Design, synthesis and biological evaluation of some novel substituted 2-mercapto-3-phenethylquinazolines as antitumor agents

Article abstract of DOI:10.1007/s00044-013-0546-z

A novel series of 2-(substituted thio)-3-phenethylquinazolin-4(3H)-one and 2-([5-mercapto-4-(substituted)-4H-1,2,4-triazol-3-yl)methylthio] -3-phenethylquinazolin-4(3H)-one (1-25) were designed, synthesized, and evaluated for their in vitro antitumor activity. A single dose (10 μM) of the test compounds was used in the National Cancer Institute (NCI) 60 cell lines panel assay. Compound 2 showed sensible selective activities toward renal and breast cancer cell lines, whereas breast cancer cell lines showed moderate sensitivity to compound 13. At the same time, compound 22 yielded reasonable selective activities toward leukemia and non-small cell lung cancer cell lines. The results achieved can be used as a useful template for future development and further derivatization or modification to obtain more potent and selective antitumor agents. Graphical Abstract: [Figure not available: see fulltext.]

Full text of DOI:10.1007/s00044-013-0546-z

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-013-0546-z
ORIGINAL RESEARCH
Design, synthesis and biological evaluation of some novel
substituted 2-mercapto-3-phenethylquinazolines as antitumor
agents
•
Amer M. Alanazi Ibrahim A. Al-Suwaidan Alaa A.-M. Abdel-Aziz
•
•
•
Menshawy A. Mohamed Ahmad M. El_Morsy Adel S. El-Azab
•
Received: 24 December 2012 / Accepted: 15 February 2013
Ó Springer Science+Business Media New York 2013
Abstract A novel series of 2-(substituted thio)-3-phen-
ethylquinazolin-4(3H)-one and 2-([5-mercapto-4-(substi-
tuted)-4H-1,2,4-triazol-3-yl)methylthio]-3-phenethylquinaz-
olin-4(3H)-one (1–25) were designed, synthesized, and
evaluated for their in vitro antitumor activity. A single dose
(10 lM) of the test compounds was used in the National
Cancer Institute (NCI) 60 cell lines panel assay. Compound 2
showed sensible selective activities toward renal and breast
cancer cell lines, whereas breast cancer cell lines showed
moderate sensitivity to compound 13. At the same time,
compound 22 yielded reasonable selective activities toward
leukemia and non-small cell lung cancer cell lines. The
results achieved can be used as a useful template for future
development and further derivatization or modification to
obtain more potent and selective antitumor agents.
Introduction
Cancer is continuing to be a major health problem in
developed as well as undeveloped countries (Xue et al.,
2004; Honkanen et al., 1983; Zhou et al., 2004; Panner-
selvam et al., 2003; Refaie et al., 2005). The great cancer
incidence worldwide increases the search for new, safer
and efficient anticancer agents, aiming the prevention or
the cure of this illness. In spite of all the efforts to combat
cancer, the success of the treatment of certain types of
tumors has shown little progress due to their aggressiveness
and the mechanisms of malignant cell metastasis. Although
many classes of drugs are being used for the treatment of
cancer, the need for more potent selective antitumor agents
is still not precluded.
Quinazolines are frequently used in medicine because of
their wide spectrum of biologic activities (Zhou et al.,
2004; Aziza et al., 1996; El-Azab, 2007; Habib et al.,
2000; Al-Omar et al., 2006; Alafeefy et al., 2008; Kumar
et al., 2003; Alagarsamy et al., 2007; El-Azab et al., 2011;
El-Azab and Eltahir, 2012a, b; Kashaw et al., 2009;
Archana and Kumar, 2004; El-Azab and Eltahir, 2012a, b;
Al-Omary et al., 2010; Al-Obaid et al.,2009; El-Azab
et al., 2010; Al-Rashood et al., 2006; Abdel Gawad et al.,
2010). In the scope of identifying various chemical sub-
stances which may serve as leads for designing novel
antitumor agents, we are particularly interested in the present
study with quinazoline derivatives which have been identified
as a new class of cancer chemotherapeutic agents with sig-
nificant therapeutic efficacy against solid tumors (Al-Omary
et al., 2010; Al-Obaid et al.,2009; El-Azab et al., 2010;
Al-Rashood et al., 2006; Abdel Gawad et al., 2010).
Keywords Synthesis Á Quinazoline Á
In-vitro antitumor evaluation Á Selective activity Á
NCI
A. M. Alanazi Á I. A. Al-Suwaidan Á A. A.-M. Abdel-Aziz Á
A. S. El-Azab (&)
Department of Pharmaceutical Chemistry, College of Pharmacy,
King Saud University, P.O. Box 2457, Riyadh 11451,
Saudi Arabia
e-mail: adelazaba@yahoo.com
A. A.-M. Abdel-Aziz
Department of Medicinal Chemistry, Faculty of Pharmacy,
University of Mansoura, Mansoura 35516, Egypt
M. A. Mohamed Á A. M. El_Morsy Á A. S. El-Azab
Department of Organic Chemistry, Faculty of Pharmacy,
Al-Azhar University, Cairo 11884, Egypt
Quinazolines as anticancer agents have attracted
increased interest since the discovery of raltitrexed I and
thymitaq II (Fig. 1), Moreover, many quinazolines
M. A. Mohamed
Department of Pharmaceutical Chemistry, College of Pharmacy,
Salman Bin Abdulaziz University, AlKharj, Saudi Arabia
123

Med Chem Res
contributed to the quest for an ultimate antitumor chemo-
therapeutic agent (Al-Omary et al., 2010; Al-Obaid et al.,
2009). Interestingly, it was reported that 2-thioxo-3-ben-
zylquinazolinones and their S-methylthioether counterparts
IV (Fig. 1) showed promising antitumor potency (Abdel
Gawad et al., 2010). In addition, 2-(2-oxo-2-substi-
tuted phenylethylthio)-4(3H)-quinazolinone (III) (Fig. 1)
revealed effective antitumor activity (Abdel Gawad et al.,
2010).
with various halides in acetone in the presence of potas-
sium carbonate at room temperature gave the correspond-
ing 2-(substituted thio)-3-phenethylquinazolin-4(3H)-ones
2–14 in 81–95 % yield, (Scheme 1).
On the other hand, 2-mercapto-3-phenethylquinazolin-
4(3H)-one (1) was reacted with ethyl bromoacetate in dry
acetone in the presence of potassium carbonate at room
temperature thereby affording 95 % yield of ethyl-2-(4-oxo-
3-phenethyl-3,4-dihydroquinazolin-2-ylthio)acetate (15) which
was treated with hydrazine hydrate in ethanol at room
temperature to furnish 2-(4-oxo-3-phenethyl-3,4-dihy-
droquinazolin-2-ylthio)acetohydrazide (16) as a second key
intermediate in 90 % yield. Reaction of acid hydrazide 16
with various isothiocyanates in ethanol at room temperature
produced N-(substituted)-2-[2-(4-oxo-3-phenethyl-3,4-dihy-
droquinazolin-2-ylthio)acetyl]hydrazinecarbothioamides
17–21 in 80–86 % yield. Compounds 17–21 were cyclized
according to the reported procedure (El-Azab et al., 2011) to
the corresponding 2-([5-mercapto-4-(substituted)-4H-1,2,4-
triazol-3-yl)methylthio]-3-phenethylquinazolin-4(3H)-ones
22–25 by boiling in ethanol containing triethylamine.
Compounds 22–25 were also obtained in another pathway by
treatment of 16 with various isothiocyanates in boiling eth-
anol containing triethylamine in 85–90 % yield (Scheme 2).
We have recently studied a series of substituted qui-
nazoline derivatives which were evaluated for their anti-
tumor activities (El-Azab and Eltahir, 2012a; Al-Obaid
et al., 2009; El-Azab et al., 2010). Continuing our studies
on quinazoline derivatives as attractive antitumor candi-
dates, we have designed a number of new quinazoline
derivatives containing 2-substituted mercapto fragments
and have biologically evaluated their in vitro antitumor
activities (Fig. 1).
In the present study, the substitution pattern at the
2-substituted mercaptoquinazoline pharmacophores was
selected based on different electronic environments which
would affect the lipophilicity, and hence the activity of the
target molecules. The objective of forming these hybrids is
an attempt to attain an active antitumor agent with poten-
tiated activity and selectivity toward cancerous cells.
Antitumor screening
Results and discussion
The synthesized compounds 1–25 were subjected to the
National Cancer Institute (NCI) in vitro disease-oriented
human cells screening panel assay for 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;
Chemistry
Synthesis of 2-mercapto-3-phenethylquinazolin-4(3H)-one
(1) as a first key intermediate was achieved by the reaction
of anthranilic acid with 2-phenylethyl isothiocyanate in
absolute ethanol in 78 % yield. Reaction of compound 1
Fig. 1 Reported and proposed
quinazoline derivatives as
antitumor agents.
123

Med Chem Res
Cl
Scheme 1 Reactions of
2-mercapto-3-
phenethylquinazolin-4(3H)-one
(1) with various halides
X
N
N
X
R
N
SH
N
O
S
N
R CH2Cl
N
O
S
N
O
N
1
O
Br
Cl
n
N
13: X=C
14: X=O
R
O
O
2
: R=H
3: R=CH3
4: R=Ph
5: R=p-Cl-Ph
6: R=p-NO2-Ph
: R=p-COOH-Ph
8: R=CN
R
S
7
O
N
O
N
O
n
N
N
O
S
N
O
9
11
: R=H
12: R=F
: n=1
10: n= 2
Scheme 2 Synthesis and
reactions of 2-(4-oxo-3-
phenethyl-3,4-
dihydroquinazolin-2-
ylthio)acetohydrazide (16)
NH2
HN
O
O
O
O
N
S
N
N
O
SH
N
O
S
Br
O
NH2NH2
N
N
O
15
16
S
C
C
N
EtOH, TEA,
reflux
S
R
N
H
O
t
R
E
,
t
.
r
R
HN
S
SH
NH
R
HN
N
N
O
N
N
O
S
N
O
S
EtOH, TEA,
reflux
N
N
22: R=Et
23: R=Ph
17
18: R=Ph
: R=Et
24
19
: R=p-OCH3-Ph
: R=p-OCH3-Ph
25: R=Bn
20: R=p-F-Ph
21: R=Bn
Monks et al., 1991; Boyd and Paull, 1995). The data
reported as mean-graph of the percent growth of the treated
cells, and presented as percentage growth inhibition (GI %)
caused by the test compounds (Table 1).
With regard to selective antitumor activity, close
examination of the data presented in Table 1 revealed that
compound 2 showed sensible selective activities toward
renal and breast cancer cell lines, whereas compound 22
123

Med Chem Res
Table 1 Percentage growth inhibition (GI %) of in vitro subpanel tumor cell lines at 10 lM concentration
Subpanel tumor cell lines
% Growth inhibition (GI %)
1
2
6
10
11
12
13
14
22
23
24
25
Leukemia
HL-60(TB)
MOLT-4
11
23
16
nt
nt
nt
nt
nt
nt
nt
nt
nt
nt
nt
nt
nt
nt
nt
nt
nt
30
29
27
nt
nt
nt
nt
nt
nt
nt
nt
nt
nt
CCRF-CEM
Non-small cell lung cancer
A549/ATCC
EKVX
28
13
13
–
18
26
–
12
29
12
11
16
–
16
19
–
18
16
–
18
18
–
11
16
–
13
30
11
–
10
–
16
15
22
35
–
–
31
24
–
–
31
–
12
17
–
HOP-62
–
NCI-H226
NCI-H23
–
–
–
–
–
22
–
–
15
–
–
–
20
13
–
23
–
–
–
–
NCI-H322 M
NCI-H460
NCI-H522
Colon cancer
COLO 205
HCC-2998
HCT-116
–
–
–
–
27
31
L
–
–
–
–
–
–
–
–
–
–
–
–
–
10
–
13
11
–
11
–
–
–
46
–
–
19
–
–
–
–
–
–
–
–
–
25
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
18
–
37
39
–
20
–
21
31
13
–
19
–
18
–
27
20
70
–
35
12
–
–
–
24
–
HCT-15
25
–
25
–
HT29
–
15
–
–
–
–
KM12
–
28
12
–
–
–
–
–
–
SW-620
–
–
–
–
–
11
–
–
–
–
CNS cancer
SF-268
–
13
–
10
–
–
–
–
–
–
–
–
–
–
18
–
25
–
–
13
10
–
–
–
–
–
–
–
–
–
–
–
–
–
–
12
–
–
12
–
–
–
–
–
–
–
SF-295
SF-539
–
–
13
–
SNB-19
–
–
–
–
–
–
SNB-75
–
–
–
18
11
–
13
14
–
–
U251
–
12
15
19
11
11
Melanoma
LOX IMVI
MALME-3M
M14
–
–
11
–
–
–
–
–
–
14
–
–
–
–
–
–
–
–
–
19
–
–
–
–
–
–
–
–
–
26
–
10
–
10
–
14
–
–
–
–
–
–
12
16
–
–
–
–
MDA-MB-435
SK-MEL-28
SK-MEL-5
UACC-257
UACC-62
Ovarian cancer
IGROV1
–
47
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
–
13
–
19
–
–
43
–
–
24
–
18
12
15
24
24
–
–
–
–
–
20
12
22
26
16
–
19
19
17
–
–
–
–
–
–
–
24
–
–
–
–
–
–
–
21
–
22
–
–
–
–
–
–
–
–
–
–
16
–
16
–
–
–
OVCAR-3
OVCAR-4
OVCAR-5
OVCAR-8
NCI/ADR-RES
SK-OV-3
Renal cancer
786-0
21
–
–
–
–
–
14
12
–
15
–
–
–
–
–
–
–
–
–
–
–
–
–
–
15
10
–
31
10
–
11
27
–
–
–
–
18
–
12
–
–
13
–
–
–
16
–
12
–
–
–
–
13
10
32
14
–
19
–
–
–
123

Med Chem Res
Table 1 continued
Subpanel tumor cell lines
% Growth inhibition (GI %)
1
2
6
10
11
12
13
14
22
23
24
25
A498
46
–
18
34
–
–
–
20
–
46
–
–
24
21
–
17
–
–
–
–
15
–
41
–
51
–
–
–
–
–
–
–
–
ACHN
CAKI-1
–
17
–
34
–
22
–
27
19
–
–
17
–
17
–
RXF 393
SN12C
–
30
–
–
–
–
–
–
–
–
–
–
–
–
TK-10
–
–
–
–
–
–
–
–
–
–
–
UO-31
33
37
–
19
22
42
43
14
24
30
30
Prostate cancer
PC-3
13
–
33
–
–
51
–
14
–
13
–
–
14
–
17
–
30
–
30
–
12
–
DU-145
24
11
Breast cancer
MCF7
31
–
34
30
14
–
–
19
19
–
–
–
11
–
10
23
25
–
37
34
–
–
–
–
–
16
18
–
28
20
–
28
20
–
27
28
–
MDA-MB-231/ATCC
HS 578T
BT-549
14
–
–
–
30
–
–
14
35
–
28
27
15
–
–
–
T-47D
–
59
84
15
3
–
18
–
38
–
–
38
–
MDA-MB-468
22
14
–
38
nt not tested, – GI \ 10 %, L compound proved lethal to the cancer cell line
NCI-H23 cell lines with GI values of 20 and 23 %;
meanwhile, compound 22 showed moderate activity
against NCI-H322 M cell line in 27 %, NCI-H226 in 35 %,
and lethal effect on NCI-H522 cancer cells. Compound 25
showed practical effect against NCI-H226 and NCI-H522
cancer cells in 22 and 46 %, respectively.
SH
N
N
N
N
O
S
N
N
N
O
S
N
O
S
N
N
With respect to colon cancer, compounds 2, 5, 10, 13,
22, and 25 showed GI values of 37, 20, 21, 27, 35, and
24 % with colon HCT-116 cell line, while 2, 10, 13, 23,,
and 24 demonstrated moderate activities against HCT-15
cancer cell line with GI values 39, 34, 20, 25, and 25 %,
respectively. On the other hand, compound 15 verified
sensitivity in 25 and 70 % to colon COLO 205 and HT29
cancer cells, while compound 2 showed activity toward
colon KM12 cell line with GI value 28 %.
2
13
22
Fig. 2 Structures of the most active antitumor agents
yielded reasonable selective activities toward leukemia and
non-small cell lung cancer cell lines. At the same time,
breast cancer cell lines showed moderate sensitivity to
compound 13 (Fig. 2).
Regarding the activity toward individual cell lines,
compounds 1 and 22 showed selective activities against
leukemia cell lines HL-60 (TB), MOLT-4, and CCRF-
CEM with GI values of 11, 23, 16 % and 30, 29, 27 %,
respectively, while compounds 23 and 25 illustrated certain
activities against leukemia CCRF-CEM cell lines with GI
values of 28 and 13 %, respectively.
Concerning CNS cancer, compound 12 showed certain
activities against CNS SF-268 and U251 cancer cells lines
with GI values of 25 and 19, respectively.
Regarding Melanoma, compounds 2 and 22 are active
against MDA-MB-435 and LOX IMVI cell lines with GI
values of 47 and 26 %, respectively. Compounds 10, 13,
23, and 24 showed moderate activity toward SK-MEL-5
cell line with GI values of 43, 24, 24, and 24 %, respec-
tively. Compounds 1, 5, and 10 illustrated certain activities
through Melanoma UACC-62 cell line with GI values of
20, 22, and 26 %, respectively.
Non-small cell lung EKVX cell line proved to be
selectively sensitive to 2, 13, 23,, and 24 with GI values of
29, 30, 31, and 31 %, respectively. In addition, compounds
1, 22, and 23 proved to be susceptible to the HOP-62 cell
line with GI values of 26, 22, and 24 %, respectively.
Compounds 12 and 13 have sensible activity against
With respect to ovarian cancer, compounds 2, 12, and 13
showed moderate activities against Ovarian IGROV1 cell
123

Med Chem Res
line with GI values of 24, 21, and 22 %, while compounds
2 and 22 were active against Ovarian OVCAR-4 and
Ovarian NCI/ADR-RES cell lines with GI values of 21 and
27 %, respectively.
reduction of the antitumor activity. Changeover of 4-chlo-
robenzyl group of 2-(chlorobenzylthio)-3-phenethylqui-
nazolin-4(3H)-one (5) with propylisoindoline-1,3-dione
function enhanced the antitumor activity in compound 10.
Exchange of the 2-methylthio group of compound 2
with 2-phenacylthio, 2-[2-(piperidin-1-yl)ethylthio], and/or
2-(2-morpholinoethylthio) groups afforded compounds
11–14 accompanied with decrease in the antitumor activ-
ities. The presence of electron-withdrawing group such as
fluorine atom at aromatic ring of 2-(2-oxo-2-phenylethyl-
thio)-3-phenethylquinazolin-4(3H)-one (11) increases the
antitumor activity match up to unsubstituted phenyl ring;
for example, compound 11 was less active than compound
12. Substitution of piperidine moiety into morpholine
moiety improved the antitumor activity, such as compound
13 is more active than 14.
In relation to renal cancer, renal CAKI-1 cell line was
sensitive to compounds 10, 11, 12, and 13 with GI values
of 34, 22, 21, and 27 %; in addition, compounds 1, 2, 11,
12, 13, 22, 23, and 24 showed certain activities against
renal UO-31cell line with GI values of 33, 37, 22, 42, 43,
24, 30, and 30 %, respectively. Compounds 10, 11, 22, 23,
and 24 were responsive to renal A498 cell line with GI
values of 20, 46, 41, 51, and 46 %, while compounds 2 and
12 were active against renal ACHN cell line with GI values
of 34 and 24 %. Finally, compounds 2 and 12 showed
certain selectivities against renal RXF 393 and 786-0 cell
lines with GI values of 30 and 32 %, respectively.
Prostate DU-145 cell line proved to be selectively sen-
sitive to compound 5 with GI value of 24 %, while com-
pounds 2, 10, 23, and 24 showed GI effectiveness against
Prostate PC-3 cell line with values of 33, 51, 30, and 30 %,
respectively.
Replacement of the 2-methylthio group of compound 2
with 2-[(5-Mercapto-4-substituted-4H-1,2,4-triazol-3-yl)me-
thylthio] groups afforded compounds 22–25 accompanied
with reduction of the antitumor activities. Replacement of
ethyl group of 2-[(4-ethyl-5-mercapto-4H-1,2,4-triazol-3-
yl)methylthio]-3-phenethylquinazolin-4(3H)-one (22) with
phenyl, 4-methoxyphenyl, and/or benzyl groups produced
compounds 23–25 with a mild reduction of the antitumor
activities. Substitution of benzyl moiety of 2-[(4-benzyl-5-
mercapto-4H-1,2,4-triazol-3-yl)methylthio]-3-phenethylqui-
nazolin-4(3H)-one (25) with phenyl and/or 4-methoxyphenyl
moieties gave compounds 23–24 with mildly improved anti-
tumor activities.
Pertaining to breast cancer, breast MCF7 cell line
proved to be selectively sensitive to compounds 1, 2, 22,
23, 24, and 25 with GI values of 31, 34, 28, 28, and 27 %,
respectively. Compounds 2, 10, 13, 22, 23, and 25 showed
GI effectiveness against breast T-47D cell line with values
of 59, 30, 35, 27, 38, and 38 %; concomitantly, 2, 12, 23,
24, and 25 demonstrated activities against breast cancer
MDA-MB-231/ATCC cell line with GI values of 30, 23,
20, 20, and 28 %, respectively. Concurrently, compounds
1, 2, and 24 showed remarkable potencies against breast
MDA-MB-468 cell line with GI values of 22, 84, and
38 %; at the same time, compounds 12 and 22 showed
certain activities toward breast HS 578T and BT-549 cell
lines with GI values of 25 and 28 %, respectively.
Conclusion
New derivatives of 4(3H)-quinazolinones (1–25) were
synthesized and evaluated for their in vitro antitumor
activity. A single dose (10 lM) of the test compounds was
used in the National Cancer Institute (NCI) 60 cell lines
panel assay. The results of this study demonstrated that
compound 2 showed sensible selective activities (Fig. 3)
toward colon cancer cell lines (HCT-116 and HCT-15),
melanoma cancer cell lines (MDA-MB-435), renal cancer
cell lines (AHCN, RXF 393, and UO-31), prostate cancer
cell line (PC-3), and breast cancer cell lines (MCF7, MDA-
MB-231/ATCC, T-47D, and MDA-MB-468). Compound
22 yielded reasonable selective activities (Fig. 4) toward
leukemia cell line (HL-60(TB), MOLT-4, and CCRF-
CEM), non-small Cell lung cancer cell lines (NCI-H226,
NCI-H460, and NCI-H522), and colon cancer cell line
(HCT-116). In addition, non-small cell lung cancer cell line
(EKVX), colon cancer cell line (HT29), renal cancer cell
line (UO-31), and breast cancer cell lines (MCF7, MDA-
MB-231/ATCC, and T-47D) showed moderate sensitivity
to compound 13 (Fig. 5).
Structure–activity correlations
Compounds of the present investigation that belong to
2-(substituted thio)-3-phenethylquinazolin-4(3H)-one and
2-([5-mercapto-4-(substituted)-4H-1,2,4-triazol-3-yl)methyl-
thio]-3-phenethylquinazolin-4(3H)-one revealed that com-
pound 14 was devoid of any antitumor potency.
Structure–activity correlation revealed that replacement
of the hydrogen atom of thiol function of compound 1
with variety of substituted alkyl or aralkyl groups pro-
duced 2-(substituted thio)-3-phenethylquinazolin-4(3H)-
ones (1–25) analogs with variable potency. Alkylation of
compound 1 with methyl iodide gave 2-(methylthio)-3-
phenethylquinazolin-4(3H)-one (2) with increase in the
antitumor activity.
Substitution of methyl group of compound 2 with
4-chlorobenzyl group produced compound 5 with a mild
123

Med Chem Res
Fig. 3 The percentages of
growth inhibition of compound
2 over the most sensitive tumor
cell lines at 10 lM
90
80
70
60
HCT-116
HCT-15
concentration
MDA-MB-435
ACHN
RXF 393
UO-31
50
40
30
20
10
0
PC-3
MCF7
MDA-MB-231/ATCC
T-47D
MDA-MB-468
Fig. 4 The percentages of
growth inhibition of compound
22 over the most sensitive tumor
cell lines at 10 lM
100
90
concentration
80
HL-60(TB)
MOLT-4
70
CCRF-CEM
NCI-H226
NCI-H522
NCI-H460
HCT-116
60
50
40
30
20
10
0
Fig. 5 The percentages of
growth inhibition of compound
13 over the most sensitive tumor
cell lines at 10 lM
70
60
50
concentration
EKVX
HT29
40
30
20
10
0
UO-31
MDA-MB-231/ATCC
MCF7
T-47D
1
Experimental
recorded on a Perkine-Elmer spectrometer. H NMR and
13C NMR were recorded in DMSO-d6, CDCl3, and/or
CDCl3-TFA on a Jeol 500 MHz instrument using TMS as
an internal standard (chemical shifts in d ppm). Mass
Melting points (corrected) were recorded on Barnstead
9100 Electrothermal melting apparatus. IR spectra were
123

Med Chem Res
spectra were recorded on a Shimadzu PQ-5000 GC–MS
apparatus. Solvent evaporation was performed under
reduced pressure using Buchan Rotatory Evaporator unless
otherwise stated. T.L.C. was performed on precoated silica
gel plates (60- F254, 0.2 mm), manufactured by E.M.
Sciences, Inc, and shortwave UV (254) nm was used to
detect the U.V. absorbing compounds (CH2Cl2, EtOH
10:1).
2H, J = 7.0, 7.5 Hz), 3.09 (t, 2H, J = 8.0, 8.5 Hz), 1.48 (t,
3H, J = 7.5 Hz). 13C NMR (CDCl3): d 14.1, 26.6, 34.1,
46.0, 119.4, 125.6, 126.1, 126.7, 126.9, 128.7, 129.0,
134.2, 138.0, 147.6, 156.2, 161.7. MS: M? = 310, 281,
100 %), IR (KBr, cm-1) m: 3043 (Ar. CH), 2976 (Al. CH),
1680 (CO), 1609 (C=N).
2-(Benzylthio)-3-phenethylquinazolin-4(3H)-one (4) Mp:
1
92–94 °C, yield 87 %, H NMR (CDCl3): d 8.28 (d, 1H,
Chemistry
J = 7.0), 7.75 (t, 1H, J = 7.0, 6.5 Hz), 7.66 (d, 1H,
J = 7.0 Hz), 7.53 (d, 2H, J = 7.0 Hz), 7.45–7.29 (m, 9H),
4.61 (s, 2H), 4.33 (t, 2H, J = 8.0 Hz), 3.09 (t, 2H,
J = 8.0 Hz). 13C NMR (CDCl3): d 34.2, 36.6, 46.1, 119.5,
125.8, 126.1, 126.8, 127.0, 127.7, 128.7, 129.0, 129.5,
134.4, 136.5, 137.9, 147.5, 155.9, 161.6. MS: (M? = 372,
177, 100 %), IR (KBr, cm-1) m: 3021 (Ar. CH), 2980 (Al.
CH), 1669 (CO), 1614 (C=N).
2-Mercapto-3-phenethylquinazolin-4(3H)-one (1)
A mixture of anthranilic acid (7 mmol, 960 mg) and
2-phenylethylisothiocyanate (7 mmol, 955 mg) in 25 ml
absolute ethanol containing triethylamine (7 mmol,
710 mg) was heated under reflux for 2 h. The reaction
mixture was filtered while hot, the solvent was removed
under reduced pressure, and the solid obtained was dried
and recrystallized from ethanol.
2-(4-Chlorobenzylthio)-3-phenethylquinazolin-4(3H)-one
1
(5) Mp: 140–142 °C, yield 88 %, H NMR (CDCl3): d
1
Mp: 244–245 °C, yield, 78 %, H NMR (CDCl3, TFA):
8.27 (d, 1H, J = 8.0), 7.34 (t, 1H, J = 7.0 Hz), 7.63 (d, 1H,
J = 8.0 Hz), 7.45–7.42 (m, 3H), 7.35–7.26 (m, 7H), 4.54 (s,
2H), 4.31 (t, 2H, J = 8.0, 8.5 Hz), 3.07 (t, 2H, J = 8.0,
8.5 Hz). 13C NMR (CDCl3): d 34.2, 35.7, 46.2, 119.5, 126.0,
126.1, 126.8, 127.0, 128.7, 128.8, 129.0, 130.7, 133.5, 134.4,
135.2, 137.8, 147.3, 155.5, 161.1. MS: M? = 406,
M ? 2 = 408, 191, 100 %), IR (KBr, cm-1) m: 3019 (Ar.
CH), 2992 (Al. CH), 1682 (CO), 1618 (C=N), 755 (C–Cl).
d 11.37(s, 1H), 8.19 (d, 1H, J = 7.5 Hz), 7.77 (t, 1H,
J = 7.5, 8.0 Hz), 7.45–7.30 (m, 7H), 4.75 (t, 2H, J = 7.5,
8.0 Hz), 3.13 (t, 2H, J = 8.0 Hz). 13C NMR (CDCl3,
TFA): d 31.0, 48.5, 125.9, 126.8, 128.4, 128.7, 129.0,
136.2, 137.8, 138.5, 159.5, 159.9, 160.2, 160.5, 175.7. MS:
(M? = 282, 191, 100 %).
General procedure for the synthesis of compounds (2–14)
2-(4-Nitrobenzylthio)-3-phenethylquinazolin-4(3H)-one
1
A mixture of 2-mercapto-3-phenethylquinazolin-4(3H)-one
(1) (2 mmol, 564 mg) and the appropriate alkyl, aryl, and/
or aralkyl halide (2.1 mmol) in 15 ml acetone containing
anhydrous potassium carbonate (3 mmol, 415 mg) was
stirred at room temperature for 10–12 h. The reaction
mixture was filtered, the solvent was removed under
reduced pressure, and the solid obtained was dried and
recrystallized from ethanol.
(6) Mp: 144–146 °C, yield 86 %, H NMR (CDCl3): d
8.25 (d, 2H, J = 8.5 Hz), 8.20 (d, 2H, J = 8.0 Hz), 7.75 (t,
1H, J = 7.0 Hz), 7.69 (d, 2H, J = 8.5 Hz), 7.60–7.59 (m,
2H), 7.44 (t, 1H, J = 7.0, 7.5 Hz), 7.33-7.30 (m, 3H), 4.63
(s, 2H), 4.31 (t, 2H, J = 8.0 Hz), 3.06 (t, 2H, J = 8.0 Hz).
13C NMR (CDCl3): d 34.2, 35.3, 46.2, 119.5, 123.8, 125.9,
126.1, 126.8, 127.1, 128.7, 128.9, 130.2, 134.5, 137.3,
144.8, 147.1, 147.3, 154.7, 161.5. MS: (M? = 417, 281,
100 %). IR (KBr, cm-1) m: 3023 (Ar. CH), 2991 (Al. CH),
1685 (CO), 1613 (C=N).
2-(Methylthio)-3-phenethylquinazolin-4(3H)-one (2) Mp:
120–122 °C, yield 95 %, 1H NMR (CDCl3): d 8.15 (d, 1H,
J = 7.0), 7.60 (t, 1H, J = 7.0), 7.49 (d, 1H, J = 8.0),
7.31–7.17 (m, 6H), 4.23 (t, 2H, J = 8.0, 8.5 Hz), 2.98 (t,
2H, J = 8.0, 8.5 Hz), 2.60 (s, 3H), 13C NMR (CDCl3): d
15.0, 34.1, 46.1, 119.3, 125.7, 126.1, 126.8, 126.9, 128.7,
128.9, 134.3, 138.0, 147.5, 156.6, 161.6. MS: (M? = 296,
281, 100 %), IR (KBr, cm-1) m: 3022 (Ar. CH), 2988 (Al.
CH), 1674 (CO), 1611 (C=N).
4-[(4-Oxo-3-phenethyl-3,4-dihydroquinazolin-2-ylthio)
methyl]benzoic acid (7) Mp: 185–187 °C, yield 81 %, 1H
NMR (CDCl3): d 8.27 (br. s, 1H), 7.82 (d, 1H,
J = 6.5 Hz), 7.72 (d, 1H, J = 7.0 Hz), 7.63 (d, 2H,
J = 3.5 Hz), 7.54-7.53 (m, 4H), 7.35–7.30 (m, 5H), 4.69
(s, 2H), 4.39 (t, 2H, J = 7.5 Hz), 3.09 (t, 2H, J = 7.5 Hz).
13C NMR (CDCl3): d 33.9, 36.3, 45.1, 118.5, 125.3, 127.0,
127.1, 127.2, 128.6, 128.8, 128.9, 129.5, 130.9, 135.5,
137.1, 142.7, 143.7, 146.2, 156.1. MS: (M? = 416, 145,
100 %). IR (KBr, cm-1) m: 3420 (OH), 3021 (Ar. CH),
2987 (Al. CH), 1695, 1676 (CO), 1609 (C=N).
2-(Ethylthio)-3-phenethylquinazolin-4(3H)-one (3) Mp:
1
83–85 °C, yield 90 %, H NMR (CDCl3): d 8.26 (d, 1H,
J = 7.5), 7.71 (t, 1H, J = 7.0), 7.58 (d, 1H, J = 8.0 Hz),
7.42–7.24 (m, 6H), 4.34 (t, 2H, J = 8.0, 8.5 Hz), 3.35 (q,
123

Med Chem Res
2-(4-Oxo-3-phenethyl-3,4-dihydroquinazolin-2-ylthio)aceto-
nitrile (8) Mp: 151–153 °C, yield 92 %, 1H NMR
(CDCl3): d 8.16 (d, 1H, J = 6.5 Hz), 7.76–7.64 (m, 1H),
7.55 (d, 1H, J = 8.0 Hz), 7.38–7.35 (m, 1H), 7.27–7.17
(m, 5H), 4.16 (t, 2H, J = 8.0, 8.5 Hz), 4.01 (s, 2H), 2.97 (t,
2H, J = 8.0 Hz). 13C NMR (CDCl3): d 17.7, 34.2, 46.5,
115.8, 119.5, 126.4, 126.7, 127.0, 128.8, 128.9, 134.7,
137.3, 146.8, 152.1, 161.2. MS: (M? = 321, 122, 100 %).
IR (KBr, cm-1) m: 3021 (Ar. CH), 2940 (Al. CH), 2259
(CN), 1686 (CO), 1607 (C=N).
J = 7.0 Hz), 7.39–7.37 (m, 5H), 7.30-7.23 (m, 3H), 7.16
(d, 1H, J = 8.0 Hz), 4.71 (s, 2H), 4.38 (t, 2H, J = 8.5 Hz),
3.14 (t, 2H, J = 8.0 Hz).13C NMR (CDCl3): d 34.2, 38.9,
46.5, 115.9, 116.0, 119.4, 125.7, 126.0, 126.8, 127.0,
128.7, 129.0, 131.2, 131.3, 132.8, 134.3, 137.7, 147.0,
154.9, 161.4, 192.0. MS: (M? = 418, 107, 100 %). IR
(KBr, cm-1) m: 3027 (Ar. CH), 2994 (Al. CH), 1692, 1673
(CO), 16107 (C=N).
3-Phenethyl-2-[2-(piperidin-1-yl)ethylthio]quinazolin-4(3H)-
1
one (13) Mp:[330 °C, yield 82 %, H NMR (CDCl3): d
2-[2-(4-Oxo-3-phenethyl-3,4-dihydroquinazolin-2-ylthio)-
ethyl]isoindoline-1,3-dione (9) Mp: 202–204 °C, yield
84 %, H NMR (CDCl3): d 8.10 (d, 1H, J = 7.5 Hz), 7.71
8.25 (d, 1H, J = 8.0 Hz), 7.71 (t, 1H, J = 7.0 Hz), 7.55 (d,
1H, J = 8.0 Hz), 7.42–7.26 (m, 6H), 4.35 (t, 2H, J = 8.0,
8.5 Hz), 3.48 (t, 2H, J = 7.5 Hz), 3.09 (t, 2H, J = 8.0,
8.5 Hz), 2.75 (t, 2H, J = 7.0, 7.5 Hz), 2.57 (s, 4H), 1.65 (s,
4H), 1.49 (s, 2H). 13C NMR (CDCl3): d 18.4, 25.9, 29.1,
34.1, 46.0, 54.4, 63.4, 119.4, 125.6, 126.0, 126.7, 126.9,
128.6, 128.9, 134.2, 138.0, 147.5, 156.2, 161.6. MS:
(M? = 393, 104, 100 %). IR (KBr, cm-1) m: 3030, 3021
(Ar. CH), 2940 (Al. CH), 1676 (CO), 1604 (C=N).
1
(dd, 2H, J = 3.0 Hz), 7.62–7.56 (m, 4H), 7.30 (t, 1H,
J = 7.0 Hz), 7.21–7.15 (m, 5H), 4.17 (t, 2H, J = 8.0 Hz),
4.10 (t, 2H, J = 6.5 Hz), 3.54 (t, 2H, J = 6.5 Hz), 2.94 (t,
2H, J = 8.0 Hz). 13C NMR (CDCl3): d 30.0, 34.0, 37.0,
46.1, 119.4, 123.3, 125.8, 126.3, 126.7, 126.8, 128.6,
128.9, 131.9, 134.0, 134.3, 137.9, 147.3, 154.8, 161.5,
168.1. MS: (M? = 455, 63, 100 %). IR (KBr, cm-1) m:
3015 (Ar. CH), 2963 (Al. CH), 1771, 1719, 1668 (CO),
1603 (C=N).
2-(2-Morpholinoethylthio)-3-phenethylquinazolin-4(3H)-one
(14) Mp:[330 °C, yield 83 %, 1H NMR (CDCl3): d 8.26
(d, 1H, J = 6.5 Hz), 7.72 (t, 1H, J = 6.5 Hz), 7.54 (d, 1H,
J = 8.0 Hz), 7.41–7.37 (m, 6H), 4.36 (t, 2H, J = 8.0 Hz),
3.78 (s, 4H), 3.50 (t, 2H, J = 7.0 Hz), 3.09 (t, 2H, J = 8.0,
8.5 Hz), 2.80 (t, 2H, J = 6.5 Hz), 2.57 (s, 4H). 13C NMR
(CDCl3): d 28.9, 34.1, 46.0, 53.5, 57.5, 66.9, 119.4, 125.7,
125.9, 126.7, 126.9, 128.6, 128.9, 134.3, 137.9, 147.4,
156.0, 161.6. MS: (M ? 1 = 396, 120, 100 %). IR (KBr,
cm-1) m: 1674 (CO), 1603 (C=N).
2-[3-(4-Oxo-3-phenethyl-3,4-dihydroquinazolin-2-ylthio)pro-
pyl]isoindoline-1,3-dione (10) Mp: 116–118 °C, yield
82 %, 1H NMR (CDCl3): d 8.23 (d, 1H, J = 7.5 Hz),
7.88–7.86 (m, 2H), 7.74–7.73 (m, 2H), 7.64 (t, 1H,
J = 6.5, 7.0 Hz), 7.44–7.22 (m, 7H), 4.30 (t, 2H, J = 8.5,
8.0 Hz), 3.91 (t, 2H, J = 6.5 Hz), 3.44 (t, 2H, J = 6.5 Hz),
3.06 (t, 2H, J = 8.0 Hz), 2.19 (t, 2H, J = 6.5 Hz). 13C
NMR (CDCl3): d 28.3, 29.2, 34.1, 37.0, 46.0, 119.4, 123.3,
125.7, 126.1, 126.7, 126.8, 128.7, 129.0, 132.1, 134.0,
134.2, 138.0, 147.3, 156.6, 161.6, 168.4. MS: (M? = 469,
146, 100 %). IR (KBr, cm-1) m: 3022 (Ar. CH), 2951 (Al.
CH), 1771, 1715, 1674 (CO), 1609 (C=N).
Ethyl 2-(4-oxo-3-phenethyl-3,4-dihydroquinazolin-2-ylthio)-
acetate (15)
A mixture of 2.82 g 2-mercapto-3-phenethylquinazolin-
4(3H)-one (1, 10 mmol), 1.84 g ethyl bromoacetate
(11 mmol), and 1.66 g anhydrous potassium carbonate
(12 mmol) in 50 ml dry acetone was stirred at room tem-
perature for 6 h. The reaction mixture was filtered, the
solvent was removed under reduced pressure, and the solid
obtained was dried and recrystallized from ethanol. Mp:
132–134 °C, yield 95 %, 1H NMR (CDCl3): d 8.24 (d, 1H,
J = 7.0 Hz), 7.72 (t, 1H, J = 7.0 Hz), 7.52 (d, 1H,
J = 8.0 Hz), 7.43-7.29 (m, 6H), 4.35 (t, 2H, J = 7.0,
7.5 Hz), 4.29 (q, 2H, J = 7.0, 7.5 Hz), 4.08 (s, 2H), 3.12 (t,
2H, J = 7.0, 7.5 Hz), 1.34 (t, 3H, J = 7.5, 7.0 Hz). 13C
NMR (CDCl3): d 14.2, 34.2, 34.5, 46.3, 61.9, 119.4, 126.0,
126.1, 126.8, 126.9, 128.7, 128.9, 134.3, 137.7, 147.2,
154.7, 161.4, 168.5. MS: (M? = 368, 63, 100 %). IR
(KBr, cm-1) m: 3035, 3026 (Ar. CH), 2980 (Al. CH), 1726,
1680 (CO), 1601 (C=N).
2-(2-Oxo-2-phenylethylthio)-3-phenethylquinazolin-4(3H)-
one (11) Mp: 154–156 °C, yield 88 %, 1H NMR
(CDCl3): d 8.22 (d, 1H, J = 7.0 Hz), 8.15 (d, 2H,
J = 7.0 Hz), 7.69–7.58 (m, 4H), 7.40–7.37 (m, 5H),
7.30–7.28 (m, 1H), 7.17 (d, 1H, J = 7.5 Hz), 4.76 (s, 2H),
4.39 (t, 2H, J = 8.0 Hz), 3.15 (t, 2H, J = 8.0 Hz).13C
NMR (CDCl3): d 34.2, 39.2, 46.5, 119.4, 125.8, 126.8,
126.9, 128.5, 128.7, 128.8, 128.9, 133.6, 134.2, 136.4,
137.7, 147.1, 155.0, 161.4, 193.5. MS: (M? = 400, 119,
100 %). IR (KBr, cm-1) m: 3020 (Ar. CH), 2957 (Al. CH),
1682, 1674 (CO), 1611 (C=N).
2-[2-(4-Fluorophenyl)-2-oxoethylthio]-3-phenethylquinaz-
olin-4(3H)-one (12) Mp: 141–143 °C, yield 91 %, 1H
NMR (CDCl3): d 8.28–8.17 (m, 3H), 7.61 (t, 1H,
123

Med Chem Res
2-(4-Oxo-3-phenethyl-3,4-dihydroquinazolin-2-ylthio)acet-
ohydrazide (16)
N-(4-Methoxyphenyl)-2-[2-(4-oxo-3-phenethyl-3,4-dihy-
droquinazolin-2-ylthio)acetyl]hydrazinecarbothioamide
(19) Mp: 184–186 °C, yield 83 %, 1H NMR (DMSO-d6):
d 10.39 (s, 1H), 9.71 (s, 1H), 9.45 (s, 1H), 8.08 (d, 1H,
J = 7.0 Hz), 7.75 (t, 1H, J = 7.0 Hz), 7.59 (d, 1H,
J = 8.0 Hz), 7.45 (t, 1H, J = 7.0 Hz), 7.40-7.23 (m, 7H),
6.89 (d, 2H, J = 8.5 Hz), 4.27 (t, 2H, J = 7.5, 8.0 Hz),
A mixture of 3.68 g ester 15 (10 mmol) and 750 mg
hydrazine hydrate (15 mmol) in 50 ml absolute ethanol
was stirred at room temperature for 8 h. The reaction
mixture was filtered and dried. Mp: 160–162 °C, yield
1
90 %, H NMR (CDCl3): d 8.26 (d, 1H, J = 7.0 Hz), 7.75
4.19 (s, 2H), 3.75 (s, 3H), 3.03 (t, 2H, J = 7.5, 8.0 Hz). 13
C
(t, 1H, J = 7.0 Hz), 7.58 (d, 1H, J = 8.0 Hz), 7.46 (t, 1H,
J = 7.0, 7.5 Hz), 7.36–7.29 (m, 5H), 4.32 (t, 2H,
J = 8.0 Hz), 3.97 (s, 2H), 3.93 (s, 2H), 3.08 (t, 2H,
J = 8.0 Hz). 13C NMR (DMSO-d6): d 33.1, 34.1, 46.5,
119.4, 125.7, 126.5, 126.9, 127.2, 128.7, 129.0, 134.7,
137.4, 146.7, 155.9, 161.1, 169.2. MS: (M? = 354, 49,
100 %). IR (KBr, cm-1) m: 3325, 3285 (NH), 3026(Ar.
CH), 2926 (Al. CH), 1719, 1680 (CO), 1609 (C=N).
NMR (DMSO-d6): d 33.4, 34.4, 45.5, 55.2, 113.3, 114.1,
118.3, 118.7, 126.0, 126.1, 126.3, 126.7, 127.3, 128.5,
128.6, 131.7, 134.6, 137.7, 146.6, 155.6, 156.8, 160.3,
166.7, 181.1. MS: (M? = 519, 56, 100 %). IR (KBr,
cm-1) m: 3322, 3212 (NH), 3024 (Ar. CH), 2971 (Al. CH),
1688, 1654 (CO), 1609 (C=N), 1248 (CS).
N-(4-Fluorophenyl)-2-(2-(4-oxo-3-phenethyl-3,4-dihy-
droquinazolin-2-ylthio)acetyl)hydrazinecarbothioamide
(20) Mp: 94–96 °C, yield 80 %, 1H NMR (DMSO-d6): d
10.43 (s, 1H), 9.86 (s, 1H), 9.56 (s, 1H), 8.08 (d, 1H,
J = 7.5 Hz), 7.75 (t, 1H, J = 7.0 Hz), 7.60 (d, 1H,
J = 8.0 Hz), 7.45 (t, 1H, J = 7.0, 7.5 Hz), 7.36–7.26 (m,
7H), 7.15 (t, 2H, J = 8.5 Hz), 4.27 (t, 2H, J = 7.5,
8.0 Hz), 4.19 (s, 2H), 3.03 (t, 2H, J = 7.5, 8.0 Hz). 13C
NMR (DMSO-d6): d 33.4, 34.4, 45.5, 114.6, 114.8, 118.7,
126.0, 126.1, 126.3, 126.7, 128.0, 128.5, 128.6, 134.6,
135.2, 137.6, 146.5, 155.6, 158.5, 160.3, 166.7, 181.1. MS:
(M? = 507, 40, 100 %). IR (KBr, cm-1) m: 3256, 3150
(NH), 3022 (Ar. CH), 2965 (Al. CH), 1717, 1676 (CO),
1609 (C=N), 1216 (CS).
General procedure for the synthesis of compounds (17–21)
A mixture of 708 mg acid hydrazide 16 (2.0 mmol) and
appropriate isothiocyanate (2.0 mmol) in 20 ml absolute
ethanol was stirred at room temperature for 9–12 h. The
solvent was removed under reduced pressure, and the solid
obtained was dried and recrystallized from ethanol.
N-Ethyl-2-(2-(4-oxo-3-phenethyl-3,4-dihydroquinazolin-2-
ylthio)acetyl)hydrazinecarbothioamide (17) Mp: 114–116 °C,
yield 86 %, 1H NMR (DMSO-d6): d 10.19 (s, 1H), 9.35 (s,
1H), 8.09 (d, 1H, J = 7.0 Hz), 7.99 (dd, 2H, J = 8.5 Hz),
7.62 (d, 1H, J = 8.0 Hz), 7.47 (t, 1H, J = 7.0, 7.5 Hz),
7.36–7.26 (m, 5H), 4.26 (t, 2H, J = 7.5, 8.0 Hz), 4.12 (s,
2H), 3.41 (q, 2H, J = 6.5, 7.0 Hz), 3.02 (t, 2H, J = 7.5,
8.0 Hz), 0.98 (t, 3H, J = 6.5, 7.0 Hz). 13C NMR (CDCl3):
d 14.3, 33.3, 34.3, 38.4, 45.4, 118.7, 126.1, 126.3, 126.7,
128.5, 128.6, 134.6, 137.6, 146.6, 155.5, 155.7, 160.3,
166.6, 180.8. MS: (M? = 441, 63, 100 %). IR (KBr,
cm-1) m: 3465, 3181 (NH), 3033 (Ar. CH), 2967 (Al. CH),
1685, 1654(CO), 1608 (C=N), 1252 (CS).
N-Benzyl-2-(2-(4-oxo-3-phenethyl-3,4-dihydroquinazolin-2-
ylthio)acetyl)hydrazinecarbothioamide (21) Mp: 1018 °C,
yield 86 %, 1H NMR (DMSO-d6): d 10.37 (s, 1H), 9.61 (s,
1H), 8.22 (t, 1H, J = 7.0 Hz), 8.04 (d, 1H, J = 7.5 Hz),
7.78 (t, 1H, J = 7.0 Hz), 7.57 (d, 1H, J = 8.0 Hz), 7.45 (t,
1H, J = 7.5 Hz), 7.37–7.21 (m, 7H), 7.17 (d, 1H,
J = 7.5 Hz), 7.14 (d, 2H, J = 6.5 Hz), 4.65 (d, 2H,
J = 5.0), 4.22 (t, 2H, J = 8.0 Hz), 4.12 (s, 2H), 2.99 (t,
2H, J = 8.0 Hz). 13C NMR (DMSO-d6): d 33.3, 34.2, 45.4,
46.6, 118.7, 125.9, 126.0, 126.3, 126.5, 126.6, 126.7,
127.3, 127.9, 128.5, 128.6, 134.6, 137.7, 138.7, 146.5,
155.9, 160.2, 166.8, 181.9. MS: (M? = 503, 44, 100 %).
IR (KBr, cm-1) m: 3277, 3132 (NH), 3031 (Ar. CH), 2974
(Al. CH), 1684, 1647 (C), 1606 (C=N), 1292 (CS).
2-[2-(4-Oxo-3-phenethyl-3,4-dihydroquinazolin-2-ylthio)a-
cetyl]-N-phenylhydrazinecarbothioamide (18) Mp: 192–194
°C, yield 81 %, 1H NMR (DMSO-d6): d 10.43 (s, 1H), 9.81
(s, 1H), 9.55 (s, 1H), 8.08 (d, 1H, J = 7.0 Hz), 7.55 (t, 1H,
J = 7.5, 6.5 Hz), 7.60 (d, 1H, J = 8.0 Hz), 7.45 (t, 1H,
J = 7.0, 7.5 Hz), 7.39–7.16 (m, 10H), 4.27 (t, 2H, J = 7.5,
8.0 Hz), 4.19 (s, 2H), 3.03 (t, 2H, J = 7.5, 8.0 Hz). 13C NMR
(DMSO-d6): d 33.4, 34.4, 45.5, 118.8, 125.2, 126.0, 126.1,
126.3, 126.7, 128.1, 128.5, 128.6, 134.6, 137.6, 138.9, 146.6,
155.6, 160.3, 166.7, 180.8. MS: (M? = 489, 49, 100 %). IR
(KBr, cm-1) m: 3319, 3208, 3152 (NH), 3028 (Ar. CH), 2968
(Al. CH), 1685, 1653 (CO), 1607 (C=N), 1230 (CS).
General procedure for the synthesis of compounds (22–25)
Method A A mixture of 708 mg acid hydrazide 16
(2.0 mmol) and appropriate isothiocyanate (2.0 mmol) in
20 ml absolute ethanol containing 405 mg TEA (4 mmol)
was refluxed for 10–12 h. The reaction mixture was
allowed to cool, the solvent was removed under reduced
123

Med Chem Res
pressure, and the solid obtained was washed with water,
dried, and recrystallized from ethanol.
2H, J = 7.0 Hz), 7.47–7.25 (m, 10H), 5.46 (s, 2H), 4.68 (s,
2H), 4.18 (t, 2H, J = 8.0 Hz), 2.97 (t, 2H, J = 8.0 Hz).
13C NMR (CDCl3): d 25.9, 34.1, 46.3, 47.4, 119.4, 125.9,
126.4, 126.9, 127.2, 127.5, 128.2, 128.7, 128.9, 133.1,
134.4, 134.7, 137.4, 146.7, 149.0, 153.5, 161.3, 168.7. MS:
(M? = 485, 106, 100 %). IR (KBr, cm-1) m: 3026 (Ar.
CH), 2991 (Al. CH), 1681(CO), 1609 (C=N).
Method B N-Substituted hydrazinecarbothioamide 17–21
(1.0 mmol) was refluxed in 20 ml absolute ethanol in the
presence of 203 mg TEA (1.5 mmol) for 6–8 h. The reaction
mixture was allowed to cool, the solvent was removed under
reduced pressure, and the solid obtained was washed with
water, dried, and recrystallized from ethanol.
Antitumor screening
2-[(4-Ethyl-5-mercapto-4H-1,2,4-triazol-3-yl)methylthio]-
3-phenethylquinazolin-4(3H)-one (22) Mp: 196–198 °C,
yield 90 %, 1H NMR (CDCl3): d 12.29 (s, 1H), 8.28 (d, 1H,
J = 7.0 Hz), 7.74 (t, 1H, J = 6.5, 7.0 Hz), 7.54 (d, 1H,
J = 8.0 Hz), 7.46 (t, 1H, J = 7.0 Hz), 7.32–7.26 (m, 5H),
4.71 (s, 2H), 4.31 (t, 2H, J = 7.5, 8.0 Hz), 4.23 (dd, 2H,
J = 7.5 Hz), 3.07 (t, 2H, J = 8.0 Hz), 1.45 (t, 3H,
J = 7.5 Hz). 13C NMR (CDCl3): d 14.0, 25.7, 34.2, 39.7,
36.4, 119.4, 125.8, 126.5, 127.0, 127.2, 128.7, 128.9,
134.7, 137.4, 146.7, 148.5, 153.6, 161.3. MS: (M? = 423,
44, 100 %). IR (KBr, cm-1) m: 3022 (Ar. CH), 2989 (Al.
CH), 1673 (CO), 1609 (C=N).
Under a sterile condition, cell lines were grown in RPMI
1640 media (Gibco, NY, USA) supplemented with 10 %
fetal bovine serum (Biocell, CA, USA); 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).
2-[(5-Mercapto-4-phenyl-4H-1,2,4-triazol-3-yl)methylthio]-
3-phenethylquinazolin-4(3H)-one (23) Mp: 194–196 °C,
yield 85 %, 1H NMR (DMSO-d6): d 13.92 (s, 1H), 8.32 (s,
1H), 8.05 (d, 1H, J = 7.0 Hz), 7.81 (t, 1H, J = 7.5 Hz),
7.75-7.72 (m, 1H), 7.54-7.47 (m, 4H), 7.40–7.7.23 (m, 6H),
4.57 (s, 2H), 4.13 (t, 2H, J = 8.0 Hz), 2.90 (t, 2H,
J = 8.0 Hz). 13C NMR (DMSO-d6): d 25.8, 33.3, 45.4,
118.7, 125.8, 126.2, 126.4, 126.7, 128.3, 128.6, 129.3,
129.4, 133.3, 134.7, 137.5, 146.2, 148.5, 154.0, 160.2,
168.2. MS: (M? = 471, 41, 100 %). IR (KBr, cm-1) m:
3020 (Ar. CH), 2987 (Al. CH), 1680 (CO), 1609 (C=N).
Acknowledgments The authors extend their appreciation to the
Deanship of Scientific Research at King Saud University for funding
the work through the research group project No. RGP-VPP-163.
Thanks are due to the NCI, Bethesda, MD, USA for performing the
antitumor testing of the synthesized compounds.
2-([5-Mercapto-4-(4-methoxyphenyl)-4H-1,2,4-triazol-3-yl)
methylthio]-3-phenethylquinazolin-4(3H)-one (24) Mp:
1
221–223 °C, yield 88 %, H NMR (CDCl3): d 11.73 (s,
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