Synthesis, Docking, and Anticancer Activity of New Thiazole Clubbed Thiophene, Pyridine, or Chromene Scaffolds

Article abstract of DOI:10.1002/jhet.3493

2-Cyanoacetamido-4-methylthiazole (1) was utilized as a versatile precursor for the construction of new thiazole clubbed thiazolidine, thiophene, pyridine, or chromene scaffold. The base-catalyzed addition of 1 to phenyl isothiocyanate followed by subsequ

Full text of DOI:10.1002/jhet.3493

Month 2019
Synthesis, Docking, and Anticancer Activity of New Thiazole Clubbed
Thiophene, Pyridine, or Chromene Scaffolds
a
Ahmed S. Radwan
and Mohamed A. A. Khalida,b
*
aDepartment of Chemistry, Turabah University College, Taif University, Taif 21995, Saudi Arabia
bChemistry Department, Faculty of Science, University of Khartoum, Khartoum P.O. Box 321, Sudan
*E-mail: a_radwan2000@yahoo.com; a.radwan@tu.edu.sa
Received September 23, 2018
DOI 10.1002/jhet.3493
Published online 00 Month 2019 in Wiley Online Library (wileyonlinelibrary.com).
2-Cyanoacetamido-4-methylthiazole (1) was utilized as a versatile precursor for the construction of new
thiazole clubbed thiazolidine, thiophene, pyridine, or chromene scaffold. The base-catalyzed addition of 1
to phenyl isothiocyanate followed by subsequent treatment of the produced thiocarbamoyl intermediate with
ethyl chloroacetate or chloroacetonitrile furnished the corresponding thiazolyl-thiazolidine and thiazolyl-
thiophene hybrids. The reactions of compound 1 with chemical reagents, namely, acetylacetone,
malononitrile, and/or 2-(4-anisylidene)-malononitrile have been studied and furnished the corresponding
thiazole-pyridine hydrides 8–10. Furthermore, treatment of the precursor 1 with salicylaldehyde, various aryl
diazonium chlorides, and/or aromatic aldehydes afforded their corresponding thiazolyl-chromene hybrid 12,
arylhydrazono-nitriles 13, and unsaturated nitriles 14, respectively. The cytotoxicity of the synthesized com-
pounds was screened against the cell lines HepG2, HCT-116, and MCF-7. Compounds 8, 10, and 12 re-
corded the best results, which was illustrated by molecular docking. Molecular Operating Environment
molecular docking calculations carried out here is to rationalize correlation between docking results and bi-
ological data of thymidylate synthase (Protein Data Bank code: IHVY) inhibition. Docking has been carried
out in the same co-crystallographic inhibitor binding site to predict if the binding mode of active compounds
is analogous to that of native inhibitor.
J. Heterocyclic Chem., 00, 00 (2019).
INTRODUCTION
clinical use for over 30 years, for example, famotidine is
used for the treatment of peptic ulcer and controls gastro
esophageal reflux [12], and proved to be nine times more
potent than ranitidine [13]; Abafungin as antifungal agent
is used in the treatment of dermatomycoses [14], and
Cefdinir is well-known FDA-approved antibiotic and a
third generation broad spectrum cephalosporin [15].
Recently, some new thiazoles have been synthesized and
Thiazole-containing heterocycles are important class of
compounds that have a wide range of biological activities
[1]. They are well established to possess antimicrobial
[2], anti-inflammatory [3], antitubercular [4,5],
anticonvulsant [6,7], and anticancer [8–11] activities.
Aminothiazole-containing medicines have been applied in
© 2019 Wiley Periodicals, Inc.

A. S. Radwan and M. A. A. Khalid
Vol 000
proved to possess antioxidant property and DNA damage
inhibition ability [16,17]. The biological and synthetic
significance of thiazole-containing heterocycles prompted
us to design and synthesize new thiazole clubbed
thiazolidine, thiophene, pyridine, or chromene derivatives
to screen its activity as anticancer.
containing potassium hydroxide furnished the non-
isolable intermediate potassium sulfide salt 2, which
underwent in situ addition of ethyl chloroacetate at room
temperature to afford 2-cyano-2-(4-oxo-3-phenylthiazolidin-
2-ylidene)-N-(4-methylthiazol-2-yl)acetamide
(3)
(Scheme 1). The chemical structure of this thiazolidinone
was established based on its spectral and elemental
analyses. Infrared spectrum of thiazolidinone derivative
3 showed the characteristic absorption bands at wave
numbers 3127, 2199, and 1740 cmꢀ1 to indicate the
presence of the functional groups NH of amide, cyano,
and carbonyl of the thiazolidine ring, respectively. The
singlet signal for two protons at δ 4.04 ppm (1H-NMR
spectrum), clearly indicated the presence of methylene
group of the thiazolidinone ring. The in situ addition
of chloroacetonitrile to potassium salt 2 proceeded at
room temperature afforded 2-cyano-2-(4-imino-3-
phenylthiazolidin-2-ylidene)-N-(4-methylthiazol-2-yl)acetamide
(4). The chemical structure of this product was assured
from its spectral and elemental analyses. Its IR spectrum
clearly displayed characteristic absorption bands at wave
numbers 3346, 2194, and 1664 cmꢀ1 that refer to N–H of
amide, cyano, and carbonyl functions, respectively. The
singlet signal for two protons at δ 3.92 ppm (1H-NMR
spectrum) clearly indicated the presence of methylene
group of the thiazolidine ring.
2-Cyano-3-mercapto-3-(phenylamino)-N-(4-methylthiazol-
2-yl)acrylamide (5) has been achieved via treatment of 1 with
phenyl isothiocyanate in DMF as a solvent and potassium
hydroxide as a catalyst, followed by neutralization with
dilute hydrochloric acid (Scheme 1). Different behavior,
rather than the formation of thiazole derivatives, was
observed when thiocarbamoyl scaffold 5 was allowed to
react with α-halogenated reagents in ethanol containing
catalytic amount of Et3N. The reaction of compound 5
with ethyl chloroacetate in hot ethyl alcohol containing
drops of triethyl amine furnished ethyl 4-(4-
methylthiazol-2-ylcarbamoyl)-3-amino-5-(phenylamino)-
thiophene-2-carboxylate (6). In addition, heterocyclization
of compound 5 with chloroacetonitrile by reflux in ethyl
alcohol containing drops of triethyl amine furnished the
The enzyme thymidylate synthase (TS) is very important
in the synthesis of 20-deoxythymidine-50-monophosphate,
which consider to be quite essential in DNA biosynthesis
[18–20], and this explain why this enzyme is attracted so
many researchers in the field of cancer chemotherapy [19].
The most prominent inhibitor for TS is 5-fluorouracil,
which have been used widely for the treatment of breast,
ovarian, pancreatic, head, neck, gastric, and colorectal
cancers [21]. Schmitz and his co-authors found that the
activity of 5-fluorouracil in colorectal cancer treatment
can be enhanced by the addition of leucovorin and
reduced folate, and the response rates of these
combinations remain in the range 25–30%; this finding
leads to put much efforts that focused on designing new
and more potent TS inhibitors [21]. Raltitrexed, as a
folate analogue inhibitor, is used widely in Australia,
Japan, Canada, and Europe as first-line therapy for treat-
ment of colorectal cancer, although is considered to be un-
der investigation in the United States. For now, so many
TS inhibitors are available for general clinical treatment;
further researches are needed to connect between the criti-
cal biochemical and molecular factors that determine the
tumor specificity and efficacy of each compound.
The most intuitive and effective research method used to
study the binding between target proteins and drug
molecules is the molecular docking, and recently, this
method gets more attention from researchers worldwide;
it is easy with this method to reveal insight information
about the mechanism of interaction between target
proteins and drug molecules as well as the
conformational change of the resulted complex from
different aspects. In this study, series of active new
compounds were prepared and presented using a direct
synthesis approach, and the interaction mode between the
synthesized compounds and TS active site was
demonstrated by molecular modeling techniques using
Molecular Operating Environment (MOE) software.
corresponding
4-amino-5-cyano-2-(phenylamino)-N-(4-
methylthiazol-2-yl)thiophene-3-carboxamide (7). Various
spectral techniques were utilized to secure the suggested
chemical structures of these newly synthesized thiophene
scaffolds. For example, IR spectrum of thiophene
derivative 6 exhibited absorption bands at wave numbers
3416 and 3243 cmꢀ1 and 1638 cmꢀ1 for the N-H stretch
vibrations (NH2 and NH) and carbonyl functions,
respectively. 1H-NMR spectrum of the same thiophene
scaffold 6 displayed triplet signals at δ 1.31 ppm and
quartet signal at δ 4.30 ppm for the ethyl of ester
(COOCH2CH3), singlet for three protons at δ 2.11 ppm
(CH3), singlet signal for two protons at δ 6.90 ppm (NH2),
RESULTS AND DISCUSSION
Chemistry.
The
key
4-methyl-2-thiazolyl-
cyanoacetamide (1) has been synthesized by heating 2-
amino-4-methylthiazole with cyanoacetic acid in the
presence of acetic anhydride according to the previously
published procedure [22]. Treatment of 4-methyl-2-
thiazolyl-cyanoacetamide (1) with equimolar amount of
phenyl isothiocyanate in dimethylformamide (DMF)
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DOI 10.1002/jhet

Month 2019
Synthesis, Docking, and Anticancer Activity of Thiazole Clubbed Thiophene,
Pyridine, or Chromene
Scheme 1. Reactions of thiazolyl-cyanoacetamide 1 with phenyl isothiocyanate/ethyl chloroacetate and/or chloroacetonitrile.
and multiplet in the region from δ 7.28 to δ 7.64 ppm for the
aromatic and thiazole-C5 protons. In addition, deshielded
two singlet signals at δ 10.24 and δ 11.82 ppm were
assigned for the protons of two NH groups.
diaminopyridone hybrid 9, which was identified from its
spectral and elemental analyses. Thus, IR spectrum of
compound
9 exhibited the characteristic stretching
vibrations for the amino (NH2), nitrile (C≡N), and
carbonyl (C=O) functions at 3372, 3281, and 3216; 2218;
1668 cmꢀ1, respectively. The 1H-NMR spectrum of
pyridone derivative 9 displayed singlet signal at δ
2.08 ppm attributed to the methyl protons. The proton of
pyridine-C5 resonated as singlet at δ 4.74 ppm, while the
proton of thiazole-C5 was verified at δ 7.56 ppm. The
protons of the amino groups were verified as two singlet
signals at δ 5.46 and δ 6.51 ppm.
Scheme 2 represents the chemical trends of thiazolyl-
cyanoacetamide derivative
1
with acetylacetone,
malononitrile, and 2-benzylidene-malononitrile. Thus, the
reaction of 1 with acetylacetone was achieved by
refluxing in ethanol containing drops of piperidine to
furnish
the
corresponding
1-thiazol-2-yl-4,6-
dimethylpyridine hybrid 8, which was identified based on
its spectral and elemental analysis. In a similar manner,
heating of compound 1 with malononitrile in ethanol and
0.5 mL of piperidine furnished the 1-thiazol-2-yl-4,6-
Furthermore, the reaction of compound 1 with 2-(4-
methoxybenzylidene) malononitrile was achieved by
refluxing in ethanol containing piperidine to afford the
corresponding 1-(thiazol-2-yl)-6-aminopyridone hybrid
10. Structure proof of compound 10 was verified from its
spectral and elemental analyses. The IR spectrum
exhibited the characteristic absorption bands at wave
Scheme 2. Synthesis of thiazolyl-pyridine hybrids 8, 9, and 10.
numbers 3412 and 3317, 2209, and 1659 cmꢀ1
,
indicating the presence of the functional groups NH2,
C ≡ N, and C=O, respectively. The two singlet signals in
1H-NMR spectrum of compound 10, each integrated for
three protons and resonated at δ 2.08 and δ 3.98 ppm,
clearly indicated the methyl group at thiazole and the
methoxy group. The aromatic protons resonated as two
doublet signals at δ 7.14 and δ 7.53 ppm. The proton at
the fifth position of thiazole resonated at δ 7.62 ppm
while the protons of amino group was verified as singlet
at δ 8.74 ppm.
Treatment of the key compound 1 with salicylaldehyde
in ethanol containing piperidine under reflux for 4 h
Journal of Heterocyclic Chemistry
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A. S. Radwan and M. A. A. Khalid
Vol 000
furnished 2-imino-N-(4-methylthiazol-2-yl)-2H-chromene-
3-carboxamide (12). A plausible mechanism for the
reaction of 1 with salicylaldehyde is indicated in
Scheme 3. The reaction starts through Knoevenagel
condensation of thiazolyl-cyanoacetamide 1 (from the
active methylene group) and to afford intermediate 11,
which underwent intramolecular cyclization via
nucleophilic addition of the –OH function to the C ≡ N
group promoted the formation of thiazolyl-chromene
scaffold 12. According to IR spectrum of 12, the
absorptions at 3383 and 3218 cmꢀ1 and 1686 cmꢀ1
indicated the presence of two NH and C=O functions,
respectively, while disappearance of any absorption band
near 2200 cmꢀ1 indicated the lack of nitrile function. The
1H-NMR spectrum of 12 revealed signals at 2.10 ppm
(singlet for three protons, CH3), 7.29–7.83 ppm
(multiplet for four aromatic protons and thiazole-H5),
8.61 ppm (singlet for the proton of chromene-C4), and
9.81 and 14.17 ppm for two protons of NH functions.
two singlet signals at 11.84 and 12.68 ppm corresponding
to the protons of two (NH) functions.
Knoevenagel condensation of cyanoacetamide 1 with
various aryl/heteroaryl aldehydes (viz., p-tolualdehyde,
p-anisaldehyde, and thiophene-2-carbaldehyde) was
proceeded by reflux in ethanol and piperidine to furnish
the corresponding α,β-unsaturated nitrile derivatives 14a–
c (Scheme 4). The IR spectrum of 14b was characterized
by the presence of absorptions at 3368, 2213, and
1677 cmꢀ1 corresponding to NH, nitrile, and carbonyl
functions, respectively. The 1H-NMR of 14b displayed
singlet at 2.11 ppm for three protons (thiazole-CH3),
singlet at 3.88 ppm for three protons (OCH3), two
doublet signals at 7.02 and 7.91 ppm for the aromatic
protons, and singlet for one proton at 7.61 ppm (thiazole-
C5). The two singlet signals at 8.32 and 12.26 ppm were
verified the olefinic proton (CH=C) and the proton of
NH, respectively.
The diazo-coupling reaction of 2-cyano-3-aryl-N-(4-
methylthiazol-2-yl)-acrylamide derivatives 14 could not
avoid the reaction at the thiazole ring. Thus, diazo-
coupling reaction of 14b with diazotized 4-
aminoacetophenone furnished the corresponding 3-anisyl-
2-cyano-N-(5-arylazo-thiazol-2-yl)-acrylamide derivative
15. The diazo-coupling reaction was carried out in
pyridine at 0–5°C and occurred at the active methine site
(C-5) of the thiazole ring. Assignment of these products
was based on its correct spectral and elemental analyses.
The IR spectrum of 15 showed absorption bands at 3327,
2209, and 1670 cmꢀ1 corresponding to the imino (N-H),
2-Cyano-N-(4-methylthiazol-2-yl)-acetamide
(1)
showed valuable reactivity toward a series of chemical
reagents; it is distinguished by the presence of two active
sites for electrophilic substitution reaction with aryl
diazonium chlorides. The methylene function proved to
be highly reactive toward diazo-coupling reaction with
aryl diazonium chlorides than the thiazole C-5. Thus,
diazo-coupling reaction of compound 1 with diazotized
substituted
anilines
(viz.,
4-aminophenol,
4-
aminoacetophenone, and 4-aminobenzoic acid) proceeded
in pyridine at 0–5°C to furnish the corresponding N-(4-
methylthiazol-2-yl)-2-arylhydrazono-2-cyanoacetamide
derivatives 13a–c (Scheme 3). The chemical structure of
thiazoles 13a–c has been established because of their
elemental analysis and spectral data. In the IR spectrum of
13b, the presence of absorptions at 3287 cmꢀ1 referred to
the (NH) functions, 2218 cmꢀ1 for the nitrile function
(C ≡ N), and 1668 cmꢀ1 for the carbonyl group (C=O).
The 1H-NMR spectrum of 13b displayed singlet at
2.11 ppm for three protons (thiazole-CH3), singlet at
2.42 ppm for three protons (COCH3), singlet at 7.60 ppm
for one proton (thiazole-H5), and two doublet signals at
7.68 and 8.06 ppm for the aromatic protons in addition to
nitrile (C
≡ N), and carbonyl (C=O) functions,
respectively. The 1H-NMR spectrum of 15 showed
singlet signal integrated for three protons at 2.27 ppm
(thiazole-CH3), singlet for three protons at 2.44 ppm
(COCH3), and singlet for three protons at 3.86 ppm
(OCH3). The aromatic protons resonated as doublet and
multiplet signals in the region 7.07–7.96 ppm for the
aromatic protons. The singlet signals at 8.40 and
12.38 ppm pointed to the olefinic proton (C=CH) and the
proton of (NH) function, respectively.
In vitro antitumor activity.
The pharmacological
activities of the synthesized thiazolyl-thiazolidines 3 and
4, thiazolyl-thiophenes 6 and 7, thiazolyl-pyridines 8, 9,
and 10, and thiazolyl-chromene hybrid 12 were performed
against three types of human cancer cell lines, namely,
HepG2 (hepatocellular cancer), HCT-116 (colon cancer),
and MCF-7 (breast cancer) using MTT colorimetric assay.
Doxorubicin (DOX) was included in the experiment as
the positive control cytotoxic compound for the cell lines.
The IC50 values were listed in Table 1 and indicated great
variety in the cytotoxicity. The thiazolyl-pyridine hybrid 8
exhibited the highest cytotoxic activity with IC50 values
Scheme 3. Synthesis of thiazole-2-yl-chromene derivative 12.
ranges from 5.12
0.3 to 8.33
0.6 for HepG2 and
MCF-7, respectively, was very close to the value of
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DOI 10.1002/jhet

Month 2019
Synthesis, Docking, and Anticancer Activity of Thiazole Clubbed Thiophene,
Pyridine, or Chromene
Scheme 4. Reactions of thiazolyl cyanoacetamide 1 with aryl diazonium chlorides and aromatic aldehydes.
standard drug used. The reactivity of 8 may be attributed to
its chemical structure, where two function groups (C ≡ N
and C=O) present on one side of pyridine ring without
any steric hindrances facilitate bonding with the receptors
that was explained by molecular docking. Despite of the
compound 10 that has more than one function group on
the pyridine ring (2C ≡ N, NH2, and C=O), its
cytotoxicity (9.39 0.6 HCT-116 and 11.86 0.7 MCF-
7) was less than compound 8 that may be related to the
presence of p-methoxybenzene in position 4 of pyridine
ring. Compound 12 with the chromene substituted part
was less active than compounds 8 and 10 (14.46 1.1
HepG2 and 18.48 1.2 HCT-116) although it is closer to
the structure of DOX. It was expected that the fused rings
of compound 12 will play the same rale of as DOX,
where doxorubicin inhibits the progression of
topoisomerase II, an enzyme which relaxes supercoils in
DNA for transcription [23], and stabilizes the
topoisomerase II complex after it has broken the DNA
chain for replication, preventing the DNA double helix
from being resealed and thereby stopping the process of
replication [24].
Molecular docking. The docking experiment on 1HVY
(TS) was carried out by superimposing the energy
minimized ligand on the active site in the Protein Data
Bank file 1HVY, after which the ligand was deleted. The
method of docking calculations in MOE is the default
Triangle Matcher placement along with London DG refine-
ment. Ranking of the final poses was carried out according
to the free energy of binding of the ligand using
GBVI/WSA dG scoring function. For each ligand, 10
poses were selected and the ligand–enzyme complex with
lowest score (binding energy) was selected.
Table 1
Cytotoxic activity of the synthesized thiazolyl-thiazolidine, thiazolyl-
thiophene, thiazolyl-pyridine, and thiazolyl-chromene hybrids.
In vitro cytotoxicity IC50 (μg/mL)
Docking analysis.
From biological data, the most
Compound
HepG2
HCT-116
MCF-7
antitumor active compounds over MCF-7, HCT-116, and
HepG2 cell lines are compounds 8, 10, 12, and DOX,
and molecular docking calculations have been performed
using 1HVY inhibitor binding site to elucidate its
interactions with these active compounds and to predict
if these compounds have analogous binding mode to the
native inhibitor assuming that the active compounds 8,
10, 12, and DOX might demonstrate antiproliferative
action against MCF-7, HepG2, and HCT-116 cell
lines through inhibition of TS as it can be seen from
Table 1.
To validate of the docking procedure and accuracy,
native co-crystallized ligand (raltitrexed) docking was
used; raltitrexed was redocked in the same inhibitor
binding site and found that is exactly superimposed on
the native co-crystallized one with root-mean-square
DOX
1
3
4
6
7
8
9
10
12
13a
13b
13c
14a
14b
14c
15
4.50 0.2
33.82 1.5
29.04 1.3
34.61 1.8
52.44 2.1
42.08 1.8
5.12 0.3
20.21 1.2
12.62 1.1
14.46 1.1
67.27 2.3
54.28 1.4
71.04 2.1
34.06 0.8
23.62 1.0
41.17 1.2
64.16 2.6
5.23 0.3
38.48 1.8
32.37 1.4
38.62 1.6
48.61 1.8
49.46 2.1
11.45 0.8
26.41 1.4
9.39 0.6
18.48 1.2
61.84 2.4
58.34 1.8
55.08 2.4
39.62 1.1
36.02 1.2
44.63 1.5
57.46 2.5
4.17 0.2
31.43 1.3
30.41 0.9
32.68 1.2
55.33 2.0
58.71 2.2
8.33 0.6
28.16 1.6
11.86 0.7
22.52 0.9
58.55 1.7
50.36 1.6
67.43 2.4
32.12 0.7
24.73 0.8
53.27 1.4
59.19 2.8
IC50 (μg/mL): 1–10 (very strong); 11–20 (strong); 21–50 (moderate); 51–
100 (weak); above 100 (non-cytotoxic); DOX, doxorubicin.
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A. S. Radwan and M. A. A. Khalid
Vol 000
Figure 1. Re-docking of raltitrexed ligand in the (1HVY) X-ray crystal structure. The root-mean-square deviation between re-docked ligands and the cor-
responding X-ray crystal structure coordinates is ≤0.75 Å. [Color figure can be viewed at wileyonlinelibrary.com]
deviation being less than or equal to 0.75 Å (Fig. 1) and
binding free energies of ꢀ37.52 kcal/mol. Hydrogen
bonding network between the amino acids and the
docked ligand was the same as those between the amino
acids and the native ligand compound; this demonstrate
the accuracy of docking procedure.
Docking calculations performed here is carried out using
MOE 2010.12 software installed on 8.0G, 64-bit, Core
Figure 2. The interaction of the co-crystalized ligand (raltitrexed) and the binding site within the (1HVY) thymidylate synthase, seven water molecules were
H-bond bridged between binding site residues and donor atoms from the co-crystalized ligand. [Color figure can be viewed at wileyonlinelibrary.com]
Journal of Heterocyclic Chemistry
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Month 2019
Synthesis, Docking, and Anticancer Activity of Thiazole Clubbed Thiophene,
Pyridine, or Chromene
(TM) I5. MOE 2010.12; automated docking program was
used to dock ligands along with the inhibitor (raltitrexed)
into inhibitor binding site. Force field MMFF94 was used
to energy-minimized the complexes till to reach gradient
convergence of 0.01 kcal/mol. The validation of the
binding mode as per the amino acid residue predicted to
be part of the binding site is shown (Fig. 2). Amino acid
residues involved in the binding of protein to raltitrexed
were predicted as Lys77, Leu221, Asp218, Arg50,
Met309, Ile307, Lys107, and Trp109 (Fig. 3).
Binding affinity of the compounds is represented in
Table 2 along with the hydrogen bond interaction with
the target receptor. The compounds that give the best
docking scores, according to their binding free energy
and the best H-bond interactions, were compounds 8
(Fig. 4), 10 (Fig. 5), and 12 (Figs 6 and 7). Most of the
synthesized compounds gave binding affinity less than
the native ligand (raltitrexed) which binding free
energy was ꢀ37.52 kcal/mol, while the score of binding
free energy of most of the new synthesized compounds
was around ꢀ10 to ꢀ19 kcal/mol. The overall correlation
between binding free energy (represented as p-docking
score) and the biological activity data of the synthesized
compounds (represented as IC50) against MCF-7,
HepG2, and HCT-116 are shown in (Fig. 8). Some of
the synthesized compounds’ biological activities are
Figure 3. Ramchandran plot [(1HVY) thymidylate synthase] after energy
and residue optimization, this is revealing the health of the protein. [Color
figure can be viewed at wileyonlinelibrary.com]
Table 2
Comparative docking scores, Ki values, and H-bond interaction between ligands and binding site of (1HVY) thymidylate synthase.
H-bond interaction
Docking
score
(kcal/mol)
P-docking
score
Involved
receptor
Atom of
compound
Atom of
receptor
H-bond
length
Molecule
1
Ki value
2.37E-08
RMSD Å
1.29
ꢀ10.39
1.02
Asp218
CH ring
CO
C=NH
NH
C=NH
SH
NH
CO
CN
CO
CH ring
CN
NH
CN ring
CN
CO
CN
CN
CN
CN
CO
CO
NH
NH
NH
NH
CO
CO
NH
NH
NH
CO
NH
CO
NH
NH
NH
NH
NH
NH
NH
NH
CO
1.93
2.44
2.67
1.85
2.12
3.67
2.05
1.99
1.88
1.75
2.10
2.53
1.59
1.89
2.38
1.97
2.37
2.63
1.90
2.25
1.67
1.75
3
4
5
6
7
8
ꢀ13.56
ꢀ15.22
ꢀ13.88
ꢀ13.32
ꢀ13.91
ꢀ18.42
1.13
1.18
1.14
1.12
1.14
1.27
1.12E-10
6.78E-12
6.56E-11
1.69E-10
6.21E-11
3.04E-14
Lys77
Arg50
Arg50
Asp218
Asp218
Arg50
1.85
1.32
1.85
1.62
1.30
1.08
9
ꢀ14.27
1.15
3.38E-11
Arg50
Asp218
Lys77
Asp218
Arg50
Lys77
Arg50
Arg50
Lys77
Arg50
1.56
10
12
ꢀ17.72
ꢀ17.39
ꢀ12.17
ꢀ12.09
ꢀ12.59
ꢀ13.58
ꢀ12.98
ꢀ12.74
1.25
1.248
1.09
1.08
1.10
1.13
1.11
1.11
9.923E-14
1.73E-13
1.18E-09
1.34E-09
5.78E-10
1.09E-10
2.98E-10
4.48E-10
1.81
1.50
0.87
1.19
1.14
1.11
1.18
1.07
13a
13b
13c
14a
14b
14c
15
DOX
ꢀ15.09
ꢀ19.35
1.18
1.29
8.45E-12
6.35E-15
Arg50
Asp218
1.22
1.87
NH
RMSD, root-mean-square deviation.
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

A. S. Radwan and M. A. A. Khalid
Vol 000
Loughborough, UK). The IR spectra were measured on a
Thermo Scientific Nicolet iS10 FTIR spectrometer
(Waltham, MA). 1H-NMR spectra were recorded in
DMSO-d6 on Bruker WP spectrometer (Rheinstetten,
Germany) at 400 MHz using tetramethylsilane as an inter-
nal standard. The mass spectra were recorded on a Quadru-
pole GC/MS Thermo Scientific Focus/DSQII (Waltham,
MA) at 70 eV. Elemental analyses (C, H, and N) were de-
termined on Perkin-Elmer 2400 analyzer (PerkinElmer In-
struments, Shelton, CT).
Synthesis of 2-cyano-2-(3-phenylthiazolidin-2-ylidene)-N-
(4-methylthiazol-2-yl)-acetamide scaffolds 3 and 4.
To a
stirred suspension of 2-cyano-N-(4-methylthiazol-2-yl)
acetamide (1) (5 mmol, 0.90 g) and potassium hydroxide
(5 mmol, 0.28 g) in 15 mL of DMF, phenyl
isothiocyanate (5 mmol, 0.6 mL) was added, and the
reaction mixture was allowed to stir at an ambient
temperature for 4 h. After which, 5 mmol of the
Figure 4. The interaction of the active compound 8 ligand and the binding
site within the (1HVY) thymidylate synthase, four water molecules were H-
bond bridged between binding site residues and donor atoms from the ac-
tive compound 8. [Color figure can be viewed at wileyonlinelibrary.com]
appropriate
α-chlorinated
reagent
(viz.,
ethyl
chloroacetate and chloroacetonitrile) was added, and the
stirring was continued for additional 4 h. The solid that
formed by pouring the reaction mixture onto ice water
has been collected by filtration. The crude product was
purified by recrystallization from ethyl alcohol.
2-Cyano-N-(4-methylthiazol-2-yl)-2-(4-oxo-3-
phenylthiazolidin-2-ylidene)-acetamide
(3).
Yellow
powder, yield 62%; m.p. 192–194°C. IR (KBr): vmax.
/
cmꢀ1 = 3127 (N-H), 2199 (C ≡ N), 1740 (C=O). H-
NMR (DMSO-d6) δ/ppm: 2.11 (s, 3H, CH3), 4.04 (s, 2H,
CH2), 7.32–7.51 (m, 5H, Ar-H), 7.58 (s, 1H, thiazole-
H5), 11.88 (s, 1H, NH). Anal. Calcd for C16H12N4O2S2
(356): C, 53.92; H, 3.39; N, 15.72%. Found: C, 53.71; H,
3.46; N, 15.81%.
1
2-Cyano-2-(4-imino-3-phenylthiazolidin-2-ylidene)-N-(4-
methylthiazol-2-yl)-acetamide (4). Yellow powder, yield
48%, m.p. 166–167°C. IR (KBr): vmax./cmꢀ1 = broad at
3346 (N-H), 2194 (C ≡ N), 1664 (C=O). 1H-NMR
(DMSO-d6) δ/ppm: 2.12 (s, 3H, CH3), 3.92 (s, 2H, CH2),
7.05–7.48 (m, 5H, Ar-H), 7.56 (s, 1H, thiazole-H5), 9.82
(s, 1H, NH), 12.04 (s, 1H, NH). Anal. Calcd for
C16H13N5OS2 (355): C, 54.07; H, 3.69; N, 19.70%.
Found: C, 54.21; H, 3.76; N, 19.58%.
Figure 5. The interaction of the active compound 10 ligand and the bind-
ing site within the (1HVY) thymidylate synthase, four water molecules
were H-bond bridged between binding site residues and donor atoms from
the active compound 10. [Color figure can be viewed at
wileyonlinelibrary.com]
Synthesis of 2-cyano-3-mercapto-3-(phenylamino)-N-(4-
methylthiazol-2-yl)-acrylamide (5).
To
a
stirred
suspension of cyanoacetamide scaffold 1 (10 mmol,
1.81 g) and potassium hydroxide (10 mmol, 0.56 g) in
25 mL of DMF, phenyl isothiocyanate (10 mmol,
1.2 mL) was dropwise added and permitted to stir at an
ambient temperature for 4 h. After which, the reaction
mixture was poured onto ice water and neutralized by
diluted HCl. The solid formed has been collected up by
filtration and recrystallized by heating in ethyl alcohol.
Yellow powder, yield 76%, m.p. 166–168°C. IR (KBr):
correlated with their binding free energy, and some are out
of correlation.
EXPERIMENTAL
All melting points (uncorrected) were determined on an
electrothermal Gallenkamp apparatus (Weiss-Gallenkamp,
v
max./cmꢀ1 = 3314, 3196 (N-H), 2182 (C ≡ N), 1659
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2019
Synthesis, Docking, and Anticancer Activity of Thiazole Clubbed Thiophene,
Pyridine, or Chromene
1
(C=O). H-NMR (DMSO-d6) δ/ppm: 2.08 (s, 3H, CH3),
2.72 (s, 1H, SH), 7.05–7.45 (m, 5H, Ar-H), 7.58 (d, 1H,
thiazole-H5), 10.28 (s, 1H, NH), 11.94 (s, 1H, NH). Anal.
Calcd for C14H12N4OS2 (316): C, 53.36; H, 3.90; N,
17.71%. Found: C, 53.14; H, 3.82; N, 17.83%.
Synthesis of 5-substituted-4-amino-2-(phenylamino)-N-(4-
methylthiazol-2-yl)-thiophene-3-carboxamide scaffolds 6 and
7. To a solution of thiocarbamoyl scaffold 5 (2 mmol,
0.63 g) in 15 mL of ethanol, the appropriate α-
chlorinated reagent (viz., ethyl chloroacetate and
chloroacetonitrile, 2 mmol) and 0.5 mL of (C2H5)3N
were added, and the reaction mixture was refluxed for
2 h, after which left to cool to 25°C. The solid formed
was filtered off and dried to afford the thiophene
scaffolds 6 and 7.
Ethyl
4-(4-methylthiazol-2-ylcarbamoyl)-3-amino-5-
(6).
(phenylamino)thiophene-2-carboxylate Yellow
powder, yield 64%, m.p. 220–221°C. IR (KBr): vmax.
/
cmꢀ1 = 3416, 3243 (N-H stretch of NH2 and NH), broad
at 1638 (C=O). 1H-NMR (DMSO-d6) δ/ppm: 1.31 (t,
J = 7.1 Hz, 3H, CH3), 2.11 (s, 3H, CH3), 4.30 (q,
J = 7.2 Hz, 2H, CH2), 6.90 (s, 2H, NH2), 7.28–7.64 (m,
6H, Ar-H and thiazole-H5), 10.24 (s, 1H, NH), 11.82 (s,
1H, NH). Anal. Calcd for C18H18N4O3S2 (402): C, 53.71;
H, 4.51; N, 13.92%. Found: C, 53.86; H, 4.57; N, 13.83%.
4-Amino-5-cyano-2-(phenylamino)-N-(4-methylthiazol-2-
Figure 7. The interaction of the active compound doxorubicin ligand and
the binding site within the (1HVY) thymidylate synthase, four water mol-
ecules were H-bond bridged between binding site residues and donor
atoms from the active compound doxorubicin. [Color figure can be
viewed at wileyonlinelibrary.com]
NH), 12.04 (s, 1H, NH). Anal. Calcd for C16H13N5OS2
(355): C, 54.07; H, 3.69; N, 19.70%. Found: C, 54.19; H,
3.65; N, 19.62%.
yl)thiophene-3-carboxamide (7).
Yellowish brown
powder, yield 72%, m.p. 213–215°C. IR (KBr): vmax.
/
cmꢀ1 = 3416, 3220, 3175 (N-H stretch of NH2 and NH),
2172 (C ≡ N), shoulder near 1633 (C=O). 1H-NMR
(DMSO-d6) δ/ppm: 2.11 (s, 3H, CH3), 6.62 (s, 2H, NH2),
7.21–7.61 (m, 6H, Ar-H and thiazole-H5), 10.41 (s, 1H,
Synthesis of 4,6-disubstituted-2-oxo-1-(4-methylthiazol-2-
yl)-1,2-dihydro pyridine-3-carbonitriles
8
and 9.
A
solution of cyanoacetamide scaffold 1 (4 mmol, 0.72 g)
and acetylacetone or malononitrile (4 mmol) in 20 mL of
Figure 6. The interaction of the active compound 12 ligand and the binding site within the (1HVY) thymidylate synthase, four water molecules were H-
bond bridged between binding site residues and donor atoms from the active compound 12. [Color figure can be viewed at wileyonlinelibrary.com]
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

A. S. Radwan and M. A. A. Khalid
Vol 000
1
(C=O). H-NMR (DMSO-d6) δ/ppm: 2.08 (s, 3H, CH3),
3.86 (s, 3H, OCH3), 7.14 (d, J = 8.8 Hz, 2H, Ar-H), 7.53
(d, J = 8.8 Hz, 2H, Ar-H), 7.62 (s, 1H, thiazole-H5), 8.74
(s, 2H, NH2). Anal. Calcd for C18H13N5O2S (363): C,
59.49; H, 3.61; N, 19.27%. Found: C, 59.58; H, 3.65; N,
19.35%.
Synthesis
of
2-imino-N-(4-methylthiazol-2-yl)-2H-
chromene-3-carboxamide (12).
A
suspension of
cyanoacetamide scaffold 1 (4 mmol, 0.72 g) and
salicylaldehyde (4 mmol, 0.42 mL) was refluxed for 4 h
in 15 mL of EtOH containing 0.5 mL of piperidine. After
which, the reaction mixture was cooled to room
temperature, and the solid formed was collected by
filtration. Recrystallization of the product has been
achieved by heating in ethyl alcohol.
Yellow crystals, yield 64%, m.p. 132–134°C. IR (KBr):
1
v
max./cmꢀ1 = 3383, 3218 (N-H), 1686 (C=O). H-NMR
(DMSO-d6) δ/ppm: 2.10 (s, 3H, CH3), 7.29–7.83 (m, 5H,
Ar-H, thiazole-H5), 8.61 (s, 1H, chromene-H4), 9.81 (s,
1H, NH), 14.17 (s, 1H, NH). Anal. Calcd for
C14H11N3O2S (285): Calcd: C, 58.94; H, 3.89; N,
14.73%. Found: C, 58.82; H, 3.96; N, 14.81%.
Figure 8. The correlation between IC50 (μg/mL) enzymatic inhibition
and the Molecular Operating Environment p-docking score. [Color
figure can be viewed at wileyonlinelibrary.com]
EtOH containing 0.5 mL of piperidine was heated under
reflux for 6 h. After which, the reaction mixture was
cooled to 25°C and the solid formed was collected by
filtration. Recrystallization was carried out from dioxane
to afford the pyridine derivatives 8 and 9, respectively.
Synthesis
N-aryl-2-((4-methylthiazol-2-yl)amino)-2-
oxoacetohydrazonoyl cyanide 13a–c. To a cold solution
of the cyanoacetamide scaffold 1 (5 mmol, 0.90 g) in
pyridine (20 mL), the appropriate diazonium salt of the
appropriate
4-aminoacetophenone,
aromatic
amine
and 4-aminobenzoic
(4-hydroxy-aniline,
acid)
4,6-Dimethyl-2-oxo-1-(4-methylthiazol-2-yl)-1,2-
dihydropyridine-3-carbonitrile (8).
Yellowish white
crystals, yield 69%, m.p. 242–244°C. IR (KBr): vmax.
/
(5 mmol) was added. The addition was carried out
portion wise with stirring at 0–5°C over a period of
30 min. After complete addition, the reaction mixture
was kept in an ice bath for 12 h and finally diluted with
water. The solid that formed was filtrated, washed with
water, dried, and finally recrystallized from the
EtOH/EMF mixture (2:1) to afford the corresponding
hydrazonoyl cyanides 13a–c.
cmꢀ1 = 2222 (C ≡ N), 1674 (C=O). H-NMR (DMSO-
d6) δ/ppm: 2.08 (s, 3H, CH3), 2.39 (s, 3H, CH3), 2.40 (s,
3H, CH3), 6.49 (s, 1H, pyridine-H5), 7.57 (s, 1H,
thiazole-H5). Anal. Calcd for C12H11N3OS (245): C,
58.76; H, 4.52; N, 17.13%. Found: C, 58.92; H, 4.45; N,
17.24%.
1
4,6-Diamino-1-(4-methylthiazol-2-yl)-2-oxo-1,2-
dihydropyridine-3-carbonitrile (9). Brown powder, yield
N-(4-Hydroxyphenyl)-2-((4-methylthiazol-2-yl)amino)-2-
oxoacetohydrazonoyl cyanide (13a). Orange crystals, yield
69%, m.p. 192–193°C. IR (KBr): vmax./cmꢀ1 = 3372,
1
69%, m.p. 271-273°C. IR (KBr): vmax./cmꢀ1 = 3241 (O-
3281, 3216 (NH2), 2218 (C ≡ N), 1668 (C=O). H-NMR
1
(DMSO-d6) δ/ppm: 2.08 (s, 3H, CH3), 4.74 (s, 1H,
pyridine-H5), 5.46 (s, 2H, NH2), 6.51 (s, 2H, NH2), 7.56
(s, 1H, thiazole-H5). Anal. Calcd for C10H9N5OS (247):
C, 48.57; H, 3.67; N, 28.32%. Found: C, 48.34; H, 3.60;
N, 28.44%.
H), 3173 (N-H), 2216 (C ≡ N), 1664 (C=O). H-NMR
(DMSO-d6) δ/ppm: 2.10 (s, 3H, CH3), 7.14 (d, 2H, Ar-
H), 7.44 (d, 2H, Ar-H), 7.62 (s, 1H, thiazole-H5,), 9.54
(s, 1H, OH), 11.58 (s, 1H, NH), 12.63 (s, 1H, NH). Anal.
Calcd for C13H11N5O2S (301): C, 51.82; H, 3.68; N,
23.24%. Found: C, 51.96; H, 3.62; N, 23.34%.
Synthesis of 6-amino-4-(4-anisyl)-1,2-dihydro-2-oxo-1-(4-
methylthiazol-2-yl)pyridine-3,5-dicarbonitrile 10.
To a
N-(4-Acetylphenyl)-2-((4-methylthiazol-2-yl)amino)-2-
solution of cyanoacetamide scaffold 1 (4 mmol, 0.72 g)
and 2-(4-methoxybenzylidene) malononitrile (4 mmol,
0.74 g) in 20 mL of ethanol, five drops of piperidine
were dropwise added. After which, the reaction mixture
was boiled under reflux for 2 h, and the solid product
was filtered off to give the desired pyridine derivative 10.
Brown crystals, yield 69%, m.p. 275–277°C. IR (KBr):
oxoacetohydrazonoyl cyanide (13b).
Red crystals, yield
74%; m.p. 264-266°C. IR (KBr): vmax./cmꢀ1 = 3287 (N-
H), 2218 (C ≡ N), broad at 1668 (C=O). 1H-NMR
(DMSO-d6) δ/ppm: 2.11 (s, 3H, CH3), 2.42 (s, 3H, CH3),
7.60 (s, 1H, thiazole-H5), 7.68 (d, 2H, Ar-H), 8.06 (d,
2H, Ar-H), 11.84 (s, 1H, NH), 12.68 (s, 1H, NH). Anal.
Calcd for C15H13N5O2S (327): C, 55.03; H, 4.00; N,
21.39%. Found: C, 55.19; H, 4.04; N, 21.28%.
v
max./cmꢀ1 = 3412, 3317 (NH2), 2209 (C ≡ N), 1659
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

Month 2019
Synthesis, Docking, and Anticancer Activity of Thiazole Clubbed Thiophene,
Pyridine, or Chromene
N-(4-Carboxyphenyl)-2-((4-methylthiazol-2-yl)amino)-2-
collected by filtration, washed with water, dried, and
finally recrystallized from dioxane.
Brown powder, yield 56%, m.p. 274–276°C. IR (KBr):
oxoacetohydrazonoyl cyanide (13c).
Red crystals, yield
58%, m.p. 255-256°C. IR (KBr): vmax./cmꢀ1 = 3276,
(N-H), 2748 (O-H), 2220 (C ≡ N), broad at 1678
v
max./cmꢀ1 = 3327 (N-H), 2209 (C ≡ N), broad at 1670
1
1
(C=O). H-NMR (DMSO-d6) δ/ppm: 2.10 (s, 3H, CH3),
(C=O). H-NMR (DMSO-d6) δ/ppm: 2.27 (s, 3H, CH3),
2.44 (s, 3H, CH3), 3.86 (s, 3H, OCH3), 7.07 (d, 2H, Ar-H),
7.46–7.96 (m, 6H, Ar-H), 8.25 (s, 1H, CH=C), 12.38 (s,
1H, NH). Anal. Calcd for C23H19N5O3S (445): C, 62.01;
H, 4.30; N, 15.72%. Found: C, 62.20; H, 4.22; N, 15.60%.
7.64 (s, 1H, thiazole-H5), 7.72 (d, 2H, Ar-H), 8.15 (d,
2H, Ar-H), 11.73 (s, 1H, NH), 12.63 (s, 1H, OH),
12.91 (s, 1H, NH). Anal. Calcd for C14H11N5O3S
(329): C, 51.06; H, 3.37; N, 21.27%. Found: C, 50.93;
H, 3.40; N, 21.20%.
Anticancer screening.
For the estimation of the
Synthesis
of
3-aryl-2-cyano-N-(4-methylthiazol-2-yl)-
cytotoxicity effects of the investigated thiazole-containing
heterocycles derived from N-(4-methylthiazol-2-yl)-
cyanoacetamide, three human cancer cell lines were used
(viz., hepatocellular cancer HepG-2, colon cancer HCT-
116, and breast cancer MCF-7). These cell lines were
obtained from ATCC via holding company for biological
products and vaccines (VACSERA), Cairo, Egypt. Cyto-
toxicity determinations are based the transformation of
the yellow 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetra-
zolium bromide (MTT) to a purple formazan derivative by
mitochondrial succinate dehydrogenase in practical cells.
The method of this MTT assay was performed as previ-
ously described in detail [25–28].
Molecular docking study. Docking calculations carried
out here were performed on (Intel Core I5) Toshiba
Satellite with running Windows 10, installed MOE
software version 2010.12, respectfully available from
CCG (Chemical Computing Group Inc.), 1010
Sherbrooke Street West, Suite 910, Montreal, QC [29].
Selection of crystal structures of the protein.
Crystallographic structure of the ligand bound of our
target protein (TS) is downloaded from the Protein Data
Bank website (https://www.rcsb.org). In this study,
1HVY crystal structure have been selected and evaluated
for docking. Furthermore, errors of the protein structure
were corrected using MOE structure preparation process.
Initially, and for generation of suitable protein structure
for docking the hydrogen atoms were assigned, water
molecules contained in the protein structure with distance
further than 10 Å were removed, partial charges were
assigned, and energy of the remaining structure was
minimized using the default parameters of MOE energy
minimization algorithm (gradient: 0.01, Force field:
MMFF94X). This is performed based on default rules
(Temperature of the system is 300 K, pH is 7.0, and
dielectric constant is 1.0). Finally, collection of residues
acrylamides 14a–c. To a solution of the cyanoacetamide
1 (5 mmol, 0.90 g) and the appropriate aromatic aldehydes
(4-methylbenzaldehyde, 4-methoxybenzaldehyde, and
thiophene-2-carbaldehyde) (5 mmol) in dioxane (20 mL),
five drops of piperidine was added, and the reaction
mixture was refluxed for 4 h. The solid that formed was
filtered off, dried, and finally recrystallized from dioxane.
2-Cyano-N-(4-methylthiazol-2-yl)-3-(4-tolyl)-acrylamide
(14a). Yellow crystals, yield 82%; m.p. 235–238°C. IR
(KBr): vmax./cmꢀ1 = 3337 (N-H), 2216 (C ≡ N), 1675
1
(C=O). H-NMR (DMSO-d6) δ/ppm: 2.12 (s, 3H, CH3),
2.40 (s, 3H, CH3), 7.42 (d, 2H, Ar-H), 7.55 (s, 1H,
thiazole-H5), 7.83 (d, 2H, Ar-H), 8.38 (s, 1H, CH=C),
12.28 (s, 1H, NH). Anal. Calcd for C15H13N3OS (283):
C, 63.58; H, 4.62; N, 14.83%. Found: C, 63.46; H, 4.66;
N, 14.75%.
3-(4-Anisyl)-2-cyano-N-(4-methylthiazol-2-yl)-acrylamide
(14b). Yellow crystals, yield 73%, m.p. 230–233°C. IR
(KBr): vmax./cmꢀ1 = 3368 (N-H), 2213 (C ≡ N), 1677
1
(C=O). H-NMR (DMSO-d6) δ/ppm: 2.11 (s, 3H, CH3),
3.88 (s, 3H, OCH3), 7.02 (d, 2H, Ar-H), 7.61 (s, 1H,
thiazole-H5), 7.91 (d, 2H, Ar-H), 8.32 (s, 1H, CH=C),
12.26 (s, 1H, NH). Anal. Calcd for C15H13N3O2S (299):
C, 60.18; H, 4.38; N, 14.04%. Found: C, 60.26; H, 4.34;
N, 14.10%.
2-Cyano-N-(4-methylthiazol-2-yl)-3-(2-thienyl)-acrylamide
(14c). Yellow crystals, yield 65%, m.p. 240–242°C. IR
(KBr): vmax./cmꢀ1 = 3307 (N-H), 2221 (C ≡ N), 1674
1
(C=O). H-NMR (DMSO-d6) δ/ppm: 2.12 (s, 3H, CH3),
7.28 (m, 1H, thiophene-H4), 7.64 (s, 1H, thiazole-H5),
7.65 (d, 1H, thiophene-H3), 8.15 (d, 1H, thiophene-H5),
8.44 (s, 1H, CH=C), 12.53 (s, 1H, NH). Anal. Calcd for
C12H9N3OS2 (275): C, 52.34; H, 3.29; N, 15.26%.
Found: C, 52.18; H, 3.22; N, 15.37%.
Synthesis of N-(5-(4-acetylphenylazo)-4-methylthiazol-2-
yl)-2-cyano-3-(4-methoxy phenyl)acrylamide (15).
To a
within distance of 6.5 Å from the bound co-
cold solution of 14b (5 mmol, 1.50 g) in pyridine
(20 mL), the diazonium salt derived from 4-
aminoacetophenone (5 mmol, 0.68 g) was added. The
addition was carried out portion wise with stirring at 0–
5°C over a period of 30 min. After complete addition, the
reaction mixture was kept in an ice chest overnight and
finally diluted with water. The solid that formed was
crystallographic inhibitor was used to define the active
site of the protein.
Preparation of the ligand for docking.
Molecular
Operating Environment (MOE) builder tool is used in
building the ligand structure, followed by correction of
atom types, including hybridization states, and defining of
the bond types, then addition of hydrogen atoms, assigning
Journal of Heterocyclic Chemistry
DOI 10.1002/jhet

A. S. Radwan and M. A. A. Khalid
Vol 000
[7] Agarwal, A.; Lata, S.; Saxena, K. K.; Srivastava, V. K.;
Kumar, A. Eur J Med Chem 2006, 41, 1223.
[8] Wang, S.; Zhao, Y.; Zhang, G.; Lv, Y.; Zhang, N.; Gong, P.
Eur J Med Chem 2011, 46, 3509.
[9] Kamel, M. M.; Ali, H. I.; Anwar, M. M.; Mohamed, N. A.;
Soliman, A. M. Eur J Med Chem 2010, 45, 572.
of atom charges, and then, the structures were subject
to energy minimization using MMFF94x method until a
gradient of 0.01 kcal/mol is reached; this process is applied
for co-crystallographic ligand and synthesized ligands.
[10] Havrylyuk, D.; Mosula, L.; Zimenkovsky, B.; Vasylenko, O.;
Gzella, A.; Lesyk, R. Eur J Med Chem 2010, 45, 5012.
[11] Pansare, D. N.; Shelke, R. N.; Shinde, D. B. J Heterocyclic
Chem 2017, 54, 3077.
CONCLUSION
[12] Laine, L.; Kivitz, A. J.; Bello, A. E.; Grahn, A. Y.; Schiff, M.
H.; Taha, A. S. Am J Gastroenterol 2012, 107, 379.
[13] Howard, J. M.; Chremos, A. N.; Collen, M. J.; Mcarthur,
K. E.; Cherner, J. A.; Maton, P. N.; Ciarleglio, C. A.; Cornelius,
M. J.; Gardner, J. D.; Jensen, R. T. Gastroenterology 1985, 88,
1026.
[14] Borelli, C.; Schaller, M.; Niewerth, M.; Nocker, K.; Baasner,
B.; Berg, D.; Tiemann, R.; Tietjen, K.; Fugmann, B.; Lang-Fugmann,
S.; Korting, H. C. Chemotherapy 2008, 54, 245.
[15] Guay, D. R. P. Clin Ther 2002, 24, 473.
[16] Yapati, H.; Devineni, S. R.; Chirumamilla, S.; Kalluru, S. J
Chem Sci 2016, 128, 43.
[17] Shubakara, K.; Umesha, K. B.; Srikantamurthy, N.; Chethan,
J. J Chem Sci 2014, 126, 1913.
A series of thiazole derivatives contains thiazolidine,
thiophene, pyridine, or chromene was synthesized, and
the structures were confirmed by spectral and elemental
analysis. The antiproliferative activity of the new
heterocyclic compounds was screened in vitro against cell
lines of hepatocellular cancer (HepG-2), colon cancer
(HCT-116), and breast cancer (MCF-7). The most
effective compounds were pyridine derivatives 8, 10, and
the fused chromene structure 12 compared by the
reference drug (doxorubicin) which is used in this study.
The molecular docking was helpful in illustrating the
interaction mode between the active compounds and the
target protein (thymidylate thynsase in this case);
hydrogen bonding network have been investigated and
found that the most attractive residues that bind
effectively with active compounds are Asp218, Arg50,
Met309, Ile307, Lys107, and Trp109.
[18] Brandt, D. S.; Chu, E. Oncol Res 1997, 9, 403.
[19] Chu,
E.;
Allegra,
C.
Antifolates;
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