Synthesis, crystal structure, anti-HIV, and antiproliferative activity of new pyrazolylthiazole derivatives

Article abstract of DOI:10.1007/s00044-017-1963-1

The development of new HIV-1 non-nucleoside reverse transcriptase inhibitors offers the possibility of generating novel structures of increased potency. Based on the bioisosteric principle, new series of N′-benzylidene-2-(5-(4-chlorophenyl)-3-phenyl-4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide schiff bases 5a–x containing 1,3-thiazole clubbed with 2-pyrazoline was synthesized and characterized by spectroscopic techniques. The structure of the synthesized compounds was unambiguously confirmed by single-crystal X-ray diffraction analysis of compound 5k. All the new analogs were evaluated in vitro for antiviral activity against the replication of HIV-1 and HIV-2 in MT4 cells using MTT assay. The results showed that only compounds 5n, and 5r possess potent activity against HIV-1 replication (IC₅₀ = 0.50, 0.45 μM, SI = 3 and 5), respectively. None of the compounds are active against HIV-2. Furthermore, compounds 5a, 5i, 5n, and 5r were evaluated for their antiproliferative activity against two solid tumor-derived cell lines consisting MCF-7 (breast cancer) and Hep-G2 (human hepatocarcinoma).

Full text of DOI:10.1007/s00044-017-1963-1

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-017-1963-1
ORIGINAL RESEARCH
Synthesis, crystal structure, anti-HIV, and antiproliferative
activity of new pyrazolylthiazole derivatives
Murtaza Madni1 Shahid Hameed1 Muhammad N. Ahmed2 Muhammad N. Tahir3
●
●
●
●
Najim A. Al-Masoudi4,6 Christophe Pannecouque5
●
Received: 9 January 2017 / Accepted: 14 June 2017
© Springer Science+Business Media, LLC 2017
Abstract The development of new HIV-1 non-nucleoside
reverse transcriptase inhibitors offers the possibility of
generating novel structures of increased potency. Based on
the bioisosteric principle, new series of N′-benzylidene-2-
(5-(4-chlorophenyl)-3-phenyl-4,5-dihydropyrazol-1-yl)thiazole-
4-carbohydrazide schiff bases 5a–x containing 1,3-thiazole
clubbed with 2-pyrazoline was synthesized and character-
ized by spectroscopic techniques. The structure of the
synthesized compounds was unambiguously confirmed by
single-crystal X-ray diffraction analysis of compound 5k.
All the new analogs were evaluated in vitro for antiviral
activity against the replication of HIV-1 and HIV-2 in MT4
cells using MTT assay. The results showed that only
compounds 5n, and 5r possess potent activity against HIV-
1 replication (IC50 = 0.50, 0.45 μM, SI = 3 and 5), respec-
tively. None of the compounds are active against HIV-2.
Furthermore, compounds 5a, 5i, 5n, and 5r were evaluated
for their antiproliferative activity against two solid tumor-
derived cell lines consisting MCF-7 (breast cancer) and
Hep-G2 (human hepatocarcinoma).
●
●
Keywords Anti-HIV activity Antiproliferative activity
●
●
●
Crystal structure NNRTIs 1,3-Thiazole Pyrazole
* Shahid Hameed
shameed@qau.edu.pk
* Najim A. Al-Masoudi
Najim.al-masoudi@gmx.de
Introduction
Murtaza Madni
murtaza.madni@gmail.com
HIV disease is caused either by HIV-1 or HIV-2 which
gradually leads to AIDS by destroying helper
T-lymphocytes (CD4 cells) (de Silva et al. 2008; Jaffar et al.
2004). Infected individuals show both cellular and humoral
immune response but these responses are unable to contain
the gradual progression of disease in majority of patients
(Haynes et al. 1996). Currently, management of HIV is
based on highly active antiretroviral therapy (HAART)
(Tiberi et al. 2014; Antonelli and Turriziani 2012). HAART
decision is based on combining three to four medications of
different classes of antiretrovirals to prevent the progression
of human immune virus (HIV). Due to viral resistance to the
current available antiviral agents, there is a dire need to
develop newer inhibitors with reduced toxicity and
improved activity and resistance profiles (Esté and Cihlar
2010; Asahchop et al. 2012; De Luca et al. 2013).
Muhammad N. Ahmed
aromatics790@gmail.com
Christophe Pannecouque
christophe.pannecouque@rega.kuleuven.be
1
Department of Chemistry, Quaid-i-Azam University, Islamabad
45320, Pakistan
2
Department of Chemistry, The University of Azad Jammu and
Kashmir, Muzaffarabad 13100, Azad Jammu and Kashmir,
Pakistan
3
Department of Physics, University of Sargodha, Sargodha 40100,
Pakistan
4
Department of Chemistry, College of Science, University of
Basrah, Basrah, Iraq
5
Rega Institute for Medical Research, Katholieke Universiteit
Leuven, Leuven 3000, Belgium
6
Present address: Am Tannenhof 8, 78464 Konstanz, Germany

Med Chem Res
dihydropyrazole-1-carbothioamide (2). Reaction of 2 with
α-bromopyruvate yielded thiazole-4-carboxylate derivative
3, which on treatment with hydrazine hydrate furnished 4.
The target compounds 5a–x were obtained by refluxing 4
with appropriate aldehydes.
Both analytical and spectral data of the synthesized
compounds 5a–x was fully in agreement with the proposed
1
structures, which were confirmed by their infrared (IR), H
nuclear magnetic resonance (NMR), and 13C NMR spectra.
In the IR spectra, absorption band in the range of
1552–1593 cm−1 was attributed to C=N functionality
indicated the successful synthesis. The absence of absorp-
tion bands at 3315, 3164 cm−1 corresponding to the NH
stretchings observed in compound 4 also supported the
synthesis. In 1H NMR spectra, a singlet in the range
δ 10.60–11.53 ppm assigned to CH proton of the imine
functionality, confirmed successful synthesis of desired
compounds 5a–x. The aromatic protons have also been
fully assigned (cf. Experimental section). In the 13C NMR
spectra, the low field resonances in the regions δ
164.8–164.1 and 160.0–157.0 ppm were assigned to C-2 of
the thiazole moiety and C=O group, respectively. C-4 and
C-5 of the thiazole ring resonated in the regions δ
146.3–145.0 and 117.0–115.6 ppm, respectively. C-3′ and
C-4′ of the pyrazole moiety were observed in the range of δ
63.8–63.5 and 43.5–43.4 ppm, respectively, while the
resonance in the range δ 154.7–156.4 ppm was assigned to
C-5′ of the same ring. The carbon atom of the imine residue
(CH=N) appeared in the region δ 149.1–139.6 ppm.
In addition, the OMe group protons in different compounds
appeared in the range δ 56.3–55.8 ppm, whereas aromatic
carbon atoms carrying OH group resonated in the range
δ 154.3–148.8 ppm. The other substituents and aromatic
carbons were also fully analyzed (cf. Experimental section).
Compound 5r was selected for further study via the HMBC
(Willker et al. 1993) NMR spectroscopic measurements.
The gradient‐selected HMBC spectrum of 5r showed a 2JC,
Fig.
1 5(5-((4-Bromophenyl)diazenyl)-4-methylthiazol-2-yl)-4-(4-
chlorophenyl)-3-phenyl-5,6-dihydro-4H-pyrazolo[4,3-d]isoxazole lead
compound (IC50 HIV RT = 0.016 nM)
Majority of compounds proven to act as anti-HIV agents
have integral heterocyclic pharmacophoric moieties
including thiazoles (Xu et al. 2014; Vicini et al. 2003; Bell
et al. 1995; Siddiqui et al. 2011; Pandeya et al. 1999;
Al-Soud et al. 2010), pyrazoles (El-Sabbagh et al. 2009; Ali
et al. 2007; Rizvi et al. 2012; Wu et al. 2012; Tantawy et al.
2012) and triazines (Chen et al. 2012, 2015; Desai et al.
2011; Krečmerová et al. 2007). Furthermore, in the thiazole
series, several four-substituted derivatives bearing small
alkyl, cyano, trifluoromethyl, and ethoxycarbonyl sub-
stituents, were found quite potent inhibitors for HIV activity
(Bell et al. 1995). Recently, Gomha et al. 2014 have
reported a new series of pyrazolo[4,3-d]isoxazole and pyr-
azolothiazole derivatives as potential anti-HIV agents, since
one of these analogs, 5-(5-((4-bromophenyl)diazenyl)-4-
methylthiazol-2-yl)-4-(4-chlorophenyl)-3-phenyl-5,6-dihy-
dro-4H-pyrazolo[4,3-d]isoxazole (Fig. 1), exhibited
remarkable anti-HIV-1 inhibition activity with an IC50
0.016 nM.
a
=
As a continuation of our previous work on the synthesis
of new anti-HIV agents (Khan et al. 2010, 2012, 2015,
2016; Zahid et al. 2009; Akhtar et al. 2008), herein we
report the synthesis and anti-HIV activity of new com-
pounds based on thiazole and 2-pyrazoline as backbone
scaffold. The aim of performing these structural modifica-
tions was to explore the anti-HIV effect of combination of
more than one anti-HIV heterocyclic moiety in a single
molecule.
heteronuclear correlation of C-4′ of pyrazole ring (δC
H
43.4 ppm) to the H-5′ proton (δC 5.77 ppm) of the same
ring. Further H-5 of the thiazole moiety at δ 7.73 ppm
3
showed two JC;H correlations: one to C-2 of the same ring
at δ 164.8 ppm, and the other to the carbonyl carbon atom of
the carbohydrazide group at δ 157.4 ppm. A 3JC,H coupling
of the benzylidene proton at δH 11.3 ppm to aromatic carbon
atom Carom.–OH at δ 154.5 ppm was also observed (Fig. 2).
The structures of newly synthesized 2,4-disubstituted
pyrazolothiazoles were unambiguously confirmed by single
crystal X-ray diffraction analysis of compound 5k. In the
molecular structure of 5k, the 4-chlorophenyl group A
(C1–C6/Cl1), 4,5-dihydro-1H-pyrazole ring B (C7–C9/N1/
N2), benzene ring C (C10–C15), 1,3-thiazole ring D
(C16–C18/N3/S1), formic hydrazide group E (C19/O1/N4/
N5) and a part of 2-methoxybenzaldeyde F (C20–C27/O2)
Results and discussion
Chemistry
The reaction sequence employed for the synthesis of target
heterocycles is outlined in Scheme 1. Treatment of 3-(4-
chlorophenyl)-1-phenylprop-2-en-1-one (1), prepared by
the reaction of acetophenone and 4-chlorobenzaldehyde
under basic conditions, with thiosemicarbazide in the pre-
sence of NaOH afforded 5-(4-chlorophenyl)-3-phenyl-4,5-

Med Chem Res
Scheme 1 Reagents and
conditions: (i) NH2CSNHNH2,
NaOH, EtOH, reflux, 4 h; (ii)
ethyl 3-bromo-2-oxopropanoate,
EtOH, reflux, 3 h; (iii) NH2NH2.
H2O, EtOH, reflux, 10 h; (iv)
Ar-CHO, CH3CO2H, EtOH,
reflux, 6 h
ROD), and monitored by the inhibition of the virus-induced
cytopathic effect in the human T-lymphocyte (MT-4) cells,
using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium
bromide (MTT) method (Pannecouque et al. 2008). The
results are summarized in Table 1, in which the data for
nevirapin, azidothymidine (AZT) (Mitsuya et al. 1985), and
lamivudine (3TC) (Coates et al. 1992) are included for
comparison purposes. The cytotoxicity of the compounds
was determined in parallel. Of the title compounds tested,
compounds 5a (IC50 > 0.45 μM), 5i (IC50 > 0.47 μM), 5n
(IC50 = 0.50 μM), and 5r (IC50 = 0.45 μM) were found to
be the active compounds which inhibited HIV-1 replication
in cell culture. However, the therapeutic indexes of these
derivatives are generally low (<1) in comparison with that
of the pyrazolothiazole (Fig. 1). Due to the marked cyto-
toxicity of 5a and 5i, against the human CD4+ lymphocytes
(MT-4), they were evaluated for their in vitro anti-
proliferative activity against two solid tumor-derived cell
lines. However, none of the synthesized compounds were
active against HIV-2 (ROD).
From the SAR analysis, we found that the 4-fluoro‐ or 2-
hydroxy-4-chlorobenzylidine substituents at C‐4 of the
thiazole ring, e.g. compounds 5n or 5r, were well tolerated
in the hydrophobic binding pocket of HIV-1 reverse tran-
scriptase (RT) and showed higher activity than those of
other substituents at C‐4 of the same ring. On the basis of
the chemical structure and the fact that these compounds
inhibit HIV-1, but not HIV-2 replication, these molecules
can be proposed to act as HIV-1 non-nucleoside reverse
Fig. 2 JC,H Correlations in the HMBC NMR spectrum of 5r
is planar with r. m. s. deviations of 0.0056, 0.0730, 0.0018,
0.0790, 0.0730, 0.0004, and 0.0391 Å, respectively. The
dihedral angle between A/B, B/C, A/C, B/D, D/E and E/F is
81.50 (6)°, 4.81 (16)°, 79.67 (7)°, 13.11 (11)°, 5.67(12)°,
and 15.75 (9)°, respectively. S(5) ring motif is formed due
to N–H…N hydrogen bond (Fig. 3). In the molecular
packing, C–H…π and C–Cl…π interactions are present
(Fig. 4).
Biology
In vitro anti-HIV activity
Compounds 3, 4, and 5a–x were evaluated for their inhi-
bitory activity against HIV-1 (strain IIIB) and HIV-2 (strain

Med Chem Res
Fig. 3 Molecular structure of
5k. Anisotropic displacement
ellipsoids are drawn at 50%
probability level. H atoms are
shown as small circles of
arbitrary radii
5r were inactive against Hep-G2 (IC50 > 50 μM), while 5i
showed activity with IC50 = 2.59 0.11 μM. These results
suggested that 4-fluoro- and 3-nitrobenzylidene moieties
linking pyrazolo-thiazole derivative have potent anticancer
activities and be worth being further investigated as can-
didates of anticancer agents. However, all compounds did
not show superior activity than doxorubicin against both
Hep-G2 and MCF-7.
Experimental
Chemistry
All reagents were commercially available and used without
further purification. Melting points were determined on a
Stuart SMP3 melting point apparatus and are uncorrected.
IR spectra were recorded on a Thermo Scientific Nicolet
Fig. 4 Packing diagram of dimer formed via C–H…O interactions
(dashed lines) in the crystal structure of compound 5k
1
6700 FTIR spectrophotometer using ATR facility. H and
13C NMR spectra were recorded on a Bruker Avance 300
MHz instrument in deuterated solvents and the chemical
shifts are referenced to TMS. Reactions were monitored
using thin layer chromatography (TLC) on silica gel 60F254
coated aluminum sheets (Merck, Germany). X-ray dif-
fractometer analysis was carried out on Bruker Kappa
APEX-IICCD diffractometer.
transcriptase inhibitors (NNRTIs). Generally, the antiviral
regularity of this series was inconspicuous.
In vitro antiproliferative activity
Compounds 5a, 5i, 5n, and 5r were selected for the anti-
proliferative activity screening and tested in vitro against
two solid tumor derived cell lines consisting MCF-7
(human breast adenocarcinoma) and Hep-G2 (human
hepatocarcinoma) using the microculture tetrazolium assay
(MTT) method (Alley et al. 1988). Doxorubicin (Uyeki
et al. 1981; Panasci et al. 1996) was used for comparative
purposes of the cytotoxic activities and the results are pre-
sented in Table 2. Compounds 5n and 5r exhibited
activity against MCF-7 cell lines with IC50 = 3.39 0.09
and 4.46 0.10 μM, respectively, while 5a and 5i were
inactive (IC50 > 50 μM). However, compounds 5a, 5n, and
Synthesis of 3-(4-chlorophenyl)-1-phenylprop-2-en-1-one
(1)
A
mixture of acetophenone (5.0 mmol) and 4-
chlorobenzalaldehyde (5.0 mmol) in 20 mL EtOH was
stirred at room temperature followed by the dropwise
addition of aq. 10 M NaOH. The stirring was continued for
2 h. After reaction completion (TLC), the reaction mixture
was poured into ice cold water to obtain yellow precipitates.

Med Chem Res
Table 1 In vitro anti-HIV-1 and HIV-2 activity of compounds 3, 4
and 5a–x
Table 1 continued
Compd.
Virus
strain
av. IC50
av. CC50
SIc
SIc
(μM)a
(μM)b
Compd.
Virus
strain
av. IC50
av. CC50
(μM)a
(μM)b
ROD
IIIB
>6.26
6.26
<1
3
IIIB
>11.51
>11.51
>125.00
>125.00
>0.45
11.51
<1
<1
X1
X1
<1
<1
<1
<1
<1
<1
<1
<1
XI
XI
<1
<1
XI
XI
XI
XI
<1
<1
<1
<1
<1
<1
XI
XI
XI
XI
5
5v
5w
5x
>125.00
>125.00
>125.00
>125.00
>125.00
>125.00
0.05
>125.00
>125.00
>125.00
>125.00
>125.00
>125.00
>4
<1
ROD
IIIB
11.51
ROD
IIIB
XI
4
>125.00
>125.00
0.45
XI
ROD
IIIB
ROD
IIIB
XI
5a
5b
5c
5d
5e
5f
XI
ROD
IIIB
>0.45
0.45
ROD
XI
>7.33
7.33
Nevirapin III
ROD
>80
<1
ROD
IIIB
>7.33
7.33
>4
>4
>66.85
>66.85
>17.75
>17.75
>125.00
>125.00
>64.50
>64.50
>125.00
>125.00
>125.00
>125.00
>0.47
66.85
AZT
IIIB
0.0019
0.0018
0.51
>25
>13144
>14245
>39
>10
ROD
IIIB
66.85
ROD
IIIB
>25
17.75
3TC
>20
ROD
IIIB
17.75
ROD
2.02
>20
>125.00
>125.00
64.50
Anti-HIV-1 activity measured against strain IIIB; anti-HIV-2 activity
measured against strain ROD
a Compound concentration required to achieve 50% protection of MT-
4 cells from the HIV-1 and 2-induced cytopathogenic effect
b Average CC50: compound concentration that reduces the viability of
mock-infected MT-4 cells by 50%
ROD
IIIB
ROD
IIIB
64.50
5g
5h
5i
>125.00
>125.00
>125.00
>125.00
0.47
ROD
IIIB
c SI: selectivity index (CC50/IC50). All data represents the mean values
of at least two separate experiments
ROD
IIIB
ROD
IIIB
>0.47
0.47
Table 2 The anti-proliferative activities for compounds 5a, 5i, 5n,
and 5r
5j
>105.90
>105.90
>10.32
>10.32
>125.00
>125.00
>125.00
>125.00
0.50
105.90
105.90
10.32
ROD
IIIB
Compd.
IC50 (μM)a
5k
5l
ROD
IIIB
10.32
MCF-7
Hep-G2
>125.00
>125.00
>125.00
>125.00
2.50
5a
5i
>50
>50
ROD
IIIB
>50
2.59 0.11
>50
5m
5n
5o
5p
5q
5r
5s
5t
5n
5r
C
3.39 0.09
4.46 0.10
1.90
ROD
IIIB
>50
0.03
ROD
IIIB
>0.50
0.50
<1
XI
XI
<1
<1
<1
<1
3
a Values are means of three experiments. C: doxorubicin as a positive
>125.00
>125.00
>61.75
>61.75
>60.10
>60.10
0.45
>125.00
>125.00
61.75
control
ROD
IIIB
ROD
IIIB
61.75
Solid mass was filtered, washed with excess of water and
recrystallized from EtOH to give 1 (1.05 g, 87%) as a yel-
low solid, Mp: 115–116 °C (Lit. Nielsen et al. 1998; Sarda
et al. 2009; Tanemura et al. 2005), Mp: 115–116 °C]; Rf:
0.58 (n-hexane:ethyl acetate; 4:1).
60.10
ROD
IIIB
60.10
1.35
ROD
IIIB
>0.45
0.45
<1
XI
XI
<1
<1
<1
>125.00
>125.00
>94.90
>94.90
>6.26
>125.00
>125.00
94.90
ROD
IIIB
Synthesis of 5-(4-chlorophenyl)-3-phenyl-4,5-dihydropyrazole-
1-carbothioamide (2)
ROD
IIIB
94.90
5u
6.26
Compound 1 (1.0 mmol) and thiosemicarbazide (1.0 mmol)
were dissolved in 25–30 mL EtOH and stirred vigorously.

Med Chem Res
Pellets of NaOH (1.5 mol) were added to the reaction
mixture and heated under reflux. After reaction completion
(TLC), the suspension was poured into ice cold water.
Light yellow precipitates formed were filtered and recrys-
tallized from MeOH to give 2 as colorless crystals (233 mg,
74%), Mp 195–197 °C (Lit. Ali et al. 2012; Bhandari et al.
2013), Mp 195–197 °C]; Rf: 0.55 (n-hexane:ethyl
acetate; 7:3).
General procedure for the synthesis of schiff bases (5a–x)
Compound 4 (398 mg, 1.00 mmol) and respective benzal-
dehyde (1.00 mmol) were added in 20 mL EtOH containing
catalytic amount of acetic acid. The reaction mixture was
refluxed till reaction completion (TLC). The mixture was
poured into ice cold water and the precipitate was filtered
then recrystallized from CHCl3:EtOH (3:1).
N′-Benzylidene-2-(5-(4-chlorophenyl)-3-phenyl-4,5-dihy-
Synthesis of ethyl 2-(5-(4-chlorophenyl)-3-phenyl-4,5-
dihydropyrazol-1-yl)thiazole-4-carboxylate (3)
dropyrazol-1-yl)thiazole-4-carbohydrazide
(5a) Yield:
369 mg (76%); Mp 207 °C; FTIR (νmax, cm−1): 1536
(C=C), 1552 (C=N), 1699 (C=O amidic); 2979 (CH,
aliphatic), 3030 (CH, aromatic), 3241 (NH). 1H NMR (300
MHz, CDCl3): δ = 3.44 (dd, 1H, Jcis = 6.0 Hz, Jgem = 18.0
Hz, H4pyrazole), 4.12 (1H, dd, Jtrans = 11.7 Hz, Jgem = 17.7
Hz, H4pyrazole), 5.75 (dd, 1H, Jcis = 6.0 Hz, Jtrans = 11.7 Hz,
H5pyrazole), 7.44–7.53 (m, 10H, Harom.), 7.70 (s, 1H,
H5thiazole), 7.75–7.84 (m, 4H, Harom.), 8.41 (s, 1H, NH),
10.85 (s, 1H, Hbenzylidene). 13C NMR (75 MHz, DMSO): δ
= 43.4 (C4pyrazole), 63.7 (C3pyrazole), 116.4 (C5thiazole),
127.1, 127.7, 129.1, 129.3, 130.7, 130.7, 131.1, 132.8,
134.6, 140.8 (Carom.), 145.3 (C4thiazole), 148.7 (Cbenzylidene
= N), 154.5 (C5pyrazole), 157.3 (C=O), 164.7 (C2thiazole).
Anal. calcd for C26H20ClN5OS (485.99): C, 64.26; H, 4.15;
N, 14.41. Found: C, 63.97; H, 4.21; N, 14.13.
Compound 2 (1.00 mmol) and α-bromopyruvate (1.0 mmol)
were dissolved in EtOH and stirred vigorously at 50–60 °C
for 3–4 h. 2,4-Disubstituted 1,3-thiazole precipitated was
filtered out and the solid mass obtained was washed with
cold EtOH and recrystallized from CHCl3:EtOH (3:1) to
give 3 (375 mg, 91%) as a yellow solid, Mp 158 °C; Rf:
0.43 (n-hexane:ethyl acetate; 7:3); FTIR (νmax, cm−1): 1696
1
(C=O), 2979 (C–H), 3038 (C=C–H). H NMR (300 MHz,
CDCl3): δ = 1.35 (t, 3 H, J = 7.2 Hz, CH3), 3.31 (dd, 1H,
Jcis = 5.4 Hz, Jgem = 17.4 Hz, H4pyrazole), 3.92 (dd, 1H,
Jtrans = 12.0 Hz, Jgem = 17.7 Hz, H4pyrazole), 4.31 (m, 2H,
CH2), 5.75 (dd, 1H, Jcis = 5.7 Hz, Jtrans = 12.0 Hz, H5′
pyr-
azole), 7.31–7.46 (m, 7H, Harom.), 7.52 (s, 1H, H5thiazole),
7.75–7.78 (m, 2H, Harom.). 13C NMR (75 MHz, CDCl3): δ
= 14.3 (OCH2CH3), 43.5 (C4pyrazole), 60.9 (OCH2CH3),
63.3 (C3pyrazole), 118.9 (C5thiazole), 126.5, 127.9, 128.8,
129.0, 130.2, 131.0, 133.7, 139.6 (Carom.), 143.8 (C4thiazole),
152.4 (C5pyrazole), 161.6 (C=O), 164.8 (C2thiazole).
N′-(2-Hydroxybenzylidene)-2-(5-(4-chlorophenyl)-3-phenyl
-4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide (5b)
Yield: 251 mg (50%); Mp 233–236 °C; FTIR (νmax, cm−1):
1564 (C=C), 1576 (C=N), 1712 (C=O amidic); 2977 (CH,
aliphatic), 3027 (CH, aromatic), 3236 (NH). 1H NMR (300
MHz, CDCl3): δ = 3.44 (dd, 1H, Jcis = 5.4 Hz, Jgem = 18.0
Hz, H4pyrazole), 4.13 (dd, 1H, Jtrans = 11.7 Hz, Jgem = 18.0
Hz, H4pyrazole), 5.77 (dd, 1H, Jcis = 5.7 Hz, Jtrans = 11.7 Hz,
H5pyrazole), 6.91–7.56 (m, 11H, Harom.), 7.72 (s, 1H,
H5thiazole), 7.80–7.83 (m, 2H, Harom.), 8.65 (s, 1H, NH),
11.19 (s, 1H, OH), 11.24 (s, 1H, Himine). 13C NMR (75
MHz, DMSO): δ = 43.4 (C4pyrazole), 63.5 (C3pyrazole), 116.7
(C5thiazole), 119.2, 119.8, 127.1, 129.11, 129.2, 129.3,
129.9, 130. 8, 131.1, 131.9, 132.8, 140.7 (Carom.), 145.0
(C4thiazole), 149.1 (Cbenzylidene=N), 154.5 (C5pyrazole), 157.3
(Carom.–OH), 157.9 (C=O), 164.8 (C2thiazole). Anal. calcd
for C26H20ClN5O2S (501.99): C, 62.21; H, 4.02; N, 13.95.
Found: C, 62.33; H, 3.92; N, 14.08.
Synthesis of 2-(5-(4-chlorophenyl)-3-phenyl-4,5-
dihydropyrazol-1-yl)thiazole-4-carbohydrazide (4)
The intermediate 3 (1.0 mmol) and hydrazine hydrate (1.6
mmol) were heated refluxed until the reaction was complete
(TLC, ~10 h). The mixture was added into ice cold water to
furnish precipitates that were filtered and washed with cold
MeOH. Recrystallization from EtOH afforded 4 (290 mg,
73%); Mp 197 °C; FTIR (νmax, cm−1): 1526 (C=C), 1538
(C=N), 1651 (C=O amidic); 2972 (CH, aliphatic), 3020
(CH, aromatic), 3315, 3164 (NHNH2). 1H NMR (300 MHz,
CDCl3): δ = 3.28 (dd, 1H, Jcis = 6.9 Hz, Jgem = 17.7 Hz,
H4pyrazole), 3.94 (m, 3H, H4pyrazole + NH2), 5.52 (dd, 1H,
Jcis = 6.9 Hz, Jtrans = 12.0 Hz, H5pyrazole), 7.26–7.46 (m,
7H, Harom.), 7.48 (s, 1H, H5thiazole), 7.74–7.77 (m, 2H,
N′-(3-Hydroxybenzylidene)-2-(5-(4-chlorophenyl)-3-phenyl
-4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide (5c)
Yield: 266 mg (53%); Mp 237–239 °C; FTIR (νmax, cm−1):
1553 (C=C), 1579 (C=N), 1704 (C=O amidic); 2965 (CH,
aliphatic), 3020 (CH, aromatic), 3242 (NH). 1H NMR (300
MHz, CDCl3): δ = 3.44 (dd, 1H, Jcis = 5.7 Hz, Jgem = 18.0
Hz, H4pyrazole), 4.12 (dd, 1H, Jtrans = 11.7 Hz, Jgem = 18.0
H
arom.), 7.87 (s, 1H, NH). 13C NMR (75 MHz, CDCl3): δ =
43.8 (C4pyrazole), 63.9 (C3pyrazole), 114.7 (C5thiazole), 126.5,
127.5, 128.8, 129.2, 130.3, 130.8, 133.8, 139.8 (Carom.),
144.5 (C4thiazole), 152.5 (C5pyrazole), 162.1 (C=O), 165.0
(C2thiazole).

Med Chem Res
Hz, H4pyrazole), 5.75 (dd, 1H, Jcis = 5.7 Hz, Jtrans = 11.4 Hz,
H5pyrazole), 6.84–7.50 (m, 11H, Harom.), 7.69 (s, 1H,
H5thiazole), 7.81–7.82 (m, 2H, Harom.), 8.30 (s, 1H, NH),
9.64 (s, 1H, OH), 10.79 (s, 1H, Himine). 13C NMR (75 MHz,
DMSO): δ = 43.4 (C4pyrazole), 63.7 (C3pyrazole), 116.3
(C5thiazole), 118.0, 119.4, 127.1, 129.1, 129.3, 130.4, 130.7,
131.1, 132.8, 135.9, 140.7 (Carom.), 145.3 (C4thiazole), 148.7
(Cbenzylidene=N), 154.5 (C5pyrazole), 157.3 (Carom.–OH),
158.2 (C=O), 164.7 (C2thiazole). Anal. calcd for
C26H20ClN5O2S (501.99): C, 62.21; H, 4.02; N, 13.95.
Found: C, 62.10; H, 3.79; N, 14.17.
(C=C), 1576 (C=N), 1702 (C=O amidic); 2974 (CH, ali-
phatic), 3028 (CH, aromatic), 3247 (NH). H NMR (300
1
MHz, CDCl3): δ = 3.44 (dd, 1H, Jcis = 5.7 Hz, Jgem = 18.0
Hz, H4pyrazole), 4.12 (dd, 1H, Jtrans = 12.0 Hz, Jgem = 18.0
Hz, H4pyrazole), 5.75 (dd, 1H, Jcis = 5.7 Hz, Jtrans = 12.0 Hz,
H5pyrazole), 7.44–7.70 (m, 10H, Harom.), 7.72 (s, 1H,
H5thiazole), 7.79–7.83 (m, 3H, Harom.), 8.40 (s, 1H, NH),
10.99 (s, 1H, Himine). 13C NMR (75 MHz, DMSO): δ =
43.4 (C4pyrazole), 63.6 (C3pyrazole), 116.7 (C5thiazole), 126.3,
126. 9, 127.1, 129.2, 129.3, 130.3, 130.8, 131.1, 131.2,
132.8, 134.1, 136.9, 140.7, 145.1 (Carom. + C4thiazole), 147.0
(Cbenzylidene=N), 154.5 (C5pyrazole), 157.5 (C=O), 164.7
(C2thiazole). Anal. calcd for C26H19Cl2N5OS (520.43): C,
60.00; H, 3.68; 13.62; N, 13.46. Found: C, 60.37; H, 3.81;
N, 13.59.
N′-(4-Hydroxybenzylidene)-2-(5-(4-chlorophenyl)-3-phe-
nyl-4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide
(5d) Yield: 286 mg (57%); Mp 240–241 °C; FTIR (νmax
,
cm−1): 1542 (C=C), 1584 (C=N), 1703 (C=O amidic);
1
2964 (CH, aliphatic), 3022 (CH, aromatic), 3229 (NH). H
N′-(4-Chlorobenzylidene)-2-(5-(4-chlorophenyl)-3-phenyl-
4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide (5g)
Yield: 379 mg (73%); Mp 228 °C; FTIR (νmax, cm−1): 1567
(C=C), 1572 (C=N), 1702 (C=O amidic), 2980 (CH, ali-
NMR (300 MHz, CDCl3): δ = 3.43 (dd, 1H, Jcis = 6.0 Hz,
Jgem = 18.0 Hz, H4pyrazole), 4.11 (dd, 1H, Jtrans = 11.7 Hz,
Jgem = 18.0 Hz, H4pyrazole), 5.74 (dd, 1H, Jcis = 6.0 Hz,
Jtrans = 11.7 Hz, H5pyrazole), 6.85–7.60 (m, 11H, Harom.),
7.65 (s, 1H, H5thiazole), 7.79–7.82 (m, 2H, Harom.), 8.26
(s, 1H, NH), 9.96 (s, 1H, OH), 10.61 (s, 1H, Himine). 13C
NMR (75 MHz, DMSO): δ = 43.4 (C4pyrazole), 63.8
(C3pyrazole), 116.2 (C5thiazole), 125.5, 127.1, 129.1, 129.3,
129.5, 130.8, 131.1, 132.8, 140.8 (Carom.), 145.4 (C4thiazole),
148.8 (Cbenzylidene = N), 154.5 (C5pyrazole), 157.1
(Carom.–OH), 160.0 (C=O), 164.6 (C2thiazole). Anal. calcd
for C26H20ClN5O2S (501.99): C, 62.21; H, 4.02; N, 13.95.
Found: C, 62.23; H, 3.91; N, 13.77.
1
phatic), 3030 (CH, aromatic), 3252 (NH). H NMR (300
MHz, CDCl3): δ = 3.44 (dd, 1H, Jcis = 6.0 Hz, Jgem = 18.0
Hz, H4pyrazole), 4.12 (dd, 1H, Jtrans = 11.7 Hz, Jgem = 18.0
Hz, H4pyrazole), 5.75 (dd, 1H, Jcis = 6.0 Hz, Jtrans = 11.7 Hz,
H5pyrazole), 7.43–7.55 (m, 9H, Harom.), 7.70 (s, 1H,
H5thiazole), 7.75–7.83 (m, 4H, Harom.), 8.40 (s, 1H, NH),
10.93 (s, 1H, Himine). 13C NMR (75 MHz, DMSO): δ =
43.4 (C4pyrazole), 63.6 (C3pyrazole), 116.5 (C5thiazole), 127.1,
129.1, 129.3, 129.3, 129.4, 130. 8, 131.1, 132.
8, 133.6, 135.1, 140.7, 145.2 (Carom. + C4thiazole), 147.4
(Cbenzylidene=N), 154.5 (C5pyrazole), 157.4 (C = O), 164.7
(C2thiazole). Anal. calcd for C26H19Cl2N5OS (520.43): C,
60.00; H, 3.68; 13.62; N, 13.46. Found: C, 60.21; H, 3.71;
N, 13.37.
N′-(2-Chlorobenzylidene)-2-(5-(4-chlorophenyl)-3-phenyl-
4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide (5e)
Yield: 348 mg (67%); Mp 221 °C; FTIR (νmax, cm−1): 1570
(C=C), 1588 (C=N), 1706 (C=O amidic); 2979 (CH,
aliphatic), 3036 (CH, aromatic), 3246 (NH). 1H NMR (300
MHz, CDCl3): δ = 3.44 (dd, 1H, Jcis = 5.7 Hz, Jgem = 17.7
Hz, H4pyrazole), 4.12 (dd, 1H, Jtrans = 11.7 Hz, Jgem = 18.0
Hz, H4pyrazole), 5.77 (dd, 1H, Jcis = 6.0 Hz, Jtrans = 12.0 Hz,
H5pyrazole), 7.41–7.57 (m, 10H, Harom.), 7.73 (s, 1H,
H5thiazole), 7.80–8.01 (m, 3H, Harom.), 8.80 (s, 1H, NH),
11.24 (s, 1H, Himine). 13C NMR (75 MHz, CDCl3): δ = 43.4
(C4pyrazole), 63.7 (C3pyrazole), 116.0 (C5thiazole), 127.1, 127.5,
128.1, 129.1, 129.3, 129.3, 130.4, 130.8, 131.1, 132.0,
132.8, 133.7, 140.7, 144.5 (Carom.), 145.2 (C4thiazole), 148.5
(Cbenzylidene=N), 154.5 (C5pyrazole), 157.6 (C=O), 164.1
(C2thiazole). Anal. calcd for C26H19Cl2N5OS (520.43):
C, 60.00; H, 3.68; 13.62; N, 13.46. Found: C, 59.88: H,
3.73: N, 13.77.
N′-(2-Nitrobenzylidene)-2-(5-(4-chlorophenyl)-3-phenyl-
4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide (5h)
Yield: 345 mg (65%); Mp 243 °C.; FTIR (νmax, cm−1):
1544 (C=C), 1561 (C=N), 1700 (C=O amidic); 2924 (CH,
aliphatic), 3013 (CH, aromatic), 3237 (NH). 1H NMR (300
MHz, CDCl3): δ = 3.44 (dd. 1H, Jcis = 6.0 Hz, Jgem = 18.0
Hz, H4pyrazole), 4.12 (dd, 1H, Jtrans = 11.7 Hz, Jgem = 18.0
Hz, H4pyrazole), 5.77 (dd, 1H, Jcis = 6.0 Hz, Jtrans = 11.7 Hz,
H4pyrazole), 7.40–7.72 (m, 8H, Harom.), 7.75 (s, 1H,
H5thiazole), 7.80–8.11 (m, 5H, Harom.), 8.83 (s, 1H, NH),
11.33 (s, 1H, Himine). 13C NMR (75 MHz, DMSO): δ =
43.4 (C4pyrazole), 63.6 (C3pyrazole), 116.9 (C5thiazole), 125.2,
127.1, 128.6, 129.1, 129.3, 129.3, 130.8, 131.1, 131.2,
132.8, 134.2, 140.7, 143.8, 145.0 (Carom. + C4thiazole), 148.7
(Cbenzylidene=N + Carom.–NO2), 154.5 (C5pyrazole), 157.6 (C
= O), 164.7 (C2thiazole). Anal. calcd for C26H19ClN6O3S
(530.99): C, 58.81; H, 3.61; N, 15.83. Found: C, 59.07; H,
3.77; N, 16.00.
N′-(3-Chlorobenzylidene)-2-(5-(4-chlorophenyl)-3-phenyl-
4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide (5f)
Yield: 363 mg (70%); Mp 225 °C; FTIR (νmax, cm−1): 1560

Med Chem Res
N′-(3-Nitrobenzylidene)-2-(5-(4-chlorophenyl)-3-phenyl-
4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide (5i)
Yield: 366 mg (69%); Mp 239 °C; FTIR (νmax, cm−1): 1558
(C=C), 1573 (C=N), 1695 (C=O amidic); 2912 (CH, ali-
(Cbenzylidene=N), 154.5 (Carom.–OMe + C5pyrazole), 157.3
(C=O), 164.7 (C2thiazole). Anal. calcd for C27H22ClN5O2S
(516.01): C, 62.84; H, 4.30; N, 13.57. Found: C, 62.55; H,
4.13; N, 13.89.
1
phatic), 3028 (CH, aromatic), 3223 (NH). H NMR (300
MHz, CDCl3): δ = 3.45 (dd, 1H, Jcis = 5.7 Hz, Jgem = 18.0
Hz, H4pyrazole), 4.13 (dd, 1H, Jtrans = 11.7 Hz, Jgem = 18.0
Hz, H4pyrazole), 5.76 (dd, 1H, Jcis = 6.0Hz, Jtrans = 11.7 Hz,
H5pyrazole), 7.44–7.50 (m, 7H, Harom.), 7.74 (s, 1H,
H5thiazole), 7.76–8.29 (m, 5H, Harom.), 8.55 (br s, 2H, NH +
N′-(4-Methoxybenzylidene)-2-(5-(4-chlorophenyl)-3-phe-
nyl-4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide
(5l) Yield: 304 mg (59%); Mp: 213 °C; FTIR (νmax
,
cm−1): 1568 (C=C), 1590 (C=N), 1695 (C=O amidic);
1
2996 (CH, aliphatic), 3049 (CH, aromatic), 3236 (NH). H
H
arom.), 11.11 (s, 1H, Himine). 13C NMR (75 MHz, DMSO):
NMR (300 MHz, CDCl3): δ = 3.44 (dd, 1H, Jcis = 6.0 Hz,
Jgem = 18.0 Hz, H4pyrazole), 3.82 (s, 3H, OMe), 4.12 (dd,
1H, Jtrans = 12.0 Hz, Jgem = 18.0 Hz, H4pyrazole), 5.74 (dd,
1H, Jcis = 6.0 Hz, Jtrans = 12.0 Hz, H5pyrazole), 7.02–7.53
(m, 9H, Harom.), 7.67 (s, 1H, H5thiazole), 7.68–7.83 (m, 4H,
δ = 43.4 (C4pyrazole), 63.6 (C3pyrazole), 116.9 (C5thiazole),
121.6, 124.8, 127.01, 129.2, 129.3, 130.8, 130.9, 131.1,
132.8, 133.8, 136.5, 140.7, 145.0 (Carom.) + 146.3
(C4thiazole), 148.7 (Cbenzylidene=N + Carom.–NO2), 154.5
(C5pyrazole), 157.5 (C=O), 164.7 (C2thiazole). Anal. calcd for
C26H19ClN6O3S (530.99): C, 58.81; H, 3.61; N, 15.83.
Found: C, 58.97; H, 3.53; N, 15.71.
H
arom.), 8.32 (s, 1H, NH), 10.69 (s, 1H, Himine). 13C NMR
(75 MHz, DMSO): δ = 43.4 (C4pyrazole), 55.8 (OMe), 63.7
(C3pyrazole), 114.8 (Carom.), 116.1 (C5thiazole), 127.1, 127.1,
129.1, 129.3, 130.8, 131.1, 132. 8, 140.8, 145.4 (Carom.),
N′-(4-Nitrobenzylidene)-2-(5-(4-chlorophenyl)-3-phenyl-
4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide (5j)
Yield: 382 mg (72%); Mp: 241 °C; FTIR (νmax, cm−1):
1548 (C=C), 1577 (C=N), 1696 (C=O amidic); 2936 (CH,
aliphatic), 3028 (CH, aromatic), 3243 (NH). 1H NMR (300
MHz, CDCl3): δ = 3.40 (dd, 1H, Jcis = 5.7 Hz, Jgem = 18.0
Hz, H4pyrazole), 4.13 (dd, 1H, Jtrans = 11.7 Hz, Jgem = 18.0
Hz, H4pyrazole), 5.76 (dd, 1H, Jcis = 5.7 Hz, Jtrans = 11.7 Hz,
H5pyrazole), 7.44–7.52 (m, 7H, Harom.), 7.76 (s, 1H,
H5thiazole), 7.80–8.34 (m, 6H, Harom.), 8.54 (s, 1H, NH),
11.20 (s, 1H, Himine). 13C NMR (75 MHz, DMSO): δ =
43.4 (C4pyrazole), 63.6 (C3pyrazole), 117.0 (C5thiazole), 124.6,
127.1, 128.6, 129.2, 129.3, 129.4, 130.8, 131.1,
132.8, 140.7, 140.9, 145.0 (Carom. + C4thiazole), 148.4
(Cbenzylidene=N + Carom.–NO2), 154.6 (C5pyrazole), 157.5 (C
= O), 164.7 (C2thiazole). Anal. calcd for C26H19ClN6O3S
(530.99): C, 58.81; H, 3.61; N, 15.83. Found: C, 59.01; H,
3.71; N, 16.09.
145.5
(C4thiazole),
148.5
(Cbenzylidene=N),
154.5
(Carom.–OMe + C5pyrazole), 157.1 (C=O), 164.6 (C2thiazole).
Anal. calcd for C27H22ClN5O2S (516.01): C, 62.84; H,
4.30; N, 13.57. Found: C, 62.73; H, 4.44; N, 13.79.
N′-(4-Methylbenzylidene)-2-(5-(4-chlorophenyl)-3-phenyl-
4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide (5m)
Yield: 273 mg (53%); Mp 234 °C; FTIR (νmax, cm−1): 1528
(C=C), 1554 (C=N), 1698 (C=O amidic); 2928 (CH, ali-
1
phatic), 3020 (CH, aromatic), 3238 (NH). H NMR (300
MHz, CDCl3): δ = 2.35 (s, 3H, CH3), 3.44 (dd, 1H, Jcis
6.0 Hz, Jgem = 18.0 Hz, H4pyrazole), 4.12 (dd, 1H, Jtrans
11.7 Hz, Jgem = 18.0 Hz, H4pyrazole), 5.75 (dd, 1H, Jcis
=
=
=
6.0 Hz, Jtrans = 12.0 Hz, H5pyrazole), 7.27–7.65 (m, 11H,
H
arom.), 7.68 (s, 1H, H5thiazole), 7.80–7.83 (m, 2H, Harom.),
8.35 (s, 1H, NH), 10.77 (s, 1H, Himine). 13C NMR (75 MHz,
DMSO): δ = 21.5 (Me), 43.4 (C4pyrazole), 63.7 (C3pyrazole),
116.2 (C5thiazole), 127.1, 127. 7, 129.1, 129.3, 129.9,
130.87, 131.1, 131.9, 132.8, 140.5 (Carom.), 140.8
N′-(2-Methoxybenzylidene)-2-(5-(4-chlorophenyl)-3-phe-
nyl-4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide
(Carom.–Me),
145.3
(Carom. + C4thiazole),
148.5
(Cbenzylidene=N), 154.7 (C5pyrazole), 157.3 (C=O), 164.7
(C2thiazole). Anal. calcd for C27H22ClN5OS (500.01): C,
64.86; H, 4.43; N, 14.01. Found: C, 63.99; H, 4.14; N,
13.86.
(5k) Yield: 237 mg (46%); Mp 209 °C; FTIR (νmax
,
cm−1): 1546 (C=C), 1583 (C=N), 1701 (C=O amidic);
1
2916 (CH, aliphatic), 3022 (CH, aromatic), 3228 (NH). H
NMR (300 MHz, CDCl3): δ = 3.45 (dd, 1H, Jcis = 6.0 Hz,
Jgem = 18.0 Hz, H4pyrazole), 3.92 (s, 3H, OMe), 4.12 (dd,
1H, Jtrans = 12.0 Hz, Jgem = 18.0 Hz, H4pyrazole), 5.76 (dd,
1H, Jcis = 6.0 Hz, Jtrans = 12.0 Hz, H5pyrazole), 7.00–7.54
(m, 10H, Harom.), 7.68 (s, 1H, H5thiazole), 7.80–7.86 (m, 3H,
N′-(4-Fluorobenzylidene)-2-(5-(4-chlorophenyl)-3-phenyl-
4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide (5n)
Yield: 367 mg (73%); Mp 231 °C; FTIR (νmax, cm−1): 1560
(C=C), 1586 (C=N), 1706 (C=O amidic); 2910 (CH, ali-
1
H
arom.), 8.70 (s, 1H, NH), 10.92 (s, 1H, Himine). 13C NMR
phatic), 3023 (CH, aromatic), 3230 (NH). H NMR (300
(75 MHz, DMSO): δ = 43.4 (C4pyrazole), 56.2 (OMe), 63.7
(C3pyrazole), 112.3 (Carom.), 116.2 (C5thiazole), 121.2,
122.6, 126.2, 127.1, 129.0, 129.3, 130.7, 131.1, 132.2,
132.8, 140.8, 144.0 (Carom.), 145.4 (C4thiazole), 148.7
MHz, CDCl3): δ = 3.95 (dd, 1H, Jcis = 6.0 Hz, Jgem = 18.0
Hz, H4pyrazole), 4.13 (dd, 1H, Jtrans = 11.7 Hz, Jgem = 18.0
Hz, H4pyrazole), 5.75 (dd, 1H, Jcis = 5.7 Hz, Jtrans = 11.7 Hz,
H5pyrazole), 7.29–7.52 (m, 9H, Harom.), 7.70 (s, 1H,

Med Chem Res
H5thiazole), 7.78–7.83 (m, 4H, Harom.), 8.40 (s, 1H, NH),
10.86 (s, 1H, Himine). 13C NMR (75 MHz, DMSO): δ =
43.4 (C4pyrazole), 63.7 (C3pyrazole), 116.4 (d, JC,F = 21.5 Hz),
116.4 (d, JC,F = 13.6 Hz, Carom), 116.6 (C5thiazole), 127.7 (d,
JC,F = 3.6 Hz, Carom.), 129.1, 129.3, 129.8, 129.9, 130.8,
131.1, 131.2 (d, JC,F = 8.2 Hz, Carom.), 132. 8, 140.6
(Carom.), 145.2 (C4thiazole), 148.7 (Cbenzylidene=N), 154.6
(C5pyrazole), 157.3 (C=O), 164.7 (d, JC,F = 252 Hz,
C4arom.–F + C2thiazole). Anal. calcd for C26H19ClFN5OS
(503.98): C, 61.96; H, 3.80; N, 13.90. Found: C, 62.18; H,
4.00; N, 14.15.
N′-(4-Hydroxy-3-methoxybenzylidene)-2-(5-(4-chlorophe-
nyl)-3-phenyl-4,5-dihydropyrazol-1-yl)thiazole-4-carbohy-
drazide (5q) Yield: 260 mg (49%); Mp 224–227 °C; FTIR
(νmax, cm−1): 1557 (C=C), 1573 (C=N), 1698 (C=O
amidic); 2934 (CH, aliphatic), 3018 (CH, aromatic), 3246
1
(NH). H NMR (300 MHz, CDCl3): δ = 3.44 (dd, 1H, Jcis
= 6.3 Hz, Jgem = 18.0 Hz, H4pyrazole), 3.84 (s, 3H, OMe),
4.12 (dd, 1H, Jtrans = 11.7 Hz, Jgem = 18.0 Hz, H4pyrazole),
5.74 (dd, 1H, Jcis = 6.0 Hz, Jtrans = 12.0 Hz, H5pyrazole),
6.85–7.54 (m, 10H, Harom.), 7.66 (s, 1H, H5thiazole),
7.80–7.83 (m, 2H, Harom.), 8.25 (s, 1H, NH), 9.58 (s, 1H,
OH), 10.62 (s, 1H, Himine). 13C NMR (75 MHz, DMSO): δ
= 43.4 (C4pyrazole), 56.1 (OMe), 63.8 (C3pyrazole), 109.7
(Carom.), 115.6 (C5thiazole), 122.7, 125.9, 127.1, 129.1,
129.4, 130.8, 131.1, 132.8, 140.8 (Carom.), 145.4 (C4thiazole),
148.5 (Cbenzylidene=N), 149.2 (Carom.–OH), 149.6
N′-(2-Hydroxy-3-methoxybenzylidene)-2-(5-(4-chlorophe-
nyl)-3-phenyl-4,5-dihydropyrazol-1-yl)thiazole-4-carbohy-
drazide (5o) Yield: 218 mg (41%); Mp 221–222 °C; FTIR
(νmax, cm−1): 1564 (C=C), 1587 (C=N), 1702 (C=O
amidic); 2926 (CH, aliphatic), 3014 (CH, aromatic), 3242
C
arom.–OMe), 154.5 (C5pyrazole), 157.1 (C=O), 164.6
1
(NH). H NMR (300 MHz, CDCl3): δ = 3.44 (dd, 1H, Jcis
(C2thiazole). Anal. calcd for C27H22ClN5O3S (532.01): C,
60.96; H, 4.17; N, 13.16. Found: C, 61.17; H, 4.21; N,
13.29.
= 5.7 Hz, Jgem = 18.0 Hz, H4pyrazole), 3.82 (s, 3H, OMe),
3.85 (s, 1H, OH), 4.12 (dd, 1H, Jtrans = 11.7 Hz, Jgem
=
=
18.0 Hz, H4pyrazole), 5.78 (dd, 1H, Jcis = 5.7 Hz, Jtrans
11.7 Hz, H5pyrazole), 6.85–7.51 (m, 9H, Harom.), 7.72 (s, 1H,
H5thiazole), 7.80–7.83 (m, 3H, Harom.), 8.67 (s, 1H, NH),
11.25 (s, 1H, Himine). 13C NMR (75 MHz, DMSO):
δ = 43.4 (C4pyrazole), 56.3 (OMe), 63.5 (C3pyrazole), 114.4
(Carom.), 116.7 (C5thiazole), 119.4, 119.5, 121.3, 127.1,
129.1, 129.2, 129.4, 130.8, 131.09, 132.8, 140.7 (Carom.),
N′-(4-Chloro-2-hydroxybenzylidene)-2-(5-(4-chlorophe-
nyl)-3-phenyl-4,5-dihydropyrazol-1-yl)thiazole-4-carbohy-
drazide (5r) Yield: 252 mg (47%); Mp 252–254 °C; FTIR
(νmax, cm−1): 1546 (C=C), 1561 (C=N), 1698 (C=O
amidic); 2918 (CH, aliphatic), 3027 (CH, aromatic), 3245
1
(NH). H NMR (300 MHz, CDCl3): δ = 3.44 (dd, 1H, Jcis
145.0
(C4thiazole),
147.6
(Carom.–OMe),
148.4
= 5.1 Hz, Jgem = 18.0 Hz, H4pyrazole), 4.12 (dd, 1H, Jtrans
12.0 Hz, Jgem = 18.0 Hz, H4pyrazole), 5.77 (dd, 1H, Jcis
=
=
(Cbenzylidene=N), 154.5 (C5pyrazole), 149.0 (Carom.–OH),
157.3 (C=O), 164.8 (C2thiazole). Anal. calcd for
C27H22ClN5O3S (532.01): C, 60.96; H, 4.17; N, 13.16.
Found: C, 60.72; H, 3.99; N; 13.37.
5.1 Hz, Jtrans = 11.4 Hz, H5pyrazole), 6.95–7.64 (m, 10H,
H
arom.), 7.73 (s, 1H, H5thiazole), 7.80–7.81 (m, 2H, Harom.),
8.63 (s, 1H, NH), 11.20 (s, 1H, OH), 11.32 (s, 1H, Himine).
13C NMR (75 MHz, DMSO): δ = 43.4 (C4pyrazole), 63.5
(C3pyrazole), 116.8 (C5thiazole), 118.7, 121.2, 123.5, 127.1,
128.0, 129.1, 129.2, 129.3, 130.8, 131.1, 131.3, 132.8,
140.7 (Carom.), 145.0 (C4thiazole), 146.6 (Cbenzylidene=N),
154.5 (C5pyrazole), 156.5 (C–OH), 157.4 (C=O), 164.8
(C2thiazole). Anal. calcd for C26H19Cl2N5O2S (536.43): C,
58.21; H, 3.57; N, 13.06. Found: C, 57.99; H, 3.41; N,
12.86.
N′-(3-Hydroxy-4-methoxybenzylidene)-2-(5-(4-chlorophe-
nyl)-3-phenyl-4,5-dihydropyrazol-1-yl)thiazole-4-carbohy-
drazide (5p) Yield: 250 mg (47%); Mp 230–232 °C; FTIR
(νmax, cm−1): 1546 (C=C), 1572 (C=N), 1698 (C=O
amidic); 2927 (CH, aliphatic), 3014 (CH, aromatic), 3246
1
(NH). H NMR (300 MHz, CDCl3): δ = 3.44 (dd, 1H, Jcis
= 6.0 Hz, Jgem = 18.0 Hz, H4pyrazole), 3.82 (s, 3H, OMe),
4.18 (dd, 1H, Jtrans = 11.7 Hz, Jgem = 18.0 Hz, H4pyrazole),
5.74 (dd, 1H, Jcis = 6.0 Hz, Jtrans = 11.7 Hz, H4pyrazole),
6.98–7.53 (m, 10H, Harom.), 7.66 (s, 1H, H5thiazole),
7.80–7.83 (m, 2H, Harom.), 8.22 (s, 1H, NH), 9.32 (s, 1H,
OH), 10.64 (s, 1H, Himine). 13C NMR (75 MHz, DMSO): δ
= 43.4 (C4pyrazole), 56.1 (OMe), 63.8 (C3pyrazole), 112.4,
112.9 (Carom.), 115.6 (C5thiazole), 120.9, 127.1, 127.4, 129.1,
129.4, 130.8, 131.1, 132.8, 140.8 (Carom.), 145.4 (C4thiazole),
147.4 (Cbenzylidene=N), 148.8 (Carom.–OH), 150.4
(Carom.–OMe), 154.5 (C5pyrazole), 157.1 (C=O), 164.6
(C2thiazole). Anal. calcd for C27H22ClN5O3S (532.01): C,
60.96; H, 4.17; N, 13.16. Found: C, 61.33; H, 4.28; N,
12.93.
N′-(5-Bromo-2-hydroxybenzylidene)-2-(5-(4-chlorophe-
nyl)-3-phenyl-4,5-dihydropyrazol-1-yl)thiazole-4-carbohy-
drazide (5s) Yield: 284 mg (49%); Mp 260–262 °C; FTIR
(νmax, cm−1): 1568 (C=C), 1582 (C=N), 1703 (C=O
amidic); 2896 (CH, aliphatic), 3014 (CH, aromatic), 3242
1
(NH). H NMR (300 MHz, CDCl3): δ = 3.44 (dd, 1H, Jcis
= 5.4 Hz, Jgem = 18.0 Hz, H4pyrazole), 4.12 (dd, 1H, Jtrans
12.0 Hz, Jgem = 18.0 Hz, H4pyrazole), 5.77 (dd, 1H, Jcis
=
=
5.4 Hz, Jtrans = 12.0 Hz, H5pyrazole), 6.90–7.51 (m, 9H,
H
arom.), 7.73 (s, 1H, H5thiazole), 7.77–7.83 (m, 3H, Harom.),
8.62 (s, 1H, NH), 11.20 (s, 1H, OH), 11.32 (s, 1H, Himine).
13C NMR (75 MHz, DMSO): δ = 43.4 (C4pyrazole), 63.5

Med Chem Res
(C3pyrazole), 110.9 (Carom.), 116.9 (C5thiazole), 119.2, 121.8,
127.1, 129.1, 129.2, 129.3, 130.8, 131.1, 132.8, 134.12,
140.7 (Carom.), 145.0 (C4thiazole), 146. 4 (Cbenzylidene=N),
154.5 (C5pyrazole), 156.9 (C–OH), 157.4 (C=O), 164.8
(C2thiazole). Anal. calcd for C26H19BrClN5O2S (580.88): C,
53.76; H, 3.30; N, 12.06. Found: C, 53.42; H, 3.27; N,
12.35.
Jgem = 18.0 Hz, H4pyrazole), 5.78 (dd, 1H, Jcis = 5.7 Hz,
Jtrans = 12.0 Hz, H5pyrazole), 7.40–7.50 (m, 10H, Harom.),
7.77 (s, 1H, H5thiazole), 8.22–8.68 (m, 2H, Harom.), 8.87 (s,
1H, NH), 11.54 (s, 1H, Himine). 13C NMR (75 MHz,
DMSO): δ = 43.5 (C4pyrazole), 63.6 (C3pyrazole), 117.4
(C5thiazole), 121.7, 125.7, 127.1, 129.1, 129.1, 129.3, 130.8,
131.1, 132.1, 132.8, 133.6 (Carom.), 139.6 (Cbenzylidene=N),
140.7, 142.5 (Carom.), 145.0 (C4thiazole), 147.2 (C–NO2),
154.5 (C5pyrazole), 157.8 (C = O), 164.8 (C2thiazole). Anal.
calcd for C26H18Cl2N6O3S (565.43): C, 55.23; H, 3.21; N,
14.86. Found: C, 54.97; H, 3.07; N, 15.03.
N′-(2,4-Dichlorobenzylidene)-2-(5-(4-chlorophenyl)-3-phe-
nyl-4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide
(5t) Yield: 349 mg (63%); Mp 246 °C; FTIR (νmax, cm−1):
1564 (C=C), 1593 (C=N), 1701 (C=O amidic); 2975 (CH,
aliphatic), 3035 (CH, aromatic), 3247 (NH). 1H NMR (300
MHz, CDCl3): δ = 3.43 (dd, 1H, Jcis = 5.7 Hz, Jgem = 18.0
Hz, H4pyrazole), 4.12 (dd, 1H, Jtrans = 11.7 Hz, Jgem = 18.0
Hz, H4pyrazole), 5.76 (dd, 1H, Jcis = 6.0 Hz, Jtrans = 12.0 Hz,
H5pyrazole), 7.40–7.73 (m, 9H, Harom.), 7.74 (s, 1H,
H5thiazole), 7.79–8.00 (m, 3H, Harom.), 8.76 (s, 1H, NH),
11.31 (s, 1H, Himine). 13C NMR (75 MHz, DMSO): δ =
43.5 (C4pyrazole), 63.6 (C3pyrazole), 116.9 (C5thiazole), 127.1,
128.5, 128.7, 129.1, 129.2, 129.3, 129.9, 130.77, 131.1,
131.1, 132.8, 134.4, 135.6 (Carom.), 140.7 (Cbenzylidene=N),
143.4 (Carom.), 145.1 (C4thiazole), 154.5 (C5pyrazole), 157.6
(C=O), 164.8 (C2thiazole). Anal. calcd for C26H18Cl3N5OS
(554.88): C, 56.28; H, 3.27; N, 12.62. Found: C, 56.51; H,
3.33; N, 12.89.
N′-(4-Benzyloxybenzylidene)-2-(5-(4-chlorophenyl)-3-phe-
nyl-4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide
(5w) Yield: 319 mg (54%); Mp 234–236 °C; FTIR (νmax
,
cm−1): 1543 (C=C), 1571 (C=N), 1700 (C=O amidic);
1
2937 (CH, aliphatic), 3030 (CH, aromatic), 3242 (NH). H
NMR (300 MHz, CDCl3): δ = 3.43 (dd, 1H, Jcis = 6.0 Hz,
Jgem = 18.0 Hz, H4pyrazole), 4.12 (dd, 1H, Jtrans = 11.7 Hz,
Jgem = 18.0 Hz, H4pyrazole), 5.17 (s, 2H, CH2), 5.74 (dd, 1H,
Jcis = 6.0 Hz, Jtrans = 11.7 Hz, H5pyrazole), 7.10–7.83 (m,
19H, Harom. + H5thiazole), 8.32 (s, 1H, NH), 10.69 (s, 1H,
H
imine). 13C NMR (75 MHz, DMSO): δ = 43.4 (C4pyrazole),
63.7 (C3pyrazole), 69.9 (OCH2Ph), 115.7 (Carom.), 116.1
(C5thiazole), 127.1, 127.3, 128.2, 128.4, 128.9, 129.1, 129.3,
130.8, 131.1, 132.8, 137.2, 140.8 (Carom.), 145.4 (C4thiazole),
148.5 (Cbenzylidene=N), 154.5 (C5pyrazole), 157.2 (C=O),
164.6 (C4arom.–benzyl), 164.8 (C2thiazole). Anal. calcd for
C33H26ClN5O2S (592.11): C, 66.94; H, 4.43; N, 11.83.
Found: C, 67.12; H, 4.41; N, 12.09.
N′-(2,6-Dichlorobenzylidene)-2-(5-(4-chlorophenyl)-3-phe-
nyl-4,5-dihydropyrazol-1-yl)thiazole-4-carbohydrazide
(5u) Yield: 327 mg (59%); Mp 241 °C; FTIR (νmax
,
cm−1): 1560 (C=C), 1583 (C=N), 1707 (C=O amidic);
1
2945 (CH, aliphatic), 3044 (CH, aromatic), 3254 (NH). H
NMR (300 MHz, CDCl3): δ = 3.44 (dd, 1H, Jcis = 6.0 Hz,
Jgem = 18.0 Hz, H4pyrazole), 4.12 (dd, 1H, Jtrans = 12.0 Hz,
Jgem = 18.0 Hz, H4pyrazole), 5.75 (dd, 1H, Jcis = 6.0 Hz,
Jtrans = 12.0 Hz, H5pyrazole), 7.40–7.59 (m, 10H, Harom.),
7.74 (s, 1H, H5thiazole), 7.80–7.83 (m, 2H, Harom.), 8.60 (s,
1H, NH), 11.21 (s, 1H, Himine). 13C NMR (75 MHz,
DMSO): δ = 43.5 (C4pyrazole), 63.7 (C3pyrazole), 116.9
(C5thiazole), 127.1, 129.18, 129.3, 129.5, 130.78, 131.0,
131.1, 131.7, 132.8, 134.4 (Carom.), 140.7 (Cbenzylidene=N),
143.9, 143.4 (Carom.), 145.0 (C4thiazole), 154.5 (C5pyrazole),
157.5 (C=O), 164.7 (C2thiazole). Anal. calcd for
C26H18Cl3N5OS (554.88): C, 56.28; H, 3.27; N, 12.62.
Found: C, 56.03; H, 3.19; N, 12.77.
N′-(4-(Benzyloxy)-3-methoxybenzylidene)-2-(5-(4-chloro-
phenyl)-3-phenyl-4,5-dihydropyrazol-1-yl)thiazole-4-carbo-
hydrazide (5x) Yield: 317 mg (51%); Mp 240–241 °C;
FTIR (νmax, cm−1): 1550 (C=C), 1576 (C=N), 1702 (C=O
amidic); 2938 (CH, aliphatic), 3031 (CH, aromatic), 3244
1
(NH). H NMR (300 MHz, CDCl3): δ = 3.44 (dd, 1H, Jcis
= 6.0 Hz, Jgem = 18.0 Hz, H4pyrazole), 3.84 (s, 3H, OMe),
4.12 (dd, 1H, Jtrans = 11.7 Hz, Jgem = 18.0 Hz, H4pyrazole),
5.16 (s, 2H, CH2), 5.74 (dd, 1H, Jcis = 6.0 Hz, Jtrans = 11.7
Hz, H5pyrazole), 7.13–7.54 (m, 15H, Harom.), 7.67 (s, 1H,
H5thiazole), 7.80–7.82 (m, 2H, Harom.), 8.31 (s, 1H, NH),
10.70 (s, 1H, Himine). 13C NMR (75 MHz, DMSO): δ =
43.4 (C4pyrazole), 56.0 (OMe), 63.7 (C3pyrazole), 70.4
(OCH2Ph), 109.2, 113.6 (Carom.), 116.1 (C5thiazole), 122.4,
127.1, 127.6, 128.4, 128.4, 128.9, 129.1, 129.4, 130.7,
131.1, 132. 8, 137.2, 140.8 (Carom.), 145.3 (C4thiazole), 148.8
(Cbenzylidene=N), 149.9 (Carom.), 150.3 (C–OMe), 154.5
(C5pyrazole), 157.1 (C=O), 164.6 (C2thiazole). Anal. calcd for
C34H28ClN5O3S (622.14): C, 65.64; H, 4.54; N, 11.26.
Found: C, 65.85; H, 4.43; N, 11.41.
N′-(2-Chloro-5-nitrobenzylidene)-2-(5-(4-chlorophenyl)-3-
phenyl-4,5-dihydropyrazol-1-yl) thiazole-4-carbohydrazide
(5v) Yield: 311 mg (55%); Mp 247–249 °C; FTIR (νmax
,
cm−1): 1557 (C=C), 1582 (C=N), 1701 (C=O amidic);
1
2914 (CH, aliphatic), 3028 (CH, aromatic), 3252 (NH). H
NMR (300 MHz, CDCl3): δ = 3.43 (dd, 1H, Jcis = 5.7 Hz,
Jgem = 18.0 Hz, H4pyrazole), 4.12 (dd, 1H, Jtrans = 12.0 Hz,

Med Chem Res
Table 3 Summary of crystallographic data
test compounds were added in 50 μL volumes to two series
of triplicate wells to allow simultaneous evaluation of their
effects on mock and HIV-infected cells at the beginning of
each experiment. Serial 5-fold dilutions of test compounds
were made directly in flat-bottomed 96-well microtiter trays
using a Biomek 3000 robot (Beckman instruments).
Untreated control, HIV-, and mock-infected cell samples,
were included for each sample. HIV-1 (IIIB) (Popovic et al.
1984) or HIV-2 (ROD) (Barré-Sinoussi et al. 1993) stock
(50 μL) at 100–300 CCID50 (50% cell culture infectious
dose) or culture medium (10% heat-inactivated Fetal Calf
Serum (FCS), 2 mM-glutamine, 0.1% sodium bicarbonate
and 20 μg/mL gentamicin was added to either of the
infected or mock-infected wells of the microtiter tray.
Mock-infected cells were used to evaluate the effect of test
compound on uninfected cells in order to assess the cyto-
toxicity of the test compounds. Exponentially growing MT-
4 cells (Miyoshi et al. 1982) were centrifuged for 5 min at
1000 rpm (Minifuge T, rotor 2250; Heraeus, Germany), and
the supernatant was discarded. The MT-4 cells were
resuspended at 6 × 105 cells per mL, and 50 μL volumes
were transferred to the microtiter tray wells. Five days after
infection, the viability of the mock- and HIV-infected cells
was examined spectrophotometrically.
Compound
5k
Formula
Mr
C27H22ClN5O2S
516.01
Cryst. size (mm)
Crystal system
Space group
T (K)
0.38 × 0.32 × 0.28
monoclinic
P21/n
296 (2)
a (Å)
11.7324 (5)
16.2624 (9)
13.2945 (9)
4
b (Å)
c (Å)
Z
Dcalcd
1.372 mg m−3
μ (MoKα) (mm−1
)
0.272
F(000)
1072
Rint
0.0363
λ(Å)
0.71073
GOF
1.014
R1/wR2 (all data)
Index ranges
Unique refl.
0.0628/0.1008
h,k,l -15/13, -20/17, -13/16
5450
Δρfin (max/min) (e Å−3
)
0.251/−0.306
Viruses
X-ray structure determinations
The origins of virus stocks were as described previously:
The HIV-1 (IIIB) strain was originally provided by Prof. R.
C. Gallo and Dr M. Popovic (at that time at the NIH,
Bethesda, MD, USA); HIV-2 (ROD) was provided by Dr L.
Montagnier and was obtained from the culture supernatant
of infected MT-4 cells.
A colorless block of compound 5k was mounted in inert oil
on a glass fiber and transferred to the cold gas stream of the
diffractometer (Oxford Diffraction Xcalibur E). Intensities
were registered using monochromated Mo Kα radiation
(λ = 0.71073 Å). Absorption corrections were based on
multi-scans. The structure was refined anisotropically on F2
using the program SHELXL-97 (Sheldrick 2015). Hydro-
gen atoms were included using a riding model starting from
calculated positions. Table 3 presents the summary of
crystallographic data.
Crystallographic data have been deposited with the
Cambridge Crystallographic Data Centre as supplementary
publication no. CCDC-1009303. Copies of the data can be
obtained free of charge from www.ccdc.cam.ac.uk/data_
request/cif.
Cytotoxicity assays
Cell cultures were seeded at 1 × 105 cells per mL in 96
multiwell plates in specific media supplemented (5%) with
10% FCS and antibiotics, then incubated at 37 °C in a
humidified CO2 atmosphere in the absence or presence of
serial dilutions of test compounds. Cell viability was
determined after 96 h at 37 °C using MTT method. Com-
pounds were dissolved in DMSO at 100 μM and then
diluted into the culture medium.
Biological evaluation
In vitro anti-HIV assay
Conclusion
Evaluation of the antiviral activity of compounds 3, 4, and
5a–x against HIV-1 (IIIB) and HIV-2 (ROD) strains in MT-
4 cells was performed using an MTT assay as described
previously (Pannecouque et al. 2008; Pauwles et al. 1988).
In brief, stock solutions (ten times final concentration) of
The target compounds 5a–x were synthesized from easily
available starting materials in a multistep sequence. The
structures of synthesized compounds were established using
spectroscopic techniques and unambiguously verified
through single crystal analysis of compound 5k. The

Med Chem Res
Phenethylthiazolethiourea (PETT) compounds, a new class of
HIV-1 reverse transcriptase inhibitors. 1. Synthesis and basic
structure–activity relationship studies of PETT analogs. J Med
Chem 38:4929–4936
synthesized analogs were evaluated for their activity against
HIV-I (IIIB) and HIV-2 (ROD). The results showed that
compounds 5n (IC50 = 0.50 μM, SI = 5), and 5r (IC50
=
0.45 μM, SI = 3) were the most active analogs of the series
against HIV-1, while compounds 5a and 5i displayed
activity against HIV-1 (IC50 > 0.45 and >0.47 μM), but no
selectivity can be witnessed (SI < 1). Due to the cytotoxicity
of the latter compounds, they have been selected for eva-
luation of their antiprofilerative activity against solid tumor-
derived cell lines. This study provides useful information to
further design new anti-HIV agents. Furthermore, four
compounds were tested against two solid tumor-derived cell
lines consisting MCF-7 (breast cancer) and Hep-G2 (human
hepatocarcinoma). Compound 5i showed a moderate anti-
tumor activity against Hep-G2 (IC50 = 2.59 0.11 μM) and
led to be promising agent for further structural modification.
Bhandari S, Tripathi AC, Saraf SK (2013) Novel 2-pyrazoline deri-
vatives as potential anticonvulsant agents. Med Chem Res
22:5290–5296
Chen X, Meng Q, Qiu L, Zhan P, Liu H, DeClercq E, Pannecouque C,
Liu X (2015) Design, synthesis, and anti-HIV evaluation of novel
triazine derivatives targeting the entrance channel of the NNRTI
binding pocket. Chem Biol Drug Des 86:122–128
Chen X, Zhan P, Liu X, Cheng Z, Meng C, Shao S, Pannecouque C,
DeClercq E, Liu X (2012) Design, synthesis, anti-HIV evaluation
and molecular modeling of piperidine-linked amino-triazine
derivatives as potent non-nucleoside reverse transcriptase inhi-
bitors. Bioorg Med Chem 20:3856–3864
Coates JA, Cammack N, Jenkinson HJ, Jowett AJ, Pearson BA, Penn
CR, Rouse PL, Viner KC, Cameron JM (1992) The separated
enantiomers of 2′-deoxy-3′-thiacytidine (BCH 189) both inhibit
human immunodeficiency virus replication in vitro. Antimicrob
Agents Chemother 36:733–739
De Luca A, Dunn D, Zazzi M, Camacho R, Torti C, Fanti I, Kaiser R,
Sonnerborg A, Codoñer FM, Van Laethem K, Vandamme AM,
Bansi L, Ghisetti V, van de Vijver DA, Asboe D, Prosperi MC,
Di Giambenedetto S, SEHERE Collaboration in Chain (2013)
Declining prevalence of HIV-1 drug resistance in antiretroviral
treatment-exposed individuals in Western Europe. J Infect Dis
207:1216–1220
Compliance with ethical standards
Conflict of interest The authors declare that they have no competing
interests.
de Silva TI, Cotton M, Rowland-Jones SL (2008) HIV-2: the forgotten
AIDS virus. Trends Microbiol 16:588–595
Desai SD, Desai KR, Chikhalia KH, Pannecouque C, DeClercq E
(2011) Int J Drug Des Discov 2:361–368
El-Sabbagh OI, Baraka MM, Ibrahim SM, Pannecouque C, Andrei G,
Snoeck R, Balzarini J, Rashad AA (2009) Synthesis and antiviral
activity of new pyrazole and thiazole derivatives. Eur J Med
Chem 44:3746–3753
Esté JA, Cihlar T (2010) Current status and challenges of antiretroviral
research and therapy. Antiviral Res 85:25–33
References
Akhtar T, Hameed S, Al-Masoudi NA, Loddo R, La Colla P (2008) In
vitro antitumor and antiviral activities of new benzothiazole and
1,3,4-oxadiazole-2-thione. Acta Pharm 58:135–149
Ali MA, Yar MS, Siddiqui AA, Sriram D, Yogeeswari P, De Clercq E
(2007) Synthesis and anti-HIV activity of N1-nicotinoyl-3-(4′-
hydroxy-3′-methylphenyl)-5-[substituted phenyl]-2-pyrazolines.
Acta Pol Pharm 63:423–428
Gomha SM, Badrey MG, Abdalla MM, Arafa RK (2014) Novel anti-
HIV-1 NNRTIs based on a pyrazolo[4,3-d]isoxazole backbone
scaffold: design, synthesis and insights into the molecular basis of
action. Med Chem Commun 5:1685–1692
Haynes BF, Pantaleo G, Fauci AS (1996) Toward an understanding of
the correlates of protective immunity to HIV infection. Science
271:324–328
Ali I, Wani WA, Khan A, Haque A, Ahmad A, Saleem K, Manzoor N
(2012) Synthesis and synergistic antifungal activities of a pyr-
azoline based ligand and its copper(II) and nickel(II) complexes
with conventional antifungals. Microb Pathog 53:66–73
Alley MC, Scudiero DA, Monks A, Hursey ML, Czerwinski MJ, Fine
DL, Abbott BJ, Mayo LG, Schoemaker RH, Boyd MR (1988)
Feasibility of drug screening with panels of human tumor cell
Jaffar S, Grant AD, Whitworth J, Smith PG, Whittle H (2004) The
natural history of HIV-1 and HIV-2 infections in adults in Africa:
a literature review. Bull World Health Organ 82:462–469
Khan MH, Akhtar T, Yasin KA, Al-Masoudi NA, Jones PG, Hameed
S (2010) Synthesis, crystal structure and biological evaluation of
lines using
48:589–601
a microculture tetrazolium assay. Cancer Res
Al-Soud YA, Al-Sa’doni HH, Sabera SOW, Al-Shaneek RHM, Al-
Masoudi NA, Loddo R, La Colla P (2010) Synthesis, in vitro
antiproliferative and anti-HIV activity of new derivatives of 2-
piperazino-1,3-benzo[d]thiazoles. Z Naturforsch 65b:1372–1380
Antonelli G, Turriziani O (2012) Antiviral therapy: old and current
issues. Int J Antimicrob Agents 40:95–102
Asahchop EL, Wainberg MA, Sloan RD, Tremblay CL (2012) Anti-
viral drug resistance and the need for development of new HIV-1
reverse transcriptase inhibitors. Antimicrob Agents Chemother
56:5000–5008
6-adamantyl-3-aryl[1,2,4]triazolo[3,4-b][1,3,4] thiadiazoles.
Z
Naturforsch 65b:178–184
Khan MH, Akhtar T, Al-Masoudi NA, Stoeckli-Evans H, Hameed S
(2012) Synthesis, crystal structure and anti-HIV activity of 2-
adamantyl /adamantylmethyl-5-aryl-1,3,4-oxadiazoles. Med
Chem 8:1190–1197
Khan MH, Hameed S, Farman M, Al- Masoudi NA, Stoeckli-Evans H
(2015) Synthesis, anti HIV and molecular modeling study of 3-
aryl-6-adamantyl-methyl-[1,2,4-]triazolo[3,4-b]thiazdiazole deri-
vatives. Z Naturforsch 70b:609–616
Barré-Sinoussi F, Chermann JC, Rey F, Nugeyre MT, Chamaret S,
Gruest J, Dauguet C, Axler-Blin C, Vezinet-Brun F, Rouzioux C,
Rozenbaum W, Montagnier
L (1993) Isolation of a T-
Khan MH, Hameed S, Akhtar T, Al-Masoudi NA, Al-Masoudi WA,
Jones PG, Pannecouque C (2016) Synthesis, crystal structure,
anti-HIV, and antiproliferative activity of new oxadiazole and
thiazole analogs. Med Chem Res 25:2399–2409
Krečmerová M, Holý A, Pískala A, Masojídková M, Andrei G,
Naesens L, Neyts L, Balzarini J, DeClercq E, Snoeck R (2007)
lymphotropic retrovirus from a patient at risk for acquired
immune deficiency syndrome (AIDS). Science 220:868–871
Bell FW, Cantrell AS, Hoegberg M, Jaskunas SR, Johansson NG,
Jordan CL, Kinnick MD, Lind P, Morin Jr JM, Noreen R, Oberg
B, Palkowitz JA, Parrish CA, Pranc P, Sahlberg C, Ternansky RJ,
Vasileff RT, Vrang L, West SJ, Zhang H, Zhou X-X (1995)

Med Chem Res
Ester prodrugs of cyclic 1-(S)-[3-hydroxy-2-(phosphono-
Sarda S, Jadhav W, Bhusare S, Wasmatkar S, Dake S, Pawar R (2009)
Solvent free NaOH Al2O3 supported synthesis of 1,3-diaryl-2-
propene-1-ones. Int J Chem Tech Res 2:265–269
methoxy)propyl]-5-azacytosine: synthesis and antiviral activity. J
Med Chem 50:1069–1077
Mitsuya H, Weinhold KJ, Furman PA, St. Clair MH, Lehrmann SN,
Gallo R (1985) 3′-Azido-3′-deoxythymidine (BW A509U), an
antiviral agent that inihibits the ineffectivity and cytopathic
effect of human T-lymphotropic virus type III/lymphadenopathy-
associates virus in vitro. Proc Natl Acad Sci USA 82:7096–7100
Miyoshi I, Taguchi H, Kobonishi I, Yoshimoto S, Ohtsuki Y,
Shiraishi Y, Akagi T (1982) Type C virus-producing cell lines
derived from adult T cell leukemia. Gann Monogr Cancer Res
28:219–228
Nielsen SF, Christensen SB, Cruciani G, Kharazmi A, Liljefors T
(1998) Antileishmanial chalcones: statistical design, synthesis,
and three-dimensional quantitative structure–activity relationship
analysis. J Med Chem 41:4819–4832
Panasci L, Jean-Claude BJ, Vasilescu D, Mustafa A, Damian S,
Damian Z, Georges E, Liu Z, Liu Z, Batist G, Leyland-Jones B
(1996) Sensitization to doxorubicin resistance in breast cancer
cell lines by tamoxifen and megestrol acetate. Biochem Phar-
macol 52:1097–1102
Pandeya SN, Sriram D, Nath G, DeClercq E (1999) Synthesis, anti-
bacterial, antifungal and anti-HIV activities of Schiff and Man-
nich bases derived from isatin derivatives and N-[4-(4′-
chlorophenyl)thiazol-2-yl]thiosemicarbazide. Eur J Pharm Sci
9:25–31
Sheldrick GM (2015) Crystal structure refinement with SHELXL.
Acta Cryst C71:3–8
Siddiqui N, Arya SK, Ahsan W, Azad
B (2011) Diverse
biological activities of thiazoles: retrospect. Int J Drug Dev Res
3:55–67
Tanemura K, Suzuki T, Nishida Y, Horaguchi T (2005) Aldol con-
densation in water using polyethylene glycol 400. Chem Lett
34:576–577
Tantawy AS, Nasr MNA, El-Sayed MA, El-Sayed MAA (2012)
Synthesis and antiviral activity of new 3-methyl-1,5-diphenyl-
1H-pyrazole derivatives. Med Chem Res 21:4139–4149
Tiberi M, Tintori C, Ceresola ER, Fazi R, Zamperini C, Calandro P,
Franchi L, Selvaraj M, Botta L, Sampaolo M, Saita D, Ferrarese
R, Clementi M, Canducci F, Botta M (2014) 2-Aminothiazolones
as anti-HIV agents that act as gp120-CD4 Inhibitors. Antimicrob
Agents Chemother 58:3043–3052
Uyeki EM, Nishio A, Wittek PJ, Cheng CC (1981) Antiproliferative
activity of doxorubicin and aminoanthraquinone derivatives on
chinese hamster ovary cell. J Pharm Sci 70:1011–1014
Vicini P, Geronikaki A, Incerti M, Busonera B, Poni G, Cabras CA, La
Colla P (2003) Synthesis and biological evaluation of benzo[d]
isothiazole, benzothiazole and thiazole Schiff bases. Bioorg Med
Chem 11:4785–4789
Pannecouque C, Daelemans D, DeClercq E (2008) Tetrazolium-based
colorimetric assay for the detection of HIV replication inhibitors:
revisited, 20 years later. Nat Protoc 3:427–434
Willker W, Leibfritz D, Kerssebaum R, Bermel W (1993) Gradient
selection in inverse heteronuclear correlation spectroscopy. Magn
Reson Chem 31:287–292
Pauwles R, Balzarini J, Baba M, Snoeck R, Schols D, Herdewijn P,
Wu J, Shi Q, Chen Z, He M, Jin L, Hu D (2012) Synthesis and
bioactivity of pyrazole acyl thiourea derivatives. Molecules
17:5139–5150
Xu Z, Ba M, Zhou H, Cao Y, Tang C, Yang Y, He R, Liang Y, Zhang
X, Li Z (2014) 2,4,5-Trisubstitutedthiazole derivatives: a novel
and potent class of non-nucleoside inhibitors of wild type
and mutant HIV-1 reverse transcriptase. Eur J Med Chem
85:27–42
Desmyter J, De Clercq
E (1988) Rapid and automated
tetrazolium-based colorimetric assay for the detection of anti-HIV
compounds. J Virol Methods 20:309–321
Popovic M, Sarngadharan MG, Read E, Gallo RC (1984) Detection,
isolation, and continuous production of cytopathic retroviruses
(HTLV-III) from patients with AIDS and pre-AIDS. Science
224:497–500
Rizvi SUF, Siddiqui HL, Johns M, Detorio M, Schinazi RF (2012)
Anti-HIV-1 and cytotoxicity studies of piperidyl-thienyl chal-
cones and their 2-pyrazoline derivatives. Med Chem Res
21:3741–3749
Zahid M, Yasin KA, Akhtar T, Rama NH, Hameed S, Al-Masoudi
NA, Loddo R, La Colla P (2009) New 2-(4-aryl)-5-(2-ada-
mantylthiazol-4-yl)-1,3,4-oxadiazoles
as
potential
anti-
proliferative and antiviral agents. Arkivoc xi:85–93