10.63 (s, 1H, NH-1), 9.87 (s, 2H, NH-2, NH-4), 7.96 (d, 2H,
J2′,3′ = J6′,5′ = 8.4 Hz, H-2′, H-6′), 7.71 (s, 1H, H-2″), 7.60 (d, 2H,
J3′,2′ = J5′,6′ = 8.4 Hz, H-3′, H-5′), 7.51 (d, 1H, J4″,5″ = 7.6 Hz, H-4″),
7.34 (m, 2H, H-5″, H-6″); EI-MS: m/z (rel. abund. %), 385 [M]+ (6),
139 (100), 215 (94), 181 (5), 171 (61), 111 (70), 57 (40).
2.5. Conclusion
Synthetic 1-[(4′-chlorophenyl)carbonyl-4-(aryl)thiosemicarbazide
derivatives 1–25 were showed potent urease inhibitory activity as
compared to the standard thiourea. Compounds 3, 6, 10, 20, and 25
were found to be many folds more active than the standard. Structure-
activity relationship (SAR) revealed that the nature of the groups at-
tached to aryl ring is responsible for the varying inhibitory potential. In
silico study showed the efficient binding of all compounds to the active
site of urease enzyme. Decisively, this study has identified many lead
molecules as potent urease inhibitors and can be used for further studies
in the area of drug design and discovery.
3.2.4. 4-(2″-Chlorophenyl)-1-[(4′-chlorophenyl)carbonyl]
thiosemicarbazide (4)
Solid; Yield: 82%; m.p. 175–177 °C; 1H NMR: (400 MHz, DMSO‑d6):
δ
H 10.66 (s, 1H, NH-1), 9.83 (s, 1H, NH-2), 9.64 (s, 1H, NH-4), 7.96 (d,
2H, J2′,3′ = J6′,5′ = 8.0 Hz, H-2′, H-6′), 7.58 (d, 2H,
J3′,2′ = J5′,6′ = 8.0 Hz, H-3′, H-5′), 7.48 (d, 1H, J3″,4″ = 7.6 Hz, H-3″),
7.39 (bd.s, 1H, H-6″), 7.35 (t, 1H, J4″(3″,5″) = 7.2 Hz, H-4″) 7.28 (t, 1H,
J5″(4″,6″) = 8.0 Hz, H-5″); EI-MS: m/z (rel. abund. %), 304 [M+-HCl]
(49), 139 (100), 304 (49), 212 (29), 169 (72), 111 (84), 75 (83), 90
(37).
3. Experimental
3.2.5. 4-(3″-Chlorophenyl)-1-[(4′-chlorophenyl)carbonyl]
thiosemicarbazide (5)
3.1. Materials and methods
Solid; Yield: 84%; m.p. 180–182 °C; 1H NMR: (400 MHz, DMSO‑d6):
δH 10.64 (s, 1H, NH-1), 9.88 (s, 2H, NH-2, NH-4), 7.96 (d, 2H,
J2′,3′ = J6′,5′ = 8.4 Hz, H-2′, H-6′), 7.60 (s, 1H, H-2″), 7.60 (d, 2H,
J3′,2′ = J5′,6′ = 8.4 Hz, H-3′, H-5′), 7.45 (d, 1H, J4″,5″ = 8.0 Hz, H-4″),
7.36 (t, 1H, J5″(4″,6″) = 8.0 Hz, H-5″), 7.21 (d, 1H, J6″,5″ = 7.6 Hz, H-6″);
EI-MS: m/z (rel. abund. %), 339 [M]+ (5), 139 (100), 169 (77), 152
(11), 111 (61), 75 (19), 50 (6).
All reagents and solvents were purchased from Sigma-Aldrich USA
and of analytical grade and were as used as received. Pre-coated silica
gel, GF-254 (Merck, Germany) was used for thin layer chromatography.
Spots were visualized under ultraviolet light at 254 and 366 nm. Mass
spectra were recorded on a Finnigan MAT-311A (Germany) mass
spectrometer. The 1H NMR was carried out on Avance Bruker AM
spectrometers, operating at 400 MHz. The chemical shift values are
presented in ppm (δ), relative to tetramethylsilane (TMS) as an internal
standard and the coupling constant (J) are in Hz. Melting points of the
compounds were determined on Stuart® SMP10 melting point appa-
ratus.
3.2.6. 1-[(4′-Chlorophenyl)carbonyl-4-(4″-chlorophenyl)
thiosemicarbazide (6)
Solid; Yield: 80%; m.p. 198–200 °C (lit. 193 °C) [39]; 1H NMR:
(400 MHz, DMSO‑d6): δH 10.62 (s, 1H, NH-1), 9.81 (s, 2H, NH-2, NH-4),
7.96 (d, 2H, J2′,3′ = J6′,5′ = 8.4 Hz, H-2′, H-6′), 7.59 (d, 2H,
J3′,2′ = J5′,6′ = 8.4 Hz, H-3′, H-5′), 7.46 (ovp, 2H, H-3″, H-5″), 7.38 (d,
2H, J2″,3″ = J6″,5″ = 8.8 Hz, H-2″, H-6″); EI-MS: m/z (rel. abund. %),
339 [M]+ (4), 139 (100), 305 (46), 169 (79), 127 (28), 111 (63), 75
(23), 50 (8).
3.2. General experimental procedure for synthesis of compounds 1–25
The reaction mixture containing 4-chlorophenyl hydrazide
(0.5 mmol) and aryl isothiocyanate (0.5 mmol) in absolute ethanol
(10 mL) was refluxed at 80 °C for 20–30 min and monitored through
TLC. Precipitates were appeared in the reaction mixture which were
filtered and washed with hot hexane then cold ethanol [37]. Product
was dried in vacuum and collected. All compounds 1–25 were char-
acterized by spectroscopic techniques such as EI-MS and 1H NMR.
Spectral data of all compounds are as follows.
3.2.7. 4-(2″,3″-Dichlorophenyl)-1-[(4′-chlorophenyl)carbonyl]
thiosemicarbazide (7)
Solid; Yield: 84%; m.p. 192–194 °C; 1H NMR: (400 MHz, DMSO‑d6):
δ
H 10.70 (s, 1H, NH-1), 9.94 (s, 1H, NH-2), 9.77 (s, 1H, NH-4), 7.96 (d,
2H, J2′,3′ = J6′,5′ = 7.6 Hz, H-2′, H-6′), 7.59 (d, 2H,
J3′,2′ = J5′,6′ = 8.4 Hz, H-3′, H-5′), 7.55 (t, 1H, J5″(4″,6″) = 4.2 Hz, H-5″),
7.38 (ovp, 2H, J6″,5″ = J4″,5″ = 7.6 Hz, H-4″, H-6″); MS (FAB+) m/z :
374, EI-MS: m/z (rel. abund. %), 340 [M+ -Cl] (5), 203 (100), 212 (16),
161 (23), 139 (79), 111 (33), 75 (12), 50 (4).
3.2.1. 1-[(4′-Chlorophenyl)carbonyl-4-phenyl)thiosemicarbazide (1)
Solid; Yield: 88%; m.p. 180–182 °C (lit. 180 °C) [38]; 1H NMR:
(400 MHz, DMSO‑d6): δH 10.60 (s, 1H, NH-1), 9.80 (s, 1H, NH-2), 9.69
(s, 1H, NH-4), 7.96 (d, 2H, J2′,3′ = J6′,5′ = 8.4 Hz, H-2′, H-6′), 7.59 (d,
2H, J3′,2′ = J5′,6′ = 8.4 Hz, H-3′, H-5′), 7.42 (ovp, 2H, H-2″, H-6″), 7.33
(t, 2H, J3″(2″, 4″) = J5″(4″,6″) = 7.6 Hz, H-3″, H-5″), 7.16 (t, 1H,
J4″(3″,5″) = 7.2 Hz, H-4″); EI-MS: m/z (rel. abund. %), 305 [M]+ (5), 139
(100), 170 (18), 111 (34), 77 (36).
3.2.8. 4-(2″,5″-Dichlorophenyl)-1-[(4′-chlorophenyl)carbonyl]
thiosemicarbazide (8)
Solid; Yield: 84%; m.p. 162–164 °C; 1H NMR: (400 MHz, DMSO‑d6):
δ
H 10.71 (s, 1H, NH-1), 10.00 (s, 1H, NH-2), 9.70 (s, 1H, NH-4), 7.96 (d,
2H, J2′,3′ = J6′,5′ = 7.6 Hz, H-2′, H-6′), 7.59 (d, 2H,
3.2.2. 4-(2″-Bromophenyl)-1-[(4′-chlorophenyl)carbonyl]
thiosemicarbazide (2)
J3′,2′ = J5′,6′ = 8.8 Hz, H-3′, H-5′), 7.54 (d, 1H, J3″,4″ = 8.4 Hz, H-3″),
7.46 (s, 1H, H-6″) 7.36 (d, 1H, J4″,3″ = 7.6 Hz, H-4″); EI-MS: m/z (rel.
abund. %), 338 [M+-HCl] (5), 75 (100), 212 (97), 203 (72), 161 (57),
139 (85), 111 (77).
Solid; Yield: 92%; m.p. 175–177 °C (lit. 174–176 °C) [36]; 1H NMR:
(400 MHz, DMSO‑d6): δH 10.66 (s, 1H, NH-1), 9.82 (s, 1H, NH-2), 9.64
(s, 1H, NH-4), 7.96 (d, 2H, J2′,3′ = J6′,5′ = 7.6 Hz, H-2′, H-6′), 7.64 (d,
1H, J3″,4″ = 7.6 Hz, H-3″), 7.56 (d, 2H, J3′,2′ = J5′,6′ = 8.0 Hz, H-3′, H-
5′), 7.39 (t, 1H, J4″(3″,5″) = 7.6 Hz, H-4″) 7.20 (t, 1H, J5″(4″,6″) = 8.0 Hz,
H-5″) 7.17 (d, 1H, J6″,5″ = 6.8 Hz, H-6″); EI-MS: m/z (rel. abund. %),
304 [M+ -Br] (11), 139 (100), 215 (76), 171 (30), 111 (80), 75 (80), 90
(35).
3.2.9. 4-(3″,4″-Dichlorophenyl)-1-[(4′-chlorophenyl)carbonyl]
thiosemicarbazide (9)
Solid; Yield: 82%; m.p. 206–208 °C; 1H NMR: (400 MHz, DMSO‑d6):
δ
H 10.66 (s, 1H, NH-1), 9.98 (s, 1H, NH-2), 9.89 (s, 1H, NH-4), 7.96 (d,
2H, J2′,3′ = J6′,5′ = 7.6 Hz, H-2′, H-6′), 7.81 (s, 1H, H-2″), 7.60 (ovp, 4H,
H-3′, H-5′, H-5″, H-6″); MS (FAB+) m/z : 374, EI-MS: m/z (rel. abund.
%), 339 [M+_H2S] (3), 203 (100), 170 (11), 161 (17), 139 (88), 111
(45), 75 (22), 50 (10).
3.2.3. 4-(3″-Bromophenyl)-1-[(4′-chlorophenyl)carbonyl]
thiosemicarbazide (3)
Solid; Yield: 82%; m.p. 200–202 °C; 1H NMR: (400 MHz, DMSO‑d6):
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BioorganicChemistry79(2018)363–371
3.2.10. 4-(5″-Chloro-2″-methylphenyl)-1-[(4′-chlorophenyl)carbonyl]
thiosemicarbazide (10)
3.2.17. 1-[(4′-Chlorophenyl)carbonyl-4-(5″-fluoro-2″-methylphenyl)
thiosemicarbazide (17)
Solid; Yield: 82%; m.p. 168–170 °C; 1H NMR: (400 MHz, DMSO‑d6):
Solid; Yield: 80%; m.p. 192–194 °C; 1H NMR: (400 MHz, DMSO‑d6):
δ
H 10.64 (s, 1H, NH-1), 9.78 (s, 1H, NH-2), 9.61 (s, 1H, NH-4), 7.95 (d,
2H, J2′,3′ = J6′,5′ = 8.4 Hz, H-2′, H-6′), 7.58 (d, 2H,
δ
H 10.62 (s, 1H, NH-1), 9.74 (s, 1H, NH-2), 9.58 (s, 1H, NH-4), 7.94 (d,
2H, J2′,3′ = J6′,5′ = 8.4 Hz, H-2′, H-6′), 7.57 (d, 2H,
J3′,2′ = J5′,6′ = 8.4 Hz, H-3′, H-5′), 7.23 (ovp, 2H, H-3″, H-4″), 7.12 (s,
1H, H-6″), 2.14 (s, 3H, CH3-2″); MS (FAB+) m/z : 354, EI-MS: m/z (rel.
abund. %), 319 [M+−H2S] (2), 106 (100), 183 (15), 141 (95), 139
(75), 111 (41), 77 (75), 51 (45).
J3′,2′ = J5′,6′ = 8.4 Hz, H-3′, H-5′), 7.24 (t, 1H, J4″(3″,5″F) = 7.6 Hz, H-
4″), 7.02 (m, 1H, H-3″), 6.94 (s, 1H, H-6″), 2.12 (s, 3H, CH3-2″); EI-MS:
m/z (rel. abund. %), 303 [M+−H2S] (1), 139 (100), 213 (12), 167(8 4),
152 (21), 111 (86), 75 (76), 50 (38).
3.2.11. 1-[(4′-Chlorophenyl)carbonyl-4-(2″-fluorophenyl)
thiosemicarbazide (11)
3.2.18. 1-[(4′-Chlorophenyl)carbonyl-4-(4″-nitrophenyl)
thiosemicarbazide (18)
Solid; Yield: 90%; m.p. 170–172 °C; 1H NMR: (400 MHz, DMSO‑d6):
Solid; Yield: 82%; m.p. 166–168 °C; 1H NMR: (400 MHz, DMSO‑d6):
δH 10.71 (s, 1H, NH-1), 10.13 (s, 2H, NH-2, NH-4), 8.21(d, 2H,
J3″,2″ = J5″,6″ = 8.7 Hz, H-3″, H-5″), 7.96 (d, 2H, J2′,3′ = J6′,5′ = 9.0 Hz,
H-2′, H-6′), 7.90 (d, 2H, J2″,3″ = J6″,5″ = 8.7 Hz, H-2″, H-6″), 7.61 (d,
2H, J3′,2′ = J5′,6′ = 8.4 Hz, H-3′, H-5′); EI-MS: m/z (rel. abund. %), 350
[M+−H2S], 139 (100), 212 (88), 180 (67), 152 (55), 111 (50), 92 (32),
65 (51).
δ
H 10.67 (s, 1H, NH-1), 9.86 (s, 1H, NH-2), 9.61 (s, 1H, NH-4), 7.96 (d,
2H, J2′,3′ = J6′,5′ = 8.0 Hz, H-2′, H-6′), 7.58 (d, 2H,
J3′,2′ = J5′,6′ = 8.8 Hz, H-3′, H-5′), 7.26 (m, 4H, H-3″, H-4″, H-5″, H-6″);
EI-MS: m/z (rel. abund. %), 323 [M]+ (7), 111 (100), 212 (23), 170
(28), 139 (85), 95 (48), 75 (77).
3.2.12. 1-[(4′-Chlorophenyl)carbonyl-4-(3″-fluorophenyl)
thiosemicarbazide (12)
3.2.19. 1-[(4′-Chlorophenyl)carbonyl-4-(2″,6″-dimethylphenyl)
thiosemicarbazide (19)
Solid; Yield: 92%; m.p. 197–199 °C; 1H NMR: (400 MHz, DMSO‑d6):
δH 10.63 (s, 1H, NH-1), 9.86 (s, 2H, NH-2, NH-4), 7.96 (d, 2H,
J2′,3′ = J6′,5′ = 8.4 Hz, H-2′, H-6′), 7.60 (d, 2H, J3′,2′ = J5′,6′ = 8.4 Hz,
H-3′, H-5′), 7.37 (s, 1H, H-2″), 7.35 (t, 1H, J4″(5″,3″F) =7.6 Hz, H-4″),
7.29 (d, 1H, J6″,5″ = 8.0 Hz, H-6″), 6.99 (t, 1H, J5″(4″,6″) = 7.6 Hz, H-5″);
EI-MS: m/z (rel. abund. %), 323 [M]+ (2), 139 (100), 289 (44), 153
(85), 111 (55), 95 (33), 75 (24).
Solid; Yield: 72%; m.p. 185–187 °C (lit. 185–186 °C) [35]; 1H NMR:
(400 MHz, DMSO‑d6): δH 10.60 (s, 1H, NH-1), 9.56 (s, 1H, NH-2), 9.39
(s, 1H, NH-4), 7.96 (d, 2H, J2′,3′ = J6′,5′ = 8.0 Hz, H-2′, H-6′), 7.57 (d,
2H, J3′,2′ = J5′,6′ = 8.0 Hz, H-3′, H-5′), 7.03 (m, 3H, H-3″, H-4″, H-5″)
2.14 (s, 6H, CH3-2″, CH3-6″); EI-MS: m/z (rel. abund. %), 333 [M]+
(21), 139 (100), 212 (26), 163 (85), 111 (71), 75 (59), 77 (61).
3.2.13. 1-[(4′-Chlorophenyl)carbonyl-4-(2″,4″-difluorophenyl)
thiosemicarbazide (13)
3.2.20. 1-[(4′-Chlorophenyl)carbonyl-4-(3″,5″-dimethylphenyl)
thiosemicarbazide (20)
Solid; Yield: 84%; m.p. 190–192 °C; 1H NMR: (400 MHz, DMSO‑d6):
Solid; Yield: 76%; m.p. 187–189 °C; 1H NMR: (400 MHz, DMSO‑d6):
δ
H 10.68 (s, 1H, NH-1), 9.91 (s, 1H, NH-2), 9.58 (s, 1H, NH-4), 7.96 (d,
2H, J2′,3′ = J6′,5′ = 8.0 Hz, H-2′, H-6′), 7.58 (d, 2H,
δ
H 10.56 (s, 1H, NH-1), 9.67 (s, 1H, NH-2), 9.61(s, 1H, NH-4), 7.95 (d,
2H, J2′,3′ = J6′,5′ = 8.0 Hz, H-2′, H-6′), 7.58 (d, 2H,
J3′,2′ = J5′,6′ = 8.4 Hz, H-3′, H-5′), 7.29 (d, 2H, J5″,6″ = J6″,5″ = 8.0 Hz,
H-5″, H-6″), 7.08 (apparent t, 1H, J3″(2″F,4″F) = 7.6 Hz, H-3″); EI-MS: m/
z (rel. abund. %), 341 [M]+ (2), 139 (100), 307 (54), 179 (43), 171
(98), 111 (80), 75 (36), 50 (15).
J3′,2′ = J5′,6′ = 8.4 Hz, H-3′, H-5′), 7.04 (ovp, 2H, H-2″, H-6″), 6.78 (s,
1H, H-4″) 2.23 (s, 6H, CH3-3″, CH3-5″); MS (FAB+) m/z : 334, EI-MS:
m/z (rel. abund. %), 299 [M+ -H2S] (7), 163 (100), 139 (91), 121 (31),
111 (40), 77 (18), 44 (18).
3.2.14. 1-[(4′-Chlorophenyl)carbonyl-4-(2″,6″-difluorophenyl)
thiosemicarbazide (14)
3.2.21. 1-[(4′-Chlorophenyl)carbonyl-4-(2″-methoxyphenyl)
thiosemicarbazide (21)
Solid; Yield: 84%; m.p. 191–192 °C; 1H NMR: (400 MHz, DMSO‑d6):
Solid; Yield: 84%; m.p. 184–186 °C; 1H NMR: (400 MHz, DMSO‑d6):
δ
H 10.72 (s, 1H, NH-1), 10.03 (s, 1H, NH-2), 9.43 (s, 1H, NH-4), 7.96 (d,
2H, J2′,3′ = J6′,5′ = 8.4 Hz, H-2′, H-6′), 7.58 (d, 2H,
δH 10.68 (s, 1H, NH-1), 9.76 (s, 1H, NH-2), 9.25 (s, 1H, NH-4), 7.95 (d,
2H, J2′,3′ = J6′,5′ = 8.4 Hz, H-2′, H-6′), 7.75 (ovp, 1H, H-3″), 7.60 (d,
2H, J3′,2′ = J5′,6′ = 8.4 Hz, H-3′, H-5′), 7.17 (t, 1H, J4″(3″,5″) = 7.6 Hz, H-
4″), 7.04 (d, 1H, J6″,5″ = 8.0 Hz, H-6″), 6.93 (t, 1H, J5″(4″,6″) = 7.6 Hz,
H-5″), 3.73 (s, 3H, OCH3-2″); EI-MS: m/z (rel. abund. %), 335 [M]+ (4),
139 (100), 212 (20), 165 (85), 123 (91), 80 (83), 75 (93).
J3′,2′ = J5′,6′ = 8.8 Hz, H-3′, H-5′), 7.37 (t, 1H, J4″(3″,5″) =8.0 Hz, H-4″),
7.13 (t, 2H, J3″(4″,2″F) = J5″(4″,6″F) = 8.0 Hz, H-3″, H-5″); MS (FAB+) m/
z : 342, EI-MS: m/z (rel. abund. %), 226 (22), 139 (100), 179.2 (27),
152 (68), 111 (83), 75 (94), 50 (50).
3.2.15. 1-[(4′-Chlorophenyl)carbonyl-4-(2″-trifluoromethylphenyl)
thiosemicarbazide (15)
3.2.22. 1-[(4′-Chlorophenyl)carbonyl-4-(3″-methoxyphenyl)
thiosemicarbazide (22)
Solid; Yield: 75%; m.p. 206–208 °C; 1H NMR: (400 MHz, DMSO‑d6):
Solid; Yield: 83%; m.p. 176–178 °C; 1H NMR: (400 MHz, DMSO‑d6):
δ
H 10.63 (s, 1H, NH-1), 9.84 (s, 1H, NH-2), 9.60 (s, 1H, NH-4), 7.96 (d,
δ
H 10.58 (s, 1H, NH-1), 9.75 (s, 1H, NH-2), 9.70 (s, 1H, NH-4), 7.95 (d,
2H, J2′,3′ = J6′,5′ = 8.4 Hz, H-2′, H-6′), 7.58 (d, 2H,
2H, J2′,3′ = J6′,5′ = 8.0 Hz, H-2′, H-6′), 7.70 (m, 2H, H-3″, H-4″), 7.58
(d, 2H, J3′,2′ = J5′,6′ = 8.8 Hz, H-3′, H-5′), 7.49 (t, 1H,
J5″(4″,6″) = 7.6 Hz, H-5″), 7.41 (ovp, 1H, H-6″); EI-MS: m/z (rel. abund.
%), 373 [M]+ (4), 139 (100), 203 (91), 111 (43), 75 (17), 50 (6).
J3′,2′ = J5′,6′ = 8.4 Hz, H-3′, H-5′), 7.23 (t, 1H, J5″(4″,6″) = 8.0 Hz, H-5″),
7.11 (s, 1H, H-2″), 7.02 (d, 1H, J4″,5″ = 8.0 Hz, H-4″), 6.73 (d, 1H,
J6″,4″ = 8.4 Hz, H-4″) 3.71 (s, 3H, OCH3-3″); EI-MS: m/z (rel. abund.
%), 335 [M]+ (8), 165 (100), 212 (43), 170 (31), 139 (92), 111 (74), 77
(67), 50 (48).
3.2.16. 1-[(4′-Chlorophenyl)carbonyl-4-(3″-trifluoromethylphenyl)
thiosemicarbazide (16)
Solid; Yield: 78%; m.p. 204–206 °C; 1H NMR: (400 MHz, DMSO‑d6):
δH 10.67 (s, 1H, NH-1), 9.96 (s, 2H, NH-2, NH-4), 7.96 (d, 2H,
J2′,3′ = J6′,5′ = 8.4 Hz, H-2′, H-6′), 7.83 (d, 2H, J3′,2′ = J5′,6′ = 7.6 Hz,
H-3′, H-5′), 7.60 (d, 1H, J4″,5″ = 8.4 Hz, H-4″), 7.55 (s, 1H, H-2″), 7.53
(m, 2H, H-5″, H-6″); EI-MS: m/z (rel. abund. %), 373 [M]+ (13), 139
(100), 203 (61), 211 (37), 161 (66), 111 (91), 75 (86).
3.2.23. 1-[(4′-Chlorophenyl)carbonyl-4-(4″-methoxyphenyl)
thiosemicarbazide (23)
Solid; Yield: 84%; m.p. 180–182 °C; 1H NMR: (400 MHz, DMSO‑d6):
δ
H 10.56 (s, 1H, NH-1), 9.68 (s, 1H, NH-2), 9.59 (s, 1H, NH-4), 7.95 (d,
2H, J2′,3′ = J6′,5′ = 8.4 Hz, H-2′, H-6′), 7.58 (d, 2H,
J3′,2′ = J5′,6′ = 8.4 Hz, H-3′, H-5′), 7.27 (d, 2H, J2″,3″ = J6″,5″ = 7.6 Hz,
369

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BioorganicChemistry79(2018)363–371
H-2″, H-6″), 6.89 (d, 2H, J3″,2″ = J5″,6″ = 8.8 Hz, H-3″, H-5″), 3.73 (s,
3H, OCH3-4″); EI-MS: m/z (rel. abund. %), 335 [M]+ (1), 139 (100),
165 (95), 150 (79), 122 (55), 111 (55), 75 (23), 50 (13).
Acknowledgement
This work was financially supported by the Higher Education
Commission (HEC) Pakistan under the National Research Program for
Universities (Project No. 20-1910).
3.2.24. 1-[(4′-Chlorophenyl)carbonyl-4-(4″-ethoxyphenyl)
thiosemicarbazide (24)
Appendix A. Supplementary material
Solid; Yield: 82%; m.p. 190–192 °C; 1H NMR: (400 MHz, DMSO‑d6):
δ
H 10.57 (s, 1H, NH-1), 9.68 (s, 1H, NH-2), 9.59 (s, 1H, NH-4), 7.96 (d,
2H, J2′,3′ = J6′,5′ = 8.4 Hz, H-2′, H-6′), 7.58 (d, 2H,
Supplementary data associated with this article can be found, in the
online version, at https://doi.org/10.1016/j.bioorg.2018.05.017.
J3′,2′ = J5′,6′ = 8.4 Hz, H-3′, H-5′), 7.26 (d, 2H, J3″,2″ = J5″,6″ = 8.0 Hz,
H-3″, H-5″), 6.87 (d, 2H, J2″,3″ = J6″,5″ = 8.8 Hz, H-2″, H-6″), 4.02 (q,
2H, –OCH2CH3), 1.32 (t, 3H, –OCH2CH3); EI-MS: m/z (rel. abund. %),
349 [M]+ (1), 151 (100), 315 (25), 179 (82), 139 (92), 111 (43), 75
(19), 50 (8).
References
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3.2.25. 1-[(4′-Chlorophenyl)carbonyl-4-(2″,4″-dimethoxyphenyl)
thiosemicarbazide (25)
Solid; Yield: 88%; m.p. 192–194 °C; 1H NMR: (400 MHz, DMSO‑d6):
δ
H 10.60 (s, 1H, NH-1), 9.60 (s, 1H, NH-2), 9.15 (s, 1H, NH-4), 7.95 (d,
2H, J2′,3′ = J6′,5′ = 8.0 Hz, H-2′, H-6′), 7.58 (d, 2H,
J3′,2′ = J5′,6′ = 8.4 Hz, H-3′, H-5′), 7.38 (ovp, 1H, H-6″), 6.58 (s, 1H, H-
3″), 6.50 (d, 1H, J5″,6″ = 8.0 Hz, H-5″), 3.75 (s, 6H, OCH3-2″, OCH3-4″);
MS (FAB+) m/z : 366, EI-MS: m/z (rel. abund. %), 365 [M]+ (1), 195
(100), 331 (20), 180 (25), 139 (85), 152 (53), 111 (37), 75 (12), 50 (5).
[6] A. Hameed, M. Yaqub, M. Hussain, A. Hameed, M. Ashraf, H. Asghar, M.M. Quart-
ul-Ain, K. Naseer, M. Mahmood, M.N. Tahir Muddassar, Z. Shafiq, Coumarin-based
thiosemicarbazones as potent urease inhibitors: synthesis, solid state self-assembly
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and energy minimized using the default parameters of the MOE (gra-
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in mdb (Molecular Data Base) file format.
3D structure of the target protein was retrieved from the protein
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