Synthesis and cytotoxicity of fused thiophene and pyrazole derivatives derived from 2-N-acetyl-3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophene

Article abstract of DOI:10.1007/s00044-014-1273-9

Abstract The reaction of 2-amino-3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophene with chloroacetyl chloride gave the 2-chloroacetamido derivative 3. The latter reacted with hydrazine hydrate to give the hydrazine derivative 5 which was used to form the hydraz

Full text of DOI:10.1007/s00044-014-1273-9

MEDICINAL
CHEMISTRY
RESEARCH
Med Chem Res
DOI 10.1007/s00044-014-1273-9
ORIGINAL RESEARCH
Synthesis and cytotoxicity of fused thiophene and pyrazole
derivatives derived from 2-N-acetyl-3-cyano-4,5,6,7-
tetrahydrobenzo[b]thiophene
Rafat M. Mohareb
Faten I. Hamed
•
Wagnat W. Wardakhan
•
Received: 16 July 2014 / Accepted: 26 September 2014
Ó Springer Science+Business Media New York 2014
Abstract The reaction of 2-amino-3-cyano-4,5,6,7-tetra-
hydrobenzo[b]thiophene with chloroacetyl chloride gave
the 2-chloroacetamido derivative 3. The latter reacted with
hydrazine hydrate to give the hydrazine derivative 5 which
was used to form the hydrazone derivatives 7a, b and 9a, b
via its reaction with some carbonyl compounds. Moreover,
it produced the pyrazole derivatives 11a, b through its
reaction with either acetylacetone or ethyl acetoacetate. On
the other hand, compounds 5 and 3 were used to form some
thiazole, pyridine, and fused derivatives. The cytotoxicity
of the newly obtained products was evaluated against some
of the human cancer and normal cell lines where the results
showed that compounds 3, 11b, 13, 18c, 18d, 21, 23, and
women (Walker et al., 2014; Ament et al., 2014). In the US
and other western countries, alcohol-related cirrhosis, and
possibly nonalcoholic fatty liver disease associated with
obesity, is account for the majority of liver cancer cases.
Chronic infections with hepatitis B virus (HBV) and hep-
atitis C virus (HCV) are associated with less than half of
liver cancer cases in the US, although they are the major
risk factors for the disease worldwide (Upreti et al., 2014).
Although chemotherapy is the mainstay of cancer therapy,
the use of available chemotherapeutics is often limited
mainly due to undesirable side effects and a limited choice
of available anticancer drugs (Goutham Vemana et al.
2014). 2-Aminothiophenes exhibit several pharmacological
activities and have therefore attracted considerable atten-
tion from medicinal and synthetic organic chemists (Be-
hbehani et al., 2012; Du et al., 2013; Padmavathi et al.,
2011; Wang et al., 2013; Titchenell et al., 2013; Aurelio
et al., 2011; Perspicace et al., 2013; Duval et al., 2005).
They have been described to present anti-inflammatory
24 exhibited optimal cytotoxic effect against cancer cell
lines, with IC ’s in the nM range.
5
0
Keywords Benzo[b]thiophene ꢀ Pyridine ꢀ Pyrazole ꢀ
Thiazole ꢀ Cytotoxicity
(Madhusudana et al., 2012), insecticidal (Campaigne,
Introduction
1984), antibacterial (Dewal et al., 2012), antifungal (Ste-
phens et al., 2001), antiviral (Goncales et al., 2005), and
antinociceptive activities (Crouse et al., 2004). Recently
some other compounds derived from benzo[b]thiophene
series showed as potent tubulin polymerization inhibitors
(Romagnoli et al., 2010). Some similar compounds from
benzothiophene series namely 3-(aryl)benzothieno[2,3-
c]pyran-1-ones (tricyclic lactones) were prepared by a
tandem one-pot Sonogashira coupling and intramolecular
cyclization. Furthermore, the tetrahydrobenzo[b]thiophene
nucleus was adopted as a scaffold for many antimicrobial
Cancer is a major health problem worldwide. The relative
mortality rate caused by cancer is still very high in the
developed countries, accounting for more than 20 % of all
deaths. Among the various types of malignant tumors,
breast cancer is the second leading cause of death in
R. M. Mohareb (&)
Department of Chemistry, Faculty of Science, Cairo University,
Giza, A.R., Egypt
e-mail: raafat_mohareb@yahoo.com
(Refat and Fadda, 2013), antiviral (Dewal et al., 2012),
antiarrhythmic, (Amr et al., 2010), and antitumor (Abbas
et al., 2013) activities. A structure activity relationship was
established for the heterocyclic compounds derived from
W. W. Wardakhan ꢀ F. I. Hamed
National Organization for Drug Control and Research,
P.O. 29, Cairo, A.R., Egypt
123

Med Chem Res
benzo[b]thiophene series with antitumor properties were
prepared (Ferreirra et al., 2009), as well as a series of N-(2-
with either acetylacetone (10a) or ethyl acetoacetate (10b)
afforded the pyrazole derivatives 11a and 11b, respectively.
Compound 5 reacted with ethyl cyanoacetate (12) in 1,4-
dioxane to give the tetrahydrobenzo[4,5]thieno[2,3-b]thie-
no[2,3-b]pyridine derivative 13. Compound 5 reacted with
malononitrile (14) to afford the 2,5-diaminopyrazole deriv-
ative 15.
(
5-fluoro-2-(4-fluorophenylthio)benzo[b]thiophen-3-yl)e-
thyl) acylamides, which were evaluated for their binding
affinity and intrinsic activity at melatonin receptors
M e´ sangeau et al., 2011). Also, benzothiophenes offer
(
interest to pharma industry as scaffolds for synthesis of
raloxifene and relevant structural analogs of selective
estrogen receptor modulators (SERM) (Dadiboyena, 2012).
As a part of our continuing search for potential anticancer
agents related to heterocyclic thiophenes, we have previ-
ously reported synthesis and strong inhibitory activities on
several human tumor cell lines of thiophene derivatives
In our strategy, we moved through studying the reac-
tivity of compound 3 as an a-halocarbonyl compound to
react with potassium sulfide salts of some active methylene
compounds via the well-known Hantzsch reaction (Fadda
et al., 2009). Thus, the reaction of the active methylene
reagents namely malononitrile (14), ethyl cyanoacetate
(12), acetylacetone (10a), or ethyl acetoacetate (10b) with
phenylisothiocyanate (16) in dimethylformamide contain-
ing potassium hydroxide gave the intermediate potassium
sulfide salts 17a-d. The reaction of the latter intermediates
with compound 3 at room temperature gave the thiazole
derivatives 18a-d, respectively. Analytical and spectral
data of the latter products were consistent with their
respective structures (see experimental section). Com-
pound 3 reacted with aniline to give the a-anilino deriva-
tive 20 which underwent ready cyclization in sodium
hydroxide to give the 4-amino-3-chloro-5,6,7,8-tetra-
hydrobenzo[4,5]thieno[2,3-b]pyridine-2-ol (21). The latter
compound reacted with aniline to give the 3-anilino
derivative 22 its structure was based on the analytical and
spectral data (see experimental section). Further confir-
mation for the structure of compound 22 was obtained
through its synthesis via another reaction root. Thus, the
cyclization of compound 21 in sodium ethoxide solution
gave the same product 20 (m.p., mixed m.p., and finger
print IR). Compound 22 reacted with phenylisothiocyanate
(16) in 1,4-dioxane solution to give the thiourea derivative
23, and the latter underwent ready cyclization when being
heated in sodium ethoxide solution to give the annulated
derivative 24. The analytical and spectral data of 24 are in
agreement with its structure.
(
Mohareb and Al-Omran, 2012; Mohareb et al., 2013).
Results and discussion
The present investigation emphasized mainly on two
important things: of these one is to the synthesis of hetero-
cyclic compounds bearing the tetrahydrobenzo[b]thiophene
moiety and the other is to determine their cytotoxicity against
cancer and normal cell lines. Throughout our program, some
of our synthesized products were good candidates as target
anticancer agents. The synthetic strategies adopted for the
synthesis of the intermediates and target compounds are
depicted in Schemes 1, 2 and 3. In the present work, we
studied the uses of the tetrahydrobenzo[b]thiophene deriv-
ative 1 in heterocyclic chemistry through the one-pot reac-
tion to form novel heterocyclic rings derived from the
2
-amino-3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophene (1)
as potentially anticancer agents. The obtained products were
important in a different strategy, being used to obtain new
heterocyclic derivatives of the tetrahydrobenzo[b]thiophene
together with the comparison of their cytotoxic activities
toward human cancer normal cell lines. Thus, the reaction of
the 4,5,6,7-tetrahydrobenzo[b]thiophene (1) with chloro-
acetyl chloride (2) gave the 2-chloro-N-(3-cyano-4,5,6,7-
tetrahydrobenzo[b]thiophen-2-yl)acetamide (3). The struc-
ture of compound 3 was based on the analytical and spectral
data (see experimental section). Compound 3 was a good
candidate for many heterocyclic transformations. Thus, the
reaction of 3 with hydrazine hydrate gave the hydrazino
derivative 5. The high yield of compound 5 encouraged us to
study its reactivity toward some chemical reagents. Thus,
compound 5 reacted with either cyclopentanone (6a) or
cyclohexanone (6b) to give the hydrazone derivatives 7a and
Biological evaluation
In vitro cytotoxic assay
Chemicals
Fetal bovine serum (FBS) and L-glutamine were purchased
from Gibco Invitrogen Co. (Scotland, UK). RPMI-1640
medium was purchased from Cambrex (New Jersey, USA).
Dimethyl sulfoxide (DMSO), doxorubicin, penicillin,
streptomycin, and sulforhodamine B (SRB) were pur-
chased from Sigma Chemical Co. (Saint Louis, USA).
7
b, respectively. The analytical and spectral data were the
tools of their structural elucidations. Similarly, the reaction
of compound 5 with either benzaldehyde (8a) or acetophe-
none (8b) gave the hydrazone derivatives 9a and 9b,
respectively. On the other hand, the reaction of compound 5
1
23

Med Chem Res
CN
CN
NH COCH2Cl
H C
2
COCl
+
NH2
Cl
S
S
3
2
1
CN
NH COCH2NHNH2
3
+
NH NH H O
2 2. 2
S
4
5
CN
O
5
+
NH COCH2NHN
S
n
n
7
a, n = 1
6
a, n = 1
b, n = 2
b, n = 2
CN
X
O
NH COCH2NHN
5
+
Ph
Ph
X
S
9
a, X = H
8
a, X = H
b, X = CH3
b, X = CH3
CN
N
CH3
O
O
NH COCH2
N
5
+
H C
3
R
S
1
0a, R = CH3
X
b, R = OC H5
2
1
1a, X = CH3
b, X = OH
Scheme 1 Synthesis of compounds 3–11a,b
Cell cultures
cancer (MCF), nasopharyngeal carcinoma (HONE1), and
normal fibroblast cells (WI38) were kindly 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 lM gluta-
mine and antibiotics (penicillin 100 U/mL, streptomycin
The cell cultures was obtained from the European Collection
of cell Cultures (ECACC, Salisbury, UK) and human gastric
cancer (NUGC and HR), human colon cancer (DLD1),
human liver cancer (HA22T and HEPG2), human breast
123

Med Chem Res
NHNHCOCH CN
2
H N
2
CN
OH
1,4-dioxane
COOC H5
2
+
H C
2
N
CN
Et N
3
NH
COCH NHNH
S
2
2
S
12
13
5
CN
N
NH2
H C
CN
CN
2
5
+
NHCOCH2
N
S
14
H N
2
15
R
R'
DMF/KOH
H C
2
R
+
PhNCS
SK
PhHN
R'
16
17a-d
1
4, R = R' = CN
2, R = CN, R' = COOEt
1
9
a, R = R' = COCH3
b, R = COCH , R' = COOEt
9
3
R
R'
CN
CN
PhN
HN
S
1
7a-d
NH
+
COCH Cl
2
S
S
3
1
8a, R = R' = CN
b, R = CN, R' = COOEt
c, R = R' = COCH3
d, R = COCH , R' = COOEt
3
Scheme 2 Synthesis of compounds 13–15 and 18a–d
1
00 lg/mL), at 37 °C in a humidified atmosphere containing
maximum concentration (0.5 %) of DMSO used in each
assay.
5
% CO . Exponentially growing cells were obtained by
2
5
plating 1.5 9 10 cells/mL for the six human cancer cell
The heterocyclic compounds, prepared in this study,
were evaluated according to standard protocols for their
in vitro cytotoxicity (Leopoldo et al., 2013; Pranati Sa-
madder et al., 2014; Vizzotto et al., 2014) against six
human cancer cell lines including cells derived from
4
lines including cells derived from 0.75 9 10 cells/mL fol-
lowed by 24 h 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
1
23

Med Chem Res
CN
CN
+
NH COCH Cl
2
NHCOCH NH
2
S
H N
2
S
20
19
3
Cl
H N
2
OH
NaOEt
3
N
S
21
17
NHPh
H N
2
NaOEt
2
0
OH
N
S
22
S
Cl
Ph
NH C NH
OH
22
+
PhNCS
21
N
S
23
S
Ph
N
HN
OH
N
S
24
Scheme 3 Synthesis of compounds 20–24
123

Med Chem Res
human gastric cancer (NUGC), human colon cancer
DLD1), human liver cancer (HA22T and HEPG2), human
Table 1 Cytotoxicity the newly synthesized compounds against a
variety of cancer cell lines [IC50 (nM)]
(
breast cancer (MCF), nasopharyngeal carcinoma (HONE1),
and a normal fibroblast cells (WI38).
Compd. Cytotoxocity (IC50 in nM)
no.
NUGC DLDI HA22T HEPG2 HONE1 MCF WI38
Each cell line was incubated with four concentrations
(
6–62 lg/ml or the equivalent nM/mL) for each compound
and was used to create compound concentration versus
3
5
7
7
9
9
1
1
1
1
1
1
1
1
2
2
2
2
2
112
24
241
128
220
36
na
2253
2208
2114
2166
1629
2213
120
2690 2166
2128 2153
1640 2173
4840 1320
1294 2469
2146 2120
3309
1236
2859
3266
1244
2110
37
2213
1138
3266
4385
3027
3290
44
2318 na
2240 na
2285 na
1428 na
2236 na
1368 na
219 na
103 na
254 na
1328 na
1252 na
348 na
280 na
2270 na
survival fraction curves. The response parameter (IC )
5
0
a
was calculated for each cell line (Table 1). The IC50 value
corresponds to the compound’s concentration causing a net
b
a
5
0 % loss of initial cells at the end of the incubation period
b
(
48 h). The antitumor drug discovery screen has been
1a
1b
3
designed to distinguish between broad-spectrum antitumor
compounds and tumor selective agents. In the present
study, the active compound showed a distinctive potential
pattern of selectivity as well as broad-spectrum antitumor
activity.
140
35
203
98
38
308
210
5
1220
1535
2270
323
240
820
630
408
8a
8b
8c
8d
0
2480 1216
3129 1155
1683
2424
523
3076
1242
201
Some heterocyclic compounds were observed with sig-
nificantcytotoxicityagainst mostofthe cancercelllinestested
608
126
282
328
1483
263
531
(
IC50 = 10–1,000 nM). Normal fibroblastscells(WI38)were
1254
37
3760 2175
88 320
2125 3280
2208
122
4236
280
affected to a much lesser extent (IC [ 10,000 nM). The
reference compound used is the CHS-828 which is the pyridyl
cyanoguanidine antitumor agent.
5
0
1
37
na
2
2379
28
2312
235
1288
273
3260 na
528 na
2170 na
3
42
69
4
80
166
228
262
120
CHS 828 25
2315 2067
1245
15
18
na
Structure activity relationship
The sample concentration produces a 50 % reduction in cell growth
From Table 1, it is clear that the 4,5,6,7-tetrahydro[b]thio-
phene moiety was found to be crucial for the cytotoxic effect
of cyclic compounds 3–24. Compounds 3, 11b, 13, 18c, 18d,
NUGC gastric cancer, DLDI colon cancer, HA22T liver cancer,
HEPG2 liver cancer, HONEI nasopharyngeal carcinoma, HR gastric
cancer, MCF breast cancer, WI38 normal fibroblast cells
21, 23, and 24 exhibited optimal cytotoxic effect against
cancer cell lines, with IC ’s in the nM range. Comparing the
5
0
cytotoxicity of compounds 3 and 4, it is obvious that the
cytotoxicity of 3 is the higher than that of 4. Thus, substi-
tuting the chloroacetyl group by the hydrazinoacetyl group
decreased the cytotoxicity. However, the hydrazone deriv-
atives 7a and 7b are more potent than 5, and it is remarkable
that compound 7a showed high cytotoxicity against HA22T,
HEPG2, HONE1, and MCF cell lines with IC50 values 153,
amide derivative 20 showed low cytotoxicity against the six
cancer cell lines. The cyclized form of compound 3 produced
the
4-amino-3-chloro-5,6,7,8-tetrahydrobenzo[4,5]-thie-
no[2,3-b]pyridine-2-ol (21) showed high cytotoxicity
against the six cancer cell lines. The high cytotoxicity of
compound 21 is attributed to the presence of the theino[2,3-
b]pyridine moiety together with the electronegative chloro
group. However, cyclization of compound 20 produced
compound 22 with very low cytotoxicity. The phenylthio-
urea derivative 23 showed high cytotoxicity against the six
cancer cell lines but its cyclized form the benzo[4,5]thie-
no[2,3-b]imidazo[4,5-d]pyridine derivative 24 showed high
cytotoxicity against the five cell lines NUGC, DLDI,
HA22T, HEPG2, and HONE1, but it showed less potency
against MCF cell line.
2
63, 138, and 240 nM, respectively. Considering the pyra-
zole derivatives 11a and 11b, it is clear that compound 11b
bearing the OH group showed much cytotoxicity over 11a. It
0
is of great value to notice that the N -(4-Amino-2-hydroxy-
5
,6,7,8-tetrahydrobenzo[4,5]-thieno[2,3-b]pyridine-3-yl)-
-cyanoacetohydrazide (13) showed high cytotoxicity that is
2
attributed to the presence of the thieno[2,3-b]pyridine moi-
ety. Considering the thiazole derivatives 18a–d, it is clear
that compounds 18c and 18d are the most active compounds
among the four thiazoles 18a–d, and it is clear that the pre-
sence of the C=O moiety is responsible of the increase of the
cytotoxicity of 18c and 18d. On the other hand, compound
It is very clear from our present finding that the newly
synthesized products with halogen substituted pattern
OCH , Cl, or COOEt show greater cytotoxic property thus,
3
compounds 3, 11b, 13, 18c, 18d, 21, 23, and 24 showed
the optimal cytotoxicity.
1
8d showed less potency against the HA22T cell line. The
1
23

Med Chem Res
Table 2 Toxicity of the most potency compounds against shrimp larvae
a
Compound no.
Cons. (lg/ml)
Mortality
Toxicity
Harmful
LC50
Upper 95 % lim.
250.26
Lower 95 % lim.
120.28
3
10
4
320.13
1
1
00
5
,000
10
3
1
1
1
1
2
2
2
a
1b
3
10
Harmful
Harmful
Harmful
Harmful
Non-toxic
Non-toxic
Very toxic
18.26
660.15
77.22
253.17
124.3
–
168.33
120.14
84.40
158.32
–
1
1
00
,000
6
8
10
1
266.29
118.36
120.00
886.27
950.11
12.00
1
1
00
,000
6
10
2
8c
8d
1
10
1
1
00
,000
9
10
0
10
1
1
00
,000
8
10
0
10
1
1
00
,000
1
10
0
3
10
–
–
1
1
00
,000
0
5
4
10
6
–
–
1
1
00
,000
9
10
Ten organisms (A. salina) tested for each concentration
Toxicity
toxicity test, was slightly better than the rat test for test
compounds (Calleja and Persoone, 1992).
Bioactive compounds are often toxic to shrimp larvae.
Thus, in order to monitor these chemicals’ in vivo lethality
to shrimp larvae (Artemia salina), Brine-Shrimp Lethality
Assay (Choudhary and Thomsenm, 2001) was used.
Results were analyzed with LC50 program to determine
LC50 values and 95 % confidence intervals (Brayn et al.,
In order to prevent the toxicity results from possible false
effects originated from solubility of compounds and DMSO’s
possible toxicity effect, compounds were prepared by dis-
solving in DMSO in the suggested DMSO volume ranges. It is
clear from Table 2 that the 4-amino-3-chloro-5,6,7,8-tetra-
hydrobenzo[4,5]thieno[2,3-b]pyridine-2-ol (21) and the 1-
(3-chloro-2-hydroxy-5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-b]
pyridine-4-yl)-3-phenylthiourea (23) showed non-toxicity
against the tested organisms.
2
009). Results are given in Table 2 for the compounds
which exhibited optimal cytotoxic effect against cancer cell
lines which are the eight compounds 3, 11b, 13, 18c, 18d,
1, 23, and 24. The shrimp lethality assay is considered as
2
a useful tool for preliminary assessment of toxicity, and it
has been used for the detection of fungal toxins, plant
extract toxicity, heavy metals, cyanobacteria toxins, pesti-
cides, and cytotoxicity testing of dental materials (Carballo
et al., 2002), natural and synthetic organic compounds. It
has also been shown that A. salina toxicity test results have
a correlation with rodent and human acute oral toxicity
data. Generally, a good correlation was obtained between
A. salina toxicity test and the rodent data. Likewise, the
predictive screening potential of the aquatic invertebrate
tests for acute oral toxicity in man, including A. salina
Experimental
Chemistry
All melting points are uncorrected. IR spectra were
recorded for KBr disks on a Pye Unicam SP-1000 spec-
1
trophotometer. H-NMR and
13
C-NMR spectra were
measured on a Varian EM-390–200 MHz in DMSO as
solvent using TMS as internal standard and chemical shifts
123

Med Chem Res
are expressed as d. Analytical data were obtained from the
Microanalytical Data Unit at Cairo University, Giza,
Egypt.
(0.84 g, 0.01 mol) or cyclohexanone (0.98 g, 0.01 mol)
was added. The reaction mixture was heated under reflux
for 3 h then evaporated under vacuum, and the remaining
product was triturated with ethanol and the formed solid
product, in each case, was collected by filtration.
2
2
-Chloro-N-(3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophen-
-yl)acetamide (3)
Compound 7a Crystallized from ethanol to give yellow
crystals, yield 2.53 g (80 %), m.p. 261–263 °C. Anal.
Calculated for C H N OS (316.42): C, 60.73; H, 6.37; N,
To a solution of compound 1 (1.80 g, 0.01 mol) in 1,4-
dioxane, chloroacetyl chloride (1.13 g, 0.01 mol) was
added. The reaction mixture was heated under reflux for
1
6 20 4
17.71; S, 10.13 %. Found: C, 60.84; H, 6.67; N, 17.84; S,
9.94 %. IR, t: 3469–3342 (2 NH), 2220 (CN), 1721 (CO),
1660 (C=N), 1620 (C=C). 1H-NMR, d: 1.70–1.82 (m, 8H,
4CH ), 2.52–2.78 (m, 8H, 4CH ), 4.98 (s, 2H, CH ), 8.21,
3
h then poured onto ice/water, and the formed solid
product was collected by filtration. Crystallized from eth-
anol to give white crystals, yield 2.23 g (88 %), m.p.
2
2
2
1
3
8.32 (2s, 2H, D O exchangeable, 2NH). C-NMR, d: 19.5,
2
1
88–191 °C. Anal. Calculated for C H ClN OS (254.74):
20.7, 21.5, 24.7 24.8, 24.9, 32.0, 34.8 (8CH ), 50.3 (CH ),
2
1
1
11
2
2
C, 51.86; H, 4.35; Cl, 13.92; N, 11.00; S, 12.59 %. Found:
116.8 (CN), 120.5, 128.4, 134.2, 137.2 (thiopohene C),
166.2 (C=O).
C, 51.69; H, 4.57; Cl, 14.26; N, 10.85; S, 12.32 %. IR, t:
1
477–3321 (NH), 2220 (CN), 1702 (CO), 1623 (C=C). H-
3
NMR, d: 1.78–1.84 (m, 4H, 2CH ), 2.56–2.74 (m, 4H,
Compound 7b Crystallized from 1,4-dioxane to give pale
yellow crystals, yield 2.54 g (77 %), m.p. 248–250 °C.
Anal. Calculated for C H N OS (330.45): C, 61.79; H, 6.
2
2
CH ), 5.58 (s, 2H, CH ), 8.43 (s, 1H, D O exchangeable,
2 2 2
1
3
NH). C-NMR, d: 19.8, 20.5, 21.6, 24.6 (4CH ), 45.8
2
17 22 4
(
CH ), 116.8 (CN), 119.0, 129.7, 134.2, 136.0 (thiophene
2
71; N, 16.95; S, 9.70 %. Found: C, 61.92; H, 6.85; N, 16.
C), 166.9 (C=O).
74; S, 9.88 %. IR, t: 3473–3342 (2 NH), 2223 (CN), 1720
(CO), 1662 (C=N), 1622 (C=C). 1H-NMR, d: 1.72–1.82
(
m, 8H, 4CH ), 2.56–2.93 (m, 10H, 5CH ), 4.74 (s, 2H,
2
2
1
3
N-(3-Cyano-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-2-
CH ), 8.22, 8.31 (2s, 2H, D O exchangeable, 2NH). C-
2 2
hydrazinylacetamide (5)
NMR, d: 19.5, 20.7, 21.6, 24.7, 24.8, 32.0, 34.8, 48.02 (9
CH ), 50.6 (CH ), 116.7 (CN), 120.2, 128.4, 134.5, 137.8
2
2
To a solution of compound 3 (2.54 g, 0.01 mol) in 1,4-
dioxane (40 mL), hydrazine hydrate (0.50 g, 0.01 mol)
was added. The reaction mixture was heated under reflux
for 2 h then left to cool. The solid product formed upon
leaving the reaction mixture overnight was collected by
filtration. Crystallized from ethanol to give white crystals,
yield 2.23 g (88 %), m.p. 166–168 °C. Anal. Calculated for
C H N OS (250.32): C, 52.78; H, 5.64; N, 22.38; S,
(thiophene C), 166.6 (C=O).
2-(2-Benzylidenehydrazinyl)-N-(3-cyano-4,5,6,7-
tetrahydrobenzo[b]thiophen-2-yl)acetamide (9a) and N-(3-
cyano-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-2-(2-(1-
phenylethylidene)hydrazinyl)acetamide (9b)
1
1 14 4
1
2.81 %. Found: C, 52.93; H, 5.84; N, 22.48; S, 13.02 %.
General procedure To a solution of compound 5 (2.50 g,
0.01 mol) in dimethylformamide (20 mL) either benzal-
dehyde (1.08 g, 0.01 mol) or acetophenone (1.20 g, 0.
01 mol) was added. The reaction mixture was heated under
reflux for 2 h then poured onto ice/water and the formed
solid product was collected by filtration.
IR, t: 3489–3339 (NH , 2NH), 2223 (CN), 1719 (CO),
2
1
1
623 (C=C). H-NMR, d: 1.72–1.81 (m, 4H, 2CH2),
2
.53–2.76 (m, 4H, 2CH ), 4.98 (s, 2H, CH ), 6.77 (s, 2H,
2
2
D O exchangeable, NH ), 8.21, 8.28 (2s, 2H, D O
2
2
2
1
3
exchangeable, 2NH). C-NMR, d: 19.5, 20.7, 21.5, 24.7
(
4CH ), 38.6 (CH ), 116.4 (CN), 119.3, 129.6, 133.6, 136.6
2 2
(
thiophene C), 164.4 (C=O).
Compound 9a Crystallized from ethanol to give yellow
crystals, yield 2.43 g (72 %), m.p. 177–179 °C. Anal.
Calculated for C H N OS (338.43): C, 63.88; H, 5.36; N,
1
8 18 4
N-(3-Cyano-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-2-
2-cyclopentylidene-hydrazinyl)-acetamide (7a) and N-(3-
Cyano-4,5,6,7-tetrahydrobenzo[b]-thiophen-2-yl)-2-(2-
16.56; S, 9.47 %. Found: C, 63.64; H, 5.49; N, 16.28; S, 9.
(
77 %. IR, t: 3439–3312 (2 NH), 2226 (CN), 1683 (CO),
1
1662 (C=N), 1624 (C=C). H-NMR, d: 1.71–1.88 (m, 4H,
2CH ), 2.46–2.93 (m, 4H, 2CH ), 4.78 (s, 2H, CH ), 6.05
cyclohexaylidene-hydrazinyl)acetamide (7b)
2
2
2
(
s, 1H, N = CH), 7.29–7.38 (m, 5H, C H ), 8.23, 8.36 (2s,
6 5
1
3
General procedure: To a solution of compound 5 (2.50 g,
0
2H, D O exchangeable, 2NH). C-NMR, d: 19.5, 20.3, 21.
2
.01 mol) in 1,4-dioxane (40 mL) either cyclopentanone
5, 24.8 (4CH ), 50.8 (CH ), 116.9 (CN), 120.6, 122.3, 124.
2
2
1
23

Med Chem Res
0
8
, 127.2, 128.9, 133.6, 137.9 (thiophene, C H C), 164.8
6
N -(4-Amino-2-hydroxy-5,6,7,8-
5
(
C=N), 172.3 (C=O).
tetrahydrobenzo[4,5]thieno[2,3-b]pyridine-3-yl)-2-
cyanoacetohydrazide (13)
Compound 9b Crystallized from acetic acid to give yel-
low crystals, yield 2.39 g (68 %), m.p. 210–213 °C. Anal.
Calculated for C H N OS (352.45): C, 64.75; H, 5.72; N,
To a solution of compound 5 (2.50 g, 0.01 mol) in 1,4-
dioxane (20 mL) containing triethylamine (0.50 mL) ethyl
cyanoacetate (1.13 g, 0.01 mol) was added. The reaction
mixture was heated under reflux for 2 h then poured onto
ice/water, and the formed solid product was collected by
filtration.
1
9 20 4
1
2
1
2
5.90; S, 9.10 %. Found: C, 64.88; H, 5.60; N, 16.19; S, 9.
6 %. IR, t: 3430–3342 (2 NH), 2222 (CN), 1684 (CO),
1
664 (C=N), 1622 (C=C). H-NMR, d: 1.74–1.87 (m, 4H,
CH ), 2.43–2.90 (m, 4H, 2CH ), 3.05 (s, 3H, CH ), 4.74
2
2
3
(
s, 2H, CH ), 7.31–7.39 (m, 5H, C H ), 8.24, 8.39 (2s, 2H,
2 6 5
1
3
D O exchangeable, 2NH). C-NMR, d: 19.8, 20. 5, 21.5,
Compound 13 Crystallized from acetic acid to give buff
crystals, yield 1.74 g (55 %), m.p. [300 °C. Anal. Calcu-
2
2
4.6 (4CH ), 50.5 (CH ), 116.8 (CN), 120.8, 122.0, 124.9,
2 2
1
26.6, 128.5, 133.9, 138.3 (thiophene, C H C), 164.3(C=
6
lated for C14
07; S, 10.10 %. Found: C, 53.22; H, 4.63; N, 21.83; S, 10.
0 %. IR, t: 3560–3312 (OH, NH , 2NH), 1683 (CO),
H N O S (317.37): C, 52.98; H, 4.76; N, 22.
15 5 2
5
N), 172.6 (C=O).
3
2
1
N-(3-Cyano-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-2-
3,5-dimethyl-1H-pyrazol-1-yl)acetamide (11a) and N-(3-
Cyano-4,5,6,7-tetrahydrobenzo-[b]thiophen-2-yl)-2-(5-
1626 (C=C). H-NMR, d: 1.66–1.86 (m, 4H, 2CH
40–2.88 (m, 4H, 2CH ), 4.64 (s, 2H, CH ), 5.21 (s, 2H,
O exchangeable, NH ), 8.03, 8.33 (2s, 2H, D
exchangeable, 2NH), 10.41 (s, 1H, D O exchangeable,
OH). C-NMR, d: 19.6, 20.8, 21.6, 25.8 (4CH ), 56.0
2
), 2.
(
2
2
D
O
2
2
2
hydroxy-3-methyl-1H-pyrazol-1-yl)acetamide (11b)
2
1
3
2
General procedure To a solution of compound 5 (2.50 g,
0
(CH ), 126.2, 127.3, 128.5, 133.2, 137.6, 143.2, 148.7
2
.01 mol) in 1,4-dioxane (20 mL) containing triethylamine
(thiophene, pyridine C), 166.8 (C=N), 177.1 (C=O).
(
0.50 mL) either acetylacetone (1.0 g, 0.01 mol) or ethyl
acetoacetate (1.30 g, 0.01 mol) was added. The reaction
mixture was heated under reflux for 2 h then poured onto
ice/water, and the formed solid product was collected by
filtration.
Compound 15 Crystallized from 1,4-dioxane to give
yellow crystals, yield 2.62 g (83 %), m.p. 288–290 °C.
Anal. Calculated for C14
10; N, 26.56; S, 10.13 %. Found: C, 53.40; H, 4.88; N, 26.
3; S, 10.29 %. IR, t: 3488–3332 (2 NH , NH), 2222 (CN),
H N OS (316.38): C, 53.15; H, 5.
16 6
7
2
1
Compound 11a Crystallized from ethanol to give yellow
crystals, yield 1.88 g (60 %), m.p. 260–263 °C. Anal.
Calculated for C H N OS (314.41): C, 61.12; H, 5.77; N,
1688 (CO), 1628 (C=C). H-NMR, d: 1.65–1.89 (m, 4H,
2CH ), 2.42–2.86 (m, 4H, 2CH ), 4.76, 4.93 (2s, 4H, D
exchangeable, 2NH ), 5.23 (s, 2H, CH ), 6.88 (s, 1H,
pyrazole H-4), 8.26 (s, 1H, D O exchangeable, NH). C-
NMR, d: 19.9, 20.5, 21.9, 25.4 (4CH ), 57.3 (CH ), 124.8,
O
2
2
2
1
6 18 4
2
2
1
3
1
1
1
2
7.82; S, 10.20 %. Found: C, 61.48; H, 5.73; N, 18.05; S,
2
0.41 %. IR, t: 3458–3331 (NH), 2220 (CN), 1680 (CO),
2
2
1
632 (C=C). H-NMR, d: 1.72–1.87 (m, 4H, 2CH ), 2.28,
126.2, 129.9, 134.8, 139.2, 140.7, 147.3 (thiophene, pyra-
2
.49 (2s, 6H, 2CH ), 2.47–2.92 (m, 4H, 2CH ), 4.98 (s, 2H,
3
zole C), 164.3 (C=N), 174.0 (C=O).
2
1
3
CH ), 8.21 (s, 1H, D O exchangeable, NH). C-NMR, d:
2
2
1
3
4
9.3, 20.2, 21.5, 25.2 (4CH ), 54.6 (CH ), 116.7 (CN), 126.
2
2-(4-((3-cyano-4,5,6,7-tetrahydrobenzo[b]thiophen-2-
yl)amino)-3-phenyl-thiazol-2(3H)-ylidene)malononitrile
(18a), ethyl 2-cyano-2-(4-((3-cyano-4,5,6,7-
2
, 127.3, 128.9, 133.6, 137.9 (thiophene, pyrazole C), 164.
(C=N), 172.8 (C=O).
tetrahydrobenzo[b]thiophen-2-yl)amino-3-phenylthiazol-
2(3H)-ylidene)acetate (18b), 2-((2-(2,4-dioxopentan-3-
ylidene)-3-phenyl-2,3-dihydro-thiazol-4-yl)amino-4,5,6,7-
tetrahydrobenzo[b]thiophene-3-carbonitrile (18c)
and ethyl 2-(4-((3-cyano-4,5,6,7-
Compound 11b Crystallized from ethanol to give orange
crystals, yield 1.83 g (58 %), m.p. 230–232 °C. Anal.
Calculated for C H N O S (316.38): C, 56.94; H, 5.10;
1
5 16 4 2
N, 17.71; S, 10.14 %. Found: C, 56.72; H, 4.82; N, 17.91;
S, 10.29 %. IR, t: 3520–3321 (OH, NH), 2222 (CN), 1687
tetrahydrobenzo[b]thiophen-2-yl)amino-3-phenylthiazol-
2(3H)-ylidene)-3-oxobutanoate (18d)
1
(
CO), 1630 (C=C). H-NMR, d: 1.71–1.89 (m, 48H,
2
CH ), 2.22 (s, 3H, CH ), 2.43–2.90 (m, 4H, 2CH ), 4.96
2 3 2
(
s, 2H, CH ), 8.20 (s, 1H, D O exchangeable, NH), 10.37
2
General procedure A solution of either malononitrile (0.
66 g, 0.01 mol), ethyl cyanoacetate (1.13 g, 0.01 mol),
acetylacetone (1.0 g, 0.01 mol) or ethyl acetoacetate (1.
30 g, 0.01 mol) in dimethylformamide (30 mL) containing
potassium hydroxide (0.56 g) was stirred at room
2
1
3
(
s, 1H, D O exchangeable, OH). C-NMR, d: 19.4, 20.6,
2
2
1
1
1.5, 25.5 (4CH ), 54.8 (CH ), 116.4 (CN), 126.2, 127.3,
2 2
28.5, 133.86, 137.6 (thiophene, pyrazole C), 164.6 (C=N),
72.5 (C=O).
123

Med Chem Res
overnight. On the second day, compound 3 (2.54 g, 0.
1 mol) was added, and the whole reaction mixture was
14 (t, 3H, J = 7.09 Hz, CH ), 1.62–1.84 (m, 8H, 4CH ), 2.
3
2
0
43–2.88 (m, 8H, 4CH ), 2.84 (s, 3H, CH ), 4.22 (q, 2H,
2 3
stirred at room temperature for an additional night. The
solid product produced upon pouring onto ice/water con-
taining hydrochloric acid (till pH 6) was collected by
filtration.
J = 7.09 Hz, CH ), 6.32 (s, 1H, thiazole H-5), 7.29–7.44
2
1
(m, 5H, C H ), 8.33 (s, 1H, D O exchangeable, NH). C-
3
6
5
2
NMR, d: 19.8, 20.6, 21.5, 25.7 (4CH ), 111.3, 115.8 (C=
2
C), 117.1 (CN), 123.5, 124.6, 125.28, 128.3, 133. 2, 134.5,
139.8, 142.8, 143.4, 147.6 (thiopohene, pyrazole, C H C),
6 5
Compound 18a Crystallized from ethanol to give pall
yellow crystals, yield 2.08 g (66 %), m.p. 144–147 °C.
Anal. Calculated for C H N S (401.51): C, 62.82; H, 3.
166.4, 172.0 (2 CO).
N-(3-Cyano-4,5,6,7-tetrahydrobenzo[b]thiophen-2-yl)-2-
2
1 15 5 2
7
2
7; N, 17.44; S, 15.97 %. Found: C, 62.62; H, 4.18; N, 17.
(phenylamino)-acetamide (20)
9; S, 16.13 %. IR, t: 3452–3312 (NH), 3055 (CH aro-
1
matic), 2227, 2220 (2CN), 1628 (C=C). H-NMR, d: 1.
6
Equimolar amounts of compound 3 (2.54 g, 0.01 mol) and
aniline (0.93 g, 0.01 mol) in 1,4-dioxane (40 mL) was
heated under reflux for 3 h then poured onto ice/water
containing few drops of hydrochloric acid. The formed
solid product was collected by filtration.
5–1.87 (m, 8H, 4CH ), 2.40–2.86 (m, 8H, 4CH ), 6.23 (s,
2 2
1
H, thiazole H-5), 7.31-7.42 (m, 5H, C H ), 8.32 (s, 1H,
6
5
1
3
D O exchangeable, NH). C-NMR, d: 19.4, 20.8, 21.6, 25.
2
9
1
3
(4CH ), 109.8, 114.2 (C=C), 116.6, 117.4 (2CN), 121.6,
2
24.8, 126.2, 127.8, 129.9, 134.8, 139.2, 142.4, 143.2, 147.
(thiophene, pyrazole, C H C).
Compound 20 Crystallized from ethanol to give colorless
crystals, yield 2.43 g (82 %), m.p. 196–198 °C. Anal.
Calculated for C H N S (311.40): C, 65.57; H, 5.50; N,
6
5
Compound 18b Crystallized from ethanol to give orange
crystals, yield 2.95 g (66 %), m.p. 120–122 °C. Anal.
Calculated for C H N O S (448.56): C, 61.59; H, 4.49;
1
7 17 3 2
13.49; S, 10.30 %. Found: C, 65.81; H, 5.80; N, 13.63; S,
16.22 %. IR, t: 3489–3338 (NH), 3052 (CH aromatic),
2
3 20 4 2 2
1
N, 12.49; S, 14.30 %. Found: C, 61.69; H, 4.36; N, 12.73;
2225 (CN), 1695 (CO), 1638 (C=C). H-NMR, d: 1.63–1.
87 (m, 8H, 4CH ), 2.43–2.88 (m, 8H, 4CH ), 5.77 (s, 2H,
S, 14.52 %. IR, t: 3466–3329 (NH), 3053 (CH aromatic),
2
2
1
2
3
8
1
223 (CN), 1720 (CO), 1639 (C=C). H-NMR, d: 1.13 (t,
CH ), 7.26–7.39 (m, 5H, C H ), 8.24, 8.36 (2s, 2H, D O
2 6 5 2
1
3
H, J = 6.09 Hz, CH ), 1.66–1.84 (m, 8H, 4CH ), 2.42–2.
3
exchangeable, 2NH). C-NMR, d: 19.6, 20.6, 21.8, 25.6
(4CH ), 56.4 (CH ), 116.8 (CN), 120.8, 124.2, 126.8, 127.
2
7 (m, 8H, 4CH ), 4.23 (q, 2H, J = 6.09 Hz, CH ), 6.25 (s,
2
2
2
2
H, thiazole H-5), 7.31–7.40 (m, 5H, C H ), 8.38 (s, 1H,
5
8, 128.3, 142.4, 143.6, 144.2 (thiophene, C H C).
6 5
6
1
3
D O exchangeable, NH). C-NMR, d: 19.4, 20.8, 21.6, 25.
2
9
(4CH ), 109.5, 114.7 (C=C), 116.8 (CN), 122.06, 124.8,
2
4-Amino-3-chloro-5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-
b]pyridine-2-ol (21) and 4-amino-3-(phenylamino)-5,6,7,8-
tetrahydrobenzo[4,5]thieno[2,3-b]pyridine-2-ol (22)
1
26.6, 127.8, 131.2, 134.2, 139.6, 142.2, 143.8, 147.9
(
thiophene, pyrazole, C H C).
6 5
Compound 18c Crystallized from ethanol to give orange
crystals, yield 3.04 g (70 %), m.p. 210–212 °C. Anal.
Calculated for C H N O S (435.56): C, 63.42; H, 4.86;
General procedure A suspension of either compound 3
(2.54 g, 0.01 mol) or 20 (3.11 g, 0.01 mol) in sodium
ethoxide solution [prepared by dissolving metallic sodium
(0.46 g, 0.02 mol) in absolute ethanol (30 mL)] was heated
in a boiling water bath for 6 h. The formed solid product
upon pouring onto ice/water containing few drops of
hydrochloric acid was collected by filtration.
2
3 21 3 2 2
N, 9.65; S, 14.72 %. Found: C, 63.71; H, 4.59; N, 9.42; S,
1
2
6
9
4.39 %. IR, t: 3470–3341 (NH), 3051 (CH aromatic),
1
220 (CN), 1680–1688 (2CO), 1636 (C=C). H-NMR, d: 1.
8–1.85 (m, 8H, 4CH ), 2.41–2.83 (m, 8H, 4CH ), 2.83, 2.
2
2
0 (2s, 6H, 2CH ), 6.29 (s, 1H, thiazole H-5), 7.28–7.38
3
1
m, 5H, C H ), 8.36 (s, 1H, D O exchangeable, NH). C-
3
(
Converting compound 21 into 22
6
5
2
NMR, d: 19.6, 20.98, 21.8, 25.8 (4CH ), 109.8, 114.3 (C=
2
C), 116.5 (CN), 122.5, 124.9, 126.8, 127.9, 131.4, 134.5,
To a solution of compound 21(2.54 g, 0.01 mol) in 1,4-
dioxane (30 mL) aniline (0.93 g, 0.01 mol) was added and
the reaction mixture was heated under reflux for 6 h. After
reaching room temperature, the reaction contents were
poured onto ice/water and the formed solid product was
collected by filtration.
1
39.8, 142.0, 143.6, 147.5 (thiopohene, pyrazole, C H C).
6 5
Compound 18d Crystallized from ethanol to give orange
crystals, yield 3.63 g (77 %), m.p. 140–142 °C. Anal.
Calculated for C H N O S (465.59): C, 61.91; H, 4.98;
2
4 23 3 3 2
N, 9.03; S, 13.77 %. Found: C, 62.19; H, 4.69; N, 9.19; S,
1
2
4.02 %. IR, t: 3459–3316 (NH), 3051 (CH aromatic),
220 (CN), 1683, 1689 (2CO), 1633 (C=C). H-NMR, d: 1.
Compound 21 Crystallized from ethanol to give yellow
crystals, yield 1.93 g (76 %), m.p. 120–122 °C. Anal.
1
1
23

Med Chem Res
Calculated for C H ClN OS (254.74): C, 51.86; H, 4.35;
1
sodium (0.46 g, 0.02 mol) in absolute ethanol (30 mL)]
was heated in a boiling water bath for 12 h. The formed
solid product upon pouring onto ice/water containing few
drops of hydrochloric acid was collected by filtration.
1
11
2
N, 11.00; S, 12.59 %. Found: C, 51.74; H, 4.42; N, 11.32;
S, 12.73 %. IR, t: 3520–3318 (OH, NH), 3052 (CH aro-
1
matic), 1622 (C=C). H-NMR, d: 1.61–1.88 (m, 8H,
4
CH ), 2.42–2.89 (m, 8H, 4CH ), 4.69 (s, 2H, D O
2 2 2
exchangeable, NH ), 10.02 (s, 1H, D O exchangeable,
2
Compound 24 Crystallized from ethanol to give Pall
yellow crystals, yield 2.47 g (70 %), m.p. [300 °C. Anal.
Calculated for C H N OS (353.46): C, 61.16; H, 4.28;
2
1
3
OH). C-NMR, d: 19.8, 20.8, 21.8, 25.9 (4CH ), 122.3,
2
1
24.2, 126.6, 133.2, 138.0, 142.4, 143.2, 144.6 (thiophene,
1
8
15
3
2
pyridine C), 172.2 (C=N).
N, 11.89; S, 18.14 %. Found: C, 61.38; H, 4.11; N, 12.08;
S, 17.94 %. IR, t: 3538–3303 (OH, NH), 3056 (CH aro-
1
Compound 22 Crystallized from ethanol to give yellow
crystals, yield 2.05 g (66 %), m.p. 198–200 °C. Anal.
Calculated for C H N OS (311.11): C, 65.57; H, 5.50; N,
matic), 1633 (C=C), 1200-1190 (C=S). H-NMR, d: 1.
62–1.87 (m, 8H, 4CH ), 2.41–2.83 (m, 8H, 4CH ), 7.34–7.
2
2
37 (m, 5H, C H ), 8.48 (s, 1H, D O exchangeable, NH),
6
1
7
17
3
5
2
1
3
1
1
3.49; S, 10.30 %. Found: C, 65.77; H, 5.69; N, 13.73; S,
10.32 (s, 1H, D O exchangeable, OH). C-NMR, d: 19.6,
20.59, 21.8, 25.9 (4CH ), 120.5, 122.6, 123.5, 126.3, 127.4,
2
2
0.13 %. IR, t: 3541–3330 (OH, NH , NH), 3056 (CH
2
1
aromatic), 1618 (C=C). H-NMR, d: 1.63–1.87 (m, 8H,
128.7, 129.3, 133.2, 138.6, 143.8, 144.8, 146.2, 149.2
(thiophene, imidazole, pyridine, C H , C), 172.0 (C=N).
4
CH ), 2.43–2.90 (m, 8H, 4CH ), 4.67 (s, 2H, D O
2 2 2
6 5
exchangeable, NH ), 7.28–7.38 (m, 5H, C H ), 8.33 (s, 1H,
2 6 5
D O exchangeable, NH), 10.02 (s, 1H, D O exchangeable,
2
2
1
3
Conclusions
OH). C-NMR, d: 19.4, 20.7, 21.8, 25.4 (4CH ), 120.2,
2
1
22.1, 123.5, 125.6, 128.9, 133.2, 138.0, 142.4, 143.0, 144.
Novel 4,5,6,7-tetrahydrobenzo[b]thiophene derivatives
were synthesized in good yields. Some compounds were
used to produce annulated products. The antitumor evalu-
ation of the newly synthesized products showed in every
case it was observed that molecules with electronegative
substitutions as compounds 3, 11b, 13, 18c, 18d, 21, 23,
and 24 showed higher cytotoxicity because them were
either oxygen or chlorine substituted as well as comprised
with similar structural features. The toxicity of the com-
pounds of optimal cytotoxicity showed that compounds 21
and 32 are non toxic against shrimp larvae.
8
(thiophene, pyridine, C H , C), 171.2 (C=N).
6
5
1
-(3-Chloro-2-hydroxy-5,6,7,8-tetrahydrobenzo
[
4,5]thieno[2,3-b]pyridine-4-yl)-3-phenylthiourea (23)
To a solution of compound 22 (3.11 g, 0.01 mol) in 1,4-
dioxane (30 mL) containing triethylamine (0.50 mL)
phenylisothiocyanate (1.30 g, 0.01 mol) was added. The
reaction mixture was heated under reflux for 6 h then
evaporated under vacuum, and the remaining product was
triturated by diethyl ether, and the solidified product was
collected by filtration.
Acknowledgments R M. Mohareb would like to express his deepest
thanks for the Alexander von Humboldt foundation for affording a
fellowship in Munich during Summer 2012 for doing research and
completing this work.
Compound 23 Crystallized from ethanol to give orange
crystals, yield 3.34 g (86 %), m.p. 205–208 °C. Anal.
Calculated for C H ClN OS (389.92): C, 55.45; H, 4.14;
1
8
16
3
2
N, 10.78; S, 16.45 %. Found: C, 55.39; H, 4.42; N, 10.58;
References
S, 16.29 %. IR, t: 3555–3323 (OH, 2 NH), 3058 (CH
1
aromatic), 1625 (C=C). H-NMR, d: 1.60–1.87 (m, 8H,
Abbas SE, Abdel Gawad NM, George RF, Akar YA (2013) Synthesis,
antitumor and antibacterial activities of some novel tetra-
hydrobenzo[4,5]thieno[2,3-d]pyrimidine derivatives. Eur J Med
Chem 65:195–204
Ament SMC, Gillissen F, Maessen JMC, Dirksen CD, Bell AVR,
Vissers YL, Weijden TV, Meyenfeldt MF (2014) Sustainability
of short stay after breast cancer surgery in early adopter
hospitals. Breast 23:429–434
Amr AE, Sherif MH, Assy MG, Al-Omar MA, Ragab I (2010) o
Antiarrhythmic, serotonin antagonist and antianxiety activities of
novel substituted thiophene derivatives synthesized from
2-amino-4,5,6,7-tetrahydro-N-phenylbenzo[b]thiophene-3-carbox-
amide. Eur J Med Chem 45:5935–5942
4
CH ), 2.44–2.95 (m, 8H, 4CH ), 7.32–7.39 (m, 5H,
2 2
C H ), 8.28, 8.36 (s, 1H, D O exchangeable, 2NH), 10.29
6
5
2
1
3
(
s, 1H, D O exchangeable, OH). C-NMR, d: 19.2, 20.9,
2
2
1.8, 25.6 (4CH ), 120.8, 121.8, 123.5, 125.26, 129.3, 133.
2
2
, 138.60, 142.8, 143.6, 145.2 (thiophene, pyridine, C H ,
5
6
C), 171.2 (C=N).
4
-Hydroxy-3-phenyl-7,8,9,10-tetrahydro-1H-benzo
4,5]thieno[2,3-b]imidazo[4,5-d]pyridine-2(3H)-thione
24)
[
(
Aurelio L, Christopoulos A, Flynn BL, Scammells PJ, Sexton PM, Valant C
(
4
2011) The synthesis and biological evaluation of 2-amino-
,5,6,7,8,9-hexahydrocycloocta[b]thiophenes as allosteric modulators
of the A1 adenosine receptor. Bioorg Med Chem Lett 21:3704–3807
A suspension of compound 23 (3.53 g, 0.01 mol) in
sodium ethoxide solution [prepared by dissolving metallic
123

Med Chem Res
Behbehani H, Ibrahim HM, Makhseed S, Elnagdi MH, Mahmoud H
2012) 2-Aminothiophenes as building blocks in heterocyclic
synthesis: Synthesis and antimicrobial evaluation of a new class
M e´ sangeau C, Fraise M, Delagrange P, Caignard DH, Boutin JA,
Berthelot P, Yous S (2011) Preparation and pharmacological
evaluation of a novel series of 2-(phenylthio)benzo[b]thiophenes
as selective MT2 receptor ligands. Eur J Med Chem 46:1835–1840
Mohareb RM, Al-Omran F (2012) Reaction of pregnenolone with
cyanoacetylhydrazin Novel synthesis of hydrazide–hydrazone,
pyrazole, pyridine, thiazole, thiophene derivatives and their
cytotoxicity evaluations. Steroids 77:1551–1559
Mohareb RM, El-Sayed NEE, Abdelaziz MA (2013) The Knoevenagel
reactions of pregnenolone with cyanomethylene reagents: Syn-
thesis of thiophene, thieno[2,3-b]pyridine, thieno[3,2-d]isoxazole
derivatives of pregnenolone and their in vitro cytotoxicity towards
tumor and normal cell lines. Steroids 78:1209–1219
(
of pyrido[1,2-a]thieno[3,2-e]pyrimidine, quinoline and pyridin-
2
-one derivatives. Eur J Med Chem 52:51–65
Brayn B, Timothy M, Tore S (2009) General and applied toxicology,
vol 6, 3rd edn. Wiley, New york, p 52
Calleja MC, Persoone G (1992) The potential ofecotoxicological tests
for the prediction of acute toxicityin man as evaluated on the 1st
1
0 chemicals on the meic program. ATLA 20:396–405
Campaigne E (1984) Thiophenes and their benzo derivatives: (iii)
synthesis and applications. Compreh Het Chem 4:863–934
Carballo JL, Inda ZLH, P e´ rez P, Gr a´ valos MDG (2002) A comparison
between two brine shrimp assays to detect in vitro cytotoxicity in
marine natural products. BMC Biotechnol 2:17
Padmavathi V, Reddy GD, Reddy SN, Mahesh K (2011) Synthesis and
biological activity of 2-(bis((1,3,4-oxadiazolyl/1,3,4-thiadiazol-
Choudhary MI, Thomsen WJ (2001) Bioassay techniques for drug
development. Harwood Academic Publishers, Amsterdam,
pp 9–10
Crouse KA, Chew KB, Tarafder MTH, Kasbollah A, Ali AM, Yamin
BM, Fun HK (2004) Synthesis, characterization and bio-activity
of S-2-picolyldithiocarbazate (S2PDTC), some of its Schiff bases
and their Ni(II) complexes and X-ray structure of S-2-picolyl-b-N-
yl)-methylthio)methylene)malononitriles. Eur
46:1367–1373
J Med Chem
Perspicace E, Hureaux VJ, Ragno R, Ballante F, Sartini S, Motta CL,
Settimo FD, Chen B, Kirsch G, der Schnei S, Faivre B, Hesse S
(2013) Design, synthesis and biological evaluation of new
classes of thieno[3,2-d]pyrimidinone and thieno[1,2,3]triazine as
inhibitor of vascular endothelial growth factor receptor-2
(VEGFR-2). Eur J Med Chem 63:765–781
(2-acetylpyrrole)dithiocarbazate. Polyhed 23:161–168
Dadiboyena S (2012) Recent advances in the synthesis of raloxifene:
a selective estrogen receptor modulator. Eur J Med Chem
Pranati Samadder P, Yaozu XuY, Frank Schweizer F, Gilbert Arthur
G (2014) Cytotoxic properties of D-gluco-, D-galacto- and
D-manno-configured 2-amino-2-deoxy-glycerolipids against epi-
thelial cancer cell lines and BT-474 breast cancer stem cells. Eur
J Med Chem 78:225–235
Refat HM, Fadda AA (2013) Synthesis and antimicrobial activity of
some novel hydrazide, benzochromenone, dihydropyridine,
pyrrole, thiazole and thiophene derivatives. Eur J Med Chem
70:419–426
5
1:17–34
Dewal MB, Wani AS, Vidaillac C, Oupick y´ D, Rybak MJ, Firestine
SM (2012) Thieno[2,3-d]pyrimidinedione derivatives as anti-
bacterial agents. Eur J Med Chem 51:145–153
Du QS, Shi YX, Lia PF, Zhao ZJ, Zhua WP, Qian XH, Li BJ (2013)
Novel plant activators with thieno[2,3-d]-1,2,3-thiadiazole-6-
carboxylate scaffold: Synthesis and bioactivity. Chin Chem Lett
2
4:967–969
Romagnoli R, Baraldi PG, Carrion MD, Cruz-Lopez O, Tolomeo M,
Grimaudo S, Cristina AD, Pipitone MR, Balzarini J, Brancale A,
Hamel E (2010) Substituted 2-(30,40,50- trimethoxybenzoyl)-
benzo[b]thiophene derivatives as potent tubulin polymerization
inhibitors. Bioorg Med Chem 18:5114–5122
Stephens CE, Felder TM, Sowell JW, Andrei G, Balzarini J, Snoeck
R, Clercq ED (2001) Synthesis and antiviral/antitumor evalua-
tion of 2-amino- and 2-carboxamido-3-arylsulfonylthiophenes
and related compounds as a new class of diarylsulfones. Bioorg
Med Chem 9:1123–1132
Titchenell PM, Showalter HD, Pons JF, Barber AJ, Jin Y, Antonetti
DA (2013) Synthesis and structure–activity relationships of
2-amino-3-carboxy-4-phenylthiophenes as novel atypical protein
kinase C inhibitors. Bioorg Med Chem Lett 13:3034–3038
Upreti SR, Gurung S, Patel M, Dixit SM, Krause LK, Shakya G,
Wannemuehler K, Rajbhandari R, Bohara R, Schluter WW
(2014) Prevalence of chronic hepatitis B virus infection before
and after implementation of a hepatitis B vaccination program
among children in Nepal. Vaccine 32:4304–4309
Vizzotto M, Porter W, Byrne D, Zevallos LC (2014) Polyphenols of
selected peach and plum genotypes reduce cell viability and
inhibit proliferation of breast cancer cells while not affecting
normal cells. Food Chem 164:363–370
Duval E, Case A, Stein RL, Cuny GD (2005) Structure–activity
relationship study of novel tissue transglutaminase inhibitors.
Bioorg Med Chem. Lett 15:1885–1889
Fadda AA, Abdel-Latif EA, El-Mekawy RE (2009) Synthesis and
molluscicidal activity of some new thiophene, thiadiazole and
pyrazole derivatives. Eur J Med Chem 44:1250–1256
Ferreirra AP, da Silva JLF, Duarte MP, da Piedade MFM, Robalo MP,
HarjivanSG, MarzanoC,GandinV,MarquesMM(2009)Synthesis
and characterization of new organometallic Benzo[b]thiophene
derivatives with potential antitumor properties. Organometalics
2
8:5412–5423
Goncales CEP, Araldi D, Panatieri RB, Rocha JBT, Zeni G, Nogueira
CW (2005) Antinociceptive properties of acetylenic thiophene
and furan derivatives: evidence for the mechanism of action.
Life Sci 76:2221–2234
Goutham Vemana G, Kenneth G, Nepple KG, Joel Vetter J,
Gurdarshan Sandhu G, Seth A, Strope SA (2014) Defining the
potential of neoadjuvant chemotherapy use as a quality indicator
for bladder cancer care. J Urol 192:43–49
Leopoldo C, Baratto LC, Mariana V, Porsani MV, Ida C, Pimentel IC,
Adaucto B, Pereira Netto AB, Reinhard Paschke R, Br a´ s H,
Oliveira BH (2013) Preparation of betulinic acid derivatives by
chemical and biotransformation methods and determination of
cytotoxicity against selected cancer cell lines. Eur J Med Chem
Walker MJ, Mirea L, Glendon G, Ritvo P, Andrulis IL, Knight JA,
Chiarelli AM (2014) Relevance date relevance—selected all
access types all access types. Breast 23:482–488
6
8:121–131
Madhusudana K, Shireesha B, Naidu VGM, Ramakrishna S, Narsaiah
B, Rao AR, Diwan PV (2012) Anti-inflammatory potential of
thienopyridines as possible alternative to NSAIDs. Eur J
Pharmacol 678:48–54
Wang W, Shangguan S, Qiu N, Hu C, Zhang L, Hu Y (2013) Design,
synthesis and biological evaluation of novel 3,4,5-trisubstituted
aminothiophenes as inhibitors of p53–MDM2 interaction. Part 1.
Bioorg Med Chem 21:2879–2885
1
23