Synthesis, antimicrobial and antiproliferative activities, molecular docking, and computational studies of novel heterocycles

Article abstract of DOI:10.1007/s13738-021-02251-7

We studied the reaction of enaminone 3 with some nitrogen nucleophiles to afford the corresponding pyrazole 4, isoxazole 5, and pyrimidine 6 derivatives, and the reactivity of enaminone 3 with heterocyclic amines to afford the corresponding fused pyrrolo[

Full text of DOI:10.1007/s13738-021-02251-7

Journal of the Iranian Chemical Society
https://doi.org/10.1007/s13738-021-02251-7
ORIGINAL PAPER
Synthesis, antimicrobial and antiproliferative activities, molecular
docking, and computational studies of novel heterocycles
Asmaa M. Fahim1 · Hala E. M. Tolan2 · Hanem Awad3 · Eman H. I. Ismael4
Received: 17 February 2021 / Accepted: 2 April 2021
© Iranian Chemical Society 2021
Abstract
We studied the reaction of enaminone 3 with some nitrogen nucleophiles to aford the corresponding pyrazole 4, isoxazole 5,
and pyrimidine 6 derivatives, and the reactivity of enaminone 3 with heterocyclic amines to aford the corresponding fused
pyrrolo[1,2-a]pyrimidine 9a, imidazo[1,2-a]pyrimidine 9b, phenylpyrrolo[1,2-a]pyrimidine 9c, and benzo[4,5]imidazo[1,2-
a]pyrimidine 11 derivatives. Additionally, the electrophilic azo-coupling reaction of enaminone 3 with aromatic diazonium
salts in pyridine aforded the corresponding intermediate hydrazines 13a–d, which cyclized to pyrazolo[5,1-c][1,2,4]triazine
derivatives 14a–d. Moreover, addition of (E)-3-(dimethylamino)-1-(2-hydroxyphenyl)prop-2-en-1-one (3) with hydrazonoyl
chloride derivatives 15a,b gave novel pyrazole derivatives 17a,b. Almost all of the synthesized heterocyclic compounds
exhibited antimicrobial and in vitro anticancer activity (HepG2 and MCF-7 cell lines). Furthermore, the molecular docking of
the most efective compound, i.e., 7-(4-fuorophenyl)pyrazolo[5,1-c][1,2,4]triazin-3-yl)(2-hydroxyphenyl)methanone (14c),
was studied against (PDB ID: 3t88), (PDB ID: 2wje), (PDB ID: 4ynt), and (PDB ID: 1tgh) to investigate its antimicrobial
activity when attached to diferent proteins with short bond length. Compound 14a docked with (PDB ID: 4hdq) and (PDB
ID: 3pxe) with energy afnity of −9.946 and −10.55 kcal/mol, with the pyrazolo[5,1-c][1,2,4]triazine derivative involved
in the pockets of the proteins. Moreover; the theoretical and investigational studies of compounds 14a,c were compatible
with spectral data obtained at HF/6-31G(d) and DFT/B3LYP/6-31G(d) level.
Keywords Heterocycles · Biological activity · Molecular docking · Computational studies
Introduction
attached to the hydroxyl group, e.g., ancistrocladidine (I),
candoxatril (II), and dopamine (III) shown in Fig. 1.
Moieties containing OH group, which include heterocyclic
compounds such as pyrazole, pyrimidine, thiazole, isoxa-
zole, and fused heterocyclic [1–5], have industrial and bio-
logical applications [6–11]. Some drugs include heterocycles
Previous studies have indicated that heterocycles contain-
ing the hydroxyl group functionality exhibit many activities,
including antihelmintic [12], antitubercular [13], and antit-
rypanosomal efects [14]. Based on the reported importance
of pyridine and carboxamide derivatives, and in continuation
of our interest in the exploration of novel heterocycles for
biological evaluation [15–17], we report herein the synthesis
of some heterocycles bearing the OH functional group.
We synthesize novel heterocyclic compounds from
2-hydroxyacetophenone that exhibit antimicrobial and anti-
tumor activities, and evaluate them through molecular dock-
ing studies of the active compounds, as well as estimation
of their energies, which is very important in terms of their
theoretical study, chemical reactivity, and stability [18, 19].
* Asmaa M. Fahim
asmaamahmoud8521@hotmail.com;
asmaamahmoud8521@gmail.com
1
Department of Green Chemistry, National Research Center,
P.O. Box.12622, Dokki, Cairo, Egypt
2
Department of Photochemistry, National Research Centre,
P.O. Box.12622, Dokki, Cairo, Egypt
3
Tanning Materials Leather Technology Department, National
Research Centre, El-Behouth St., Dokki 12622, Cairo, Egypt
4
Department of Organometallic and Organometalloid
Chemistry, National Research Centre, P.O. Box.12622,
Dokki, Cairo, Egypt
Vol.:(0123456789)
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Journal of the Iranian Chemical Society
O
O
OH
HO
O
N
H
N
HO
NH2
O
OH
O
O
O
O
O
Dopamine
Candoxatril
Ancistrocladidine
(III)
(II)
(I)
Fig. 1 Some drugs with attached OH group
protons at δ 7.02–8.02. Its mass spectrum revealed a peak
corresponding to the molecular ion at m/z 191 (M+).
Reaction of enaminone (3) with nitrogen nucleophiles
such as hydrazine hydrate in presence of ethanol and a
few drops of triethylamine as catalyst aforded the cor-
responding 2-(4H-pyrazole-3-yl)phenol (4), as confrmed
by the FT-IR absorption band at 3452 cm−1 due to OH. 1H
NMR revealed signals at δ 8.02 due to the olefn proton of
pyrazole. Its mass spectrum revealed an m/z peak at 160
(Scheme 1). Also, reaction of 3 with hydroxylamine hydro-
chloride in presence of K2CO3 for basic condition gave the
corresponding 2-(isoxazole-5-yl)phenol (5) as confrmed
by spectral data such as 1H NMR signals at 6.55 and 8.17
due to isoxazole ring. The mass spectrum showed a signal
at m/z = 161.
Results and discussion
Chemistry
The reactant 1-(2-hydroxyphenyl)ethanone (1) was treated
with dimethylformamide dimethylacetal (DMF-DMA)
in dry tetrahydrofuran (THF) at heating refux to aford
an orange crystalline solid that was identified as (E)-
3-(dimethylamino)-1-(2-hydroxyphenyl)prop-2-en-1-one
(3) based on elemental analysis and Fourier-transform
infrared (FT-IR), 1H and 13C nuclear magnetic resonance
(NMR), and mass spectral data. For example, compound
3 was assigned the E conformation based on its 1H NMR
spectrum, which showed the olefn protons as two doublets
at δ 6.23 (=CH–CO) and δ 9.05 (=CH–N) with J=7.5 Hz,
as reported for such E-coupled protons. These fndings
are in complete agreement with recent reports [20, 21].
Also, 1H NMR revealed singlet and multiplet signals cor-
responding to two methyl groups at δ 3.54 and aromatic
Finally, reaction of enaminone 3 with guanidine in etha-
nol refux for 4 h aforded 2-(2,4-diaminopyrimidine-5-yl)
phenol (6) as confrmed by spectral data including FT-IR
absorption bands at 3403 cm−1 due to OH band and two
absorption bands due to amino groups at 3345 cm−1 and
OH
(1)
H3C
O
O
OH
O
Neat
CH3
CH3
H3C
CH3
N
N
O
CH3
CH3
(3)
(2)
NH2NH2/EtOH
TEA
NH
NH2
NH2OH/K2CO3
H2N
N
NH2
N
O
N
N
OH
OH
OH
N
NH2
(4)
(5)
(6)
Scheme 1 Reaction of (E)-3-(dimethylamino)-1-(2-hydroxyphenyl)prop-2-en-1-one (3) with nitrogen nucleophiles
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Journal of the Iranian Chemical Society
1
3267 cm−1, H NMR singlet signals at 6.23 and 8.2 ppm
bands in the region of 1675–1611 cm−1. Their mass spectra
showed, in each case, a peak corresponding to the molecular
ion (see “Experimental” section).
due to amino groups, and the singlet signal at 8.45 due to
pyrimidine ring, as well as the signal at 202 in its mass spec-
trum (Scheme 1).
Treatment of compound 3 with hydrazonoyl halides
15a,b was also conducted in refuxing ethanol, in each case
resulting in the formation of a single product as examined
through thin-layer chromatography (TLC). The structures of
the obtained products were established to be 4-(2-hydroxy
benzoyl)-1-phenyl-1H-pyrazole-3-carbaldehyde 17a and
1-(4-(2-hydroxy benzoyl)-1-phenyl-1H-pyrazole-3-yl)etha-
none 17b, respectively, through elimination of dimethyl-
amino and cyclization to aford pyrazole derivatives. The
reaction products were confrmed on the basis of their ele-
mental analyses and spectral data. In all cases, their mass
spectra showed, among other fragments, peaks correspond-
ing to the molecular ion. The structures of compounds 17a,b
were further confrmed by their independent synthesis, as
outlined in Scheme 4.
The behavior of enaminone 3 towards some heterocyclic
amines was investigated as a convenient route to access syn-
thesis of a variety of fused heterocyclic systems [22, 23].
Thus, treatment of compound 3 with 3-phenyl-1H-pyrazole-
5-amine (7a), 1H-1,2,4-triazole-5-amine (7b), and 4-methyl-
3-phenyl-1H-pyrazole-5-amine (7c) in refuxing pyridine
furnished pyrrolo[1,2-a]pyrimidine and imidazo[1,2-a]
pyrimidine derivatives 9a,b (Scheme 2). The structures of
the fnal products were confrmed by their elemental and
spectral analyses (FT-IR, H and 13C NMR, and mass);
1
For example, the IR spectrum of 9a revealed the lack of
a band corresponding to the carbonyl function group and
showed the hydroxyl group at 2398 cm−1, while its 1H NMR
spectrum showed a singlet signal due to pyrrole proton at δ
5.99. Its mass spectrum revealed a peak corresponding to its
molecular ion at m/z 286 (M+). Furthermore, the reaction
of enaminone 3 with aminobenzimidazole (10) in pyridine
aforded 2-(benzo[4,5]imidazo[1,2-a]pyrimidin-3-yl)phenol
Biological evaluation
1
(11), and H NMR revealed proton signals at 9.04 due to
Antimicrobial activity
pyrimidine moiety. Its mass spectrum showed a signal at
m/z=261 (Scheme 2).
Antimicrobial activity and structure–activity relationship
(SAR)
The enaminone 3 reacted with the diazonium salt of
3-phenyl-5-amino-1H-pyrazole derivatives (12a–d) [24,
25] to aford the nonisolable azo-coupling intermediates
13a–d, which cyclized via dimethylamine elimination to
yield the pyrazolo[5,1-c][1,2,4]triazine derivatives 14a–d
in good yields (Scheme 3). The FT-IR spectra of the latter
compounds revealed, in each case, the lack of bands corre-
sponding to endo-cyclic NH and showed carbonyl absorption
The prepared compounds were tested for their inhibitory
efects on G+ and G− bacterial strains and three antifungal
strains (Table 1). In this investigation, attachment of dif-
ferent fused heterocyclic rings to the pyrazolo[5,1-c][1,2,4]
triazine derivatives afected the antimicrobial activity. Some
of the tested compounds revealed higher and moderate
O
OH
R
NH2
CH3
X
N
Pyridine
O
N
OH
X
R
N
NH
CH3
N
H
N
H
(3)
7a-c
H
N
8a-c
NH2
R
a
X
a
N
CH
N
Ph
H
(10)
b
b
N
N
OH
N
HO
N
N
X
R
(11)
9a,b
Scheme 2 Reaction of enaminone (3) with heterocyclic amines
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Journal of the Iranian Chemical Society
Scheme 3 Reaction of enami-
none (3) with diazonium salts
O
OH
O
OH
0-5oC
CH3
R
CH3
X
N
N
-Y+N2
N
N
CH3
N
Pyridine
CH3
N
H
(3)
12a-d
X
NH
N
13a-d
OH
R
-NH(CH3)2
R
p-CH3-Ph
a
b
c
d
X =CH
Y =Cl
p-OCH3-Ph
p-F-Ph
O
N
N
p-Br-Ph
R
N
X
N
14a-d
O
R
NMe2
OH
O
OH O H
O
OH
O
Ph
N
N
CH3
NNH Ph
N
N
Ph
N
R
H
O
CH3
Cl
15a,b
(3)
R
17a,b
16a,b
R
a
H
b
CH3
Scheme 4 Reaction of enaminone (3) with hydrazonoyl halides
antimicrobial activity compared with the reference drug
[26–28]. Compounds 6, 11, 14c exhibited high activity
against all types of strain, owing to the existence of elec-
tron-withdrawing groups besides the carboxyl group. Mean-
while, compounds 9b,c showed almost the same activity. It
is worth mentioning that the incorporation of withdrawing
groups such as (Br, F) in compounds 14c,d induced high
antimicrobial activity. Compounds 9a,b,c, 17a,b revealed
moderate activity against all strains. The results listed in
Table 1 indicate that compounds 6, 11, 14c showed remark-
able activity. The investigation revealed that the F- and Br-
atom derivatives 14c,d showed better antibacterial activities
than the donating group derivatives 14a,b. Also, incorpora-
tion of pyrazolo[5,1-c][1,2,4]triazine moiety in compound
14c resulted in good antibacterial activity against Gram-
negative bacteria. Moreover, compound 14c bearing substi-
tuted pyrazolo[5,1-c][1,2,4]triazine moiety emerged as the
most active member against Gram-positive Bacillus subtilis
(30.5 0.01 mm) and fungus Syncephalastrum racemosum
(26.4 0.14 mm) among its fuorine group analogues and
the fused pyrazolo[5,1-c][1,2,4]triazine in this study.
Molecular docking simulation of compounds 14a,c
Modeling of the molecular docking of compounds 14a
(TPT) and 14c (FPT) was carried out using MOE software
[29] to identify the biological activity of pyrazolo[5,1-c]
[1,2,4]triazin-3-yl)methanones 14a,c in accordance with
the experimental data, including the docking of com-
pound 14a,c ligands with different protein receptors such
as the crystal conformation of Escherichia coli MenB in
complex with substrate analog o-succinylbenzoyl-amino
coenzyme A (OSB-NCoA) (PDBID: 3t88) [30], crystal
conformation of tyrosine phosphatase Cps4B from Strep-
tococcus pneumoniae TIGR4 (PDBID: 2wje) [31], crystal
conformation of Aspergillus flavus flavin adenine dinu-
cleotide (FAD) glucose dehydrogenase (PDBID: 4ynt)
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Journal of the Iranian Chemical Society
Table 1 Antimicrobial screening of synthesized compounds versus amphotericin B, ampicillin, and gentamicin: diameter (mm) of inhibition
zones based on well difusion assay
Sample ID
Bacillus subtilis Streptococcus pneu-
Escherichia coli Aspergillus favus
Syncephalastrum
racemosum (Sr)
Geotrichum
candidum (Gc)
(G+) (Bs)
moniae (G+) (Sp)
(G−) (Ec)
(fungus) (Af)
3
8.7 0.11
12.2 0.13
13.2 0.21
18.3 0.11
15.2 0.21
17.5 0.16
22.3 0.11
20.2 0.18
19.8 0.19
30.5 0.01
24.7 0.19
26.9 0.20
22.2 0.25
–
10.6 0.15
10.4 0.09
13.7 0.15
18.8 0.13
17.3 0.14
14.2 0.11
18.90 0.09
19.3 0.20
18.2 0.20
22.2 0.16
21.3 0.2
21.3 0.2
22.6 0.14
–
8.2 0.18
12.3 0.11
16.3 0.12
15.7 0.11
11.3 0.12
11.4 0.19
16.9 .0.21
16.2 0.19
18.0 0.18
17.9 0.30
18.03 0.21
18.3 0.19
15.7 0.21
–
9.5 0.10
13.5 0.11
19.4. 0.12
18.93 0.19
15.2 0.14
13.5 0.11
19.4 0.19
19.6 0.08
22.3 0.09
21.5 0.14
20.3 0.28
19.6 0.08
16.3 0.17
23.7 0.1
–
11.3 0.13
12.0 0.11
0.2 0.2018
19.3 0.19
14.2 0.03
18.3 0.19
14.9 0.09
20.3 0.16
20.6 0.19
26.4 0.14
24.3 0.15
21.4 0.15
25.1 0.15
28.7 0.2
–
12.5 0.20
14.2 0.19
15.5 0.18
19.3 0.18
18.3 0.11
15.2 0.19
19.4 0.12
19.3 011
22.2 0.18
23.3 0.17
22.2 013
20.4 0.08
19.6 0.07
25.4 0.1
–
4
5
6
9a
9b
11
14a
14b
14c
14d
17a
17b
Amphotericin B
Ampicillin
Gentamicin
32.4 0.3
–
23.8 0.2
–
–
19.9 0.3
–
–
–
The screening organisms, Mold: Gram-positive bacteria: B. subtilis (RCMB 010,069, Bs) and S. pneumoniae (RCMB 010,010, Sp), Gram-neg-
ative bacteria: E. coli (RCMB 010,052, Ec). Three fungi: A. fumigatus (RCMB 02,568, Af), Syncephalastrum racemosum (RCMB, 016,001,
Sr), and Geotrichum candidum (RCMB, 052,006, Gc). Inhibition zone (IZ): high activity>15 mm, moderate activity 11–14 mm, slight activity
8–10 mm, and nonsensitive 0–7 mm
Table 2 Molecular docking of 14a,c to Escherichia coli, Streptococcus pneumoniae, Aspergillus favus, and Geotrichum candidum
Escherichia coli (PDB: 3t88)
Streptococcus pneumoniae (PDB: 2wje)
Energy
Distance (Å)
Amino acids
Energy
Distance (Å)
Amino acids
afnity (kcal/
mol)
afnity (kcal/
mol)
14a −9.282
2.54 Å
2.25 Å
Thr254, Gly251, Arg230,
Arg64, Thr117
14a −11.4219
2.35 Å, 2.85 Å Arg206, Tyr166,, Gly205,
Lys171, Ser165, Lys181,
His209, Leu168, Glu212
14c −8.6456
Arg230, Pro226, Tyr65,
14c −10.255
2.75 Å
Arg139, Gly205, His166,
Lys120, Gly70 Asp67, Ile69
Arg206, Ser165, Tyr177
Aspergillus favus (PDB: 4ynt)
Geotrichum candidum (PDB: 1tgh)
Energy
Distance (Å)
Amino acids
Energy
Distance (Å)
Amino acids
afnity (kcal/
mol)
afnity (kcal/
mol)
14a −10.755
1.42 Å, 2.45 Å, 2.73 Å Tyr53, Arg501, Asn503,
Trp415, Asn318, His505,
14a −9.495
1.52 Å, 2.35 Å Lys192, Gly195, Tyr236,
Thr253, His188,
His548, gly64, Ala96,
Asn237, Pro42
Leu401, Tyr199, Syr333
14c −10.554
1.45 Å, 3.06 Å
Thr15, Ser274, Gly14,
Leu549, Val550, Asn93,
His505, Phe504, Thr89,
Gly83, Ala275, Gly276,
Ser274
14c −8.3189
3.04 Å
Asn8, Phe45, Tyr49,
Gly47, Asp199,
Asn237, Tyr236
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Journal of the Iranian Chemical Society
Fig. 2 Binding models of pyrazolo[5,1-c][1,2,4]triazin-3-yl)methanones 14a,c with a Escherichia coli (PDB: 3t88), b Streptococcus pneumo-
niae (PDB: 2wje), c Aspergillus favus (PDB: 4ynt), and d Geotrichum candidum (PDB: 1tgh)
[32], and 1.8-Å refined structure of lipase from Geotri-
chum candidum (PDBID: 1tgh) [33] (Table 2; Fig. 2).
According to this table, the energy affinity of com-
pounds 14a,c with (PDB ID: 3t88) is calculated to be
−9.282 and −8.6456 kcal/mol with bond distance of
2.54 Å and 2.25 Å, respectively, with different amino
acids: (Thr254, Gly251, Arg230, Arg64, Thr117) and
(Arg230, Pro226, Tyr65, Lys120, Gly70 Asp67, Ile69).
Also the binding energy of 14a,c with (PDBID: 2wje) is
−11.4219 kcal/mol and −10.255 kcal/mol with bond dis-
tance of 2.35 Å, 2.85 Å, and 2.75 Å with different amino
acids: (Arg206, Tyr166, Gly205, Lys171, Ser165, Lys181,
His209, Leu168, Glu212) and (Arg139, Gly205, His166,
Arg206, Ser165, Tyr177). Note that all the proteins had
greater energy stability with compound 14a due to the
presence of methyl group and localization of electrons
[34].
Antiproliferative activity
The antiproliferative activity of the various newly synthe-
sized fused heterocyclic compounds 4, 5, 9a, 14a,b, 17a,b
was studied using two human cancer cell lines, namely
Table 3 IC50 values of the synthesized compounds against MCF-7
and HepG2 tumor cells
Compound
(MCF-7)
aIC50 (µg/ml)
Compound
(HepG2)
aIC50 (µg/ml)
4
19.5 0.23
17.2 0.15
20.3 0.19
11.6 0.11
13.9 0.12
11.5 0.26
12.3 0.32
10.3 0.8
4
5
40.8 0.52
27.6 1.1
42.5 0.11
27.3 1.3
30.1 1.8
31.6 0.88
33.2 0.95
28.5 1.9
5
9a
9a
14a
14a
14b′
14b
17a
17a
17b
17b
Doxorubicin
Doxorubicin
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Journal of the Iranian Chemical Society
HepG2 hepatocellular carcinoma and MCF-7 breast cancer,
based on the sulforhodamine B (SRB) colorimetric assay
as described by Skehan et al. [35] and with doxorubicin as
reference cytotoxic compound. The outcomes are expressed
as growth inhibitory concentration (IC50) values, represent-
ing the concentration of each compound required to yield a
50% inhibition of cell growth after 72 h of incubation with
respect to untreated controls (Table 3). The results indicate
that most of the prepared compounds displayed excellent
to modest growth inhibitory activity against the tested
cancer cell lines. Investigations of the cytotoxic activity
against HepG2 indicated that it was the cell line that was
more sensitive to the new derivatives [36]. Compound 14a
(IC50 =11.6 0.11 mg/ml and IC50 =27.3 1.3 mg/ml) was
found to be the most efective derivative among the tested
compounds against MCF-7 and HepG2, approaching the
activity of doxorubicin (IC50 =10.3 0.8 and 28.5 1.9 mg/
ml) (Fig. 3). Also, compound 5 showed high activity with
IC50 values of 17.2 0.15 mg/ml and 27.6 1.1 mg/ml,
comparable to doxorubicin, against MCF-7 and Hep-G2.
Furthermore, compounds 17a,b exhibited moderate activ-
ity against tumor cells due to the presence of 1-phenyl-
1H-pyrazole moiety, with IC50 values of 11.5 0.26 and
31.6 0.88 mg/ml for compound 17a and 12.3 0.32 and
33.2 0.95 mg/ml for 17b.
infection. KSHV encodes worthless thymidylate synthase
(kTS), which shares 70% classifcation characteristics with
hTS [37]. The three-dimensional confgurations of TS have
been described for numerous and diverse organisms includ-
ing E. coli [38], Lactobacillus casei, B. subtilis, rat, and
human [39]. To confrm the cytotoxic activity profle of
the synthesized compounds, a modeling study of molecu-
lar docking was carried out. A conformational search using
an implicit solvent form was carried out for the prepared
compounds, monitored based on the improvement of the
geometry of local minima through a quantum-mechanical
(QM) method. Then, elastic docking of the compounds in
the crystallographic confguration of KSHV thymidylate
synthase was accomplished with a sulfonamide native ligand
obtained from the Protein DataBank (PDB ID: 5H38) [40]
to estimate the plausible capability of the new sulfona-
mide derivatives to bind in the active pocket of KSHV as a
potential molecular target. The confgurations obtained for
our sulfonamides were found to bind in a co-crystallized
ligand-like fashion with KSHV [41]. The evaluation of
compound 14a for the molecular docking studies against
(PDB ID: 5H38) yielded −9.946 kcal/mol with a distance
of 2.32 Å and diferent amino acids of (Arg164, Thr178,
Ala175, Ala173, Asp121, Gly118, Ser119, Thr120, Lys117,
His165, Glu313), and also KRIT1-Rap1-HEG1 ternary com-
plex encloses three NPX(Y/F) subjects, four ankyrin repeats,
and a C-terminal FERM domain and this interface displayed
the following FERM domain. The connection between Rap1
and its efector protein KRIT1 plays a noteworthy role in
the preservation of EC junctions and regulation of cell–cell
junction processes. KRIT1 associates with microtubules.
Stretchy docking of compound 5c was examined with the
Molecular docking simulation of compound 14a
Kaposi’s sarcoma-related herpesvirus (KSHV) is an onco-
virus that causes Kaposi’s sarcoma in acquired immunode-
fciency syndrome (AIDS) patients, primary efusion lym-
phoma, and various categories of multicentric Castleman’s
Fig. 3 Survival plot of HepG-2 and MCF-7 cells grown for 48 h in presence of aggregate concentrations of compounds 4,5, 9a, 14a,b, 17a,b
versus doxorubicin
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Journal of the Iranian Chemical Society
crystallographic structure of the 4hdq complex with a uracil
ligand obtained from the Protein Data Bank (PDB ID: 4hdq)
[42] to approximate the plausible ability of the innovative
uracil derivatives to the drug in the active pocket of 4hdq as
a potential molecular target. The energy afnity with 4hdq
was –10.554Kcal/mol with bond distances of 2.44 Å, 2.83 Å,
and 2.91 Å and diferent amino acids (Arg426, Ser430, Arg
432, Tyr431, Leu526, Leu529, Ile561) (Table 4; Fig. 4).
obtained at DFT/B3LYP/6-31G(d) level due to the exclusion
of electron correlation [44]. Comparison of the theoretical
data with the crystallographic data indicated slight difer-
ences in the optimized bond lengths and bond angles. Also,
fused (7-(4-fuorophenyl)pyrazolo[5,1-c][1,2,4]triazin-3-yl)
(2-hydroxyphenyl)methanone(FPT) (14c) showed a nonpla-
nar structure, as shown in Fig. 5.
Table 5 reveals that the pyrazole ring of compound
14a (TPT) has an N14–N18 bond length of 1.34376 Å for
HF/6-31G (d) but 1.36729 Å for DFT /B3LYP/6-31G(d),
and 1.40851 Å and 1.28551 Å for 14c (FPT), respectively.
Meanwhile, the N18–C17 bond length in 14a is 1.34222 Å
and 1.37011 Å, while the length of the N13–C15 bond
for 14c is 1.2809 Å and 1.39728 Å for HF/6-31G(d) and
B3LYP/6-31G(d), respectively. The C1–O1–H1 angle of
(E)-3-(dimethylamino)-1-(2-hydroxyphenyl) prop-2-en-
1-one (3) [45] is 103.1(2)°, comparable to the H24–O7–C6
angle of 107.99961° and 112.031° for compound 14a and
the H26–C25–C24 angle of 113.24136° and 109.03620° for
compound 14c, for HF/6-31G(d) and B3LYP/6-31G(d),
respectively.
Computational study
Molecular orbital calculations
The optimized molecular structure of fused (2-hydroxyphe-
nyl)(7-(p-tolyl)pyrazolo[5,1-c][1,2,4]triazin-3-yl)methanone
(TPT) (14a) is shown in Fig. 5, while selected bond lengths,
bond angles, and dihedral angles are presented in Table 5, as
calculated at B3LYP/6-31G(d) and HF/6-31G(d) level. The
molecular structure of this compound is not planar. The opti-
mized structure of 14a is compared with the crystallographic
data of the most closely associated molecule, viz. (E)-
3-(dimethylamino)-1-(2-hydroxyphenyl)prop-2-en-1-one(3)
[43]. It is recognized that the bond lengths and angles given
at HF level of theory are typically more accurate than those
Table 4 Docking of compound 14a with KSHV thymidylate synthase complex (PDB ID: 5H38) and (PDB ID: 4hdq)
KSHV thymidylate synthase complex (PDB ID: 5H38)
Ternary complex of KRIT1 bound to both the Rap1 GTPase and the Heart of
Glass (HEG1) cytoplasmic tail
(PDB ID: 4hdq)
Energy afnity (kcal/
Distance (Å) Amino acids
Energy afnity (kcal/mol) Distance (Å)
Amino acids
mol)
Compound 14a −9.946 2.32 Å
Arg164, Thr178,
Ala175, Ala173,
Asp121, Gly118,
Ser119, Thr120,
Lys117, His165,
Glu313
Compound 14a −10.554 2.44 Å, 2.83 Å, 2.91 Å Arg426, Ser430, Arg432,
Tyr431, Leu526,
Leu529, Ile561
Fig. 4 Molecular docking of compound 14a with (PDB ID: 5H38) and (PDB ID: 4hdq)
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Journal of the Iranian Chemical Society
Fig. 5 Optimized geometry, numbering system, and moieties of TPT (14a), X-ray of (E)-3-(dimethylamino)-1-(2-hydroxyphenyl)prop-2-en-1-
one (3), and FPT (14c), at HF/6-31G(d) and DFT/B3LYP/6-31G(d) level
(
)
Physical characterization
ELUMO − EHOMO
(3)
ꢀ =
,
2
The physical characteristics calculated for compounds 14a,c,
such as the absolute electronegativity (χ), chemical potential
(Pi), absolute hardness (η), absolute softness (σ), global elec-
trophilicity (ω), global softness (S), and additional electronic
charge (ΔNmax), are presented in Table 6, obtained using
the following equations and optimized via HF/6-31G(d)
and DFT/B3LYP/6-31G(d) [46]. The molecular structure
of these compounds is not planar. The potential activities
presented by the precursor compound (2-hydroxyphenyl)
(7-p-tolylpyrazolo[5,1-c][1,2,4]triazin-3-yl)methanone (TPT)
(14a) are due to the presence of pyrazolo[5,1-c][1,2,4]triazine,
and the diference between HF and DFT/6-31G(d) is 145.836
eV ≈ 3363.062 kcal/mol. Additionally, the diference of the
dipole moment is 0.8629D, indicating easy charge separation
[47] Also, the π-isoelectronic structures of (7-(4-fuorophe-
nyl)pyrazolo[5,1-c][1,2,4]triazin-3-yl)(2-hydroxyphenyl)
methanone (FPT) (14c) show a diference in energy between
DFT/ B3LYP/6-31G(d) and HF/6-31G(d) of 188.73 eV ≈
4352.41 kcal/mol, and the energy gap in DFT/B3LYP/6-
31G(d) is 1.206 eV compared with 6.67 eV for HF/6-31G(d).
Furthermore, the dipole moment diference (0.0152D) ena-
bles easily charge separation of FPT (14c) [48], as shown in
Table 6.
ꢀ = 1∕ꢁ,
Pi = −ꢀ,
S = 1∕2ꢀ,
(4)
(5)
(6)
(7)
(8)
ꢀ = Pi2∕2ꢁ,
ΔNmax = −Pi∕ꢀ.
Based on the results presented in Table 6, the following
conclusions can be drawn:
1. The energy gap of compound TPT obtained utilizing
DFT/B3LYP/6-31G(d) is 3.8 eV rather than −9.87 eV with
HF/6-31G(d). This large energy diference indicates the sta-
bility of the compound due to the presence of methyl (elec-
tron-donating) group which enhances electron donation [49].
2. The energy gap of FPT obtained utilizing DFT/
B3LYP/6-31G(d) is 1.20 eV rather than 6.67 eV with HF/6-
31G(d). This narrow energy gap is due to the presence of
electron-withdrawing fuorine group, which gives the com-
pound stability [50].
ΔE = ELUMO − EHOMO
,
(1)
3. The absolute electronegativity (χ) theoretically
describes the afnity of an atom to abstract a mutual pair
of electrons. The value of χ is 15.3744 eV ≈ 354.543 kcal/
mol for TPT (14a) and −380.4262 eV ≈ −8772.8353 kcal/
(
)
− EHOMO + ELUMO
(2)
ꢀ =
,
2
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Table 6 Ground-state energies of compounds 14a,c obtained at DFT/B3LYP/6-31G(d) and HF/6-31G(d) level and their physical parameters
Compound 14a (TPT)
DFT/ B3LYP/6-31G(d)
HF/6-31G(d)
ET (a.u.)
EHOMO (a.u.)
ELUMO (a.u.)
Eg (eV)
µ (D)
χ (eV)
η (eV)
σ (eV)
Pi (eV)
S (eV)
ω (eV)
−870.443
−0.23527
−0.09434
3.8349
ET (a.u.)
EHOMO (a.u.)
ELUMO (a.u.)
Eg (eV)
µ (D)
χ (eV)
η (eV)
σ (eV)
Pi (eV)
S (eV)
ω (eV)
−865.08362
−0.32536
0.03754
9.8750
7.0390
7.9019
4.484574
1.9174512
386.1689
−4.484574
193.0844
0.026038
63.6425
3.91599
4.93750
149.9783
−3.91599
2.468754
0.0511030
21.58165
−0.749
−0.468
−0.309
−0.232
−0.880
ΔNmax
Net charges
ΔNmax
Net charges
O7
O9
N12
N11
N14
N18
C17
−0.579
−0.318
−0.231
−0.223
−0.630
−0.221
0.194
−0.279
0.237
Compound 14c (FPT)
DFT/ B3LYP/6-31G(d)
HF/6-31G(d)
ET (a.u.)
EHOMO (a.u.)
ELUMO (a.u.)
Eg (eV)
µ (D)
χ (eV)
η (eV)
σ (eV)
Pi (eV)
S (eV)
ω (eV)
−1154.70
−0.02428
0.00363
1.2068
4.3380
0.28082164
0.379735073
2.63341540
−0.28082164
1.25833647
0.73735631
0.73952003
ET (a.u.)
EHOMO (a.u.)
ELUMO (au)
Eg (eV)
µ (D)
χ (eV)
η (eV)
σ (eV)
Pi (eV)
S (eV)
ω (eV)
ΔNmax
−1147.764
−0.31832
−0.72980
6.67609
4.3532
−14.260406
−5.59847323
21.612926
−14.2604058
15.165729
−15.895582
8.6619325
−0.348
−0.332
−0.761
−0.141
−0.708
ΔNmax
Net charges
F22
N12
N11
N13
O25
O6
−0.272
−0.185
−2.235
0.151
−0.547
−0.353
0.392
Net charges
−0.496
0.442
H26
aEg =ELUMO—EHOMO
mol for FPT (14c). The lower value for FPT confrms its
ability to attract electrons.
diference between the HF/6-31G(d) and DFT/B3LYP/6-
31G(d) values of 82.178 eV ≈ 1895.1 kcal/mol for TPT
(14a) and 142.016 eV ≈ 3274.97 kcal/mol for FPT (14c)
4. The absolute hardness (η) measures the resistance to
change in the electron density around the molecule. The
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Journal of the Iranian Chemical Society
indicates the higher electron density and stability of the lat-
ter compound [51].
of (7-(4-fuorophenyl)pyrazolo[5,1-c][1,2,4]triazin-3-yl)
(2-hydroxyphenyl) methanone (14c) indicating a uniform
distribution of surface contours on fused pyrazolo[5,1-c]
[1,2,4]triazine and (2-hydroxyphenyl)methanone, which is
associated with the experimental and biological activity [54,
55], as shown in Fig. 6.
5. The absolute softness (σ) indicates the interaction of
the compound. The diference of 236.198 eV for TPT (14a)
and 18.98 eV for FPT (14c) indicates their reaction activity
[52].
Frontier molecular orbitals (FMOs)
Experimental
FMO analysis provides a powerful guiding principle regard-
ing the electrical and optical properties, with the highest
occupied molecular orbital (HOMO) acting as an elec-
tron donor and the lowest unoccupied molecular orbital
(LUMO) acting as an electron acceptor. The energy between
the HOMO and LUMO is associated with the biological
evaluation. Moreover, it helps to characterize the reactiv-
ity and kinetic stability of the molecule. A large energy
gap between the HOMO and LUMO is refected in high
kinetic stability [53]. Figure 6 illustrates the distributions
and energy levels of the HOMO, LUMO, and orbitals
computed at the B3LYP/6-31G(d) level for (2-hydroxy-
phenyl)(7-p-tolylpyrazolo[5,1-c][1,2,4]triazin-3-yl)metha-
none (14a) (TPT) and (7-(4-fuorophenyl)pyrazolo[5,1-c]
[1,2,4]triazin-3-yl) (2-hydroxyphenyl) methanone (14c)
(FPT). The positive and negative phases are indicated by
red and green color, respectively. As shown in Fig. 6, the
HOMO of TPT (14a) is localized over the whole molecule
except the tolyl moiety, while the LUMO of the same com-
pound is not localized on the hydroxybenzene ring and the
HOMO–LUMO energy gap is −3.83 eV, Furthermore, the
molecular electrostatic potential surface (ESP) lies on the
more electronegative atoms such as O and N of benzene
or fused pyrazolo[5,1-c][1,2,4]triazine, which easily trans-
port electrons as shown in Fig. 6. Moreover, the HOMO
and LUMO of compound FPT (14c) are distributed over
the whole molecule except the p–f benzene with an energy
diference of 1.20 eV. This narrow HOMO–LUMO gap indi-
cates high excitation energies for numerous excited states
and the reactivity of this compound due to the presence of
the fuorine atom, which increases its activity. Also, the ESP
General procedure
All melting points were measured on a Gallenkamp melt-
ing point apparatus. IR spectra were recorded on a Shi-
madzu FT-IR 8101 PC infrared spectrophotometer. 1H and
13C NMR spectra were determined in dimethylsulfoxide
(DMSO)-d6 at 300 MHz on a Varian Mercury VX 300 NMR
spectrometer (1H at 300 MHz, 13C at 75 MHz) using tetra-
methylsilane (TMS) as internal standard. Mass spectra were
recorded on a Shimadzu GCMS-QP 1000 EX mass spec-
trometer at 70 eV. Elemental analyses were carried out at
the Microanalytical Center of Cairo University, Giza, Egypt.
Materials and reagents
1-(2-Hydroxyphenyl)ethanone, dimethylformamide dimeth-
ylacetal, NH2NH2, NH2OH・HCl, triethylamine, 2-amin-
obenzoimidazole, and aminopyrazole were purchased from
Aldrich Chemical CO. Ethanol, pyridine, toluene, THF,
and piperidine were purchased from Aldrich Chemical
CO. Methanol, petroleum ether, and chloroform were BDH
reagents.
Preparation of (E)‑3‑(dimethylamino)‑1‑(2‑hydroxyphenyl)
prop‑2‑en‑1‑one (3)
Solution of 1-(2-hydroxyphenyl)ethanone (1) (10 mmol) in
dry THF (50 ml) and dimethylformamide dimethylacetal
Fig. 6 HOMO–LUMO energy gap and ESP contours for compounds 14a,c at B3LYP/6-31G(d) level
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Journal of the Iranian Chemical Society
(10 mmol) was refuxed for 1 h then left to cool. The orange
precipitated was fltered of, washed with dry petroleum
ether (40–60 °C), and dried. The isolated product was crys-
tallized from EtOH/H2O to aford (E)-3-(dimethylamino)-
1-(2-hydroxyphenyl)prop-2-en-1-one (3) [25]: orange crys-
tals, 80% yield, m.p. = 150–152 °C, C11H13NO2 (191.23),
Anal% calcd (found): C: 69.09 (69.11), H: 6.85 (6.84), N:
7.32 (7.35), IR (KBr)max/cm−1: 3210 (OH), 1683 (C=O),
158 (C=O). 1H NMR (DMSO-d6): δ 3.54 (s, 6H, H3C), 6.23
(d, 1H, HC–CO, J=7.5 Hz), 6.9–7.5 (m, 4H, HC aromatic),
8.05 (d, 1H, HC–N, J=7.5 Hz), 14.4 (s, 1H, HO exchange-
able), 13C NMR (DMSO-d6): δ 44.3 (CH3), 117.3 (CH),
121.6 (CH), 129.6 (CH), 141 (CH), 155 (C–N), 157 (C–O),
188 (C=O), MS (m/z, r.i.%): 192 (M+, 100%), 121 (45%).
27.71 (27.70), IR (KBr)max/cm−1: 3403 (OH), 3345 (NH2),
1
3267 (NH2), H NMR (DMSO-d6): δ 6.23 (s, 2H, H2N
exchangeable), 7.12–7.67 (m, 4H,HC aromatic), 8.2 (s, 2H,
H2N exchangeable), 8.45 (s, 1H, HC), 12.36 (s, 1H, HO
exchangeable), 13C NMR (DMSO-d6): δ 106 (C–CH=N),
115 (CH), 124 (CH), 128 (CH), 129 (CH), 131 (CH), 153
(C–OH), 156 (C–N), 162 (C=N), MS (m/z, r.i.%): 202 (M+,
100), 180 (22%), 52 (35%).
General procedure for reaction of enaminone 3
with heterocyclic amines 7a,b, 10
A mixture of enaminone 3 (1.9 g, 10 mmol) and the appro-
priate heterocyclic amine 3-phenyl-1H-pyrazol-5-amine
(7a), 1H-1,2,4-triazol-5-amine (7b), 4-methyl-3-phenyl-1H-
pyrazol-5-amine (7c), and 1H-benzo[d]imidazol-2-amine
(10) (10 mmol) in pyridine (25 ml) was refuxed for 12 h
then left to cool. The reaction mixture was poured into cold
water, and the solid product was collected by fltration,
washed with water, dried, and fnally recrystallized from
DMF/H2O to afford the corresponding pyrazolo[1,5-a]
pyrimidine and triazolo[1,5-a]pyrimidine derivatives 9a–c
and 11 in 70% and 60% yield, respectively.
Reaction of (E)‑3‑(dimethylamino)‑1‑(2‑hydroxyphenyl)
prop‑2‑en‑1‑one (3) with nitrogen nucleophiles
Reaction of 3 with hydrazine hydrate (NH2NH2) Enaminone
(3) solution (0.19 g, 1 mmol) in ethanol (10 ml) was added
to hydrazine hydrate (1 ml, 1 mmol), and the mixture was
heated under refux for 5 h. The reaction mixture was acidi-
fed through HCl/ice mixture, and the formed product was
fltered and crystallized from ethanol. 2-(4H-Pyrazol-3-yl)
phenol (4) [25]: white solid, 77% yield, m.p.=90–94 °C,
C9H8N2O (160.06), Anal% calcd (found): C: 67.49 (67.52),
H: 5.03 (5.00), N: 17.49 (17.45), IR (KBr)max/cm−1: 3452
(OH), 1H NMR (DMSO-d6): δ 2.2 (d, 2H, H2C), 7.04–7.98
(m, 4H, HC aromatic), 7.99 (t, 1H, HC, J=12.1 Hz), 11.99
(s, 1H, HO exchangeable), MS (m/z, r.i.%): 160 (M+, 100),
104 (20%), 69 (65%).
2-(7-Phenylpyrrolo[1,2-a]pyrimidin-4-yl)phenol (9a):
dark yellow, m.p. = 200–202 °C, C19H14N2O (286.33),
Anal% calcd (found): C: 79.70 (79.69), H: 4.93 (4.94),
1
N: 9.78 (9.74), IR (KBr)max/cm−1: 3398 (OH), H NMR
(DMSO-d6): δ 5.99 (s, 1H, HC), 6.15 (s, 1H,HC), 7.03–7.54
(m, 4H, HC aromatic), 7.74–8.03 (m, 5H, HC aromatic), 8.2
(d, 1H, HC, J=6.1 Hz), 8.89 (d, 1H, HC, J=7.6 Hz), 12.03
(s, 1H, HO exchangeable), 13C NMR (DMSO-d6): δ 104
(CH), 115 (CH), 121 (CH), 127.5 (CH), 129.3 (CH), 130
(CH), 134 (CH), 151 (C–OH), 157 (C=N), 166 (C–N), MS
(m/z, r.i.%): 286 (M+, 100), 193 (45%), 68 (65%).
Reaction of 3 with hydroxylamine hydrochloride An etha-
nolic mixture of 3 (0.19, 1 mmol) and hydroxylamine hydro-
chloride (0.033, 1 mmol) NH2OH in presence of potassium
carbonate (0.5 g) was refuxed for 4 h and poured onto water.
The solid product was fltered and crystallized from ethanol.
2-(Isoxazol-5-yl)phenol (5): pale yellow, 79% yield,
m.p. = 113–115 °C, C9H7NO2 (161.16), Anal% calcd
(dound): C: 67.07 (67.10), H: 4.38 (4.35), N: 8.69 (8.70),
2-(Imidazo[1,2-a]pyrimidin-5-yl)phenol (9b): pale
brown, m.p. = 201–204 °C, C12H9N3O (211.22), Anal%
calcd (found): C: 68.24 (68.22), H: 4.29 (4.30), N: 19.89
(19.92), IR (KBr) max/cm−1: 3410 (OH), 1H NMR (DMSO-
d6): δ 7.18–7.73 (m, 4H, HC aromatic), 7.8 (d, 1H, HC,
J=3.2 Hz), 8.03 (d, 1H, HC, J=7.8 Hz), 8.15 (d, 1H,HC,
J=7.6 Hz), 8.87 (d, 1H, HC, J=6.2 Hz), 11.99 (s, 1H, HO
exchangeable), 13C NMR (DMSO-d6): δ 114 (CH), 116
(CH), 119 (CH), 129.3 (CH), 131 (CH), 148 (CH), 155
(C–OH), 158 (C=N), 166 (C-N), MS (m/z, r.i.%): 211 (M+,
100), 181 (45%), 61 (50%).
1
IR (KBr)max/cm−1: 3489 (OH), H NMR (DMSO-d6): δ
6.55 (d,1H, HC), 7.02–7.88 (m, 4H, HC aromatic), 8.17 (d,
1H,HC, J=7.6 Hz), 11.23 (s, 1H, HO exchangeable), MS
(m/z, r.i.%): 161 (M+, 100), 49 (65%), 21 (45%).
2-(Benzo[4,5]imidazo[1,2-a]pyrimidin-3-yl)phenol (11):
Yellow solid, m.p. = 230–232 °C, 87% yield, C16H11N3O
(261.28), Anal% calcd (found): C: 73.55 (73.53), H: 4.24
(4.30), N: 16.08 (16.11), IR (KBr)max/cm−1: 3458 (OH),
1H NMR (DMSO-d6): δ 6.86–7.23 (m,4H, HC aromatic),
7.39–8.22 (m, 4H, HC aromatic), 9.04 (s, 2H, HC), 12.4 (s,
1H, HO exchangeable), 13C NMR (DMSO-d6): δ 111 (CH),
118 (CH), 121 (CH), 123 (CH), 129.3 (CH), 131 (CH), 134
Reaction of 3 with guanidine A mixture of 3 (0.19, 1 mmol)
with guanidine (0.059, 1 mmol) in ethanol (15 ml) was
refuxed for 4 h. The resulting solid was fltered of, and
crystallized from EtOH/H2O to aford compound 6.
2-(2,4-Diaminopyrimidin-5-yl)phenol (6): yellow pow-
der, 77% yield, m.p. = 296–297 °C, C10H10N4O (202.21),
Anal% calcd (found): C: 59.40 (59.39), H: 4.98 (4.94), N:
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Journal of the Iranian Chemical Society
(CH), 148 (C=N), 165 (C–N), MS (m/z, r.i.%): 262 (M+1,
(found): C: 54.70 (54.68), H: 2.81 (2.80), N: 14.18 (14.20), Br:
20.22 (20.23%), IR (KBr) max/cm−1: 3410 (OH), 1611 (C=O),
1H NMR (DMSO-d6): δ 6.77 (s, 1H, HC), 6.88–7.88 (m, 4H,
HC aromatic), 7.95–8.32 (m, 4H, HC aromatic), 9.53 (s, 1H,
HC), 11.99 (s, 1H, HO exchangeable), 13C NMR (DMSO-d6):
δ 74 (CH), 117 (CH), 118 (CH), 124 (CH), 132 (CH), 136
(CH), 144 (CH), 148 (C–N), 151 (C=N), 162 (C–OH), 189
(C=O), MS (m/z, r.i.%): 395 (M+, 100), 274 (15%), 121 (40%).
100), 168 (64%), 149 (12%).
General procedure for reaction of enaminone 3
with diazonium salts of heterocyclic amines 12a–d
To a stirred cold solution of enaminone 3 (0.38 g, 2 mmol)
in pyridine (30 ml) was added the appropriate diazonium salt
of pyrazole derivatives (2 mmol) portionwise over 30 min at
0–5 °C. After complete addition, the reaction mixture was
stirred for a further 3 h at 0–5 °C. The solid that precipitated
was collected by fltration, washed with water, and dried.
Recrystallization from DMF/H2O aforded the correspond-
ing fused ring system 14a–d.
Reaction of compound 3 with hydrazonoyl halides
Reaction of compound 3 with hydrazonoyl halides 15a,b
with refux for 4 h yielded pyrazole derivatives 17a,b, which
crystallized from EtOH/H2O in excellent yield.
(2-Hydroxyphenyl)(7-p-tolylpyrazolo[5,1-c][1,2,4]tria-
zin-3-yl)methanone (14a), yellow solid, m.p.=210–212 °C,
C19H14N4O2 (330.34), Anal% calcd (found): C: 69.08
4-(2-Hydroxybenzoyl)-1-phenyl-1H-pyrazole-3-car-
baldehyde (17a), pale-orange solid, m.p. = 216–218 °C,
C17H12N2O3 (292.29), Anal% calcd (found): C: 69.86
(69.88), H: 4.14 (4.20), N: 9.58 (9.60), IR (KBr) max/cm−1:
3446 (OH), 1668 (C=O), 1592 (C=O), 1H NMR (DMSO-
d6): δ 6.76–7.34 (m, 4H, HC aromatic), 7.86–8.06 (m, 5H,
HC aromatic), 8.7 (s, 1H, HC, pyrazole), 10.09 (s, 1H, HC),
12.3 (s, 1H, HO exchangeable), 13C NMR (DMSO-d6): δ
115 (CH), 127 (CH), 129 (CH), 134 (CH), 136 (CH), 145
(C=N), 161 (C–OH), 188 (C=O), 191 (C=O), MS (m/z,
r.i.%): 292 (M+, 100%), 199 (20%), 121 (55%).
(69.10), H: 4.27 (4.30), N: 16.96 (16.98), IR (KBr)
/
max
cm−1: 3389 (OH), 1675 (C=O), H NMR (DMSO-d6): δ
2.44 (s, 3H, CH3), 6.79 (s, 1H, HC), 6.99–7.46 (m, 4H, HC
aromatic), 7.75–8.54 (m, 4H, HC aromatic), 9.80 (s, 1H,
HC), 12.03 (s, 1H, HO exchangeable), 13C NMR (DMSO-
d6): δ 29 (CH3), 102 (CH), 119 (CH), 125 (CH), 129 (CH),
134 (CH), 138 (CH), 139 (CH), 149 (C–N), 157 (C=N), 161
(C–OH), 189 (C=O), MS (m/z, r.i.%): 330 (M+, 100), 175
(15%), 111 (95%).
1
1-(4-(2-Hydroxybenzoyl)-1-phenyl-1H-pyrazol-3-yl)eth-
anone (17b), orange solid, m.p.=230–232 °C, C18H14N2O3
(306.32), Anal% calcd (found): C: 70.58 (70.55), H: 4.61
(4.20), N: 9.15 (9.11), IR (KBr) max/cm−1: 3410 (OH), 1623
(C=O), 1611 (C=O), 1H NMR (DMSO-d6): δ 2.11 (s, 3H,
H3C), 6.45–7.65 (m, 4H, HC aromatic), 7.94–8.13 (m, 5H,
HC aromatic), 8.67 (s, 1H, HC, pyrazole), 12.6 (s, 1H, HO
exchangeable), 13C NMR (DMSO-d6): δ 25.6 (CH3), 111
(CH), 119 (CH), 123 (CH), 129 (CH), 130 (CH), 134 (CH),
145(C=N), 162 (C–OH), 178 (C=O), 195 (C=O), MS (m/z,
r.i.%): 306 (M+, 100), 213 (33%), 121 (29%).
(2-Hydroxyphenyl)(7-(4-methoxyphenyl)pyrazolo[5,1-
c][1,2,4]triazin-3-yl) methanone (14b): dark-yellow
solid, m.p. = 214–216 °C, C19H14N4O3 (346.34), Anal%
calcd (found): C: 65.89 (65.92), H: 4.07 (4.10), N: 16.18
1
(16.20), IR (KBr) max/cm−1:3389 (OH), 1640 (C=O), H
NMR (DMSO-d6): δ 3.52 (s, 3H, OCH3), 6.51 (s, 1H, CH),
6.89–7.66 (m, 4H, HC aromatic), 7.81–8.05 (m, 4H, HC
aromatic), 9.85 (s, 1H, HC), 12.03 (s, 1H, HO exchange-
able), 13C NMR (DMSO-d6): δ 56.8 (CH3), 74.9 (CH), 115
(CH), 118 (CH), 127 (CH), 128 (CH), 133 (CH), 144 (CH),
147 (C–N), 153 (C=N), 158 (C–OCH3), 160 (C–OH), 187
(C=O), MS (m/, r.i.%): 346 (M+, 100), 225 (25%), 168
(55%).
Conclusions
(7-(4-Fluorophenyl)pyrazolo[5,1-c][1,2,4]triazin-3-yl)
(2-hydroxyphenyl)methanone (14c), orange powder,
m.p. =220–224 °C, C18H11FN4O2 (334.30), Anal% calcd
(found): C: 64.67 (64.65), H: 3.32 (3.35), N: 16.76 (16.77), F:
5.68 (5.66%), IR (KBr) max/cm−1: 3399 (OH), 1654 (C=O),
1H NMR (DMSO-d6): δ 6.87 (s, 1H,HC), 6.95–7.75 (m, 4H,
HC aromatic), 7.99–8.17 (m, 4H, HC aromatic), 9.43 (s, 1H,
HC), 12.02 (s, 1H, HO exchangeable), 13C NMR (DMSO-
d6): δ 72 (CH), 113 (CH), 116 (CH), 118 (CH), 124 (CH),
128 (CH), 134 (CH), 144 (CH), 150 (C–N), 162 (C–F), 189
(C=O), MS (m/z, r.i.%): 334 (M+, 100).
A novel series of heterocycles containing a bioactive nucleus
was synthesized and characterized by IR, 1H and 13C NMR,
and MS analysis. Biological evaluation of the synthesized
compounds elucidated their antimicrobial and antitumor
activities. Furthermore, docking studies of compounds 14a,c
with diferent proteins revealed that they are kinetically sta-
ble with short bond length. Characterization of pyrazole
14a,c utilizing DFT/ B3LYP/ 6-31G(d) and HF/6-31G(d)
methods supported the stability and importance of this
pyrazole. The relations between the calculated and crystal-
lographic results indicates that the B3LYP/6-31G(d) method
is better than the HF method for approximating the bond
(7-(4-Bromophenyl)pyrazolo[5,1-c][1,2,4]triazin-
3-yl)(2-hydroxyphenyl)methanone (14d): orange solid,
m.p.=260–262 °C, C18H11BrN4O2 (395.21), Anal% calcd
1 3

Journal of the Iranian Chemical Society
13. N. Obaiah, Y.D. Bodke, S. Telkar, Synthesis of 3-[(1H-benzimida-
zol-2-ylsulfanyl)(aryl)methyl]-4-hydroxycoumarin derivatives as
potent bioactive molecules. ChemistrySelect 5, 178–184 (2020).
https://doi.org/10.1002/slct.201903472
lengths, while the HOMO–LUMO gap results confrm the
high kinetic stability of these compounds.
Supplementary Information The online version contains supplemen-
14. O. Nagaraja, Y.D. Bodke, R. Kenchappa, S. Ravi Kumar, Synthe-
sis and characterization of 3-[3-(1H-benzimidazol-2-ylsulfanyl)-
3-phenyl propanoyl]-2H-chromen-2-one derivatives as potential
biological agents. Chem. Data Collect. 27, 100369 (2020)
15. R. Kenchappa, Y.D. Bodke, Synthesis, analgesic and anti-infam-
matory activity of benzofuran pyrazole heterocycles. Chem. Data
Collect. 28, 100453 (2020). https://doi.org/10.1016/j.cdc.2020.
100453
tary material available at https://doi.org/10.1007/s13738-021-02251-7.
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