Synthesis and antitumor activity of certain new thiazolo[2,3-b]quinazoline and thiazolo[3,2-a]pyrimidine analogs

Article abstract of DOI:10.1007/s00044-013-0649-6

A novel series of thiazolo[2,3-b]quinazoline (16-19, 25-28, and 34-37) and cyclohepta[d]thiazolo[3,2-a]pyrimidine (20-23, 29-32, and 38-41) analogs was designed and synthesized. Structure elucidation of the synthesized compounds was attained by the use of H¹ NMR, C¹³ NMR, and mass spectrometry. The obtained compounds were evaluated for their in vitro antitumor activity using the National Cancer Institute's 60 cell lines' panel assay that included nine tumor subpanels, namely, leukemia, non-small cell lung, colon, CNS, melanoma, ovarian, renal, prostate, and breast cancer cells. Most of the investigated compounds showed a remarkable broad-spectrum antitumor activity. Compounds 19, 28, 32, and 34 proved to be 10-, 15-, 2-, and 7-fold more active than 5-FU, with GI₅₀ MG-MID values of 2.4, 1.5, 11.2, and 3.1 μM, respectively.

Full text of DOI:10.1007/s00044-013-0649-6

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-013-0649-6
ORIGINAL RESEARCH
Synthesis and antitumor activity of certain new thiazolo
[2,3-b]quinazoline and thiazolo[3,2-a]pyrimidine analogs
Ghada S. Hassan
Received: 27 October 2012 / Accepted: 25 May 2013
Ó Springer Science+Business Media New York 2013
Abstract A novel series of thiazolo[2,3-b]quinazoline
(16–19, 25–28, and 34–37) and cyclohepta[d]thiazolo[3,2-
a]pyrimidine (20–23, 29–32, and 38–41) analogs was
designed and synthesized. Structure elucidation of the
synthesized compounds was attained by the use of H1
NMR, C13 NMR, and mass spectrometry. The obtained
compounds were evaluated for their in vitro antitumor
activity using the National Cancer Institute’s 60 cell lines’
panel assay that included nine tumor subpanels, namely,
leukemia, non-small cell lung, colon, CNS, melanoma,
ovarian, renal, prostate, and breast cancer cells. Most of the
investigated compounds showed a remarkable broad-
spectrum antitumor activity. Compounds 19, 28, 32, and 34
proved to be 10-, 15-, 2-, and 7-fold more active than 5-FU,
with GI50 MG-MID values of 2.4, 1.5, 11.2, and 3.1 lM,
respectively.
mortality and is projected to be the primary cause of death
worldwide in the future (Harris and Hollstein, 1993; Var-
mus, 2006). The search for the ideal anticancer drug
remains elusive with no drug discovered till date that
would eliminate cancerous cells without harming normal
tissues. A balance of benefit and toxicity has to be con-
sidered for the evaluation of any anticancer agents (Sas-
hidhara et al., 2010).
Thiazole—as a sulfur-containing heterocycle—is widely
represented in many biologically active materials, such as the
antibacterial sulfathiazole (Bharti et al., 2010; Gouda et al.,
2010), the anticonvulsant riluzole (Ergenc and Capan, 1994),
the antiparkinsonian talipexole (Gillespie et al., 2008), the
antivirals ritonavir and tiazofurin (Bell et al.,1995), and the
anticancer dasatinib (Cortes et al., 2007). The groove-binding
agents dactinomycin, netropsin, and thia-netropsin also rep-
resent a group of compounds that contain thiazole moiety and
were used as antitumor drugs (Popsavin et al., 2007; Wolter
et al., 2009). Furthermore, substituted thiazolo–pyrimidine
ring systems were reported to possess antitumor activity (Said
et al., 2004).
Keywords Antitumor activity Á
Thiazolo[2,3-b]quinazoline Á
Cyclohepta[d]thiazolo[3,2-a]pyrimidine
On the other hand, chalcones constitute an important
class of natural products displaying interesting biological
activities including anti-inflammatory (Ko et al., 2003),
antioxidant, cytotoxic (Go et al., 2005), antimicrobial
(Lopez et al., 2001), anti-leishmanial (Nielsen et al., 1998),
and anti-tuberculosis (Lin et al., 2002) properties. In
addition, they have a recognized synthetic utility in the
preparation of numerous pharmacologically interesting
heterocyclic systems such as pyrimidines that have drawn
the attention of medicinal chemists as chemotherapeutic
agents. Several members of this class have earned valued
places in chemotherapy as effective agents. Various liter-
ature reports displayed numerous fused pyrimidine ring
systems and their chemotherapeutic activities as anticancer
Introduction
Cancer is a malignant life-threatening disease which stands
next to cardiovascular diseases in terms of morbidity and
G. S. Hassan (&)
Department of Pharmaceutical Chemistry, College of Pharmacy,
King Saud University, P.O. Box 2457, Riyadh 11451,
Saudi Arabia
e-mail: ghadak25@yahoo.com
G. S. Hassan
Department of Medicinal Chemistry, Faculty of Pharmacy,
Mansoura University, P.O. Box 35516, Mansoura, Egypt
123

Med Chem Res
S
COOC2H5
R1
N
N
16:
n = 1, R1,R3 = H, R2=Cl
17: n = 1, R1,R3 = H, R2=OCH3
18: n = 1, R1,R2 = OCH3, R3 = H
19: n = 1, R1,R2,R3 = OCH3
R1
R2
C2H5OOC
AcOH
N
20:
n = 2, R1,R3 = H, R2=Cl
21: n = 2, R1,R3 = H, R2=OCH3
22: n = 2, R1,R2 = OCH3, R3 = H
23: n = 2, R1,R2,R3 = OCH3
R2
R3
n
S
NH2
R3
15
CH3
S
O
CHO
R2
25:
n = 1, R1,R3 = H, R2=Cl
O
26: n = 1, R1,R3 = H, R2 =OCH3
27: n = 1, R1,R2 = OCH3, R3 = H
28: n = 1, R1,R2,R3 = OCH3
29: n = 2, R1,R3 = H, R2=Cl
30: n = 2, R1,R3 = H, R2 =OCH3
31: n = 2, R1,R2 = OCH3, R3 = H
32: n = 2, R1,R2,R3 = OCH3
N
N
N
R1
R2
R1
R2
AcOH
NaOH, EtOH
R1
R2
R1
R2
+
+
CH3
S
NH2
R1
R3
n
n
R3
R3
n
24
R3
R3
3: R1,R3 = H, R2=Cl
4:
1: n = 1
2: n = 2
7:
n = 1, R1,R3 = H, R2=Cl
8: n = 1, R1,R3 = H, R2=OCH3
9: n = 1, R1,R2 = OCH3, R3 = H
n = 1, R1,R2,R3 = OCH3
11: n = 2, R1,R3 = H, R2=Cl
12: n = 2, R1,R3 = H, R2=OCH3
n = 2, R1,R2 = OCH3, R3 = H
14: n = 2, R1,R2,R3 = OCH3
R1,R3 = H, R2=OCH3
5: R1, R2 = OCH3, R3 = H
6:
R1,R2,R3 = OCH3
10:
COOC2H5
CH3
13:
S
34: n = 1, R1,R3 = H, R2=Cl
35: n = 1, R1,R3 = H, R2=OCH3
36: n = 1, R1,R2 = OCH3, R3 = H
37: n = 1, R1,R2,R3 = OCH3
38: n = 2, R1,R3 = H, R2=Cl
39: n = 2, R1,R3 = H, R2=OCH3
N
N
CH3
C2H5OOC
N
R1
R2
R1
AcOH
NH2
S
40:
n = 2, R1,R2 = OCH3, R3 = H
41: n = 2, R1,R2,R3 = OCH3
R2
n
R3
R3
33
Scheme 1 Synthesis of the target compounds 16–23, 25–32, and 34–41
(Habib et al., 2003), antibacterial (El-Bendary et al., 1998),
antifungal (Pees and Albert, 1992), and antiviral agents
(Abdel-Hafez et al., 2002).
tetrahydro-5H-thiazolo[2,3-b]quinazoline-3-carboxylates
(16–19), (E)-ethyl 10-substituted benzylidene-5-substituted
phenyl-5,6,7,8,9,10-hexahydrocyclohepta[d]thiazolo[3,2-a]
pyrimidine-3-carboxylates (20–23), (E)-9-substituted ben-
zylidene-5-substituted phenyl-2-methyl-6,7,8,9-tetrahydro-
5H-thiazolo[2,3-b]quinazolines (25–28), (E)-10-substituted
benzylidene-5-substituted phenyl-2-methyl-5,6,7,8,9,10-
hexahydro cyclohepta[d]thiazolo[3,2-a]pyrimidines (29–32),
(E)-ethyl 9-substituted benzylidene-5-substituted phenyl-3-
methyl-6,7,8,9-tetrahydro-5H-thiazolo[2,3-b]quinazoline-
2-carboxylates (34–37), and (E)-ethyl 10-substituted
benzylidene-5-substituted phenyl-3-methyl-5,6,7,8,9,10-
hexa-hydrocyclohepta[d]thiazolo[3,2-a]pyrimidine-2-car-
boxylates (38–41) is illustrated in Scheme 1. The reported
diarylidene derivatives 7–14 were prepared by reacting
either cyclohexanone (1) or cycloheptanone (2) with various
benzaldehyde analogs (3–6) in ethanolic solution of sodium
hydroxide (Al-Omary et al., 2012; Singh et al., 2009, 2011).
The target compounds 16–23, 25–32, and 34–41 were
obtained by reacting ethyl 2-aminothiazole-4-carboxylate
(15), 2-amino-5-methyl-thiazole (24), or ethyl 2-amino-4-
methylthiazole-5-carboxylate (33) with the a,b-unsaturated
ketones 7–14 in glacial acetic acid (Scheme 1). All of the
newly synthesized compounds were subjected to structure
elucidation using elemental analysis, mass spectrometry,and
1H and 13C NMR (Table 1).
Recently, some hybrid compounds containing thiazolyl–
chalcones derivatives have been synthesized and screened for
their anticancer activities (Shiet al., 2010). The used chalcone
moieties were fitted with methoxy groups, a functional group
known to enhance the antitumor potency (Rao et al., 2009;
Rostom et al., 2009; Al-Omary et al., 2012). Based on these
results and as a continuation to our previous efforts (El-Sub-
bagh et al., 1994; El-Subbagh and Al-Obaid, 1996; El-Sub-
bagh et al., 1999, 2001; El-Messery et al., 2012), a series of
new thiazolo[2,3-b]quinazoline and cyclohepta[d] thiazol-
o[3,2-a]pyrimidine analogs was designed and synthesized.
The new compounds incorporated thiazole moiety, chalcone
skeleton-bearingmethoxyfunctiontoproducederivativesthat
are expected to possess antitumor activity. The new com-
pounds were screened for their in vitro antitumor activity
using theNationalCancerInstitution(NCI)’sdisease-oriented
human cell line assay. The full NCI 60 cell lines’ panel assay
includes nine tumor subpanels, namely, leukemia, non-small
cell lung, colon, CNS, melanoma, ovarian, renal, prostate, and
breast cancer cells (Grever et al., 1992; Monks et al., 1991;
Boyd and Paull, 1995; Skehan et al., 1990).
Results and discussion
Preliminary in vitro antitumor screening
Chemistry
All of the synthesized compounds 16–23, 25–32, and
34–41 were selected by the NCI and were subjected to the
NCI’s disease-oriented human cell line screening assay to
The synthetic strategy to prepare the target compounds (E)-
ethyl 9-substituted benzylidene-5-substituted phenyl-6,7,8,9-
123

Med Chem Res
Table 1 Physicochemical properties of the newly synthesized compounds 16–23, 25–32, 34–41
COOC2H5
CH3
CH3
S
S
S
COOC2H5
N
N
N
N
N
N
R1
R2
R1
R1
R2
R1
R1
R2
R1
R2
R2
R2
R3
n
n
n
R3
R3
R3
R3
R3
16-23
25-32
34-41
Compound
n
R1
R2
R3
Yield (%)
Mp (°C)
Molecular formulaea
16
17
18
19
20
21
22
23
25
26
27
28
29
30
31
32
34
35
36
37
38
39
40
41
a
1
1
1
1
2
2
2
2
1
1
1
1
2
2
2
2
1
1
1
1
2
2
2
2
H
H
Cl
H
H
H
74
66
68
72
69
80
75
71
64
88
73
75
80
69
66
64
71
68
64
80
71
73
78
79
134–6
128–30
136–8
151–2
164–3
152–4
144–6
138–40
129–31
118–20
121–3
158–60
114–6
133–5
141–3
122–5
161–3
143–5
132–4
143–6
145–7
121–3
166–8
175–7
C26H22Cl2N2O2S
C28H28N2O4S
C30H32N2O6S
C32H36N2O8S
OCH3
OCH3
OCH3
Cl
OCH3
OCH3
H
OCH3
H
C27H24Cl2N2O2S
H
OCH3
OCH3
OCH3
Cl
H
C29H30N2O4S
C31H34N2O6S
C33H38N2O8S
OCH3
OCH3
H
H
OCH3
H
C24H20Cl2N2S
H
OCH3
OCH3
OCH3
Cl
H
C26H26N2O2S
C28H30N2O4S
C30H34N2O6S
OCH3
OCH3
H
H
OCH3
H
C25H22Cl2N2S
H
OCH3
OCH3
OCH3
Cl
H
C27H28N2O2S
C29H32N2O4S
C31H36N2O6S
OCH3
OCH3
H
H
OCH3
H
C27H24Cl2N2O2S
H
OCH3
OCH3
OCH3
Cl
H
C29H30N2O4S
C31H34N2O6S
C33H38N2O8S
OCH3
OCH3
H
H
OCH3
H
C28H26Cl2N2O2S
H
OCH3
OCH3
OCH3
H
C30H32N2O4S
C32H36N2O6S
C34H40N2O8S
OCH3
OCH3
H
OCH3
Analyzed for C,H,N; results were within 0.4 % of the theoretical values for the formulae given
be evaluated for their in vitro antitumor activity. A single
dose (10 lM) of the test compounds was used in the full
NCI 60 cell lines’ panel assay which includes nine tumor
subpanels, namely, leukemia, non-small cell lung, colon,
CNS, melanoma, ovarian, renal, prostate, and breast cancer
cells (Grever et al., 1992; Monks et al., 1991; Boyd and
Paull, 1995; Skehan et al., 1990). Compounds that satisfied
the predetermined threshold inhibition criteria would pro-
gress to the five-dose screen. The data were reported as a
mean graph of the percent growth of the treated cells are and
presented as percentage growth inhibition (GI %). The
obtained results of the tested thiazolo[2,3-b]quinazoline and
cyclohepta[d] thiazolo[3,2-a]pyrimidine analogs showed a
distinctive potential pattern of selectivity as well as broad-
spectrum antitumor activity (Tables 2, 3).
Regarding the activity toward individual cell lines, the
obtained data revealed that some of the tested subpanel
tumor cell lines exhibited variable sensitivity profiles
against most of the tested compounds. Among these tumor
cell lines, leukemia cell lines including HL-60 (TB),
K-562, MOLT-4, RPMI-8226, and SR were found to be
sensitive for most of the synthesized compounds and had a
range of GI % that started at 10.2 % in compound 40 and
reached the lethal effect in compounds 28 and 34. This
sensitivity was obviously expressed by compounds that
appeared to be inactive against most of the other cell line
subpanels such as compounds 21, 22, 31, and 36 that seem
to be selective against the leukemia cell lines. Similarly,
the melanoma MALME-3M showed another range of
sensitivity toward the tested compounds with GI % that
123

Med Chem Res
Table 2 Percentage growth inhibition (GI %) of in vitro subpanel tumor cell lines at 10 lM concentration of compounds 16–23, 25–28
Subpanel tumor cell lines
% Growth inhibition (GI %)a
16
17
18
19
20
21
22
23
25
26
27
28
Leukemia
CCRF-CEM
HL-60(TB)
K-562
12.2
20.4
–
10.5
15.4
14.8
–
–
–
–
–
–
–
83.2
48.5
61.3
47.3
77.6
68.8
–
–
–
–
–
–
–
–
41.3
44.5
64.7
56.3
80.9
41.9
–
–
–
–
–
–
–
–
98.6
L
30.5
15.5
19.2
11.4
–
26.5
17.2
17.9
18.0
13.8
–
23.8
–
–
79.6
99.0
L
MOLT-4
17.8
93.9
10.5
–
–
RPMI-8226
SR
26.8
–
60.5
–
28.8
–
100
Non-small cell lung cancer
A549/ATCC
EKVX
–
–
–
34.9
–
–
–
–
32.6
23.5
47.1
37.5
25.6
32.1
10.7
22.8
36.6
–
–
–
–
–
L
–
–
–
–
–
L
–
–
–
–
–
–
–
–
80.5
L
HOP-62
–
–
–
25.5
15.2
32.5
47.8
–
–
–
–
–
–
HOP-92
–
23.1
–
26.0
–
–
18.2
–
10.0
–
–
–
44.6
L
NCI-H226
NCI-H23
NCI-322M
NCI-H460
NCI-H522
Colon cancer
COLO 205
HCC-2998
HCT-116
HCT-15
–
–
–
–
16.2
–
–
–
–
–
–
13.2
–
–
L
–
–
–
–
–
–
–
–
–
–
76.7
–
–
–
–
–
–
98.6
L
–
–
–
11.8
18.0
20.0
–
10.4
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
47.4
24.9
80.8
42.3
87.1
L
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
16.4
25.9
16.9
38.2
21.7
20.1
–
–
–
–
–
–
–
–
–
–
L
L
L
L
L
L
L
–
–
–
50.3
–
17.4
–
–
–
HT29
17.2
33.3
–
–
15.7
–
KM12
–
SW-620
55.1
–
–
CNS cancer
SF-268
–
–
–
66.7
44.2
50.1
15.0
60.9
–
–
–
–
–
–
–
–
–
–
–
–
–
–
11.2
21.6
14.8
10.4
–
–
–
–
–
–
–
–
–
–
–
–
–
–
85.3
97.5
92.5
47.3
40.6
–
SF-295
–
–
18.8
–
21.5
26.0
SF-539
–
–
–
–
–
–
–
–
–
–
SNB-19
18.7
13.7
–
–
–
SNB-75
10.9
–
19.6
–
U251
25.3
Melanoma
LOX IMVI
MALME-3M
M14
25.1
–
–
–
–
–
–
–
–
–
–
–
77.0
25.4
83.1
79.0
–
–
–
–
18.8
47.8
–
14.8
–
–
L
–
13.2
–
20.3
–
13.9
–
20.0
–
13.3
95.2
97.5
98.0
L
–
–
–
–
–
MDA-MB-435
SK-MEL-2
SK-MEL-28
SK-MEL-5
UACC-257
UACC-62
Ovarian cancer
IGORV1
20.9
–
–
–
–
–
21.7
10.9
25.5
62.0
44.9
42.6
10.6
–
–
–
–
–
–
–
–
–
–
–
33.8
39.7
41.9
25.6
–
–
–
–
–
–
L
15.4
14.3
18.0
–
–
–
11.3
–
–
–
–
L
14.5
16.5
–
–
–
–
–
L
–
–
–
–
–
14.5
–
–
–
–
–
–
–
–
–
–
–
–
–
10.3
42.9
27.7
24.3
–
–
–
–
–
–
–
–
–
21.6
26.2
42.6
–
–
–
–
–
–
–
–
–
–
–
–
–
97.2
L
OVCAR-3
OVCAR-4
OVCAR-5
–
18.6
–
60.4
L
123

Med Chem Res
Table 2 continued
Subpanel tumor cell lines
% Growth inhibition (GI %)a
16
17
18
19
20
21
22
23
25
26
27
28
OVCAR-8
NCI/ADR-RES
SK-OV-3
Renal cancer
786-0
–
–
–
–
–
–
–
–
–
86.5
96.4
–
–
–
–
–
–
–
–
–
–
28.7
32.3
13.3
–
–
–
–
–
–
–
L
–
98.3
80.7
11.6
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
L
A498
21.9
–
17.7
–
21.7
54.1
33.7
67.4
45.6
15.3
30.1
–
–
56.0
31.3
26.7
–
13.5
23.2
–
L
ACHN
–
–
–
–
–
–
–
L
CAKI-1
–
–
–
–
–
–
–
–
89.0
L
RXF 393
SN12C
21.2
–
–
–
–
11.8
–
11.7
–
–
–
–
–
–
–
–
24.6
–
–
–
–
–
L
TK-10
–
–
–
–
–
–
97.8
L
UO-31
13.8
–
10.9
11.5
35.7
17.9
–
Prostate cancer
PC-3
–
–
–
–
–
–
22.9
91.2
–
–
–
–
12.8
–
48.2
–
–
–
–
–
13.0
–
55.5
DU-145
L
Breast cancer
MCF7
68.7
–
–
17.8
70.1
25.8
53.3
–
–
–
–
–
–
–
–
11.9
–
30.0
13.8
11.0
29.1
53.0
68.5
31.2
–
11.2
–
12.2
–
84.0
81.1
50.1
L
MDA-MB-231/ATCC
HS 578T
BT-549
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
T-47D
22.6
15.2
–
11.1
66.2
11.4
–
27.8
–
15.5
–
–
21.3
–
66.9
L
MDA-MB-468
12.5
14.9
L compound proved lethal to the cancer cell line
a
–, GI \ 10 %
ranged from 11.0 % in compound 37 to 95.2 % in com-
pound 28. Moreover, compounds 23, 32, and 41 showed
moderate growth inhibitory activity against the same cell
line with GI % values of 47.8, 45.5, and 48.3 %, respec-
tively. Furthermore, the growth of the breast cancer MCF 7
was variably affected by the compounds under investiga-
tions; it was highly affected by compound 34 and 28 with
GI % values of 100 and 84.0 %, respectively, and moder-
ately affected by compounds 16 and 41 with GI % values
of 68.7 and 39.1 %, respectively. The breast cancer T-47D
showed high sensitivity against compound 32 (GI 71.0 %)
and compound 34 (GI 74.7 %), while it expressed mod-
erate activity against compound 23 (GI 53.0 %), 28 (GI
66.9 %), and 41 (GI 54.1 %) (Tables 2, 3).
leukemia CCRF-CEM, HL-60(TB), MOLT-4, SR, non-
small cancer cell HOP-62, Melanoma MALME-3M,
UACC-257, UACC-62, Ovarian cancer OVCAR-4, renal
cancer A498, prostate cancer PC-3, and breast cancer
T-47D with GI % values of 41.3, 44.5, 56.3, 41.9, 47.1,
47.8, 44.9, 42.6, 42.6, 56.0, 48.2, and 53.0 %, respectively.
On the other hand, compound 41 showed high activity
against leukemia K-562, RPMI-8226, melanoma UACC-
62, and breast cancer MDA-MB-468 with GI % values of
68.8, 67.3, 60.1, and 74.8 %, respectively, and it showed
moderate activity against leukemia HL-60(TB), MOLT-4,
SR, non-small cancer cell HOP-62, NCI-H460, colon
cancer HCT-15, CNS cancer SF-295, Melanoma MALME-
3M, renal cancer A498, UO-31, prostate cancer PC-3,
breast cancer BT-549, and T-47D with GI % values of
50.1, 54.8, 52.6, 50.1, 40.0, 55.2, 43.5, 48.3, 48.0, 45.7,
50.2, 44.9, and 54.1 %, respectively.
Concerning the activity of the individual compounds,
compounds 23 and 41 showed remarkable activity against
most of the tested cell lines. Although they were not
selected for the five-dose screen, they can be considered as
broad-spectrum antitumor agents. Concerning compound
23, it showed high activity against leukemia K-562, RPMI-
8226, melanoma SK-MEL-5, and breast cancer MDA-MB-
468 with GI % values of 64.7, 80.9, 62.0, and 68.5 %,
respectively, while it showed moderate activity against
On close examination of the data presented in Tables 2
and 3, it was revealed that compounds 19, 28, 32, and 34
are the most active members of this study, showing
effectiveness toward numerous cell lines belonging to
different tumor subpanels. The same analogy indicated that
compounds 16, 23, 35, 40, and 41 possess moderate
123

Med Chem Res
Table 3 Percentage growth inhibition (GI %) of in vitro subpanel tumor cell lines at 10 lM concentration of compounds 29–32, 34–41
Subpanel tumor cell lines
% Growth inhibition (GI %)a
29
30
31
32
34
35
36
37
38
39
40
41
Leukemia
CCRF-CEM
HL-60(TB)
K-562
–
–
–
34.2
49.6
62.9
64.4
81.6
46.2
L
L
L
L
L
L
23.9
14.4
–
11.3
30.6
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
29.1
50.1
68.8
54.8
67.3
52.6
14.5
–
33.8
–
15.0
17.5
17.3
15.7
–
–
10.2
17.7
12.0
15.4
15.3
–
MOLT-4
12.8
–
–
15.4
81.8
12.8
16.4
–
–
RPMI-8226
SR
–
–
–
14.4
–
12.4
Non-small cell lung cancer
A549/ATCC
EKVX
–
–
–
–
–
–
–
–
–
–
–
27.2
27.3
32.3
69.2
23.1
33.6
12.2
26.6
60.3
94.9
35.4
11.8
–
11.2
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
39.7
–
–
–
–
–
HOP-62
–
–
–
–
–
50.1
–
HOP-92
–
52.4
–
–
11.7
–
–
NCI-H226
NCI-H23
NCI-322 M
NCI-H460
NCI-H522
Colon cancer
COLO 205
HCC-2998
HCT-116
HCT-15
–
52.5
89.1
–
–
–
–
–
–
11.2
–
–
11.0
12.6
10.2
–
38.1
–
–
–
–
–
–
48.2
42.0
–
–
40.0
–
15.0
–
16.4
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
91.2
L
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
18.8
15.0
32.0
55.2
33.2
32.5
17.5
24.4
26.4
45.4
28.3
25.2
11.9
–
L
20.2
–
L
HT29
L
–
KM12
L
–
SW-620
L
–
CNS cancer
SF-268
–
–
–
–
–
–
–
–
–
–
–
–
–
36.7
33.4
23.6
11.7
–
65.3
–
–
–
–
–
–
–
19.5
43.5
20.1
–
SF-295
20.8
–
–
–
20.9
–
–
22.6
–
SF-539
58.7
44.6
35.8
L
–
–
–
–
–
–
–
–
SNB-19
–
–
–
–
–
–
SNB-75
16.2
–
15.9
–
10.1
–
17.5
–
15.7
–
22.1
–
10.7
32.3
U251
17.2
Melanoma
LOX IMVI
MALME-3 M
M14
–
–
–
–
–
–
–
–
–
–
–
17.5
45.5
17.7
21.5
29.1
11.6
77.5
44.2
34.4
L
–
11.6
17.4
–
–
–
–
–
–
–
–
–
–
–
–
–
26.0
48.3
21.0
31.7
–
11.1
–
–
23.0
L
16.8
–
11.0
12.5
14.0
–
–
–
–
MDA-MB-435
SK-MEL-2
SK-MEL-28
SK-MEL-5
UACC-257
UACC-62
Ovarian cancer
IGORV1
–
–
L
26.9
–
–
–
–
–
–
–
23.5
51.2
59.2
74.3
45.4
–
–
–
–
–
–
–
–
–
–
–
17.2
–
–
–
–
10.4
–
–
–
–
–
–
11.3
18.5
–
–
–
–
–
17.4
–
16.2
16.7
19.1
60.1
–
–
–
–
–
–
–
–
–
–
–
–
32.0
39.8
40.6
–
87.2
L
–
–
–
–
–
–
–
–
–
–
–
–
–
–
16.6
–
28.4
35.5
30.7
14.4
OVCAR-3
OVCAR-4
OVCAR-5
–
–
51.7
21.9
20.9
–
12.2
–
21.3
–
123

Med Chem Res
Table 3 continued
Subpanel tumor cell lines
% Growth inhibition (GI %)a
29
30
31
32
34
35
36
37
38
39
40
41
OVCAR-8
NCI/ADR-RES
SK-OV-3
Renal cancer
786-0
–
–
–
–
–
–
–
–
–
47.0
29.7
17.7
77.1
60.6
53.0
–
–
–
–
–
–
–
–
36.4
37.9
22.2
10.4
–
–
–
–
–
10.6
11.5
13.4
13.9
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
17.7
49.5
49.3
25.8
–
L
–
–
–
–
16.0
16.6
–
–
–
A498
17.0
96.8
83.4
37.7
L
36.0
–
–
–
–
14.9
48.0
30.4
34.4
–
ACHN
–
–
–
–
–
CAKI-1
–
17.8
–
–
–
–
–
–
RXF 393
SN12C
–
–
–
–
–
–
–
25.4
30.4
40.4
41.9
41.8
46.1
10.2
–
–
–
–
–
–
24.8
–
TK-10
–
–
–
–
–
–
UO-31
18.8
17.1
31.5
21.9
16.8
21.2
31.0
45.7
Prostate cancer
PC-3
–
–
–
–
19.3
–
52.7
–
75.7
15.0
–
–
–
–
–
–
–
–
–
24.9
–
50.2
14.1
DU-145
L
Breast cancer
MCF7
–
–
–
–
–
–
–
–
–
–
–
–
–
26.6
34.2
29.5
64.5
71.0
68.4
L
22.0
–
16.2
–
–
–
–
–
–
17.6
–
10.4
–
24.8
–
39.1
28.1
–
MDA-MB-231/ATCC
HS 578T
BT-549
–
28.5
48.3
L
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
44.9
54.1
74.8
T-47D
28.4
21.8
74.7
95.6
15.3
15.2
21.4
–
20.0
–
37.7
21.0
MDA-MB-468
L compound proved lethal to the cancer cell line
a
–, GI \ 10 %
CH3
Fig. 1 Structures of the active
antitumor agents 19, 28, 32, and
34
S
S
COOC2H5
N
N
N
N
CH3O
CH3O
OCH3
CH3O
CH3O
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
OCH3
19
28
N
CH3
COOC2H5
CH3
S
S
N
N
N
CH3O
CH3O
OCH3
OCH3
OCH3
Cl
Cl
OCH3
34
32
antitumor activity, while the rest of compounds possess the
least active antitumor activity in the present investigation
(Fig. 1).
and tested against a panel of 60 different tumor cell lines at
a 5-log dose range (Grever et al., 1992; Monks et al., 1991;
Boyd and Paull, 1995; Skehan et al., 1990). Three response
parameters, GI50, TGI, and LC50, were calculated for each
cell line, using the known drug 5-Fluorouracil (5-FU) as a
positive control. Compound 19 is almost tenfold more
Compounds 19, 28, 32, and 34 passed the primary
anticancer assay at an arbitrary concentration of 100 lM.
Consequently, those active compounds were carried over
123

Med Chem Res
Fig. 2 Full panel mean-graph
midpoint (lM) of compounds
19, 28, 32, and 34 in
comparison with 5-FU
active than 5-FU, with GI50, TGI, and LC50 values of 2.4,
79.4, and [100, respectively. Compound 28 is 15-fold
more active than 5-FU, with GI50, TGI, and LC50 values of
1.5, 40.7, and 93.3, respectively, while compounds 32 and
34 are almost double and sevenfold more active than 5-FU,
with GI50, TGI, and LC50 values of 11.2, 93.3, and [100
and 3.1, 13.2, and 47.9 lM, respectively (Fig. 2; Table 4).
group at position 2—and methyl group at position
3—produced 34 with remarkable antitumor activity.
Similarly, by taking a closer look at the cyclohepta[d]
thiazolo[3,2-a]pyrimidine analogs, a pattern had been
observed. The chloro derivatives such as (E)-ethyl 10-(4-chloro
benzylidene)-5-(4-chlorophenyl)-5,6,7,8,9,10-hexahydro-
cyclohepta[d]thiazolo[3,2-a]pyrimidine-3-carboxylate (20),
(E)-10-(4-chlorobenzylidene)-5-(4-chlorophenyl)-2-methyl-
5,6,7,8,9,10-hexahydrocyclo-hepta[d]thiazolo[3,2-a]pyrim-
idine (29), and (E)-ethyl 10-(4-chlorobenzylidene)-5-(4-chlo-
rophenyl)-3-methyl-5,6,7,8,9,10-hexahydrocyclohepta[d]
thiazolo[3,2-a]pyrimidine-2-carboxylate (38) proved inac-
tive. The introduction of methoxy groups instead of the chloro
groups converts the compounds to selective anti-leukemic
agent compounds 21, 22, 31, and 40, while the trimethoxy
derivatives such as compounds 23, 32, and 41 are considered
to have remarkable broad-spectrum antitumor potency.
Structure–activity correlation
Structure–activity correlation, based on the number of cell
lines proved sensitive toward each of the synthesized
individual compounds, revealed that the trimethoxy
derivatives of either thiazolo[2,3-b]quinazolines (19 and
28) or cyclohepta[d]thiazolo[3,2-a]pyrimidines (23, 32,
and 41) are more active antitumor agents than the other
analogs at the same series.
Concerning the tested thiazolo[2,3-b]quinazoline het-
erocycles, the dimethoxy analogs such as (E)-ethyl 9-(3,4-
dimethoxybenzylidene)-5-(3,4-dimethoxyphenyl)-6,7,8,9-
tetrahydro-5H-thiazolo[2,3-b]quinazoline-3-carboxylate (18),
(E)-9-(3,4-dimethoxybenzylidene)-5-(3,4-dimethoxyphenyl)-
2-methyl-6,7,8,9-tetrahydro-5H-thiazolo[2,3-b]quinazoline
(27), and (E)-ethyl 9-(3,4-dimethoxybenzylidene)-5-(3,4-
dimethoxyphenyl)-3-methyl-6,7,8,9-tetrahydro-5H-thiazol-
o [2,3-b]quinazoline-2-carboxylate (37) proved inactive in
comparison with the rest of tested compounds. The para
methoxy analogs such as compounds 17 and 35 can be
considered as slightly moderate active compounds espe-
cially against leukemia cell lines. Regarding the chloro
analogs, the replacement of the methyl group at position
2—group of 25 with an ester group at position 3—pro-
duced 16 with slightly moderate activity and selectivity
against leukemia cell lines, while the introduction of ester
Conclusions
Compounds (E)-ethyl 9-(3,4,5-trimethoxybenzylidene)-5-
(3,4,5-trimethoxyphenyl)-6,7,8,9-tetrahydro-5H-thiazolo[2,3-
b]quinazoline-3-carboxylate (19), (E)-2-methyl-9-(3,4,5-tri-
methoxybenzylidene)-5-(3,4,5-trimethoxyphenyl)-6,7,8,9-tet-
rahydro-5H-thiazolo[2,3-b]quina-zoline (28), (E)-2-methyl-
10-(3,4,5-trimethoxybenzylidene)-5-(3,4,5-trimethoxy-
phenyl)-5,6,7,8,9,10-hexahydrocyclohepta[d]thiazolo[3,2-a]
pyrimidine (32), and (E)-ethyl 9-(4-chlorobenzylidene)-5-(4-
chlorophenyl)-3-methyl-6,7,8,9-tetrahydro-5H-thiazolo[2,3-
b]quinazol-ine-2-carboxylate (34) (Fig. 1) are the most
active broad-spectrum antitumor agents of this study with
GI50, TGI, and LC50 values of 2.4, 79.4, [100; 1.5, 40.7,
93.3; 11.2, 93.3, [100; and 3.1, 13.2, 47.9 lM, respectively.
123

Med Chem Res
123

Med Chem Res
The synthesized thiazolo[2,3-b]quinazoline and cyclohep-
ta[d]thiazolo[3,2-a]pyrimidine analogs could be considered
as a useful template for future development to obtain more
potent antitumor agent(s).
28.0, 34.2, 39.0, 40.0, 60.5, 122.5, 127.8, 128.6, 131.0,
132.0, 132.1, 133.4, 133.6, 134.1, 134.5, 134.9, 136.8,
140.8, 158.1, 161.0, 169.0. MS m/z (%): 497 (13.1, M?).
17: d 1.28 (t, 3H, J = 14 Hz, CH3CH2), 1.73 (t, 2H,
J = 4.5 Hz, cyclohexane-H), 1.84 (t, 2H, J = 5 Hz,
cyclohexane-H), 2.89 (t, 2H, J = 4.5 Hz, cyclohexane-H),
3.82 (s, 6H, OCH3), 4.27–4.30 (q, 2H, CH3CH2), 6.66 (s,
1H, oleifinic-H), 7.02 (d, 4H, J = 7.5 Hz, Ar–H), 7.52 (d,
4H, J = 8 Hz, Ar–H), 7.59 (s, 1H, thiazole-H), 8.03 (s, 1H,
pyrimidine-H). 13C NMR d 14.1, 22.4, 22.5, 23.9, 27.9,
28.2, 34.7, 55.1, 55.3, 60.5, 113.2, 114.1, 122.5, 127.9,
128.2, 131.5, 132.2, 134.2, 135.4, 136.1, 136.5, 140.8,
158.1, 159.2, 161.0, 169.0, 188.6, 191.5. MS m/z (%): 488
(5.3, M?). 18: d 1.30 (t, 3H, J = 13 Hz, CH3CH2), 1.75 (t,
2H, J = 5 Hz, cyclohexane-H), 1.85 (t, 2H, J = 4.9 Hz,
cyclohexane-H), 2.69 (t, 2H, J = 4.5 Hz, cyclohexane-H),
3.79 (s, 12H, OCH3), 4.27–4.29 (q, 2H, CH3CH2), 6.66 (s,
1H, oleifinic-H), 6.91 (d, 2H, J = 8 Hz, Ar–H), 7.04 (d,
2H, J = 8 Hz, Ar–H), 7.12 (s, 1H, Ar–H), 7.40 (s, 1H, Ar–
H), 7.61 (s, 1H, thiazole-H), 8.01 (s, 1H, pyrimidine-H).
13C NMR d 14.1, 22.5, 24.0, 27.9, 28.2, 34.9, 55.4, 55.5,
60.5, 110.9, 111.6, 113.4, 114.1, 122.4, 123.7, 123.8,
128.1, 134.3, 135.1, 135.8, 136.3, 136.8, 140.8, 147.7,
148.5, 149.1, 161.0, 169.1, 188.6, 191.8. MS m/z (%): 548
(3.9, M?). 19: d 1.31 (t, 3H, J = 13 Hz, CH3CH2), 1.86 (t,
2H, J = 4.9 Hz, cyclohexane-H), 2.72 (t, 2H, J = 5 Hz,
cyclohexane-H), 2.94 (t, 2H, J = 5 Hz, cyclohexane-H),
3.69–3.72 (q, 2H, CH3CH2), 3.78 (s, 18H, OCH3), 6.69 (s,
1H, oleifinic-H), 6.81 (s, 2H, Ar–H), 6.87 (s, 2H, Ar–H),
7.37 (s, 1H, thiazole-H), 7.60 (s, 1H, pyrimidine-H). MS m/
z (%): 609 (8.1, M?). 20: d 1.30 (t, 3H, J = 14 Hz,
CH3CH2), 1.89 (s, 4H, cycloheptane-H), 2.64 (s, 4H,
cycloheptane-H), 4.25–4.27 (q, 2H, CH3CH2), 6.15 (s, 1H,
oleifinic-H), 7.24 (d, 4H, J = 8 Hz, Ar–H), 7.52 (d, 4H,
J = 7.5 Hz, Ar–H), 7.53 (s, 1H, thiazole-H), 8.02 (s, 1H,
pyrimidine-H). 13C NMR d 14.1, 22.4, 22.9, 27.4, 27.7,
60.5, 122.5, 123.5, 128.1, 128.4, 128.7, 129.9, 131.2,
132.3, 132.9, 133.0, 133.4, 134.1, 138.4, 139.2, 140.1,
140.8, 142.0, 158.1, 161.0, 169.0, 197.5. MS m/z (%): 511
(22.5, M?). 21: d 1.29 (t, 3H, J = 14 Hz, CH3CH2), 1.90
(s, 4H, cycloheptane-H), 2.64 (s, 4H, cycloheptane-H),
3.80 (s, 6H, OCH3), 4.25–4.29 (q, 2H, CH3CH2), 7.01 (d,
4H, J = 8.5 Hz, Ar–H), 7.20 (s, 2H, thiazole-H, oleifinic-
H), 7.48 (d, 4H, J = 8.5 Hz, Ar–H), 8.03 (s, 1H, pyrimi-
dine-H). 13C NMR d 14.1, 22.3, 22.9, 27.5, 27.6, 55.2,
55.4, 60.5, 114.2, 122.5, 123.5, 127.8, 128.3, 128.8, 129.2,
129.5, 129.9, 130.2, 131.2, 134.2, 134.8, 139.3, 140.0,
140.8, 158.1, 159.3, 161.0, 169.0, 197.8. MS m/z (%): 502
(11.1, M?). 22: d 1.30 (t, 3H, J = 14 Hz, CH3CH2), 1.94
(s, 4H, cycloheptane-H), 2.67 (s, 4H, cycloheptane-H),
3.80 (s, 12H, OCH3), 4.25–4.29 (q, 2H, CH3CH2), 7.03 (d,
4H, J = 8.5 Hz, Ar–H), 7.11 (s, 2H, thiazole-H, oleifinic-
H), 7.21 (s, 2H, Ar–H), 8.03 (s, 1H, pyrimidine-H). 13C
Experimental
Melting points (°C) were determined on a Mettler FP80
melting point apparatus and are uncorrected. Microanaly-
ses were performed on a Perkin-Elmer 240 elemental
analyzer at the Central Research Laboratory, College of
Pharmacy, King Saud University. All of the new com-
pounds were analyzed for C, H, and N and agreed with the
proposed structures within 0.4 % of the theoretical val-
ues. 1H and 13C NMR were recorded on a Bruker 500 MHz
FT spectrometer; chemical shifts are expressed in d ppm
with reference to TMS. Mass spectral (MS) data were
obtained on Perkin-Elmer, Clarus 600 GC/MS, and Joel
JMS-AX 500 mass spectrometers. Thin layer chromatog-
raphy was performed on precoated (0.25 mm) silica gel
GF254 plates (E. Merck, Germany); compounds were
detected with a 254-nm UV lamp. Silica gel (60–230 mesh)
was employed for routine column chromatography sepa-
rations. All the fine chemicals and reagents used were
purchased from Aldrich Chemicals Co, USA. Compounds
7–14 were previously prepared (Al-Omary et al., 2012;
Singh et al., 2009, 2011).
Chemistry
(E)-Ethyl 9-substituted benzylidene-5-substituted phenyl-
6,7,8,9-tetrahydro-5H-thiazolo[2,3-b]quinazoline-3-
carboxylates (16–19), (E)-ethyl 10-substituted benzylidene-
5-substituted phenyl-5,6,7,8,9,10-
hexahydrocyclohepta[d]thiazolo[3,2-a]pyrimidine-3-
carboxylates (20–23)
A solution of ethyl 2-aminothiazole-4-carboxylate (15,
1.72 g, 0.01 mol) and the appropriate a,b-unsaturated
ketone (7–14, 0.01 mol) in glacial acetic acid (20 ml) was
heated under reflux for 24 h. Solvent was evaporated under
vacuum; the obtained residue was dissolved in chloroform,
washed with water, and the organic layer was separated,
dried, and evaporated. The obtained solid was recrystal-
lized from ethanol to yield compounds 16–23 (Table 1). 1H
NMR (DMSo-d6); 16: d 1.29 (t, 3H, J = 13.5 Hz,
CH3CH2), 1.72 (t, 2H, J = 5 Hz, cyclohexane-H), 1.84 (t,
2H, J = 5 Hz, cyclohexane-H), 2.87 (t, 2H, J = 5 Hz,
cyclohexane-H), 4.25–4.29 (q, 2H, CH3CH2), 6.76 (s, 1H,
oleifinic-H), 7.48 (d, 4H, J = 8.5 Hz, Ar–H), 7.52 (s, 1H,
thiazole-H), 7.59 (d, 4H, J = 15.5 Hz, Ar–H), 8.03 (s, 1H,
pyrimidine-H). 13C NMR d 14.1, 22.2, 22.4, 23.7, 27.7,
123

Med Chem Res
NMR d 14.1, 22.4, 22.6, 27.7, 27.8, 55.2, 55.3, 55.4, 55.5,
60.6, 111.7, 113.2, 122.5, 122.6, 123.4, 124.5, 127.5,
128.3, 128.5, 129.0, 130.5, 134.6, 135.1, 139.5, 140.8,
148.5, 149.1, 158.1, 161.0, 169.0, 197.8. MS m/z (%): 562
(5.9, M?). 23: d 1.30 (t, 3H, J = 14 Hz, CH3CH2), 1.97 (s,
4H, cycloheptane-H), 2.69 (s, 4H, cycloheptane-H), 3.70
(s, 9H, OCH3), 3.82 (s, 9H, OCH3), 4.25–4.29 (q, 2H,
CH3CH2), 6.52 (s, 1H, oleifinic-H), 6.83 (s, 4H, Ar–H),
7.22 (s, 1H, thiazole-H), 8.03 (s, 1H, pyrimidine-H). 13C
NMR d 14.1, 22.4, 22.9, 27.8, 28.0, 55.3, 55.5, 55.6, 55.8,
60.1, 60.5, 105.6, 106.9, 111.3, 112.4, 113.8, 114.1, 122.4,
124.1, 125.0, 127.6, 128.4, 129.0, 130.8, 134.8, 137.7,
139.4, 140.8, 142.0, 152.8, 158.1, 161.0, 169.0. MS m/z
(%): 622 (7.4, M?)
149.5, 156.2, 167.9, 188.5, 191.8. MS m/z (%): 490 (4.7,
M?). 28: d 1.63 (t, 2H, J = 5 Hz, cyclohexane-H), 1.84 (t,
2H, J = 5 Hz, cyclohexane-H), 2.96 (s, 3H, CH3), 2.98 (t,
2H, J = 5 Hz, cyclohexane-H), 3.89 (s, 18H, OCH3), 6.65
(s, 1H, oleifinic-H), 7.26 (s, 2H, Ar–H), 6.91 (s, 1H, thia-
zole-H), 7.27 (s, 2H, Ar–H), 7.73 (s, 1H, pyrimidine-H).
13C NMR d 22.9, 28.5, 55.2, 55.5, 56.1, 56.2, 56.3, 61.0,
107.1, 107.6, 107.8, 109.3, 110.0, 110.5, 111.2, 111.4,
122.4, 124.1, 125.3, 128.4, 128.5, 129.7, 131.4, 135.4,
137.1, 138.7, 153.0, 159.1, 189.9, 197.1. MS m/z (%): 550
(8.4, M?). 29: d 1.89 (s, 4H, cycloheptane-H), 2.33 (s, 3H,
CH3), 2.63 (s, 4H, cycloheptane-H), 6.65 (s, 1H, oleifinic-
H), 7.10 (s, 1H, thiazole-H), 7.24 (d, 4H, J = 7.5 Hz, Ar–
H), 7.35 (d, 4H, J = 8 Hz, Ar–H), 7.53 (s, 1H, pyrimidine-
H). 13C NMR d 11.0, 22.4, 27.4, 27.7, 29.2, 111.2, 113.2,
125.8, 128.4, 128.7, 129.9, 131.2, 131.4, 132.0, 133.0,
133.4, 134.2, 134.6, 142.0, 156.2, 158.0, 158.6, 159.0,
167.9, 197.5. MS m/z (%): 453 (10.0, M?). 30: d 1.74 (s,
4H, cycloheptane-H), 2.11 (s, 3H, CH3), 2.32 (s, 4H,
cycloheptane-H), 3.77 (s, 6H, OCH3), 6.67 (s, 1H, oleifi-
nic-H), 7.08 (d, 4H, J = 8 Hz, Ar–H), 7.11 (s, 5H, Ar–H,
thiazole-H), 7.48 (s, 1H, pyrimidine-H). MS m/z (%): 445
(7.1, M?). 31: d 1.95 (s, 4H, cycloheptane-H), 2.33 (s, 3H,
CH3), 2.68 (s, 4H, cycloheptane-H), 3.81 (s, 12H, OCH3),
6.65 (s, 1H, oleifinic-H), 7.03 (d, 4H, J = 7.5 Hz, Ar–H),
7.10 (s, 3H, Ar–H, thiazole-H), 7.21 (s, 1H, pyrimidine-H).
13C NMR d 11.0, 22.4, 27.7, 27.7, 29.1, 55.4, 55.5, 111.7,
112.1, 112.5, 113.1, 114.0, 122.6, 123.9, 125.8, 128.0,
129.4, 134.6, 134.7, 135.6, 139.5, 141.1, 141.8, 146.3,
148.5, 149.1, 156.2, 167.9, 197.8. MS m/z (%): 504 (9.9,
M?). 32: d 1.98 (s, 4H, cycloheptane-H), 2.42 (s, 3H,
CH3), 2.70 (s, 4H, cycloheptane-H), 3.69 (s, 18H, OCH3),
6.65 (s, 1H, thiazole-H), 6.83 (s, 4H, Ar–H), 7.22 (s, 1H,
oleifinic-H), 7.51 (s, 1H, pyrimidine-H). 13C NMR d 11.2,
22.4, 22.5, 27.8, 28.0, 55.3, 55.4, 55.8, 60.1, 106.9, 111.2,
112.0, 122.7, 122.9, 124.7, 126.0, 127.4, 128.1, 128.6,
129.1, 130.7, 131.0, 134.8, 135.0, 136.8, 137.7, 139.0,
140.8, 152.7, 158.3, 197.8. MS m/z (%): 564 (14.6, M?).
(E)-9-Substituted benzylidene-5-substituted phenyl-2-
methyl-6,7,8,9-tetrahydro-5H-thiazolo[2,3-b]quinazolines
(25–28), (E)-10-substituted benzylidene-5-substituted
phenyl-2-methyl-5,6,7,8,9,10-
hexahydrocyclohepta[d]thiazolo[3,2-a]pyrimidines
(29–32)
A solution of 2-amino-5-methylthiazole (24, 1.14 g,
0.01 mol) and the appropriate a,b-unsaturated ketone
(7–14, 0.01 mol) in glacial acetic acid (20 ml) was heated
under reflux for 24 h and prepared as mentioned under
compounds 16–23. 1H NMR (DMSo-d6); 25: d 1.73 (t, 2H,
J = 5 Hz, cyclohexane-H), 1.85 (t, 2H, J = 4.9 Hz,
cyclohexane-H), 2.33 (s, 3H, CH3), 2.88 (t, 2H, J =
4.9 Hz, cyclohexane-H), 6.75 (s, 1H, oleifinic-H), 7.11 (s,
1H, thiazole-H), 7.48 (d, 4H, J = 10 Hz, Ar–H), 7.57 (s,
1H, pyrimidine-H), 7.59 (d, 4H, J = 10 Hz, Ar–H). 13C
NMR d 11.0, 22.2, 22.4, 23.7, 27.7, 28.0, 34.2, 125.8,
127.8, 128.6, 131.0, 132.0, 132.1, 132.3, 133.7, 134.5,
134.9, 136.8, 138.4, 139.2, 156.2, 167.9, 188.7, 191.6. MS
m/z (%): 439 (19.3, M?). 26: d 1.73 (t, 2H, J = 4.5 Hz,
cyclohexane-H), 1.84 (t, 2H, J = 5 Hz, cyclohexane-H),
2.69 (t, 2H, J = 4 Hz, cyclohexane-H), 2.89 (s, 3H, CH3),
3.81 (s, 6H, OCH3), 6.66 (s, 1H, oleifinic-H), 7.04 (d, 4H,
J = 8 Hz, Ar–H), 7.41 (s, 1H, thiazole-H), 7.52 (d, 4H,
J = 8.5 Hz, Ar–H), 7.60 (s, 1H, pyrimidine-H). 13C NMR
d 22.5, 24.0, 27.9, 28.2, 34.7, 38.9, 55.1, 55.3, 113.2, 114.1,
115.9, 125.7, 127.9, 128.2, 131.5, 132.2, 132.3, 134.2,
134.8, 135.4, 136.2, 136.5, 159.2, 159.7, 188.6, 191.6. MS
m/z (%): 430 (12.9, M?). 27: d 1.74 (t, 2H, J = 14 Hz,
J = 4.8 Hz, cyclohexane-H), 1.85 (t, 2H, J = 4.9 Hz,
cyclohexane-H), 2.33 (s, 3H, CH3), 2.69 (t, 2H,
J = 4.5 Hz, cyclohexane-H), 3.81 (s, 12H, OCH3), 6.65 (s,
1H, oleifinic-H), 7.15 (s, 2H, Ar–H), 7.45 (s, 1H, thiazole-
H), 7.52 (d, 4H, J = 8.5 Hz, Ar–H), 7.61 (s, 1H, pyrimi-
dine-H). 13C NMR d 11.0, 22.4, 22.5, 24.0, 27.9, 28.2,
34.9, 55.4, 55.5, 110.9, 111.5, 113.4, 114.1, 123.7, 125.8,
128.1, 132.2, 134.3, 135.1, 136.3, 136.8, 147.6, 148.4,
(E)-Ethyl 9-substituted benzylidene-5-substituted phenyl-3-
methyl-6,7,8,9-tetrahydro-5H-thiazolo[2,3-b]quinazoline-
2-carboxylates (34–37), (E)-ethyl 10-substituted
benzylidene-5-substitutedphenyl-3-methyl-5,6,7,8,9,10-
hexahydrocyclohepta[d]thiazolo[3,2-a]pyrimidine-2-
carboxylates (38–41)
A solution of ethyl 2-amino-4-methylthiazole-5-carbox-
ylate (33, 1.86 g, 0.01 mol) and the appropriate a,b-
unsaturated ketone (7–14, 0.01 mol) in glacial acetic acid
(20 ml) was heated under reflux for 24 h and prepared as
mentioned under compounds 16–23. 1H NMR (DMSo-d6);
34: d 1.25 (t, 3H, J = 14 Hz, CH3CH2), 1.75 (t, 2H,
J = 5.5 Hz, cyclohexane-H), 1.84 (t, 2H, J = 4.9 Hz,
123

Med Chem Res
cyclohexane-H), 1.94 (s, 3H, CH3), 2.84 (t, 2H, J = 5 Hz,
cyclohexane-H), 4.22–4.25 (q, 2H, CH3CH2), 7.43 (s, 1H,
oleifinic-H), 7.51 (d, 4H, J = 8 Hz, Ar–H), 7.57 (d, 4H,
J = 8.5 Hz, Ar–H), 7.61 (s, 1H, pyrimidine-H). 13C NMR
d 22.2, 23.7, 27.7, 28.1, 30.7, 34.2, 38.9, 115.3, 116.9,
122.3, 127.8, 128.6, 131.0, 132.0, 132.1, 133.4, 133.7,
134.1, 134.4, 134.9, 136.8, 138.4, 139.2, 139.5, 188.7,
191.6, 206.4. MS m/z (%): 511 (13.1, M?). 35: d 1.23 (t,
3H, J = 14 Hz, CH3CH2), 1.73 (t, 2H, J = 5 Hz, cyclo-
hexane-H), 1.84 (t, 2H, J = 4.6 Hz, cyclohexane-H), 2.35
(s, 3H, CH3), 2.89 (t, 2H, J = 5.5 Hz, cyclohexane-H),
3.81 (s, 6H, OCH3), 4.25–4.32 (q, 2H, CH3CH2), 6.65 (s,
1H, oleifinic-H), 7.03 (d, 4H, J = 8.5 Hz, Ar–H), 7.53 (d,
4H, J = 8.5 Hz, Ar–H), 7.95 (s, 1H, pyrimidine-H). 13C
NMR d 22.5, 24.0, 27.9, 28.2, 30.6, 34.8, 38.9, 40.0, 55.1,
55.2, 113.1, 114.1, 127.9, 128.2, 128.9, 129.3, 131.5,
132.1, 132.2, 134.2, 134.8, 135.4, 136.1, 136.4, 159.2,
159.7, 188.6, 191.5, 206.4. MS m/z (%): 502 (12.1, M?).
36: d 1.35 (t, 3H, J = 13.5 Hz, CH3CH2), 1.81 (t, 2H,
J = 5 Hz, cyclohexane-H), 1.95 (t, 2H, J = 5.5 Hz,
cyclohexane-H), 2.10 (s, 3H, CH3), 2.92 (t, 2H, J = 5 Hz,
cyclohexane-H), 3.81 (s, 12H, OCH3), 4.32–4.34 (q, 2H,
CH3CH2), 6.66 (s, 1H, oleifinic-H), 6.93 (d, 2H, J = 8 Hz,
Ar–H), 7.05 (d, 2H, J = 8 Hz, Ar–H), 7.15 (s, 1H, Ar–H),
7.40 (s, 1H, pyrimidine-H), 7.61 (s, 1H, Ar–H). 13C NMR d
14.2, 17.0, 22.5, 24.0, 27.9, 28.2, 30.6, 34.9, 55.3, 55.4,
55.5, 60.3, 110.9, 111.5, 113.2, 114.0, 114.1, 123.6, 128.1,
134.3, 135.1, 135.8, 136.2, 136.8, 147.6, 148.4, 149.1,
156.2, 162.2, 188.6, 206.4. MS m/z (%): 562 (4.3, M?). 37:
d 1.29 (t, 3H, J = 14 Hz, CH3CH2), 1.86 (t, 2H, J = 5 Hz,
cyclohexane-H), 2.22 (s, 3H, CH3), 2.72 (t, 2H,
J = 4.5 Hz, cyclohexane-H), 2.95 (t, 2H, J = 5 Hz,
cyclohexane-H), 3.69–3.72 (q, 2H, CH3CH2), 3.83 (s, 18H,
OCH3), 6.68 (s, 1H, oleifinic-H), 6.82 (s, 2H, Ar–H), 6.87
(s, 2H, Ar–H), 6.97 (s, 1H, pyrimidine-H). MS m/z (%):
622 (1.5, M?). 38: d 1.29 (t, 3H, J = 14.5 Hz, CH3CH2),
1.82 (s, 4H, cycloheptane-H), 2.68 (s, 3H, CH3), 2.94 (s,
4H, cycloheptane-H), 4.22–4.26 (q, 2H, CH3CH2), 6.65 (s,
1H, olefinic-H), 7.23 (d, 2H, J = 8.5 Hz, Ar–H), 7.31 (d,
2H, J = 8 Hz, Ar–H), 7.36 (d, 2H, J = 8.5 Hz, Ar–H),
7.69 (s, 1H, pyrimidine-H), 7.86 (d, 2H, J = 8.5 Hz, Ar–
H). 13C NMR d 14.2, 17.1, 22.7, 22.4, 27.7, 38.9, 40.0,
60.3, 113.4, 127.0, 128.4, 128.7, 129.9, 130.8, 131.2,
131.4, 132.0, 133.1, 133.4, 133.9, 134.1, 142.0, 156.2,
160.2, 162.2, 162.5, 169.7, 197.5. MS m/z (%): 525 (2.9,
M?). 39: d 1.28 (t, 3H, J = 14 Hz, CH3CH2), 1.90 (s, 4H,
cycloheptane-H), 2.54 (s, 3H, CH3), 2.65 (s, 4H, cyclo-
heptane-H), 3.80 (s, 6H, OCH3), 4.22–4.25 (q, 2H,
CH3CH2), 6.65 (s, 1H, olefinic-H), 7.02 (d, 4H,
J = 8.5 Hz, Ar–H), 7.20 (s, 1H, pyrimidine-H), 7.50 (d,
4H, J = 8.5 Hz, Ar–H). 13C NMR d 14.2, 17.0, 22.5, 22.9,
27.5, 27.6, 55.2, 55.5, 60.4, 111.9, 112.4, 113.7, 114.1,
122.1, 122.3, 122.9, 123.0, 124.0, 127.8, 131.2, 134.2,
138.5, 138.9, 139.3, 156.1, 159.4, 162.2, 168.0, 169.3,
197.5. MS m/z (%): 516 (2.6, M?). 40: d 1.28 (t, 3H,
J = 14 Hz, CH3CH2), 1.94 (s, 4H, cycloheptane-H), 2.54
(s, 3H, CH3), 2.65 (s, 4H, cycloheptane-H), 3.65 (s, 3H,
OCH3), 3.73 (s, 3H, OCH3), 3.80 (s, 6H, OCH3), 4.22–4.25
(q, 2H, CH3CH2), 6.65 (s, 1H, olefinic-H), 7.04 (d, 4H,
J = 8.5 Hz, Ar–H), 7.11 (s, 2H, Ar–H), 7.21 (s, 1H,
pyrimidine-H), 13C NMR d 14.2, 17.0, 22.5, 27.7, 27.8,
55.4, 55.5, 55.8, 56.0, 60.4, 111.7, 112.0, 112.3, 113.1,
114.2, 115.6, 122.5, 122.1, 125.0, 127.5, 128.0, 129.3,
131.0, 132.9, 134.6, 139.5, 141.2, 148.5, 149.1, 156.1,
162.1, 197.9. MS m/z (%): 576 (11.1, M?). 41: d 1.28 (t,
3H, J = 14 Hz, CH3CH2), 1.97 (s, 4H, cycloheptane-H),
2.54 (s, 3H, CH3), 2.69 (s, 4H, cycloheptane-H), 3.70 (s,
9H, OCH3), 3.82 (s, 9H, OCH3), 4.23–4.25 (q, 2H,
CH3CH2), 6.51 (s, 1H, olefinic-H), 6.82 (s, 4H, Ar–H), 7.22
(s, 1H, pyrimidine-H), 13C NMR d 14.2, 16.9, 22.5, 27.8,
28.0, 55.6, 55.8, 55.9, 60.0, 60.1, 60.4, 105.2, 106.9, 111.2,
112.4, 113.7, 114.0, 122.1, 122.4, 123.8, 128.4, 129.3,
130.8, 134.8, 137.7, 140.8, 141.2, 142.8, 152.8, 156.1,
159.5, 162.1, 169.3, 197.8. MS m/z (%): 636 (14.4, M?).
Antitumor screening
Under sterile conditions, cell lines were grown in RPMI
1640 media (Gibco, NY, USA) supplemented with 10 %
fetal bovine serum (Biocell, CA, USA) and 5 9 105 cell/ml
was used to test the growth inhibition activity of the syn-
thesized compounds. The concentrations of the compounds
ranging from 0.01 to 100 lM were prepared in phosphate
buffer saline. Each compound was initially solubilized in
dimethyl sulfoxide (DMSO); however, each final dilution
contained less than 1 % DMSO. Solutions of different
concentrations (0.2 ml) were pipetted into separate wells of
a microtiter tray in duplicate. Cell culture (1.8 ml) con-
taining a cell population of 6 9 104 cells/ml was pipetted
into each well. Controls, containing only phosphate buffer
saline and DMSO at identical dilutions, were also prepared
in the same manner. These cultures were incubated in a
humidified incubator at 37 °C. The incubator was supplied
with 5 % CO2 atmosphere. After 48 h, cells in each well
were diluted ten times with saline and counted using a
coulter counter. The counts were corrected for the dilution
(Grever et al., 1992; Monks et al., 1991; Boyd and Paull,
1995; Skehan et al., 1990).
Acknowledgments Thanks to the NCI, Bethesda, MD, USA, for
performing the antitumor testing of the synthesized compounds.
123

Med Chem Res
and pyrazole derivatives based on 4,5,6,7-tetrahydrobenzothio-
phene moiety. Eur J Med Chem 45:1338–1345
References
Grever MR, Schepartz SA, Chabner BA (1992) The National Cancer
Institute: cancer drug discovery and development program.
Semin Oncol 19:622–638
Habib NS, Soliman R, Ismail K, Hassan AM, Sarg MT (2003)
Pyrimidines part II: synthesis of novel pyrimidines. 1,2,4-
triazolo-[4,3-a]pyrimidin-7-ones and pyrimidino[2,1-c][1,2,4]
triazi-8-ones for their antimicrobial and anticancer activities.
Boll Chim Farm 142:396–405
Harris CC, Hollstein M (1993) Clinical implications of the P53 tumor
suppressor gene. N Engl J Med 329:1318–1327
Ko HH, Tsao LT, Yu KL, Liu CT, Wang JP, Lin CN (2003)
Structure–activity relationship studies on chalcone derivatives:
the potent inhibition of chemical mediators release. Bioorg Med
Chem 11:105–111
Abdel-Hafez AA, El-Sherief HA, Jo M, Kurokawa M, Shiraki K,
Kawahata T, Otake T, Nakamura N, Hattori M (2002) Synthesis
and evaluation of anti HIV-1 and anti HSV-1 activities of
4-H-[1,2,4]triazolo[1,5-a]pyrimidin-5-one derivatives. Arznei-
mit Forschung 52:833–839
Al-Omary FA, Hassan GS, El-Messery SM, El-Subbagh HI (2012)
Substituted Thiazoles V. Synthesis and antitumor activity of
novel Thiazolo[2,3-b] quinazoline and Pyrido[4,3-d]thiazol-
o[3,2-a]pyrimidine analogs. Eur J Med Chem 47:65–72
Bell FW, Cantrell AS, Hogberg M, Jaskunas SR, Johansson NG,
Jordan CL, Kinnick MD, Lind P, Morin JM, Noreen R, Oberg B,
Palkowitz JA, Parrish CA, Pranc P, Sahlberg C, Ternansky RJ,
Vasileff RT, Vrang L, West SJ, Zhang H, Zhou XX (1995)
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
Lin YM, Zhou Y, Flavin MT, Zhou LM, Nie W, Chen FC (2002)
Chalcones and flavonoids as anti-tuberculosis agents. Bioorg
Med Chem 10:2795–2802
Lopez SN, Castelli MV, Zacchino SA, Dominguez JN, Lobo G, Jaime
CC, Cortes JCG, Ribas JC, Devia C, Ana MR, Ricardo DE
(2001) In vitro antifungal evaluation and structure–activity
relationships of a new series of chalcone derivatives and
synthetic analogs, with inhibitory properties against polymers
of the fungal cell wall. Bioorg Med Chem 9:1999–2013
Monks A, Scudiero D, Skehan P (1991) Feasibility of a high-flux
anticancer drug screen using a diverse panel of cultured human
tumor cell lines. J Natl Cancer Inst 83:757–766
Nielsen SF, Christensen SB, Cruciani G, Kharazmi A, Liljefors T
(1998) Antileishmaniai chalcones: statistical design, synthesis,
and three-dimensional quantitative structure-activity relationship
analysis. J Med Chem 41:4819–4832
Bharti SK, Nath G, Tilak R, Singh SK (2010) Synthesis, anti-bacterial
and anti-fungal activities of some novel Schiff bases containing
2,4-disubstituted thiazole ring. Eur J Med Chem 45:651–660
Boyd MR, Paull KD (1995) Some practical considerations and
applications of the national cancer institute in vitro anticancer
drug discovery screen. Drug Dev Res 34:91–109
Cortes J, Rousselot P, Kim DW, Ritchie E, Hamerschlak N, Coutre S,
Hochhaus A, Guilhot F, Saglio G, Apperley J, Ottmann O, Shah
N, Erben P, Branford S, Agarwal P, Gollerkeri A, Baccarani M
(2007) Dasatinib induces complete hematologic and cytogenetic
responses in patients with imatinib-resistant or -intolerant
chronic myeloid leukemia in blast crisis. Blood 109:3207–3213
El-Bendary ER, El-Sherbeny MA, Badria FA (1998) Synthesis and
biological evaluation of certain new thiazolopyrimidines. Boll
Chim Farm 137:115–119
Pees KJ, Albert G (1992) Triazolopyrimidine derivatives with
fungicidal activity. European patent EP 0550113 A2
´
´
´
Popsavin M, Spaic S, Svircev M, Kojic V, Bogdanovic G, Popsavin V
(2007) Synthesis and antitumour activity of new tiazofurin
analogs bearing a 2,3-anhydro functionality in the furanose ring.
Bioorg Med Chem Lett 17:4123–4127
El-Messery SM, Hassan GS, Al-Omary FA, El-Subbagh HI (2012)
Substituted thiazoles VI. Synthesis and antitumor activity of new
2-acetamido- and 2 or 3-propanamido-thiazole analogs. Eur J
Med Chem 54:615–625
Rao YK, Fang S-H, Tzeng Y-M (2009) Synthesis and biological
evaluation of 3a,4a,5a-trimethoxychalcone analogs as inhibitors
of nitric oxide production and tumor cell proliferation. Bioorg
Med Chem 17:7909–7914
Rostom SAF, Hassan GS, Subbagh HI (2009) Synthesis and
biological evaluation of some polymethoxylated fused pyridine
ring systems as antitumor agents. Arch Pharm Chem Life Sci
342:584–590
Said M, Abouzid K, Mouneer A, Ahmedy A, Osman AM (2004)
Synthesis and biological evaluation of new thiazolopyrimidines.
Arch Pharm Res 27:471–477
Sashidhara VK, Kumar A, Kumar M, Sarkar J, Sinha S (2010)
Synthesis and in vitro evaluation of novel coumarin–chalcone
hybrids as potential anticancer agents. Bioorg Med Chem Lett
20:7205–7211
Shi H-B, Zhang S-J, Ge Q-F, Guo D-W, Cai C-M, Hua W-X (2010)
Synthesis and anticancer evaluation of thiazolyl–chalcones.
Bioorg Med Chem Lett 20:6555–6559
Singh N, Pandey J, Yadav A, Chaturvedi V, Bhatnagar S, Gaikwad
AN, Sinha SK, Kumar A, Shukla PK, Tripathi RP (2009) A
facile synthesis of a, a’-(EE)-bis(benzylidene)-cycloalkanones
and their antitubercular evaluations. Eur J Med Chem 44:
1705–1709
El-Subbagh HI, Al-Obaid AM (1996) 2,4-Disubstituted thiazoles, II.
A novel class of antitumor agents, synthesis and biological
evaluation. Eur J Med Chem 31:1017–1021
El-Subbagh HI, El-Naggar WA, Badria FA (1994) Synthesis and
biological testing of 2,4-disubstituted thiazole derivatives as
potential antitumor antibiotics. Med Chem Res 3:503–516
El-Subbagh HI, Abadi AH, Lehmann J (1999) 2,4-Disustituted
thiazoles, III. Synthesis and antitumor activity of ethyl 2-sub-
stituted-aminothiazole-4-carboxylate analogs. Arch Pharm
Pharm Med Chem 332:137–142
El-Subbagh HI, Al-Khawad IE, El-Bendary ER, Al-Obaid AM (2001)
Substituted thiazoles IV. Synthesis and antitumor activity of new
substituted imidazo[2,1-b]thiazole analogs. Saudi Pharm J 9:14–20
Ergenc N, Capan G (1994) Synthesis and anticonvulsant activity of new
4-thiazolidone and 4-thiazoline derivatives. II Farmaco 49:
449–451
Gillespie RJ, Cliffe IA, Dawson CE, Dourish CT, Gaur S, Giles PR,
Jordan AM, Knight AR, Lawrence A, Lerpiniere J, Misra A,
Pratt RM, Todd RS, Upton R, Weiss SM, Williamson DS
(2008) Antagonists of the human adenosine A2A receptor. Part
2: design and synthesis of 4-arylthieno[3,2-d]pyrimidine deriv-
atives. Bioorg Med Chem Lett 18:2920–2923
Go ML, Wu X, Liu XL (2005) Chalcones: an update on cytotoxic and
chemoprotective properties. Curr Med Chem 12:483–499
Gouda MA, Berghot MA, El-Ghani GEA, Khalil AM (2010)
Synthesis and antimicrobial activities of some new thiazole
Singh N, Pandey SK, Anand N, Dwivedi R, Singh S, Sinha SK,
Chaturvedi V, Jaiswal N, Srivastava AK, Shah P, Siddiqui MI,
Tripathi RP (2011) Synthesis, molecular modeling and bio-
123

Med Chem Res
evaluation of cycloalkyl fused 2-aminopyrimidines as antitubercu-
lar and antidiabetic agents. Bioorg Med Chem Lett 21:4404–4408
Skehan P, Storeng R, Scudiero D, Monks A, McMahon J, Vistica D,
Warren JR, Bokesch H, Kenney S, Boyd MR (1990) New
colorimetric cytotoxic assay for anticancer drug screening. J Natl
Cancer Inst 82:1107–1112
Wolter FE, Molinari L, Socher ER, Schneider K, Nicholson G, Beil
W, Seitz O, Su¨ssmuth RD (2009) Synthesis and evaluation of a
netropsin-proximicin-hybrid library for DNA binding and cyto-
toxicity. Bioorg Med Chem Lett 19:3811–3815
Varmus
H (2006) The new era in cancer research. Science
312:1162–1165
123