Novel synthesis of pyran, thiophene, and pyridine derivatives incorporating thiazole ring and their antitumor evaluation

Article abstract of DOI:10.1002/jhet.3870

This study aims to design and synthesize a number of novel pyran, thiophene, and pyridine derivatives incorporating thiazole ring and evaluate their antitumor inhibition (μM) as significant anticancer agents. The reactivity of compound 1 [2-(4-oxo-4,5-dihydrothiazol-2-yl)acetonitrile] towards different chemical reagents was described. Furthermore, the reactivity of all the newly synthesized products was evaluated. The most active compounds towards all the three tumor cancer cell lines used such as MCF-7 (breast adenocarcinoma), NCI-H460 (non-small cell lung cancer) and SF-268 (CNS cancer), and normal fibroblasts human cell line (WI-38) were compounds 6d, 8, and 10b, which compared with the antiproliferative effects of the reference control doxorubicin. Also, some of the novel compounds indicate higher inhibition than doxorubicin against some of the cancer cell lines used such as 6c (especially towards MCF-7) and 2b, 6b (especially towards SF-268).

Full text of DOI:10.1002/jhet.3870

Received: 6 September 2019
DOI: 10.1002/jhet.3870
Revised: 2 December 2019
Accepted: 11 December 2019
A R T I C L E
Novel synthesis of pyran, thiophene, and pyridine
derivatives incorporating thiazole ring and their
antitumor evaluation
1
2
2
Rafat M. Mohareb
| Eid M. Khalil | Amany E. Mayhoub
|
2
Amira E. M. Abdallah
1
Department of Chemistry, Faculty of
Science, Cairo University, Giza, Egypt
Abstract
2
This study aims to design and synthesize a number of novel pyran, thiophene,
and pyridine derivatives incorporating thiazole ring and evaluate their anti-
tumor inhibition (μM) as significant anticancer agents. The reactivity of com-
Department of Chemistry, Faculty of
Science, Helwan University, Helwan,
Egypt
pound
1 [2-(4-oxo-4,5-dihydrothiazol-2-yl)acetonitrile] towards different
Correspondence
Amira E. M. Abdallah, Department of
Chemistry, Faculty of Science, Helwan
University, Ain Helwan, Cairo 11795,
A. R. Egypt.
chemical reagents was described. Furthermore, the reactivity of all the newly
synthesized products was evaluated. The most active compounds towards all
the three tumor cancer cell lines used such as MCF-7 (breast adenocarcinoma),
NCI-H460 (non-small cell lung cancer) and SF-268 (CNS cancer), and normal
fibroblasts human cell line (WI-38) were compounds 6d, 8, and 10b, which
compared with the antiproliferative effects of the reference control doxorubi-
cin. Also, some of the novel compounds indicate higher inhibition than doxo-
rubicin against some of the cancer cell lines used such as 6c (especially
towards MCF-7) and 2b, 6b (especially towards SF-268).
Email: amiraelsayed135@yahoo.com
K E Y W O R D S
antitumor, pyran, pyridine, thiazole, thiophene
[
24]
1
| INTRODUCTION
and in the cosmetic industry as sunscreens . Due to the
important role of thiazole derivatives in biological sys-
tems, which in turn encouraged us to synthesize some
new pyran, thiophene, and pyridine derivatives, the thia-
zole ring has been incorporated.
Thiazole ring has been identified as a central structural
element of a number of biological active natural products
and of pharmacological active substances. In nature, thia-
zoles play an important role where thiazolium ring pre-
sent in vitamin B1. Many pendant and fused thiazole
systems exhibit various applications in different fields,
such as in medicinal chemistry as antibacterial , anti-
fungal , anti-inflammatory , anticonvulsant , ant-
iviral
2 | RESULTS AND DISCUSSION
2.1 | Chemistry
[
1,2]
[3,4]
[5,6]
[7,8]
[9,10]
[11,12]
,
antioxidants
,
skin whitening agent
[
13,14]
[15–17]
(KHG22394)
, and anticancer.
In addition, thia-
In the current work, we are explaining the synthesis of thi-
azole derivatives together with their antitumor evaluation,
in proceedings to our concern in synthesize of bioactive
heterocyclic compounds[25–33]. Thus, compound (1)
zoles are applied in agriculture as agrochemicals 18–20].
[
[
21]
Also, used in biologically active natural products , in
materials science as sensors , molecular switches
[22]
[23]
,
J Heterocycl Chem. 2019;1–14.
wileyonlinelibrary.com/journal/jhet
© 2019 John Wiley & Sons, Ltd.
1

2
MOHAREB ET AL.
ꢀ
2
-(4-oxo-4,5-dihydrothiazol-2-yl)acetonitrile, which was
bath at 120 C to afford the respective compounds 2a-c
through the Knoevenagel reaction (Scheme 1). The struc-
tures of the latter compounds were confirmed on the basis
of their respective spectral and analytical data. Thus, the
[34]
obtained as reported in literature
malononitrile with thioglycolloic acid in acetic acid
solution, reacted with any of acetphenone,
-chloroacetophenone, or 4-methylacetophenone in an oil
by the reaction of
1
4
H-NMR spectrum of compound 2a revealed a singlet at
SCHEME 1 Synthesis of the thiazole derivatives 1; 2a-c; 3; and 4a,b

MOHAREB ET AL.
3
δ 2.50 ppm for CH group, a singlet at δ 4.97 ppm for CH2
thiophene derivative 3 (Scheme 1) in an equivalent way
3
[
35]
group, and a multiplet at δ 7.33-7.46 ppm for the existence
of the phenyl protons. Compound 2a reacted with elemen-
tal sulfur in ethanol and triethylamine to afford the
like the reported Gewald thiophene synthesis
.
The reaction of either compounds 2a or 2c with
benzenediazonium chloride gave the phenylhydrazone
SCHEME 2 Synthesis of the pyran 5a-f, pyridine 6a-f, and the benzylidene derivatives 7a,b

4
MOHAREB ET AL.
0
0
derivatives 4a and 4b, respectively. The spectral and ana-
lytical data of compounds 4a and 4b are in concord with
their structures (Scheme 1). Thus, the H-NMR spectrum
triethylamine to give the chromeno[4 ,3 :4,5]pyrano[2,3-d]
thiazole derivative 8 (Scheme 3). Formation of compound
8 took place via the loss ethanol molecule through the
intermediate of the pyran derivatives A.
1
of 4a revealed a singlet at δ 2.50 ppm for CH group, multi-
3
plet for two phenyl groups at δ 6.91-7.98 ppm, and a singlet
at δ 8.55 for the presence of NH moiety. Also, compounds
On the other hand, the reaction of compound
1 with salicylaldehyde and ethyl cyanoacetate in ethanol-
containing ammonium acetate afforded the chromeno
[4,3-d]thiazolo[4,5-b]pyridine derivative 9 (Scheme 3)
through the intermediate formation of B. In addition, the
reaction of compound 1 with furfural and either
malononitrile or ethyl cyanoacetate in ethanol containing
triethylamine gave the pyrano[2,3-d]thiazole derivatives
10a and 10b, respectively (Scheme 3). Finally, compound
1 reacted with furfural and either malononitrile or ethyl
cyanoacetate in ethanol containing ammonium acetate
gave the thiazolo[4,5-b]pyridine derivatives 11a and 11b,
respectively (Scheme 3).
4
a,b indicated a molecular formula C H N OS (m/z
19 14 4
+
+
3
46 [M ]) and C H N OS (m/z 360 [M ]) in their respec-
20 16 4
tive mass spectral data, which confirmed its structures.
Compound 1 underwent multi-component reactions
with any of benzaldehyde, 4-chlorobenzaldehyde or
4
-methoxybenzaldehyde and either malononitrile or
ethyl cyanoacetate in ethanol containing triethylamine to
afford the pyran derivatives 5a-f, respectively (Scheme 2).
The spectral and analytical data are consistent with their
1
respective structures. The H-NMR spectrum of com-
pound 5a showed a singlet at δ 4.59 ppm corresponding
to the CH group, a singlet at δ 7.34 ppm equivalent to
2
the pyran C4, a multiplet at δ 7.40-7.66 ppm indicating
the phenyl protons, and a singlet at δ 7.84 ppm for the
2.2 | In vitro cytotoxic effect on the
synthesized compounds
NH group. On the other hand, compound 5c showed a
2
singlet at δ 4.66 ppm for CH group, a singlet for pyran
2
C-4 at δ 7.47 ppm, a multiplet at δ 7.53-7.69 ppm for
C H protons, and a D O exchangeable singlet signal at δ
The three cancer cell lines were used in the cytotoxicity
evaluation and the results indicated that some of the pre-
pared compounds revealed promising results (Table 1).
The resulting values were compared with the antip-
6
4
2
7
.84 ppm corresponding to the NH group. Besides, com-
2
pound 5e showed a singlet at δ 1.90 ppm for CH group,
3
[36]
a singlet at δ 4.52 ppm for CH moiety, a singlet at δ
roliferative effects of the reference control doxorubicin.
2
7
7
.49 ppm for pyran C-4, a multiplet at δ 6.94-7.14 and
.30-7.61 ppm for C H group, and a singlet at δ 7.79 ppm
The tested compounds were dissolved in dimethyl sulfox-
ide (DMSO) at 1 mg/mL immediately before use and
diluted just before addition to the cell culture. Most of the
prepared compounds revealed substantial growth inhibi-
tory effects at the concentrations tested towards the
human tumor cells.
6
4
indicating the presence of the NH group.
2
The multi-component reaction of compound 1 with
either benzaldehyde, 4-chlorobenzaldehyde or 4-methoxy-
benzaldehyde and ethyl cyanoacetate gave the pyran
derivatives 5b, 5d, and 5f, respectively. The structures of
the previous compounds were confirmed according to
their spectral data.
2.3 | Structure activity relationship
The multi-component reactions of compound 1 with
any of the aromatic aldehydes, namely, benzaldehyde,
From Table 1, it is clear that compounds 6c (especially
towards MCF-7), 2b, 6b (especially towards SF-268), 6d,
8, and 10b exhibited optimal cytotoxic effect against the
used cancer cell lines, with IC 's in the (μM) range. Con-
4
-chlorobenzaldehyde, or 4-methoxybenzaldehyde and
either malonnitrile or ethyl cyanocetate in ethanol con-
taining ammonium acetate gave the pyridine derivatives
50
6
6
a-f, respectively (Scheme 2). In the mass spectra of 6a,
b, 6d, and 6f revealed the existing [M ] ions at
sidering the thiazole derivatives 2a-c, it is obvious that
compound 2b exhibits the highest cytotoxicity among the
three compounds, and this is attributed to the presence of
the electronegative Cl group. In addition, this compound
showed no inhibition towards the normal cell line WI38.
The thiophenylthiazole derivative 3 and the thiazole
derivatives 4a,b showed low cytotoxicity towards the
three cancer cell lines. Considering the pyrano[2,3-d]thia-
zole 5a-f, it is clear such series of compounds were of low
inhibitions toward the six cancer cell lines although com-
+
m/z = 293, m/z = 294, m/z = 329, and m/z = 324 con-
firmed their respective molecular weights.
Compound 5c reacted with either benzaldehyde or
4
7
7
-chlorobenzaldehyde to afford the pyran derivatives 7a and
b, respectively (Scheme 2). The mass spectra of compounds
a and 7b revealed molecular ion peaks at [M ] = 417 and
+
+
[M ] = 451 corresponding to their respective molecular for-
mulae C H N OSCl and C H N OSCl .
22
13
4
22 12
4
2
On the other hand, compound 1 reacted with
pound 5f (X OCH , Y OH) exhibited moderate cytotox-
3
salicylaldehyde and ethyl cyanoacetate in ethanol and
icity toward MCF-7 and NCI-460 cell lines with CI 's
5
0

MOHAREB ET AL.
5
SCHEME 3 Synthesis of pyran 8; pyridine 9; pyrano[2,3-d]thiazole-6-carbonitrile 10a,b and dihydrothiazolo[4,5-b]pyridine-
6
-carbonitrile derivatives 11a,b

6
MOHAREB ET AL.
TABLE 1 Antitumor effect of the
newly prepared compounds in GI50
(μM) on the growth of three human
tumor cell lines and normal human
cell line
a
GI50, μM
Compound
MCF-7
NCI-H460
SF-268
WI-38
>100
2
2
2
3
4
4
5
5
5
5
5
5
6
6
6
6
6
7
7
8
9
1
1
1
1
a
b
c
36.00 ± 4.29
0.33 ± 10.84
65.63 ± 10.42
10.36 ± 2.19
20.04 ± 10.01
12.30 ± 2.43
33.62 ± 2.8
23.85 ± 2.13
0.21 ± 8.33
62.01 ± 8.56
12.36 ± 2.29
18.07 ± 2.13
10.60 ± 1.26
60.49 ± 13.59
69.31 ± 12.36
48.60 ± 2.8
34.50 ± 2.38
28.60 ± 2.8
2.05 ± 0.01
30.60 ± 10.22
0.52 ± 0.08
0.42 ± 0.01
0.06 ± 0.006
4.36 ± 0.98
18.60 ± 6.06
0.80 ± 0.08
0.02 ± 0.004
65.00 ± 4.7
41.73 ± 4.50
0.04 ± 0.003
22.80 ± 4.32
18.60 ± 6.06
0.0940 ± 0.0087
24.55 ± 4.60
0.06 ± 0.008
59.49 ± 6.39
19.44 ± 5.19
10.34 ± 4.33
8.83 ± 2.36
59.29 ± 4.65
48.60 ± 5.37
78.80 ± 8.5
30.50 ± 8.0
26.80 ± 8.5
0.44 ± 4.01
41.29 ± 12.18
0.09 ± 0.001
0.63 ± 0.13
0.02 ± 0.008
2.55 ± 0.39
30.40 ± 2.36
0.10 ± 0.08
0.06 ± 0.002
55.39 ± 6.8
38.41 ± 1.29
0.01 ± 0.002
22.80 ± 6.23
30.40 ± 2.36
0.0940 ± 0.0070
>100
>100
70.55 ± 12.2
>100
a
b
a
b
c
d
e
f
>100
>100
72.21 ± 12.88
36.20 ± 2.4
>100
80.20 ± 4.6
>100
33.72 ± 3.54
26.20 ± 2.4
30.20 ± 2.6
>100
3.88 ± 0.18
a
b
c
d
f
33.58 ± 4.09
0.66 ± 0.08
>100
>100
0.04 ± 0.001
0.06 ± 0.006
1.61 ± 0.05
>100
>100
>100
a
b
12.60 ± 2.01
0.10 ± 0.04
30.6 ± 10.2
>100
0.01 ± 0.001
70.22 ± 6.12
58.00 ± 7.29
0.06 ± 0.002
22.80 ± 8.30
12.60 ± 2.01
0.0428 ± 0.0082
>100
>100
0a
0b
1a
1b
33.60 ± 6.21
>100
44.80 ± 6.0
30.60 ± 10.2
> 100
Doxorubicin
Note: Doxorubicin was used as positive control.
a
Drug concentration required to inhibit tumor cell proliferation by 50% after continuous exposure of 48 h;
data are expressed as means ± SEM of three independent experiments performed in duplicates.
3
.88 and 2.05μM, respectively, but it showed high inhibi-
0
.1
tion towards SF-268 cell line with GI50 0.44μM. On the
other hand, for the pyrido[2,3-d]thiazole 6a-f interestingly
compounds 6b (X H, Y OH), 6c (X Cl, Y NH ), and
0
.08
.06
2
0
6
d (X Cl, Y OH) exhibited high inhibitions towards the
six cancer cell lines. However, compound 6f (X OCH3,
Y OH) showed moderate inhibitions. Considering the
pyrano[2,3-d]thiazole 7a,b where compound 7b (X Cl)
showed higher inhibitions than 7a (X H). It is clear from
Table 1 that the chromeno[4 ,3 :4,5]pyrano[2,3-d]thiazole
derivative 8 showed the highest cytotoxicity toward the
three cancer cell lines. For the pyrano[2,3-d]thiazole
derivatives 10a,b, it is clear that compound 10b (Y OH)
0.04
0.02
0
6d
8
10b
Doxo.
0
0
MCF-7 NCI-H460 SF-268
FIGURE 1 The reactivity of the most active compounds
showed higher cytotoxities than 10a (Y NH ) although
towards the three cancer cell lines
2

MOHAREB ET AL.
7
determined on a FTIR plus 460IR spectrophotometer
0.1
1
13
(
Shimadzu, Japan). H-NMR and C-NMR spectra were
0.08
0.06
0.04
0.02
0
recorded on a Mercury-300BB (300 and 75 MHz, respec-
tively), at Cairo University, in DMSO-d as solvent, using
6
TMS [Si(CH ) ] as internal standard and chemical shifts
3
4
are expressed as δ ppm. Mass spectra were measured
using Hewlett Packard 5988 (USA) A GC/MS system and
GCMS-QP 1000 Ex Shimadzu (Japan) using EI (electron
impact method). Elemental analyses were carried out on
Vario EL III Elemental CHNS analyzer (Japan).
2b
6b
6c
Doxo.
MCF-7 SF-268
FIGURE 2 The most active compounds towards the MCF-7 or
SF-268 cancer cell lines
4
4
.1.1 | Synthesis of 2-(4-oxo-
,5-dihydrothiazol-2-yl)acetonitrile (1)
the pyrido[2,3-d]thiazole derivatives 11a,b exhibited low
inhibitions toward the three cancer cell lines.
Compound 1 was synthesized according to the method
reported earlier.
[
34]
From our study, it is clear that the presence of the
electronegative OH, Cl, and OCH hydrophobic groups
3
in the thiazole derivatives might play a very important
role in enhancing the cytotoxic effect. The antitumor
activity of the newly synthesized compounds towards all
the three cancer cell lines or towards some of them is
indicated through Figures 1 and 2.
4.1.2 | General procedure for the
synthesis of (Z)-2-(4-oxo-4,5-dihydrothiazol-
2-yl)-3-phenylbut-2-enenitrile derivatives
(2a-c)
To equimolar amount of 1 (1.40 g, 0.01 mol) containing a
traces amount of ammonium acetate, either acetophenone
(1.20 g, 0.01 mol), p-chloro acetophenone (1.54 g, 0.01 mol)
or p-methyl acetophenone (1.34 g, 0.01 mol) was fused in
3
| CONCLUSIONS
ꢀ
Our study describes a simple protocol for preparing 26 newly
synthesized thiazole derivatives. All data are in accordance
with their proposed structures. Moreover, the new com-
pounds were estimated for their antitumor activities on three
human cancer cell lines and normal human cell line where
most of the tested compounds were found to be promising
as anticancer agents. The results indicated that compounds
an oil bath at 120 C under reflux for about 30 minutes and
then boiled in absolute ethanol (20 mL) for few minutes.
The solid products formed upon pouring onto ice/water
mixture were crystallized from absolute ethanol.
4.1.3 | 2-(4-Oxo-4,5-dihydrothiazol-2-yl)-
3-phenylbut-2-enenitrile (2a)
6d, 8, and 10b are the most active compounds towards the
three tumor cell lines used such as MCF-7 (breast adenocar-
cinoma), NCI-H460 (non-small cell lung cancer) and SF-268
Dark brown crystals from ethanol, yield (1.98 g, 82%), mp
ꢀ
−1
(CNS cancer) tested, and normal fibroblasts human cell line
235-238 C. IR (KBr, cm ): 3057 (CH aromatic), 2971
(CH , CH ), 2200 (CN), 1692 (C O) 1602, 1449 (C C),
(WI-38) compared with the standard reference doxorubicin.
2
3
1
Also, some of the newly synthesized compounds showed
optimal cytotoxic effect towards the two cell lines, MCF-7
1563 (C N). H-NMR (300 MHz, DMSO-d ) δ: 2.50 (s,
6
3H, CH ), 4.97 (s, 2H, CH ), 7.33-7.46 (m, 5H, C H ). MS
3
2
6
5
+
+
(breast adenocarcinoma) such as compound 6c and SF-268
(EI): m/z (%) 243 [M +1] (39.42), 242 [M ] (45.26),
+
(CNS cancer) for compounds 2b and 6b.
77 [C H ] (29.93), 54 (100.00). Elemental analysis, calcu-
6
5
lated for C H N OS (242.30): C 64.44; H 4.16; N 11.56;
13
10 2
S 13.23. Found: C 64.72; H 3.99; N 11.83; S 13.53.
4
4
| EXPERIMENTAL
.1 | General
4.1.4 | 3-(4-Chlorophenyl)-2-(4-oxo-
4,5-dihdrothiazol-2-yl)but-2-enenitrile (2b)
All melting points were uncorrected and measured by an
electrothermal apparatus (Büchi 535, Switzerland) in
an open capillary tube. IR spectra (KBr discs) were
Dark brown crystals from ethanol, yield (2.10 g, 76%),
mp: 127-130 C. IR (KBr, cm ): 3100 (CH aromatic),
ꢀ
−1

8
MOHAREB ET AL.
2
965-2926 (CH , CH ), 2202 (CN), 1630 (C O), 1580, 1485
equimolar amount of diazotized aniline (0.93 mL,
0.01 mol) was gradually added while stirring. The formed
solid products upon cooling in an ice bath were collected
by filtration, washed with water, and crystallized from
absolute ethanol.
2
3
1
(C C) 1530 (C N). H-NMR (300 MHz, DMSO-d ) δ: 2.50
6
(s, 3H, CH ) 4.86 (s, 2H, CH ), 7.46 (d, J = 8.7 Hz, 2H,
3
2
Ar H), 7.54 (d, J = 8.7 Hz, 2H, Ar H). MS (EI): m/z (%)
+
+
+
2
2
7
79 [M +2] (5.29), 278 [M +1] (23.63), 277 [M ] 15.97,
76 [M −1] (59.57), 275 [M −2] (5.84), 144 (100.00),
6 [C H ] (13.66). Elemental analysis, calculated for
+
+
6
4
C H N OSCl (276.74): C, 56.42; H, 3.28; N, 10.12; S, 11.59.
Found: C, 56.72; H, 3.18; N, 10.33; S, 11.93.
4.1.8 | 2-(4-Oxo-5-(2-phenylhydrazone)-
4,5-dihydrothiazol-2-yl)-3-phenylbut-
13 9 2
2-enenitrile (4a)
4
3
.1.5 | 2-(4-Oxo-4,5-dihydrothiazol-2-yl)-
-(p-tolyl)-but-2-enenitrile (2c)
Brown crystals from ethanol, yield (3.39 g, 98%), mp:
ꢀ
−1
147-150 C. IR (KBr, cm ): 3429 (NH), 3057
CH aromatic), 2200 (CN), 1700 (C O), 1602, 1488 (C C),
(
1
Brown crystals from ethanol, yield (1.69 g, 66%), mp:
1560 (C N). H-NMR (300 MHz, DMSO-d ) δ: 2.50 (s, 3H,
6
ꢀ
−1
177-180 C. IR (KBr, cm ): 3100 (CH aramatic) 2969-2922
CH ), 6.91 (m, 1H, Ar H), 7.53 (m, 1H, Ar H), 7.56 (d,
3
(
CH , CH ), 2200 (CN), 1690 (C O), 1603, 1450 (C C), 1509
J = 7.5 Hz, 2H, Ar H), 7.64 (d, J = 7.5 Hz, 2H, Ar H),
7.69 (d, J = 6.9 Hz, 2H, Ar H), 7.98 (d, J = 6.9 Hz, 2H,
2
3
1
(C N). H-NMR (300 MHz, DMSO-d ) δ: 1.23 (s, 3H, CH ),
6 3
+
2
2
.50 (s, 3H, CH ), 4.93 (s, 2H, CH ), 7.16-7.18 (d, J = 6.0 Hz,
Ar H), 8.55 (s, 1H, NH). MS (EI): m/z (%) 347 [M +1]
3
2
+
+
H, Ar H), 7.84-7.86 (d, J = 6.0 Hz, 2H, Ar H). MS (EI):
(23.08), 346 [M ] (49.57), 345 [M −1] (4.27), 78 (100.00),
+
+
+
+
m/z (%) 258 [M +2] (3.17), 257 [M +1) (10.46), 256 [M ]
77 [C H ] (25.64). Elemental analysis, calculated for
6
5
+
(41.20), 80 (100.00), 76 [C H ] (3.65). Elemental analysis,
C H N OS (346.41): C, 65.88; H, 4.07; N, 16.17; S, 9.26.
19 14 4
6
4
calculated for C H N OS (256.32): C, 65.60; H, 4.72; N,
Found: C, 65.88; H, 4.19; N, 16.55; S, 9.42.
1
4 12 2
10.93; S, 12.51. Found: C, 65.98; H, 4.39; N, 11.29; S, 12.41.
4
.1.9 | 2-(4-Oxo-5-(2-phenylhydrozono)-
4.1.6 | Synthesis of 2-(2-amino-4-
4,5-dihydrothiazol-2-yl)-3-(p-tolyl)but-
phenylthiophen-3-yl)thiazole-4(5H)-one (3)
2-enenitrite (4b)
To a solution of compound 2a (2.42 g, 0.01 mol) in absolute
ethanol (25 mL), in triethylamine (0.50 mL), an elemental
sulfur (0.32 g, 0.01 mol) was added. Under reflux system,
the reaction was heated for 3 hours. The obtained solid
product was poured onto acidified ice/water mixture, col-
lected by filtration and crystallized from absolute ethanol.
Dark brown crystals from ethanol, yield (2.69 g, 98%),
Pale brown crystals from ethanol, yield (3.57 g, 99%), mp:
ꢀ
−1
182-185 C. IR (KBr, cm ): 3424 (NH), 2920 (2CH ), 2202
3
1
(CN), 1650 (C O), 1601, 1453 (C C). H-NMR
(300 MHz, DMSO-d ) δ: 1.23 (s, 3H, CH ), 2.35 (s, 3H,
6
3
CH ), 7.31-7.89 (m, 9H, C H , C H ), 8.15 (s, 1H, NH).
3
6
4
6
5
+
+
MS (EI): m/z (%) 361 [M +1] (63.22), 360 [M ] (66.67),
103 (100.00), 77 [C H ] (25.29). Elemental analysis, cal-
+
6
5
ꢀ
−1
mp: 207-210 C. IR (KBr, cm ): 3430, 3200 (NH ), 3092
culated for C H N OS (360.43): C, 66.65; H, 4.47; N,
20 16 4
2
(
(
CH aromatic), 2925 (CH ), 1690 (C O), 1630, 1442
15.54; S, 8.90. Found: C, 67.01; H, 4.77; N, 15.93; S, 9.20.
2
1
C C). H-NMR (300 MHz, DMSO-d ) δ: 4.98 (s, 2H,
6
CH ), 6.70 (s, 1H, thiophene C5), 7.00 (s, 2H, NH ),
2
2
+
7
(
(
.34-7.50 (m, 5H, C H ). MS (EI): m/z (%) 275 [M +1]
2.87), 274 [M ] (9.96), 273 [M −1] (4.67), 272 [M −2]
0.81), 148 (100.00). Elemental analysis, calculated for
4.1.10 | General procedure for the
synthesis of 2-(cyanomethyl)-7-phenyl-7H-
pyrano[2,3-d]thiazole-6-carbonitile
derivatives (5a-f)
6
5
+
+
+
C H N OS (274.36): C, 56.91; H, 3.67; N, 10.21; S,
13
10
2
2
2
3.37. Found: C, 57.08; H, 4.02; N, 10.29; S, 23.75.
To a solution of compound 1 (1.40 g, 0.01 mol) in absolute
ethanol (25 mL), either malononitrile (0.66 g, 0.01 mol) or
ethyl cyanoacetate (1.13 g, 0.01 mol) and either benzalde-
hyde (1.06 g, 0.01 mol), p-chlorobenzaldehyde (1.40 g,
0.01 mol) or p-methoxybenzaldehyde (1.36 g, 0.01 mol) in
triethylamine (0.50 mL) were added. The reaction mixture
was heated under reflux for 30 minutes in case of
malononitrile and 2 hours in case of ethyl cyanoacetate,
4
.1.7 | General procedure for the
synthesis of phenyl hydrozone
derivatives (4a,b)
ꢀ
To a cold solution (0-5 C) of 2a (2.42 g, 0.01 mol) or
2
c (2.56 g, 0.01 mol) in sodium acetate (1.00 g), an

MOHAREB ET AL.
9
+
+
and the solid products being formed upon pouring onto
acidified ice/water mixture was collected by filtration and
crystallized from absolute ethanol.
m/z (%) 330 [M +1] (21.69), 329 [M ] (20.88),
+
+
+
328 [M −1] (29.32), 327 [M −2] (27.31), 76 [C H ]
(17.27), 69 (100.00). Elemental analysis, calculated for
6
4
C H N OSCl (328.78): C, 54.80; H, 2.76; N, 17.04; S,
15
9 4
9.75. Found: C, 54.50; H, 3.09; N, 16.77; S, 10.13.
4
7
6
.1.11 | 5-Amino-2-(cyanomethyl)-
-phenyl-7H-pyrano[2,3-d]thiazole-
-carbonitile (5a)
4.1.14 | 7-(4-Chlorophenyl)-
-(cyanomethyl)-5-hydroxy-7H-pyrano
[2,3-d]thiazole-6-carbonitrile (5d)
2
Yellow crystals from ethanol, yield (1.76 g, 60%), mp:
ꢀ
52-255 C. IR (KBr, cm ): 3380, 3211 (NH ), 3058-3026
2
−1
2
(
(
CH aromatic), 2926 (CH ), 2250, 2201 (2 CN), 1617, 1489
Canary yellow crystals from ethanol, yield (1.98 g, 60%),
mp: 82-85 C. IR (KBr, cm ): 3410 (OH), 3050
2
1
ꢀ
−1
C C), 1557 (C N). H-NMR (300 MHz, DMSO-d ) δ:
6
4
5
2
2
.59 (s, 2H, CH ), 7.34 (s, 1H, pyran C4), 7.40-7.66 (m,
(CH aromatic), 2981 (CH ), 2260, 2205 (2 CN), 1634, 1483
2
2
1
H, C H ), 7.84 (s, 2H, NH ). MS (EI): m/z (%)
(C C), 1520 (C N). H-NMR (300 MHz, DMSO-d ) δ: 4.93
6
5
2
6
+
+
+
96 [M +2] (0.22), 295 [M +1] (0.39), 294 [M ] (1.42),
93 [M −1] (0.52), 292 [M −2] (0.33), 77 [C H ]
(s, 2H, CH ), 6.84 (s, 1H pyrano C4), 7.22 (d, J = 8.7 Hz,
2
+
+
+
2H, Ar H), 7.31 (d, J = 8.7 Hz, 2H, Ar H), 8.60 (s, 1H,
6
5
13
(24.52), 134 (100.00). Elemental analysis, calculated for
OH). C-NMR (75 MHz, DMSO-d ) δ: 13.9, 38.9, 59.2,
6
C H N OS (294.33): C, 61.21; H, 3.42; N, 19.04; S, 10.89.
Found: C, 61.49; H, 3.72; N, 18.88; S, 11.26.
117.9, 119.6, 120.8, 120.8, 129.4, 129.4, 130.9, 131.7, 143.1,
15
10 4
+
148.4, 170.8, 174.5. MS (EI): m/z (%) 332 [M +2] (1.55),
+
+
+
3
3
31 [M +1] (2.71), 330 [M ] (1.64), 329 [M −1] (8.21),
+
28 [M −2] (5.02), 264 (100.00). Elemental analysis, calcu-
4.1.12 | 2-(Cyanomethyl)-5-hydroxy-
7-phenyl-7H-pyrano[2,3-d]thiazole-
6-carbonitrile (5b)
lated for C H N O SCl (329.76): C, 54.63; H, 2.45; N,
12.74; S, 9.72. Found: C, 54.33; H, 2.33; N, 13.13; S, 10.09.
15 8 3 2
Yellow crystals from ethanol, yield (2.80 g, 95%), mp:
4.1.15 | 5-Amino-2-(cyanomethyl)-
7-(4-methoxyphenyl)-7H-pyrano[2,3-d]
thiazole-6-carbonirile (5e)
ꢀ
−1
117-120 C. IR (KBr, cm ): 3406 (OH), 3063 (CH aromatic),
2
979 (CH ), 2260, 2205 (2 CN), 1603, 1448 (C C) 1510
2
1
(C N). H-NMR (300 MHz, DMSO-d ) δ: 4.60 (s, 2H, CH ),
6 2
6
.93 (s, 1H, pyran C4), 7.26-7.28 (m, 1H, Ar H), 7.37 (d,
Orange crystal from ethanol, yield (2.27 g, 70%), mp:
ꢀ
−1
J = 7.5 Hz, 2H, Ar H), 7.56 (d, J = 7.5 Hz, 2H, Ar H), 8.61
257-260 C. IR (KBr, cm ): 3389, 3200, (NH ), 3005
2
13
(s, 1H, OH). C-NMR (75 MHz, DMSO-d ) δ: 13.7, 38.7, 58.9,
(CH aromatic), 2930-2840 (CH , CH ), 2260, 2202 (2 CN)
6
2
3
1
116.1, 118.9, 126.5, 128.6, 128.6, 129.2, 129.2, 132.8, 144.1,
1593, 1447 (C C), 1560 (C N). H-NMR (300 MHz,
+
148.4, 169.8, 170.1. MS (EI): m/z (%) 297 [M +2) (5.72),
DMSO-d ) δ: 1.90 (s, 3H, CH ), 4.52 (s, 2H, CH ), 6.94 (d,
6
3
2
+
+
+
296 [M +1) (13.87), 295 [M ] (4.91), 294 [M −1] (3.85),
J = 8.7 Hz, 1H, Ar H), 7.14 (d, J = 8.7 Hz, 1H, Ar H),
7.30 (d, 1H, Ar H), 7.49 (s, 1H, pyran C4), 7.61 (d,
+
+
293 [M −2] (2.94), 77 [C H ] (100.00). Elemental analysis,
6
5
calculated for C H N O S (295.32): C, 61.01; H, 3.07; N,
J = 8.7 Hz, 1H, Ar H), 7.79 (s, 2H, NH ). MS (EI): m/z (%)
15
9
3
2
2
+
+
+
14.23; S, 10.86. Found: C, 60.99; H, 3.37; N, 13.89; S, 10.56.
325 [M +1] (0.97), 324 [M ] (0.81), 323 [M −1] (2.18),
+
7
6 [C H ] (16.25), 243 (100.00). Elemental analysis, calcu-
6 4
lated for C H N O S (324.36): C, 59.25; H, 3.73; N,
16 12 4 2
4
2
6
.1.13 | 5-Amino-7-(4-chlorophenyl)-
-(cyanomethyl)-7H-pyrano[2,3-d]thiazole-
-carbanitile (5c)
17.27; S, 9.89. Found: C, 59.55; H, 4.02; N, 16.90; S, 10.04.
4
.1.16 | 2-(Cyanomethyl)-5-hydroxy-
Yellow crystals from ethanol, yield (2.46 g, 75%), mp:
7-(4-methoxyphenyl)-7H-pyrano[2,3-d]
ꢀ
−1
2
77-280 C. IR (KBr, cm ): 3378, 3208 (NH ), 3024
thiazole-6-carbonitrile (5f)
2
(CH aromatic), 2924 (CH ), 2257, 2203 (2 CN), 1614, 1485
2
1
(C C), 1558 (C N). H-NMR (300 MHz, DMSO-d ) δ:
Yellow crystals from ethanol, yield (1.95 g, 60%), mp:
6
ꢀ
−1
4
.66 (s, 2H, CH ), 7.47 (s, 1H, pyran C4), 7.53-7.69 (m,
247-250 C. IR (KBr, cm ): 3380 (OH), 3060 (CH aromatic),
2969-2841 (CH , CH ), 2258, 2206 (2 CN), 1637, 1450 (C C),
2
13
4
H, C H ), 7.84 (s, 2H, NH ). C-NMR (75 MHz, DMSO-
6
4
2
2
3
1
d6) δ: 38.8, 39.6, 63.5, 115.6, 118.4, 120.5, 120.5, 130.0,
30.0, 131.7, 132.8, 140.6, 147.9, 165.0, 169.6. MS (EI):
1506 (C N). H-NMR (300 MHz, DMSO-d ) δ: 3.45 (s, 3H,
6
1
CH ), 4.52 (s, 2H, CH ), 6.85 (d, J = 8.7 Hz, 1H, Ar H),
3
2

10
MOHAREB ET AL.
7.12-7.15 (d, 1H, Ar H), 7.22 (d, J = 8.7 Hz, 1H, Ar H), 7.61
7.51 (d, J = 7.8 Hz, 2H, Ar H), 7.59 (d, J = 7.8 Hz, 2H,
(
d, J = 8.7 Hz, 1H, Ar H), 7.79 (s, 1H, pyran C4), 8.59 (s, 1H,
Ar H), 7.66 (s, 1H, pyridine C4), 7.85 (s, 1H, NH), 8.60 (s,
+
+
+
+
OH). MS (EI): m/z (%) 326 [M +1]+ (65.00), 325 [M ]
1H, OH). MS (EI): m/z (%) 296 [M +1] (0.63), 295 [M +]
+
+
+
+
(76.00), 324 [M −1] (63.00), 231 (100.00). Elemental analysis,
(0.64), 294 [M ] (0.76), 293 [M −1] (0.20), 77 [C H ]
6
5
calculated for C H N O S (325.34): C, 59.07; H, 3.41; N,
(7.71), 59 (100.00). Elemental analysis, calculated for
1
6 11 3 3
12.92; S, 9.86. Found: C, 58.79; H, 3.71; N, 12.59; S, 10.03.
C H N OS (294.33): C, 61.21; H, 3.42; N, 19.04; S, 10.89.
15
10 4
Found: C, 61.51; H, 3.70; N, 18.73; S, 11.19.
4
.1.17 | General procedure for the
synthesis of 2-(cyanomethyl)-7-phenyl-
4
6
4.1.20 | 5-Amino-7-(4-chlorophenyl)-
2-(cyanomethyl)-4,7-dihydrothiazolo[4,5-b]
pyridine-6-carbonitrile (6c)
,7-dihydrothiazolo[4,5-b]pyridine-
-carbonitrile derivatives (6a-f)
To a solution of compound 1 (1.40 g, 0.01 mol) in absolute
ethanol (25 mL) containing ammonium acetate, each of
either benzaldehyde (1.06 g, 0.01 mol), p-chlorobenzaldehyde
Pale green crystals from ethanol, yield (2.82 g, 86%), mp:
ꢀ
−1
167-170 C. IR (KBr, cm ): 3425-3212 (NH, NH ), 3060
2
(CH aromatic), 2900 (CH ), 2250, 2209 (2 CN), 1618, 1491
2
1
(1.40 g, 0.01 mol), or p-methoxybenzldehyde (1.36 g,
(C C), 1554 (C N). H-NMR (300 MHz, DMSO-d ) δ: 4.67 (s,
6
0.01 mol) and either malononitrile (0.66 g, 0.01 mol) or ethyl
2H, CH ), 7.40 (d, J = 6.9 Hz, 2H, Ar H), 7.63 (d, J = 6.9 Hz,
2
cyanoacetate (1.13 g, 0.01 mol) were added. The reaction
mixture was heated under reflux for 30 minutes and then
poured onto ice/water containing a few drops of hydro-
chloric acid. The formed solid product, in each case, was fil-
tered of and crystallized from absolute ethanol.
2H, Ar H), 7.69 (s, 1H, pyrano C4), 7.71 (s, 2H, NH ), 7.86 (s,
2
+
+
1H, NH). MS (EI): m/z (%) 327 [M −1] (0.27), 326 [M −2]
+
(0.63), 76 [C H ] (8.62), 145 (100.00). Elemental analysis, cal-
6
4
culated for C H N SCl (327.79): C, 54.96; H, 3.07; N, 21.37; S,
15 10 5
9.78. Found: C, 55.26; H, 3.42; N, 21.01; S, 10.12.
4
7
.1.18 | 5-Amino-2-(cyanomethyl)-
-phenyl-4,7-dihydrothiazolo[4,5-b]
4.1.21 | 7-(4-Chlorophenyl)-
2-(cyanomethyl)-5-hydroxy-
4,7-dihydrothiazolo[4,5-b]pyridine-
pyridine-6-carbonitrile (6a)
6
-carbonitrile (6d)
Pale green crystals from ethanol, yield (2.82 g, 96%), mp:
ꢀ
−1)
1
27-130 C. IR (KBr, cm : 3378-3209 (NH, NH ), 3060-3027
Yellow crystals from ethanol, yield (1.84 g, 56%), mp:
237-240 C. IR (KBr, cm ): 3378-3250 (NH, OH), 3050
(CH aromatic), 2980-2929 (CH ), 2260, 2210 (2 CN) 1639,
1495 (C C), 1594 (C N). H-NMR (300 MHz, DMSO-d )
2
ꢀ
−1
(
CH aromatic), 2900 (CH ), 2250, 2195 (2 CN), 1618, 1493
2
1
(C C), 1558 (C N). H-NMR (300 MHz, DMSO-d ) δ: 4.61
6
2
1
(
s, 2H, CH ), 7.21-7.23 (m, 1H, Ar H), 7.29 (d, J = 9 Hz, 2H,
2
6
Ar H), 7.52 (d, J = 9 Hz, 2H, Ar H), 7.61 (s, 1H, pyridine
δ: 4.61 (s, 2H, CH ), 7.37 (s, 1H, pyridine C4), 7.61 (d,
2
13
C4), 7.86 (s, 2H, NH ), 8.02 (s, 1H, NH). C-NMR (75 MHz,
J = 9 Hz, 2H, Ar H), 7.66 (d, J = 9 Hz, 2H, Ar H), 7.83
2
13
DMSO-d ) δ: 24.3, 33.3, 63.6, 115.9, 118.7, 127.0, 128.6, 128.6,
(s, 1H, NH), 8.61 (s, 1H, OH). C-NMR (75 MHz,
6
1
29.3, 129.3, 134.6, 142.8, 147.8, 165.3, 168.9. MS (EI): m/z
DMSO-d ) δ: 13.8, 38.8, 59.1, 116.0, 119.7, 128.2, 128.2,
6
+
+
+
(%) 295 [M +2] (3.23), 294 [M +1] (15.21), 293 [M ] (6.09),
130.1, 130.1, 131.7, 135.1, 143.2, 148.5, 165.5, 167.8. MS
+
+
+
77 [C H ] (18.56), 91 (100.00). Elemental analysis, calcu-
(EI): m/z (%) 331 [M +1] (0.28), 330 [M +1] (0.49),
6
5
+
+
+
lated for C H N S (293.35): C, 61.42; H, 3.78; N, 23.87; S,
329 [M ] (0.23), 328 [M −1] (0.11), 327 [M −1] (0.18),
76 [C H ] (1.56), 59 (100.00). Elemental analysis, calcu-
15 11 5
+
10.93. Found: C, 61.03; H, 4.02; N, 23.57; S, 11.29.
6
4
lated for C H N OSCl (328.78): C, 54.80; H, 2.76; N,
15
9 4
17.04; S, 9.75. Found: C, 54.50; H, 3.06; N, 16.70; S, 10.05.
4
7
.1.19 | 2-(Cyanomethyl)-5-hydroxy-
-phenyl-4,7-dihydro-thiazolo[4,5-b]
pyridine-6-carbonitrile (6b)
4.1.22 | 5-Amino-2-(cyanomethyl)
-(4-methoxyphenyl)-4,7-dihydrothiazolo
[4,5-b]pyridine-6-carbonitrile (6e)
7
Brown crystal from ethanol, yield (1.62 g, 55%), mp:
ꢀ
−1
1
37-140 C. IR (KBr, cm ): 3406 (NH, OH), 3056-3025
(
1
CH aromatic), 2980-2931 (CH ), 2258, 2260, 2203 (2 CN),
634, 1491 (C C), 1507 (C N). H-NMR (300 MHz,
Canary yellow crystals from ethanol, yield (2.81 g, 87%),
2
1
ꢀ
−1
mp: 262-265 C. IR (KBr, cm ): 3500-3399 (NH, NH ),
2
DMSO-d ) δ: 4.04 (s, 2H, CH ), 7.39-7.42 (m, 1H, Ar H),
3100 (CH aromatic), 2929 (CH , CH ), 2200 (CN), 1562,
6
2
2
3

MOHAREB ET AL.
11
1
1
416 (C C), 1563 (C N). H-NMR (300 MHz, DMSO-d )
(CH aromatic), 2942-2859 (CH), 2189, 2220 (2 CN), 1622,
6
1
δ: 3.84 (s, 3H, CH ), 4.52 (s, 2H, CH ), 6.95 (d, J = 8.7 Hz,
1438 (C C), 1549 (C N). H-NMR (300 MHz, DMSO-d )
3
2
6
2
7
H, Ar H), 7.33 (s, 1H, pyridine C4), 7.47 (s, 2H, NH ),
.61 (d, J = 8.7 Hz, 2H, Ar H), 7.80 (s, 1H, NH). C-
δ: 4.45 (s, 1H, CH), 6.45 (m, J = 6.6 Hz, 1H, Ar H), 7.16
(s, 1H, pyran C4), 7.27 (d, J = 8.4 Hz, 2H, Ar H), 7.57 (d,
J = 8.4 Hz, 2H, Ar H), 7.69 (d, J = 6.6 Hz, 2H, Ar H),
2
13
NMR (75 MHz, DMSO-d ) δ: 27.0, 38.7, 55.5, 65.0, 114.1,
1
1
6
1
3
14.1, 115.9, 118.6, 125.3, 130.1, 130.1, 142.0, 147.7, 158.9,
61.1, 165.0. Elemental analysis, calculated for
7.78 (s, 2H, NH ), 7.92 (d, J = 6.6 Hz, 2H, Ar H),. C-
2
NMR (75 MHz, DMSO-d ) δ: 38.6, 57.0, 107.0, 115.3,
6
C H N OS (323.37): C, 59.43; H, 4.05; N, 21.66; S, 9.92.
Found: C, 59.10; H, 3.77; N, 21.44; S, 10.21.
118.9, 120.7, 120.7, 127.3, 128.7, 128.7, 129.9, 129.9, 131.8,
131.8, 132.6, 132.8, 135.0, 143.2, 148.1, 158.6, 168.6, 168.7.
16
13 5
+
+
MS (EI): m/z (%) 419 [M +2] (1.53), 418 [M +1] (1.20),
+
+
+
4
17 [M ] (1.71), 416 [M −1] (2.34), 415 [M −2] (1.91),
+
+
4
7
.1.23 | 2-(Cyanomethyl)-5-hydroxy-
-(4-methoxyphenyl)-4,7-dihydrothiazolo
76 [C H ] (9.22), 77 [C H ] (19.59), 84 (100.000). Ele-
6
4
6
5
mental
analysis,
calculated
for
C H N OSCl
22 13 4
[4,5-b]pyridine-6-carbonitrile (6f)
(416.88): C, 63.38; H, 3.14; N, 13.44; S, 7.69. Found: C,
3.01; H, 3.50; N, 13.74; S, 8.06.
6
Yellow crystals from ethanol, yield (2.11 g, 65%), mp:
ꢀ
−1
2
47-250 C. IR (KBr, cm ): 3379-3200 (NH, OH), 3065
(
1
CH aromatic), 2970-2840 (CH , CH ), 2260, 2206 (2 CN),
636, 1453 (C C), 1506 (C N). H-NMR (300 MHz, DMSO-
4.1.26 | 5-Amino-7-(4-chlorophenyl)-
2-(2-(4-chlorophenyl)-1-cyanovinyl)-7H-
pyrano[2,3-d]thiazole-6-carbonitrile (7b)
2
1
3
d ) δ: 3.82 (s, 3H, CH ), 4.52 (s, 2H, CH ), 7.15 (s, 1H, pyri-
6
3
2
dine C4), 6.85 (d, J = 6.9 Hz, 1H, Ar H), 7.13 (d, J = 6.9 Hz,
H, Ar H), 7.22 (d, 1H, Ar H), 7.60 (d, J = 6.9 Hz, 1H,
Ar H), 7.79 (s, 1H, NH), 8.59 (s, 1H, OH). C-NMR
1
Yellow crystals from ethanol, yield (3.29 g, 73%), mp:
13
ꢀ
−1
277-280 C. IR (KBr, cm ), 3424, 3380 (NH ), 3100
2
(
1
1
75 MHz, DMSO-d ) δ: 13.7, 38.7, 55.0, 58.9, 114.9, 114.9,
(CH aromatic), 2922 (CH), 2292, 2207 (2 CN), 1618, 1488
6
1
15.4, 116.3, 128.8, 131.6, 131.6, 143.0, 148.3, 158.2, 167.9,
(C C), 1560 (C N). H-NMR (300 MHz, DMSO-d ) δ:
6
+
+
68.7. MS (EI): m/z (%) 326 [M +2] (0.14), 325 [M +1]
4.67 (s, 1H, CH), 7.48 (s, 1H, pyran C4), 7.63-7.71 (m, 8H,
+
+
+
+
(0.45), 324 [M ] (0.11), 323 [M −1] (0.12), 322 [M −2]
2C H ), 7.86 (s, 2H, NH ). MS (EI): m/z (%) 453 [M +2]
6
4
2
+
+
+
+
(0.10), 76 [C H ] (0.70), 59 (100.00). Elemental analysis, cal-
(3.02), 452 [M +1] (9.49), 451 [M ] (6.77), 450 [M −1]
6
4
+
+
culated for C H N O S (324.36): C, 59.25; H, 3.73; N,
(13.86), 449 [M −2] (4.81), 76 [C H ]
(1.73),
16
12
4
2
6
4
17.27; S, 9.89. Found: C, 59.55; H, 4.11; N, 16.97; S, 10.23.
339 (100.00). Elemental analysis, calculated for
C H N OSCl (451.33): C, 58.55; H, 2.68; N, 12.41; S,
22
12
4
2
7.10. Found: C, 58.73; H, 3.01; N, 12.70; S, 7.40.
4
.1.24 | General procedure for the
synthesis of 5-Amino-7-(4-chlorophenyl)-
-(1-cyano-2-phenylvinyl)-7H-pyrano[2,3-d]
2
4.1.27 | Synthesis of 2-(5-hydroxy-6-oxo-
0
0
thiazole-6-carbonitrile derivatives (7a,b)
6,11b-dihydro-chromeno[4 ,3 :4,5]pyrano
2,3-d]thiazol-2-yl)acetonitrile (8)
[
To a solution of compound 5c (3.28 g, 0.01 mol) in abso-
lute ethanol (25 mL) in piperidine (0.5 mL), either benz-
aldehyde (1.06 g, 0.01 mol), or p-chlorobenzaldhyde
Compound (1) (1.40 g, 0.01 mol) in absolute ethanol
(25 mL) and ethyl cyanoacetate (1.13 g, 0.01 mol) was
added to salicyaldehyde (1.22 g, 0.01 mol) in triethylamine
(0.5 mL). By heating the reaction mixture under reflux for
2 hours, the solid products will be formed. Collect the
products by filtration after pouring it onto acidified
ice/water mixture and crystallized from absolute ethanol.
Pale brown crystals from ethanol, yield (3.09 g, 99%),
(1.40 g, 0.01 mol) was added. The reaction mixture, in
each case, was heated under reflux for 1 hour then
poured onto ice/water mixture containing a few drops of
hydrochloric acid. The formed solid products was filtered
off and crystallized from absolute ethanol.
ꢀ
−1
mp: 127-130 C. IR (KBr, cm ): 3410, 3316 (NH ), 2977
2
4
2
.1.25 | 5-Amino-7-(4-chlorophenyl)-
-(1-cyano-2-phenylvinyl)-7H-pyrano[2,3-d]
(CH ), 2204 (CN), 1672 (C O), 1607, 1452 (C C), 1521
2
1
(C N). H-NMR (300 MHz, DMSO-d ) δ: 4.20 (s, 2H,
6
thiazole-6-carbonitrile (7a)
CH ), 7.01 (s, 1H, pyran C4), 7.26-7.40 (m, 4H, C H ), 7.73
2
6 4
+
+
(
s, 2H, NH ). MS (EI): m/z (%) 312 [M +1] (0.95), 311 [M ]
(1.48), 310 [M −1] (1.88), 76 [C H ] (5.95), 128 (100.00).
2
+
+
Orange crystals from ethanol, yield (3.29 g, 79%), mp:
6
4
ꢀ
−1
1
47-150 C. IR (KBr, cm ): 3438, 3300 (NH ), 3100
Elemental analysis, calculated for C H N O S (311.32): C,
15 9 3 3
2

12
MOHAREB ET AL.
5
2
7.87; H, 2.91; N, 13.50; S, 10.30. Found: C, 57.59; H,
.95; N, 13.88; S, 10.15.
4.84 (s, 2H, CH ), 6.42-6.49; 6.78-6.85; 7.18-7.19 (m, 3H,
2
furan C), 7.42 (s, 1H, pyran C4), 8.16 (s, 2H, NH ). MS
2
+
(
EI): m/z (%) 285 [M +1] (0.30), 59 (100.00). Elemental
analysis, Calculated for C H N O S (284.29): C,
13
8 4 2
4
6
.1.28 | Synthesis of 2-(5-hydroxy-6-oxo-
,11b-dihydro-4H-chromeno[4,3-d]thiazolo
54.92; H, 2.84; N, 19.71; S, 11.28. Found: C, 54.59; H,
2.89; N, 19.39; S, 11.58.
[4,5-b]pyridin-2-yl)acetonitrile (9)
To a solution of compound 1 (1.40 g, 0.01 mol) in abso-
lute ethanol (30 mL) containing ammonium acetate
4.1.31 | 2-(Cyanomethyl)-7-(furan-2-yl)-
5-hydroxy-7H-pyrano[2,3-d]thiazole-
6-carbonitrile (10b)
(0.50 g), each of ethyl cyanoacetate (1.13 g, 0.01 mol) and
salicyaldehyde (1.22 g, 0.01 mol) were added. The reac-
tion mixture was heated under reflux for 30 minutes and
then poured onto ice/water mixture. The formed solid
product was collected by filtration and dried, then crys-
tallized from absolute ethanol.
Brown crystals from ethanol, yield (1.62 g, 57%), mp:
227-230 C. IR (KBr, cm ): 3407 (OH), 3125-3064
ꢀ
−1
(CH aromatic), 2979-2928 (CH ), 2260, 2207 (2 CN), 1636,
2
1
1446 (C C), 1503 (C N). H-NMR (300 MHz, DMSO-d )
6
Orange crystals from ethanol, yield (3.07 g, 99%), mp:
δ: 4.80 (s, 2H, CH ), 6.21-6.39; 6.74-6.79; 7.04-7.19 (m, 3H,
furan C), 7.48 (s, 1H pyran C4), 8.59 (s, 1H, OH). C-
2
ꢀ
−1
13
2
22-225 C. IR (KBr, cm ): 3423, 3300 (NH , NH), 2973
2
(
(
CH ), 2205 (CN), 1642 (C O), 1605, 1451 (C C), 1540
NMR (75 MHz, DMSO-d ) δ: 13.9, 34.1, 59.1, 106.1, 110.6,
116.1, 117.4, 142.1, 146.9, 148.9, 155.2, 167.8, 168.5. MS
2
6
1
C N). H-NMR (300 MHz, DMSO-d ) δ: 4.01 (s, 2H,
6
+
+
CH ), 6.67 (s, 1H, pyridine C4), 7.10-7.30 (m, 4H, C H ),
(EI): m/z (%) 287 [M +2] (0.19), 286 [M +1] (0.62),
2
6
4
+
+
+
7
3
7
.50 (s, 2H, NH ), 7.92 (s, 1H, NH). MS (EI): m/z (%)
285 [M ] (0.94), 284 [M −1] (1.97), 283 [M −2] (9.92),
255 (100.00). Elemental analysis, calculated for
C H N O S (285.28): C, 54.73; H, 2.47; N, 14.73; S, 11.24.
2
+
+
11 [M +1] (0.87), 310 [M ] (1.50), 67 (100.00),
6 [C H ] (14.85). Elemental analysis, calculated for
+
6
4
13
7 3 3
C H N O S (310.33): C, 58.05; H, 3.25; N, 18.05; S,
Found: C, 54.59; H, 2.77; N, 15.05; S, 11.54.
15
10 4 2
1
0.33. Found: C, 57.73; H, 3.50; N, 18.22; S, 10.16.
4
.1.32 | General procedure for the
4
.1.29 | General procedure for the
synthesis of 2-(cyanomethyl)-7-(furan-2-yl)-
H-pyrano[2,3-d]thiazole-6-carbonitrile
synthesis of 2-(cyanomethyl)-7-(furan-2-yl)-
4,7-dihydrothiazolo[4,5-b]pyridine-
6-carbonitrile derivatives (11a,b)
7
derivatives (10a,b)
To a solution of compound 1 (1.40 g, 0.01 mol) in abso-
lute ethanol (20 mL) containing ammonium acetate
(0.50 g), each of malononitrile (0.66 g, 0.01 mol) or ethyl
cyanoacetate (1.13 g, 0.01 mol) and furfural (0.96 g,
0.01 mol) were added. The reaction mixture was heated
under reflex for 1 hour then poured onto ice/water mix-
ture. The obtained solid products, in each case, were col-
lected by filtration and crystallized from absolute ethanol.
To a solution of compound 1 (1.40 g, 0.01 mol) in absolute
ethanol (25 mL) containing triethylamine (0.50 mL), each
of either malononitrile (0.66 g, 0.01 mol) or ethyl
cyanoacetate (1.13 g, 0.01 mol) and furfural (0.96 g,
0
.01 mol) were added. The reaction mixture was heated
under reflux for 20 minutes in case of malononitrile and
hours in case of ethyl cyanoacetate, then poured onto
3
acidified ice/water mixture, and then collected the formed
products after filtration and crystallized from absolute
ethanol.
4.1.33 | 5-Amino-2-(cyanomethyl)-
7
-(furan-2-yl)-4,7-dihydrothiazolo[4,5-b]
pyridine-6-carbonitrile (11a)
4
7
6
.1.30 | 5-Amino-2-(cyanomethyl)-
-(furan-2-yl)-7H-pyrano[2,3-d]thiazole-
-carbonitrile (10a)
Dark red crystals from ethanol, yield (1.70 g, 60%), mp:
ꢀ
−1
197-200 C. IR (KBr, cm ): 3403-3219 (NH, NH ), 3041
2
(
CH aromatic), 2973-2922 (CH ), 2260, 2204 (2 CN),
2
1
Brown crystals from ethanol, yield (1.70 g, 60%), mp:
1652, 1463 (C C), 1540 (C N). H-NMR (300 MHz,
ꢀ
−1
2
45-248 C. IR (KBr, cm ): 3388, 3326 (NH ), 3121-3023
DMSO-d ) δ: 4.84 (s, 2H, CH ), 6.41-6.48; 6.78-6.84;
2
6
2
(
(
CH aromatic), 2975 (CH ), 2220, 2195 (2 CN), 1652, 1465
7.18-7.19 (m, 3H, furan C), 7.41 (s, 1H pyridine C4), 7.58
2
1
13
C C), 1539 (C N). H-NMR (300 MHz, DMSO-d ) δ:
(s, 2H, NH ), 8.16 (s, 1H, NH). C-NMR (75 MHz,
6
2

MOHAREB ET AL.
13
DMSO-d ) δ: 31.7, 38.6, 60.8, 107.9, 110.6, 115.5, 116.2,
provided by the National Cancer Institute (NCI, Cairo,
Egypt). They grow as monolayer and routinely
maintained in RPMI-1640 medium supplemented with
5% heat inactivated FBS, 2-mM glutamine and antibiotics
6
1
2
2
43.4, 143.6, 148.3, 152.6, 168.4, 168.7. MS (EI): m/z (%)
+
+
+
85 [M +2] (0.88), 284 [M +1] (1.32), 283 [M ] (5.45),
+
+
82 [M −1] (4.53), 281 [M −2] (2.21), 124 (100.00). Ele-
ꢀ
mental analysis, calculated for C H N OS (283.31): C,
(penicillin 100 U/mL, streptomycin 100 μg/mL), at 37 C
13
9 5
5
3
5.11; H, 3.20; N, 24.72; S, 11.32. Found: C, 54.81; H,
.52; N, 24.37; S, 10.99.
in a humidified atmosphere containing 5% CO . Expo-
2
nentially growing cells were obtained by plating
5
1
0
.5 × 10 cells/mL for MCF-7 and SF-268 and
4
.75 × 10 cells/mL for NCI-H460, followed by 24 hours
4
5
.1.34 | 2-(Cyanomethyl)-7-(furan-2-yl)-
-hydroxy-4,7-dihydrothiazolo[4,5-b]
of incubation. The effect of the vehicle solvent (DMSO)
on the growth of these cell lines was evaluated in all the
experiments by exposing untreated control cells to the
maximum concentration (0.5%) of DMSO used in each
assay.
pyridine-6-carbonitrile (11b)
Orange crystals from ethanol, yield (1.82 g, 64%), mp:
ꢀ
−1
2
07-210 C. IR (KBr, cm ): 3409-3200 (OH, NH), 3100
(
CH aromatic), 2978, 2928 (CH ), 2206, 2195 (2CN), 1608,
CONFLICT OF INTEREST
The authors confirm that there is no conflict of interest.
2
1
1
2
7
455 (C C). H-NMR (300 MHz, DMSO-d ) δ: 4.82 (s,
6
H, CH ), 6.41-6.47; 6.76-6.83; 7.15-7.16 (m, 3H, furan C),
2
.53 (s, 1H pyridine C4), 8.13 (s, 1H, NH), 8.30 (s, 1H,
ORCID
OH). Elemental analysis, calculated for C H N O S
Rafat M. Mohareb https://orcid.org/0000-0003-3922-
803X
13
8 4 2
(284.29): C, 54.92; H, 2.84; N, 19.71; S, 11.28. Found: C,
5
4.60; H, 3.10; N, 20.01; S, 11.50.
Amira E. M. Abdallah https://orcid.org/0000-0002-
6773-3634
5
| ANTITUMOR ACTIVITY
REFERENCES
EVALUATION
[1] S. Abu-Melha, M.M. Edrees, H.H. Salem, N.A. Kheder, S.
M. Gomha, M.R. Abdelaziz, Molecules, 2019, 24, 539.
[
[
[
2] H. Z. Shams, R. M. Mohareb, M. H. E. Helal,
5
.1 | Materials and methods
A. E. M. Abdallah, Phosphorous Sulfur Silicon Relat Elem.
2007, 182, 237.
Fetal bovine serum (FBS) and L-glutamine were obtained
from Gibco Invitrogen Company (Scotland, UK). RPMI-
3] X. Guo, B. Zhao, Z. Fan, D. Yang, N. Zhang, Q. Wu, B. Yu,
S. Zhou, T. A. Kalinina, N. P. Belskaya, J. Agric. Food Chem.
1
640 medium was provided from Cambrex (New Jersey,
2019, 67, 1647.
USA). DMSO, doxorubicin, penicillin, streptomycin, and
sulforhodamine B (SRB) were obtained from Sigma
Chemical Company. (Saint Louis, MO, USA).
4] H. Z. Shams, R. M. Mohareb, M. H. E. Helal,
A. E. M. Abdallah, Molecules 2011, 16, 6271.
[5] S. M. Sondhi, S. Singh, J. Kumar, H. Jamal, P. P. Gupta, Eur.
J. Med. Chem. 2009, 44, 1010.
[6] H. Z. Shams, R. M. Mohareb, M. H. E. Helal,
A. E. M. Abdallah, Molecules 2011, 16, 52.
5
.2 | Samples
[
[
7] A. K. Chaturvedi, S. S. Pamar, Znd. J. Pharm. 1972, 34, 72.
8] K. Z. Łączkowski, K. Sałat, K. Misiura, A. Podkowa,
N. Malikowska, J. Enzyme, Inhib. Med. Chem. 2016, 31, 1576.
Stock solutions of compounds 2a-c to 11a,b were pre-
pared in DMSO and kept at −20 C. Just before the assays,
ꢀ
[9] A. S. Sokolova, O. I. Yarovaya, N. I. Bormotov,
suitable dilutions of the tested compounds were freshly
prepared. The concentrations of DMSO did not overlap
with the cell growth.
L. N. Shishkina, N. F. Salakhutdinov, Med. Chem. Comm.
2018, 10, 1746.
[
[
[
10] K. M. Dawood, T. M. Eldebss, H. S. El-Zahabi, M. H. Yousef,
Eur. J. Med. Chem. 2015, 102, 266.
11] M. A. Al-Omair, A. R. Sayed, M. M. Youssef, Molecules 2018,
23, 1133.
5.3 | Cell cultures
12] M. Djukic, M. Fesatidou, I. Xenikakis, A. Geronikaki,
V. T. Angelova, V. Savic, M. Pasic, B. Krilovic, D. Djukic,
B. Gobeljic, M. Pavlica, A. Djuric, I. Stanojevic, D. Vojvodic,
L. Saso, Chem Biol Interact. 2018, 286, 119.
Three human tumor cell lines, MCF-7 (breast adenocar-
cinoma), NCI-H460 (non-small cell lung cancer), and SF-
[
13] D. S. Kim, Y. M. Jeong, I. K. Park, H. G. Hahn, H. K. Lee,
S. B. Kwon, J. H. Jeong, S. J. Yang, U. D. Sohn, K. C. A. Park,
Biol Pharm Bull. 2007, 30, 180.
2
68 (CNS cancer), were used. MCF-7 was obtained from
the European Collection of Cell Cultures (ECACC,
Salisbury, UK), and NCI-H460 and SF-268 were kindly

14
MOHAREB ET AL.
[
14] X. X. Zhu, Q. S. Yu, R. G. Gulter, C. W. Culmess,
H. W. Holloway, D. K. Lahiri, M. P. Mattson, N. H. Greig,
J. Med. Chem. 2002, 45, 5090.
[28] R. M. Mohareb, Y. M. Elkholy, N. I. Abdel-Sayed,
H. Z. Shams, J. Chin. Chem. Soc. 1992, 39, 181.
[29] A. E. M. Abdallah, G. H. Elgemeie, Drug. Des. Devel. Ther.
2018, 12, 1785.
[30] A.E.M. Abdallah, R.M. Mohareb, E.M. Khalil, M.A. Elshamy,
M.A. Chem. Pharm. Bull., 2017, 65, 469.
[31] A. E. M. Abdallah, M. H. E. Helal, N. I. I. Elakabawy, Egypt.
J. Chem. 2015, 58, 699.
[32] H. Z. Shams, Y. M. Elkholy, N. S. Ibrahim, M. H. Elnagdi,
J. Prakt. Chem. 1988, 330, 817.
[33] H. Z. Shams, M. H. Helal, F. A. Mohamed, S. A. A. Abd-
Elhafiz, Pigm. Resin Technol. 2001, 30, 158.
[34] M. H. Elnagdi, M. R. H. Elmoghayar, A. E.-F. G. Hammam,
S. A. Khallaf, J. Heterocycl. Chem. 1979, 16, 1541.
[35] K. Gewald, R. Schindler, J. Prakt. Chem. 1990, 332, 223.
[36] L. Li, F.-H. Yu, Biochem. Mol. Biol. Int 1993, 31, 879.
[
[
[
15] R. M. Mohareb, A. E. M. Abdallah, M. A. Abdelaziz, Med.
Chem. Res. 2014, 23, 564.
16] R. M. Mohareb, A. E. M. Abdallah, E. A. Ahmed, Acta Pharm.
2
017, 67, 495.
17] R. M. Mohareb, A. E. M. Abdallah, A. A. Mohamed, Chem.
Pharm. Bull. 2018, 66, 309.
[
[
18] H. Yu, L. Shao, J. Fang, J. Organomet. Chem. 2007, 692, 991.
19] R. Lin, S. G. Johnson, P. J. Connolly, S. K. Wetter, E. Binnun,
T. V. Hughes, W. V. Murray, N. B. Pandey, S. J. Moreno-
Mazza, M. Adams, A. R. Fuentes-Pesquera, S. A. Middleton,
Bioorg. Med. Chem. Lett. 2009, 19, 2333.
[
20] S. S. Kulkarni, A. H. Newman, Bioorg. Med. Chem. Lett. 2007,
1
7, 2987.
[
[
21] M. V. N. De Souza, J. Sulfur, Chem. 2005, 26, 429.
22] S. Hussain, S. De, P. K. Iyer, ACS Appl. Mater. Interfaces 2013,
5, 2234.
[
[
23] B. L. Feringa, Acc. Chem. Res. 2001, 34, 504.
How to cite this article: Mohareb RM,
24] G. Li, Y. He, W. Zhou, P. Wang, Y. Zhang, W. Tong, H. Wu,
M. Liu, X. Ye, Y. Chen, Heterocycles 2014, 89, 453.
25] R. M. Mohareb, H. Z. Shams, Y. M. Elkholy, Phosphorus Sulfur
Silicon Relet Elem. 1992, 70, 317.
Khalil EM, Mayhoub AE, Abdallah AEM. Novel
synthesis of pyran, thiophene, and pyridine
derivatives incorporating thiazole ring and their
antitumor evaluation. J Heterocycl Chem. 2019;
[
[
[
26] R. M. Mohareb, H. Z. Shams, S. I. Aziz, Sulfur Lett. 1991, 13, 101.
27] R. M. Mohareb, H. Z. Shams, Y. M. Elkholy, Phosphorus, Sul-
fur and silicon 1992, 72, 93.
1–14. https://doi.org/10.1002/jhet.3870