Synthesis and anticancer evaluation of novel 3,5-diaryl-thiazolo[4,5-d] pyrimidin-2-one derivatives

Article abstract of DOI:10.1007/s00044-012-0231-7

The 2-oxo analogs of thiazolo[4,5-d]pyrimidine-2-thiones were prepared to study their cytotoxic activity. Five of the newly synthesized compounds were selected by the National Cancer Institute (Bethesda, MD, USA) for a primary in vitro antitumor assay. 7-

Full text of DOI:10.1007/s00044-012-0231-7

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-012-0231-7
ORIGINAL RESEARCH
Synthesis and anticancer evaluation of novel
3,5-diaryl-thiazolo[4,5-d]pyrimidin-2-one derivatives
•
Lilianna Becan Edwin Wagner
Received: 24 January 2012 / Accepted: 11 September 2012
Ó The Author(s) 2012. This article is published with open access at Springerlink.com
Abstract The 2-oxo analogs of thiazolo[4,5-d]pyrimi-
dine-2-thiones were prepared to study their cytotoxic
activity. Five of the newly synthesized compounds were
selected by the National Cancer Institute (Bethesda, MD,
USA) for a primary in vitro antitumor assay. 7-Chloro-3,5-
diphenyl-thiazolo[4,5-d]pyrimidin-2-one (5a) proved to be
the most active one among the screened derivatives and
was further evaluated in the full panel of 60 cell lines at
five different concentrations. The structures of compounds
receptor antagonists (display antidepressant activity) (Beck
et al., 1999).
In this study, in continuation of our work on thiazolo[4,5-
d]pyrimidine derivatives, the synthesis and in vitro cytotoxic
evaluation of thiazolo[4,5-d]pyrimidin-2-ones are reported.
These designed thiazolo[4,5-d]pyrimidine-2-ones are rela-
ted to thiazolo[4,5-d]pyrimidine-2-thiones that have been
previously reported to be potent antitumor agents (Becan and
Wagner, 2008). Thiazolo[4,5-d]pyrimidine derivatives have
been extensively studied as potential drug candidates and
also have anticancer activity (Rida et al., 1996; Fahmy et al.,
2002, 2003). Most of these compounds provided with anti-
cancer activity possess an aromatic rings and electronegative
substituent directly linked to the C-17 of the essential core
(Fig. 1) or attached at aromatic moieties. The method
involved subsequent treatment of the appropriate 3,5-diaryl-
2-thioxo-5,6-dihydro-4H-thiazolo[4,5-d]pyrimidin-7-ones
(2) and 7-chloro-3,5-diaryl-thiazolo[4,5-d]pyrimidine-2-
thiones (3) with diethyl sulfate and water for the replacement
of the 2-thioxo group by an oxygen function (Scheme 1).
Compounds 2 and 3 were obtained from 4-amino-5-car-
boxamido-3-substituted-2,3-dihydrothiazole-2-thiones (1)
(Gewald, 1966) according to a reported earlier procedure
(Becan and Wagner, 2008). Pyrimidine ring formation with
appropriate aryl aldehyde, followed by chlorination pro-
vided the desired cores 2 and 3, bearing the respective aro-
matic substituent at position 3 and 5, which could further be
treated with diethyl sulfate and hydrolyzed to yield 2-thia-
zolones 4a–4f and 5a–5f. All synthesized compounds were
submitted to the National Cancer Institute (NCI, Bethesda,
Maryland) to evaluate their growth inhibitory effects on 60
human cancer cell lines, derived from nine neoplasmatic
diseases. Five derivatives 4a, 4b, 5a, 5b, and 5d were
1
were determined by IR, H-NMR, 13C-NMR, X-ray, and
elemental analysis.
Keywords Antitumor agents ꢀ In vitro studies ꢀ
Thiazolo[4,5-d]pyrimidin-2-ones ꢀ Synthesis
Introduction
Thiazolo[4,5-d]pyrimidines, 7-thio analogs of purines are
potentially bioactive molecules. In contrast with related
2-thioxo-thiazolo[4,5-d]pyrimidine derivatives, the 2-oxo
analogs have not been very well explored in medicinal
chemistry. The synthesis and biological evaluation of the
substituted 2-oxo-thiazolo[4,5-d]pyrimidines have been the
subject of several review articles. They were reported to
possess antibacterial, antifungal (Akbari et al., 2008; Habib
et al., 2007), and anti-inflammatory activity (CXCR2-
receptor antagonists) (Walters et al., 2008), inhibit the
growth of HCMV-human cytomegalovirus (Revankar et al.,
1998), and be corticotrophin-releasing hormone (CRH-R1)
L. Becan (&) ꢀ E. Wagner
Department of Drugs Technology, Wroclaw Medical University,
Pl. Nankiera 1, 50-140 Wroclaw, Poland
e-mail: lb1963@orange.pl
selected for a primary in vitro antitumor assay, at 10-5
M
concentration. Results were expressed as percent growth of
123

Med Chem Res
data evaluated the structure of synthesized substances. In the
IR spectra of compounds 4a–4f, the two stretching bands of
6-NH group were detected in the range of 3470–3080 cm-1
.
These compounds showed the characteristic vibrations of the
1
C=O group at 1690–1670 cm-1. In the H-NMR spectra,
characteristic signal of compounds 4a–4f was one-proton
singlet of 6 N–H resonated at 13.19–13.27 ppm. Aromatic
protons have formed multiplet at 7.22–8.20 ppm.
The formation of chlorination products 5a–5f was
indicated in the IR spectra by the disappearance of
stretching bands of 6-NH group. Besides the absorption
bands due to C=N and C–S–C functions, the presence of
C=O functional group was marked by the appearance of
bond ranging from 1690 to 1680 cm-1, which was lacked
in the precursor 3. In the 1H-NMR spectra of 7-chloro
derivatives 5a–5f we were observed only aromatic protons
signal at 7.26–8.22 ppm. The 13C-NMR spectra of the
active compounds 5a, 5b, and 5d, given in Table 1, dis-
played the appropriate number of resonances that exactly
fit the number of carbon atoms. The most active compound
5a was recrystallized from a DMF solvent; the block-
shaped crystals formed as a result were submitted to X-ray
analysis. Data were collected at 100 K from a single
crystal. X-ray crystallography of the most active agent 5a
confirmed the chemical structure (Fig. 1). Crystallographic
data for the structure are depicted in Table 2.
Fig. 1 X-Ray molecular structure of compound 5a with the atom-
numbering scheme used in the crystallographic analysis
the treated cells, compound 5a showing mean percent
growth =71.26 was further tested at five different
concentrations.
Anticancer activity assay
Results and discussion
All synthesized compounds were submitted for testing at
the NCI to evaluate the growth inhibitory effect. Five
compounds 4a, 4b, 5a, 5b, and 5d were selected for a
primary in vitro antitumor assay (Monks et al., 1991; Boyd
and Paull, 1995; Shoemaker et al., 2002). A process
beginning with the evaluation of the compound against
approximately 60 different human tumor cell lines repre-
senting leukemia, melanoma, and cancers of the lung,
Chemistry
A series of the new substituted thiazolo[4,5-d]pyrimidin-
2-ones 4a–4f and 5a–5f were synthesized as shown in
Scheme 1. The method involved subsequent treatment of
the appropriate 3,5-diaryl-2-thioxo-5,6-dihydro-4H-thiazolo
[4,5-d]pyrimidin-7-ones (2) and 7-chloro-3,5-diaryl-thiaz-
olo[4,5-d]pyrimidine-2-thiones (3) (Becan and Wagner,
2008) with diethyl sulfate and water for the replacement of
the 2-thioxo group with 2-oxo. First, compounds 2 were
obtained through the reaction of the corresponding, refluxing
aromatic aldehyde with 4-amino-5-carboxamido-3-sub-
stituted-2,3-dihydrothiazole-2-thiones 1 (Gewald, 1966), in
the presence of bases according to the earlier reported pro-
cedure (Becan and Wagner, 2008). Pyrimidine ring forma-
tion with aryl aldehydes followed by chlorination with a
mixture of phosphorus pentachloride and phosphorus oxy-
chloride gave the desired cores 2 and 3 which were further
treated in boiling acetonitrile with diethyl sulfate. The
obtained positively charged 2-ethyltiothiazolium salt was
hydrolyzed to yield thiazolones-2. Yields of reaction were
variable and were higher when R1 and R2 were not substi-
tuted. Elemental analysis, IR, 1H and 13C-NMR, and X-ray
colon, brain, breast, ovary, prostate, and kidney at 10-5
M
concentration was performed. With one dose, compound
4b was devoid of cytotoxic activity (mean growth percent
99.88) and 4a was slightly active against renal cancer
CAKI-1 cell line (26.76 % growth).
Compounds 5a, 5b, and 5d which possess electron-
withdrawing 7-chloro substituent showed variable antitu-
mor activity, reported as the percentage of growth of
treated cells; the preliminary screening results are shown in
Table 3. Compounds 5a, 5b, and 5d exhibited antiprolif-
erative effect against cell lines of leukemia, non-small cell
lung cancer, colon cancer, melanoma, ovarian cancer, and
renal cancer. It is worth to mention that substance 5a
showed noticeable cytotoxic activity against renal cancer
(UO-31), melanoma (MALME-3M), and non-small cell
lung cancer (NCI-H522) while compound 5b was most
123

Med Chem Res
R1
S
R1
S
R1
S
O
R2
R2
H2N
H2N
N
N
O
N
S
N
N
S
R2
(ii)
HN
N
S
3
(i)
O
Cl
1
2
(iii)
(iii)
R1
R1
R2
R2
N
N
+
N
O
N
+
SC2H5
SC2H5
N
HN
S
S
Cl
(iiii)
(iiii)
R1
O
R1
O
R2
R2
N
N
O
N
N
S
N
HN
S
Cl
5a-f
4a-f
Scheme 1 (i) LiOH; (ii) POCl3/PCl5; (iii) (C2H5)2SO4; (iiii) H2O
effective against the last one. This limited data indicate that
the replacement of the 7-oxo group with the small, non-
polar chloro substituent substantially increased anticancer
activity. Remarkable low growth percent values against a
minimum number of cell lines (mean growth) was obtained
only for compound 5a which was approved for the further
screening test to evaluate the growth inhibition (GI), and
cytostatic and cytotoxic effects. The selected compound
was additionally evaluated at tenfold dilution of five dif-
ferent concentrations, from 10-4 to 10-8 M on approxi-
mately 60 human tumor cell lines panels. Three different
dose–response parameters, GI50, TGI, and LC50, were
calculated for each cell line. GI50 is the molar concentra-
tion of the compound required for half GI. Total growth
inhibition (TGI) is the molar concentration of the com-
pound resulting in TGI; TGI signifies the cytostatic effect.
LC50 is the molar concentration of the compound resulting
in a 50 % death of the initial cells; LC50 signifies the
cytotoxic effect. The overview of these parameters of
compound 5a is reported in Table 4 and compared with log
GI50 values of thioguanine (TG), the NCI standard anti-
cancer agent. The log GI50 values lower than -5 showed a
notable activity level. It can be noticed that compound 5a
proved to be very sensitive toward non-small cell lung
cancer NCI-H522 and renal cancer UO-31 log GI50 -5.91
and -5.88, respectively, (MG_MID: log GI50 -5.1, log
TGI -4.4, log LC50 -4.09). GI of most cell lines of
standard TG is higher than that showed by investigated
compound 5a; but against the following cell lines: K-562,
NCI-H322M, NCI-H522, SW-620, U251, SK-MEL-28,
IGROV1, A498, and HS 578T, compound 5a was more
active than TG. TG is a guanine analog and thiazolo[4,5-
d]pyrimidines can be considered as 7-thio analogs of the
purine bases guanine and adenine. Thiazolo[4,5-d]pyrimi-
dine derivatives may interfere with the synthesis of guanine
nucleotides as antimetabolites.
123

Med Chem Res
Table 1 13C-NMR data of compounds 5a, 5b, and 5d
Comp.
13C-NMR (DMSO-d6) d ppm
10
9
13
2
R2
8
3
1
14
7
4
11
5
N
6
N
12
O
15
N
16
S
17
Cl
5a R2=H
5b R2=Cl
5d R2=F
168.25 (C15), 166.79 (C5), 160.99 (C7), 157.65 (C17), 150.71 (C4), 135.08 (C6), 133.55 (C16), 133.17 (C1),
132.04 (C10), 131.69 (C13), 129.44 (C9), 129.28 (C11), 129.04 (C2), 128.94 (C3), 128.86 (C12), 128.70 (C14), 128.05 (C8)
168.21 (C15), 166.73 (C5), 159.96 (C17), 157.67 (C7), 155.87 (C4), 150.71 (C6), 136.87 (C16), 136.54 (C1),
133.96 (C10), 133.52 (C3), 133.11 (C12), 130.66 (C13), 129.34 (C9), 129.07 (C14), 129.03 (C8), 128.93 (C11), 128.81 (C2)
168.21 (C15), 166.75 (C5), 160.04 (C1), 157.59 (C17), 155.64 (C7), 150.71 (C4), 133.49 (C6), 133.11 (C16),
131.60 (C10), 130.50 (C3), 130.38 (C12), 130.19 (C9), 130.07 (C14), 129.16 (C8), 129.30 (C13), 115.97 (C2), 115.76 (C11)
The carbon atom-numbering scheme used in the crystallographic analysis was applied
Table 2 Crystallographic data
Crystal data and structure refinement
for compound 5a
Empirical formula
Formula weight
C17H10ClN3O2S
339.79
Temperature
100(2) K
˚
0.71073 A
Wavelength
Crystal system, space group
Unit cell dimensions
Monoclinic, Cc
˚
˚
a = 11.7588 (8) A a = 90
˚
˚
b = 19.4837 (14) A b = 90
˚
˚
c = 7.0758 (5) A c = 90
˚
1468.89 (18) A
3
Volume
Z, calculated density
Absorption coefficient
F (000)
4, 1.536 Mg/m3
0.409 mm-1
696
Crystal size
0.20 9 0.10 9 0.10 mm
˚
2.18–27.07
Theta range for data collection
Limiting indices
-15 ( h ( 15, -24 ( k ( 24, -9 ( l ( 9
61,281/3,225 [R (int) = 0.0320]
99.9 %
Reflection collected/unique
Completeness to theta = 27.07
Absorption correction
Max. and min transmission
Refinement method
Semi-empirical from equivalents
0.9602 and 0.9226
Full-matrix least-squares on F2
3,225/3/208
Data/restraints/parameters
Goodness-of-fit on F2
Final R indices [I [ 2sigma (I)]
R indices (all data)
1.036
R1 = 0.0195, wR2 = 0.0520
R1 = 0.0197, wR2 = 0.0524
-0.02 (3)
Absolute structure parameter
Largest diff. peak and hole
3
˚
0.202 and -0.265 e.A
123

Med Chem Res
Table 3 Anticancer activity as growth % in concentration 10-5 M for the compounds 5a, 5b, and 5d
Compound Mean
growth%
Range of
growth%
Most sensitive panel/cell line growth %
5a
5b
5d
71.26
-84.63 to
124.07
-84.63 Rc/UO-31, -77.98 M/MALME-3M, -69.53 NSCLc/NCI-H522, 3.17 Cc/HCC-2998, 8.46 Cc/
HCC-116, 16.05 M/LOX IMVI, 19.57 L/CCRF-CEM, 26.33 L/SR, 33.32 Oc/OVCAR-3
86.17
91.21
5.19 to
136.81
5.19 NSCLc/NCI-H522, 21.51 L/SR,24.35 M/LOX IMVI, 29.34 Cc/HCT-116, 33.63 L/CCRF-CEM,
34.56 L/K-562, 47.57 Cc/SW-620
-31.63 to
124.32
-31.63 NSCLc/NCI-H522, 28.57 L/SR, 35.79 L/K-562, 40.46 Cc/HCT-116, 41.76 Rc/CAKI-1
Data obtained from the NCIs in vitro disease-oriented human tumor cells
L leukemia, NSCLc non-small cell lung cancer, Cc colon cancer, M melanoma, Oc ovarian cancer, Rc renal cancer
Experimental
filtered and suspended in a hot mixture of methanol and
5 % NaHCO3. The reaction mixture was allowed to cool,
and the crude product was filtered and crystallized from
appropriate solvent.
Chemistry
Melting points were determined on a Boethius apparatus
and were uncorrected. Elemental analyses for the synthe-
sized compounds were performed on a Perkin Elmer 2400
(Waltham, MA, USA) analyzer, and results within 0.4 %
of the theoretical values were obtained for the new com-
3,5-Diphenyl-6H-thiazolo[4,5-d]pyrimidine-2,7-dione (4a)
IR (KBr) cm-1: 3450, 3080 (NH), 1680 (C=O), 1530
(C=N), 1260 (C–S–C), 760 (phenyl). 1H-NMR (d6-DMSO)
d: 7.42–7.93 (m, 10H, arom.), 13.19 (s, 1H, NH). Anal.
Calcd for C17H11N3O2S: C, 63.54; H, 3.45; N, 13.08.
Found: C, 63.44; H, 3.52; N, 13.27.
1
pounds. H-NMR and 13C-NMR spectra were acquired in
d6-DMSO on a Bruker ARX 300 MHz (Bruker Analytic,
Karlsruhe, Germany; Bruker AG, Fallanden, Switzerland)
instrument. Tetramethylsilane was used as the internal
standard and all chemical shift values were expressed in
parts per million (d, ppm). IR spectra were recorded on a
Specord M80 spectrometer using KBr pellets. X-Ray
Crystallography: the data were collected using the Bruker
KAPPA APEXII ULTRA controlled by APEXII software.
Reaction progress and the purity of the obtained com-
pounds were monitored by thin-layer chromatography on
Merck silica gel plates (Merck F254, Darmstadt, Germany)
using the solvent system dichloromethane: 1-propanol
(10:1) for elution. Iodine was used as a developing agent.
The chemicals and reagents for syntheses were obtained
from Alfa Aesar (Karlsruhe, Germany), Chempur (Piekary
Sl. Poland), and Sigma-Aldrich (Steinheim, Germany).
Starting compounds are synthesized according to the lit-
erature (Gewald et al., 1966; Becan and Wagner, 2008).
5-(4-Chlorophenyl)-3-phenyl-6H-thiazolo[4,
5-d]pyrimidine-2,7-dione (4b)
IR (KBr) cm-1: 3450, 3090 (NH), 1670 (C=O), 1590
(C=N), 1230 (C–S–C), 760 (phenyl). 1H-NMR (d6-DMSO)
d: 7.51–7.94 (m, 9H, arom.), 13.22 (s, 1H, NH). Anal.
Calcd for C17H10ClN3O2S: C, 57.39; H, 2.83; N, 11.81.
Found: C, 57.56; H, 3.01; N, 11.97.
5-(2-Chlorophenyl)-3-phenyl-6H-thiazolo[4,
5-d]pyrimidine-2,7-dione (4c)
IR (KBr) cm-1: 3470, 3080 (NH), 1680 (C=O), 1590
(C=N), 1260 (C–S–C), 760 (phenyl). 1H-NMR (d6-DMSO)
d: 7.34–7.99 (m, 9H, arom.), 13.27 (s, 1H, NH). Anal.
Calcd for C17H10ClN3O2S: C, 57.39; H, 2.83; N, 11.81.
Found: C, 57.59; H, 2.87; N, 11.85.
General procedures for the synthesis of compounds 4a–4f
and 5a–5f
To a solution of appropriate compound 2 or 3 (10 mmol) in
acetonitrile (20 ml), diethyl sulfate (4.62 g, 30 mmol) was
added, and the reaction mixture was heated under reflux for
1 h at 130 °C. After cooling, 100 ml of water was added
and the reaction mixture was refluxed with stirring for 2 h
during which the product was precipitated. The solid was
5-(4-Fluorophenyl)-3-phenyl-6H-thiazolo[4,
5-d]pyrimidine-2,7-dione (4d)
IR (KBr) cm-1: 3450, 3090 (NH), 1680 (C=O), 1610
(C=N), 1240 (C–S–C), 770 (phenyl). 1H-NMR (d6-DMSO)
d: 7.31–8.20 (m, 9H, arom.), 13.20 (s, 1H, NH). Anal.
123

Med Chem Res
Table 4 The result of the in vitro anticancer activity of compound 5a against 60 human cancer cell lines
Panel Cell line
Compound 5a
TG
Growth (%)b 10-5
M
Log Gl50
Log TGI
Log LC50
Log Gl50
Leukemia
CCRF-CEM
HL-60(TB)
K-562
c
23
38
19
54
75
8
-5.42
-5.23
-5.39
-4.89
-4.35
-5.58
–
–
–
–
–
–
–
-6.5
ns
–
–
-4.0
nsd
MOLT-4
RPMI-8226
SR
–
–
-5.9
-6.2
-4.67
Non-Small
Cell Lung C.
A549/ATCC
EKVX
87
84
15
24
20
62
78
-65
-4.36
-4.59
-5.44
-5.51
-5.44
-4.85
-4.60
-5.91
–
–
-5.3
-5.4
-6.1
-5.8
-5.5
-4.6
-6.0
-5.7
–
–
HOP-62
-4.81
-4.17
-4.51
-4.23
–
-4.14
HOP-92
–
–
–
–
–
NCI-H23
NCI-H322 M
NCI-H460
NCI-H522
Colon C.
COLO-205
HCC-2998
HCT-116
HCT-15
-5.52
52
-4.95
-4.09
-5.68
-5.33
-5.41
-4.09
-5.56
–
–
-5.6
ns
90
–
–
-53
28
-5.35
–
-5.02
-6.2
-5.6
-5.9
-5.5
-5.4
–
–
–
–
HT29
10
-4.72
–
KM12
81
SW620
-4
-5.04
CNS Cancer
SF-268
52
92
52
70
12
20
-4.98
-4.24
-4.96
-4.38
-5.73
-5.43
-4.42
–
-5.9
-5.9
-6.2
-4.1
-6.0
-5.0
SF-295
–
–
SF-539
–
–
SNB-19
–
–
SNB-75
-4.86
-4.73
-4.25
U251
–
Melanoma
LOX IMVI
MALME-3M
M14
-44
62
16
26
48
9
-5.69
-4.83
-5.42
-5.31
-5.04
-5.47
-4.81
-5.05
-4.70
-5.32
-4.10
-4.45
-4.34
-4.36
-4.88
–
-4.74
ns
–
-5.5
-6.2
-6.3
-5.8
-5.2
-5.6
-5.2
-6.4
–
MDA-MB-435
SK-MEL-2
SK-MEL-28
SK-MEL-5
UACC-257
UACC-62
Ovarian C.
IGROV1
OVCAR-3
OVCAR-4
OVCAR-5
–
–
-4.16
60
48
62
–
–
–
-4.50
–
-65
-41
31
-5.75
-5.75
-5.30
–
-5.32
-4.10
-4.45
-4.34
-4.74
-5.2
-5.8
-5.3
-6.3
–
–
–
90
123

Med Chem Res
Table 4 continued
Panel Cell line
Compound 5a
TG
Growth (%)b 10-5
M
Log Gl50
Log TGI
Log LC50
Log Gl50
OVCAR-8
NCI/ADR-RES
SK-OV-3
Renal Cancer
786-0
-45
66
-5.69
-4.67
–
-4.36
–
–
–
-6.4
-6.4
-6.3
–
–
81
41
-5.15
-5.46
-5.16
-5.63
-5.13
-4.98
-5.88
-5.62
-4.25
–
-5.8
-4.6
-5.4
-6.5
-5.1
-6.3
-6.1
-6.3
A498
44
–
–
ACHN
42
–
–
CAKI-1
-30
43
-5.24
–
-4.33
SN12C
–
TK-10
51
–
–
UO-31
-79
-4
-5.54
-5.05
–
RXF 393
Prostate C.
PC-3
-4.42
11
34
-5.48
-5.33
-4.84
-4.63
-4.09
-4.09
-5.5
-6.3
DU-145
Breast C.
MCF7
77
37
12
86
57
20
-4.19
-5.20
-5.48
–
–
–
-6.3
ns
MDA-MB-231/ATCC
HS 578T
BT-549
–
–
-4.73
–
-5.2
-5.9
-5.0
ns
–
–
T-47D
-4.77
-5.44
-5.1
–
–
MDA-MB-468
MG_MIDe
a
–
–
-4.4
-4.09
Data obtained from the NCI’s in vitro disease-oriented human tumor cells
b
c
d
e
Values greater than zero mean percentage of growth and those less than zero mean percentage of lethality to the tumor cell line
The values greater than -4 were excluded
Cell line not screened
MG_MID (mean graph midpoint) arithmetical mean value for all tested cell lines
Calcd for C17H10FN3O2S: C, 60.17; H, 2.97; N, 12.38.
Found: C, 59.98; H, 3.03; N, 12.41.
Calcd for C17H10BrN3O2S: C, 51.01; H, 2.52; N, 10.50.
Found: C, 51.14; H, 2.60; N, 10.66.
3,5-Bis(4-fluorophenyl)-6H-thiazolo[4,5-d]pyrimidine-2,
7-dione (4e)
7-Chloro-3,5-diphenyl-thiazolo[4,5-d]pyrimidin-2-one
(5a)
IR (KBr) cm-1: 3470, 3090 (NH), 1690 (C=O), 1570
(C=N), 1240 (C–S–C), 780 (phenyl). 1H-NMR (d6-DMSO)
d: 7.22–8.03 (m, 8H, arom.), 13.21 (s, 1H, NH). Anal.
Calcd for C17H9FN3O2S: C, 57.14; H, 2.54; N, 11.76.
Found: C, 57.31; H, 2.55; N, 11.94.
IR (KBr) cm-1: 1680 (C=O), 1590 (C=N), 1260 (C–S–C),
1
760 (phenyl). H-NMR (d6-DMSO) d: 7.46–8.13 (m, 10H,
arom.). Anal. Calcd for C17H10ClN3OS: C, 60.09; H, 2.97;
N, 12.37. Found: C, 59.98; H, 3.01; N, 12.38.
7-Chloro-5-(4-chlorophenyl)-3-phenyl-thiazolo[4,
5-d]pyrimidin-2-one (5b)
3-(4-Bromophenyl)-5-phenyl-6H-thiazolo[4,
5-d]pyrimidine-2,7-dione (4f)
IR (KBr) cm-1: 1680 (C=O), 1560 (C=N), 1230 (C–S–C),
1
IR (KBr) cm-1: 3450, 3080 (NH), 1680 (C=O), 1590
(C=N), 1260 (C–S–C), 760 (phenyl). 1H-NMR (d6-DMSO)
d: 7.45–8.16 (m, 9H, arom.), 13.19 (s, 1H, NH). Anal.
760 (phenyl). H-NMR (d6-DMSO) d: 7.52–8.11 (m, 9H,
arom.). Anal. Calcd for C17H9Cl2N3OS: C, 54.56; H, 2.42;
N, 11.23. Found: C, 54.60; H, 2.49; N, 11.29.
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Med Chem Res
Table 5 Characterization data of compounds 4a–4f and 5a–5f
Compound
R1
R2
m.p. (°C)
Yield %
Molecular formula
C17H11N3O2 S
Molecular weight
Solvent
4a
4b
4c
4d
4e
4f
–
–
279–280
369–370
338–339
348–349
327–328
210–211
194–195
171–172
240–241
235–236
234–235
388–390
64.55
58.77
58.88
56.51
49.73
55.77
63.87
57.45
52.32
54.73
48.67
57.46
321,35
355,81
355,81
339,31
357,33
400,25
339,80
374, 24
374,24
357,79
375,78
418,69
1-Propanol
–
4-Cl
2-Cl
4-F
4-F
–
C
C
C
C
C
C
C
17H10ClN3O2S
17H10ClN3O2S
17H10FN3O2S
17H9F2N3O2 S
17H10BrN3O2 S
17H10ClN3OS
17H9Cl2N3OS
DMF-1-propanol 3:1
DMF-1-propanol 3:1
DMF-water
–
–
4-F
4-Br
–
1-Propanol
DMF-1-propanol 3:1
DMF-1-propanol 3:1
DMF-water
5a
5b
5c
5d
5e
5f
–
–
4-Cl
2-Cl
4-F
4-F
–
–
C17 H9Cl2N3OS
DMF-1-propanol 3:1
DMF-1-propanol 3:1
DMF-1-propanol 3:1
DMF-1-propanol 3:1
–
C
C
C
17H9ClFN3OS
17H8ClF2N3OS
17H9BrClN3OS
4-F
4-Br
7-Chloro-5-(2-chlorophenyl)-3-phenyl-thiazolo
[4,5-d]pyrimidin-2-one (5c)
Antitumor in vitro screening
The antitumor studies were performed at the NCI
(Bethesda, MD, USA). The test agents were preliminarily
evaluated in the full panel of 60 different human tumor cell
lines derived from nine cancer diseases, namely leukemia,
melanoma, non-small cell lung c., colon c., brain c., breast
IR (KBr) cm-1: 1690 (C=O), 1570 (C=N), 1250 (C–S–C),
1
760 (phenyl). H-NMR (d6-DMSO) d: 7.52–8.11 (m, 9H,
arom.). Anal. Calcd for C17H9Cl2N3OS: C, 54.56; H, 2.42;
N, 11.23. Found: C, 54.65; H, 2.50; N, 11.33.
c., ovarian c., prostate c., and renal c., at single 10-5
M
concentration. Compounds with significant GI are evalu-
ated at five different concentrations ranging from 10-4 to
10-8 M. The percent growth was evaluated versus controls
not treated with tested compounds. Preparation of the tes-
ted compounds and the sulforhodamine B (SRB) protein
assay which was used to estimate cell viability of growth
were described previously (Becan and Wagner, 2008;
Monks et al., 1991; Boyd and Paull, 1995; Shoemaker
et al., 2002).
7-Chloro-5-(4-fluorophenyl)-3-phenyl-thiazolo
[4,5-d]pyrimidin-2-one (5d)
IR (KBr) cm-1: 1690 (C=O), 1600 (C=N), 1240 (C–S–C),
1
760 (phenyl). H-NMR (d6-DMSO) d: 7.27–8.15 (m, 9H,
arom.). Anal. Calcd for C17H9ClN3OS: C, 57.10; H, 2.73;
N, 11.75. Found: C, 57.21; H, 2.86; N, 11.83.
7-Chloro-3,5-bis(4-fluorophenyl)thiazolo[4,5-d]pyrimidin-
2-one (5e)
Acknowledgments The authors thank the staff of the Department of
Health and Human Services, National Institutes of Health (Bethesda,
MD, USA), for in vitro evaluation of anticancer activity.
IR (KBr) cm-1: 1690 (C = O), 1590 (C = N), 1250 (C–S–
1
C), 770 (phenyl). H-NMR (d6-DMSO) d: 7.26–8.22 (m,
8H, arom.). Anal. Calcd for C17H8ClF2N3OS: C, 54.34; H,
Open Access This article is distributed under the terms of the
Creative Commons Attribution License which permits any use, dis-
tribution, and reproduction in any medium, provided the original
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2.15; N, 11.18. Found: C, 54.42; H, 2.20; N, 11.26.
3-(4-Bromophenyl)-7-chloro-5-phenyl-thiazolo[4,5-
d]pyrimidin-2-one (5f)
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in Table 5.
123

Med Chem Res
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