Synthesis and anticoagulant activity of a new series of 1,4-dihydropyridine derivatives

Article abstract of DOI:10.1016/j.ejmech.2010.12.006

A series of 1,4-dihydropyridine derivatives (1a-g) were prepared from three compounds condensation reaction of ethylacetoacetate, aromatic aldehyde and ammonium hydroxide. A new series of compounds (2a-g) were prepared from compounds (1a-g) via reaction with thiosemicarbazide using the condensation method. The synthesized compounds were confirmed by IR, ¹H NMR, ¹³C NMR, mass spectral and elemental analyses. The synthesized compounds (1a-g) and (2a-g) were also screened for anticoagulant properties.

Full text of DOI:10.1016/j.ejmech.2010.12.006

European Journal of Medicinal Chemistry 46 (2011) 804e810
Contents lists available at ScienceDirect
European Journal of Medicinal Chemistry
journal homepage: http://www.elsevier.com/locate/ejmech
Short communication
Synthesis and anticoagulant activity of a new series of 1,4-dihydropyridine
derivatives
,
b
R. Surendra Kumar a, A. Idhayadhulla a, A. Jamal Abdul Nasser a , J. Selvin
*
a P.G & Research Dept. of chemistry, Jamal Mohamed College, Tiruchirappalli 620020, Tamil Nadu, India
b Dept. of Microbiology, Bharathidasan University, Tiruchirappalli 620024, Tamil Nadu, India
a r t i c l e i n f o
a b s t r a c t
Article history:
A series of 1,4-dihydropyridine derivatives (1aeg) were prepared from three compounds condensation
reaction of ethylacetoacetate, aromatic aldehyde and ammonium hydroxide. A new series of compounds
(2aeg) were prepared from compounds (1aeg) via reaction with thiosemicarbazide using the conden-
sation method. The synthesized compounds were confirmed by IR, 1H NMR, 13C NMR, mass spectral and
elemental analyses. The synthesized compounds (1aeg) and (2aeg) were also screened for anticoagulant
properties.
Received 16 September 2010
Received in revised form
29 November 2010
Accepted 7 December 2010
Available online 15 December 2010
Ó 2010 Elsevier Masson SAS. All rights reserved.
Keywords:
1,4-Dihydropyridine
Thiosemicarbazide
Condensation
Anticoagulant activity
Structural activity relationship (SAR)
1. Introduction
2. Chemistry
1,4-Dihydropyridine derivatives are of interest because of their
potential biological activity and use in therapeutics such as anti-
hypertensive [1e4], hypnotic, anti-inflammatory [5], antihypoxic
and antiischemic drugs [6] and calcium channel modulators of the
nifedipine type [7]. Several methods have been described for the
synthesis of 1,4-dihydropyridine [8e12]. The presence of ester
groups at the 3- and 5-position on the 1,4-dihydropyridine ring is of
crucial importance for its pharmacological effects. Recently, some
new 3, 5-substituted 1,4-dihydropyridine derivatives were
synthesized which exhibit pharmacological effects such as anti-
hypertensive, bronchodilatory and antitubercular agent [13e15]. In
view of these observations, we decided to compare the activity
levels of compounds (1aeg) with compounds (2aeg). Thio-
semicarbazide also has significant biological activities, ranging
from anti-tumour, fungicidal, bactericidal and anti-inflammatory
and antiviral activities [16e19]. The reactions of primary amines
and hydrazines with esters have been studied by several methods
[20e23]. The present study synthesized a new series of 1,4-dihy-
dropyridine derivatives and screened their anticoagulant activities.
A series of diethyl 2,6-dimethyl-(4-substitutedphenyl)-1,4-dihy-
dropyridine-3,5-dicarboxylate derivatives (1aeg) were prepared as
base compounds by following the method previously described in the
literature [24]. The 2,6-dimethyl-4-substituted phenyl-1,4-dihy-
dropyridine-3,5-dicarboxylate derivatives (1aeg) were reacted with
thiosemicarbazide to give 2,20-{[4-(4-substitutedphenyl)-2,6-dim-
ethyl-1,4-dihydropyridine-3,5-diyl]dicarbonyl}dihydrazinecarbot-
hioamide compounds (2aeg), shown in Scheme 1.
3. Results and discussion
3.1. Spectral discussion
The physicochemical characteristics of the synthesized
compounds are presented in Table 1. The IR spectra of compound
(1a) shows an absorption band at 3349 cmꢀ1 due to the NH present
in the pyridine ring, and another absorption band at 1745 cmꢀ1 due
to the carbonyl stretching of the ester groups. Compound (1b)
shows an absorption band for the CleC group at 837 cmꢀ1 and
compound (1c) shows an absorption band for the HOeC group at
1447 cmꢀ1
. Compound (1d) shows an absorption band at
1536 cmꢀ1 which corresponds to (O2NeC), other absorptions are
* Corresponding author. Tel.: þ919865560226/þ919944549026/þ919994265115.
E-mail address: jamal_abdulchem@ymail.com (A.J. Abdul Nasser).
summarized in the Experimental section.
0223-5234/$ e see front matter Ó 2010 Elsevier Masson SAS. All rights reserved.
doi:10.1016/j.ejmech.2010.12.006

R.S. Kumar et al. / European Journal of Medicinal Chemistry 46 (2011) 804e810
805
O
Ar
O
O
Ar
O
H
N
DMSO
H2N NH
S
H2N
EtO
OEt
+
N
H
NH
HN
NH2
S
S
N
H
N
H
NH2
(1a-1g)
(2a-2g)
Scheme 1. Synthesis route of compounds (2aeg).
The 1H NMR spectra of compound (1a) show a singlet at
which was attributed to the NH proton of the 1,4-dihydropyridine
ring, and another important singlet at 4.72, which was attributed
d
8.20,
Compounds (1aeg) did not exhibit anticoagulant activities but
compounds (2aeg) show some significant anticoagulant activity.
The APTT coagulation assay performed on compound (2f)
showed that this compound had a low anticoagulant activity
compared with the other compounds and that compound (2a) had
a highly active coagulation time of 720.35 s at a concentration of
d
to the CH at C4 the 1,4-dihydropyridine ring. The other 1H NMR
resonances are summarized in the Experimental section.
The IR spectrum of compound (2a) shows an absorption band at
3370 cmꢀ1 due to the NH group present the in 1,4-dihydropyridine
ring, another absorption band at 3192 cmꢀ1 which was due to the
NHeCO str and an absorption band for the C]S group was
observed at 1263 cmꢀ1 respectively, which confirmed the
compound as (2a). The above IR absorptions absent from the
spectra of the other compounds (2beg), which confirmed the other
compounds (2beg). The IR spectra are summarized in the
Experimental section.
30
mg/mL compared with the other compounds. Heparin was used
as the standard at the same concentration 30
mg/mL. These values
are summarized in Table 2. Fig. 4 indicates that the APTT assay
against compounds performance was measured the variation of
clotting time by two concentrations. The PT coagulation assay
performed using compound (2c) had a low active compared with
the other compounds and that compound (2a) had a high relative
clotting factor of 240.42 s at concentrations of 30 mg/mL and 60 mg/
The 1H NMR spectrum (Fig. 1) of compounds (2a) shows that
mL compared with the other compounds. These values are
summarized in Table 3. Fig. 5 indicates that the PT assays against
compounds performance was measured the variation of clotting
time by two concentrations. The results of these two clotting time
tests (APTT and PT) were compared in order to determine the
inhibition pathways of compounds (2aeg) at concentration of
singlet at
d 8.46, which was attributed to NH protons present in
the1,4-dihydropyridine ring. The 4CH, CONH, NHeCS and NH
protons resonated as singlets at
d 5.15, 8.12, 2.14 and 9.64 respec-
tively. The above 1H NMR values confirmed the compound as (2a).
The 1H NMR spectra of the remaining compounds (2beg) are
summarized in the Experimental section.
60 mg/mL. These results are summarized in Table 4. Based on the
APTT and PT Index, the compound 2a was considered to be having
The 13C NMR spectrum (Fig. 2) of compound (2a) shows that
peaks at
d
168.66 (C]O), 182.10(C]S), 38.70 (C4 of pyridine ring)
highest relative clotting potency.
and 18.72(CH3). The 13C NMR spectra of the remaining compounds
(2beg) are summarized in the Experimental section.
3.3. Structural activity relationship
The mass spectrum (Fig. 3) of the compound (2a) shows that
molecular ion peaks, which confirms the molecular mass of the
From the results of anticoagulant activity of the synthesized 1,4-
dihydropyridine derivatives (1aeg), the following structure activity
relationships can be derived:
compound. Scheme
2 shows the fragmentation pattern of
compound (2a), the mass spectrum of the other compounds (2beg)
is summarized in the Experimental section.
3.2. Anticoagulant screening
We examined the anticoagulant activity of these compounds on
human plasma using the APTT and PT coagulant assays. Two
concentrations were required to achieve the relative clotting times
of compounds (1aeg) and (2aeg) in human plasma (in vitro).
Table 1
Physicochemical characterization of the compounds (1aeg), (2aeg).
Compounds no
R
M.P
Yield (%)
1a
1b
1c
1d
1e
1f
1g
2a
2b
2c
2d
2e
2f
-furyl
-Ph
147
153
242
240
197
229
227
187
192
194
201
195
210
205
74
66
47
56
72
69
56
61
53
68
74
76
57
61
1,4-Dihydropyridines (DHPs) are an important class of drugs
which exert potent blocking activities on calcium (Ca2þ) currents
through voltage-dependent L e type channels [25]. Several DHPs
are clinically used in the treatment of a number of cardiovascular
diseases. Structure activity relationships of this class of compounds
have been the subject of several studies [25]. The ester groups in
the 3- and 5-positions are of crucial importance for activity. The
above structure (1aeg) showed that NH group (1), eOEt groups (2)
and substituted aromatic aldehyde presenting in the compounds
(1aeg) 1,4-dihydropyridine derivatives exhibited no response the
anticoagulant activity.
4-ClC6H4
4-OHC6H4
4-NO2C6H4
4-CH3OC6H4
4-(CH3)2NC6H4
-furyl
-Ph
4-ClC6H4
4-OHC6H4
4-NO2C6H4
4-CH3OC6H4
4-(CH3)2NC6H4
2g

806
R.S. Kumar et al. / European Journal of Medicinal Chemistry 46 (2011) 804e810
Fig. 1. 1H NMR spectrum of the compound (2a).
Fig. 2. 13C NMR spectrum of the compound (2a).
ring in 4-position of 1,4-dihydiropyridine ring and 3,5-position of
CONH, CSNH2 groups. The compounds (2aeg) have very low
response in PT assay at concentrations (30 and 60 mg/mL).
4. Experimental
4.1. Chemistry
Themeltingpointswererecordedinopencapillarytubesandwere
uncorrected. The IR spectra were recorded in KBr on an FT-IR Shi-
madzu 8201 pc (4000e400 cmꢀ1) and the 1H NMR and 13C NMR were
recorded on a Bruker DRX-400 MHz. Mass spectra (EI) were recorded
on a Jeol JMS D-300 spectro meter operating at 70 eV. Elemental
analyses (C, H, N and S) were performed using an Elemental analyzer
model vario EL III. The purity of the compounds was checked by thin
layer chromatography (TLC) with silica gel plates.
The above structure (2aeg) showed that NH group (1), CONH
group (2), CSNH2 group (3), and substituted aromatic aldehyde (4)
presenting in the compounds (2aeg) 1,4-dihydropyridine deriva-
tives exhibited response the anticoagulant activity.
The compounds (2aeg) have higher anticoagulant activity
compared with compounds (1aeg) because the activity may be due
to the sulfur group present in the compounds (2aeg).
4.1.1. Synthesis of diethyl 4-(furan-2-yl)-2,6-dimethyl-
1,4-dihydropyridine-3,5-dicarboxylate (1a)
The compound (2a) is high relative clotting factor at concentra-
A mixture of ethyl acetoacetate (0.2 mol), furfuraldehyde
(0.1 mol) and ammonium hydroxide (0.1 mol) was made up in
methanol (20 mL). It was then heated and refluxed for 4 h. The
tions (30 and 60
mg/mL) compared with the compounds (2beg) and
Heparin also in APTT assay, the activity may be the presence of furyl

R.S. Kumar et al. / European Journal of Medicinal Chemistry 46 (2011) 804e810
807
Fig. 3. Mass spectrum of the compound (2a).
obtained solid was filtered and washed with water. The solid was
then re-crystallized using absolute ethanol. The above procedure
was followed for the synthesis of compounds (1beg).
C2eCH3 and C6eCH3),1.34 (t, 6H, C2eOCH2CH3 and C6eOCH2CH3);
13C NMR (DMSO-d6
/ppm) : 142.1, 110.6, 106.7, 152.5 (furyl ring),
151.8 (C-2,6), 33.2 (C-4), 102.3 (3,5-COOCH2CH3 ), 61.1(3,5-
COOCH2CH3 ), 14.9 (3,5-COOCH2CH3), 18.1 (2,6-CH3).
,
d
C17H21NO5; Elemental Analysis: Calculated for: C, 63.94; H, 6.63;
N, 4.39; Found: C, 63.84; H, 6.61; N, 4.30%; IR (KBr, cmꢀ1):
n
¼ 3349
(NeH str), 3030 (Ar-H), 2940(CeH str of CH3), 1745 (C]O, ester),
812 (Ar-H); 1H NMR (DMSO-d6):
4.1.2. Diethyl 2,6-dimethyl-4-phenyl-1,4-dihydropyridine-
3,5-dicarboxylate (1b)
d
¼ 8.20 (s, 1H, NH of pyridine
ring), 7.27 (s, 5H, Ph-ring), 6.10e6.27 (d, 2H, furyl ring), 4.72 (s, 2H,
C4eH), 4.20 (q, 4H, C3eOCH2CH3 and C5eOCH2CH3), 2.31 (s, 6H,
C19H23NO4; C, 69.28; H, 7.04; N, 4.25; Found: C, 69.24; H, 7.07; N,
4.30%; IR (KBr, cmꢀ1):
n
¼ 3350 (NeH str), 3034 (Ar-H), 2953 (CeH
O
O
O
O
O
O
H
N
H2N
H2N
-NHCS
N
H
H3C
NH
HN
N
H
H3C
NH
N
H
S
HN
CH 3
CH 3
S
N
H
S
NH2
NH2
m/z 350.30
m/z 409.23
O
O
O
O
O
O
-NH2
-NH2
-NHCS
H2N
N
H
NH
H2N
H3C
NH
NH2
NH2
N
H
H3C
CH3
N
H
CH3
m/z 291.30
m/z 276.29
O
O
O
O
O
-2CH3
-2CONH2
H2N
H3C
NH2
CH3
N
H
N
H
N
H
H3C
CH3
m/z 261.27
m/z 147.17
m/z 175.22
Scheme 2. Fragmentation pattern of compound (2a).

808
R.S. Kumar et al. / European Journal of Medicinal Chemistry 46 (2011) 804e810
Table 2
Table 3
Comparison of anticoagulant activity compounds (2aeg) with standard Heparin.
Comparison of anticoagulant activity of the compounds (2aeg).
Compounds no Concentration ( g/mL) Clotting time(s) APTT APTT index
m
Compounds no
Concentration (
mg/mL)
Clotting time(s) PT
PT index
2a
30
60
30
60
30
60
30
60
30
60
30
60
30
60
30
60
0
720.35
>1,000a
19.78a
27.47a
2.40
5.01
2.49
2a
30
60
30
60
30
60
30
60
30
60
30
60
30
60
0
240.42
420.21
0
45.8
0
33.8
45.6
70.8
24.7
52.8
45.7
93.4
21.6
48.2
19.8
12.14a
21.22a
0
2.31
0
1.24
2.30
3.5
8.82
2.66
2.03
4.71
1.09
2.43
1.0
2b
87.5
182.4
90.7
200.4
400.8
882.7
321.2
721.8
64.7
120.2
221.8
480.0
185.0
>1.000a
36.4
2b
2c
2c
5.50
2d
11.0a
24.25a
8.82
2d
2e
2e
19.82a
1.85
2f
2f
3.30
2g
6.09
2g
13.18a
5.08
Heparin
Control
Control
27.47a
1.0
Values are expressed as mean of five trails.
a
Shows highly significant index.
Values are expressed as mean of five trails.
a
Shows highly significant index.
1.28 (t, 6H, C2eOCH2CH3 and C6eOCH2CH3); 13C NMR (DMSO-d6 ,
/ppm) : 155.6, 116.2, 131.2138.2 (Ph-OH), 151.4 (C-2,6), 44.9(C-4),
str of CH3), 1755 (C]O, ester), 802 (Ar-H); 1H NMR (DMSO-d6):
d
d
¼ 8.25 (s,1H, NH of pyridine ring), 7.33e7.27 (m, 5H, Ph-ring), 4.70
101.4 (3,5-COOCH2CH3), 62.3 (3,5-COOCH2CH3), 14.1(3,5-
COOCH2CH3), 18.4 (2,6-CH3).
(s, 2H, C4eH), 4.22 (q, 4H, C3eOCH2CH3 and C5eOCH2CH3), 2.28 (s,
6H, C2eCH3 and C6-CH3), 1.32 (t, 6H, C2eOCH2CH3 and C6-
OCH2CH3); 13C NMR ( DMSO-d6
, d/ppm) : 125.1, 128.4, 127.1, 144.8
4.1.5. Diethyl 2,6-dimethyl-4-(4-nitrophenyl)-1,4-dihydropyridine-
3,5-dicarboxlate (1e)
(Phenyl ring), 150.7 (C-2,6), 101.9 (3,5-COOCH2CH3), 62.1 (3,5-
COOCH2CH3 ), 44.1(C-4), 19.1 (2,6-CH3 ), 15.4 ( 3,5-COOCH2 CH3).
C19H22N2O6; C, 60.95; H, 7.48; N, 7.48; Found: C, 60.91; H, 7.42;
N, 7.41%; IR (KBr, cmꢀ1):
n
¼ 3354 (NeH str), 3037 (Ar-H), 2973
(CeH str of CH3), 1762 (C]O, ester), 1536 (CeNO2), 812 (Ar-H); 1H
NMR (DMSO-d6) :
4.1.3. Diethyl 4-(4-chlorophenyl)-2,6-dimethyl-
1,4-dihydropyridine-3,5-dicarboxylate (1c)
d
¼ 8.11 (s, 1H, NH of pyridine ring), 8.13e7.47 (m,
C19H22ClNO4; C, 62.72; H, 6.09; N, 3.85; Found: C, 62.75; H, 6.07;
4H, Ph-ring), 4.79 (s,1H,C4eH), 4.25 (q, 4H, C3eOCH2CH3 and
C5eOCH2CH3), 2.31 (s, 6H, C2eCH3 and C6eCH3), 1.37 (t, 6H,
N, 3.81%; IR (KBr, cmꢀ1):
n
¼ 3332 (NeH str), 3074 (Ar-H), 2942
(CeH str of CH3),1741 (C]O, ester), 837 (CeCl), 787 (Ar-H); 1H NMR
(DMSO-d6):
C2eOCH2CH3 and C6eOCH2CH3); 13C NMR (DMSO-d6
, d/ppm) :
d
¼ 8.31 (s, 1H, NH of pyridine ring), 7.36e7.19 (m, 5H,
144.8, 123.6, 126.9, 151.0 (Ph-NO2), 152.2 (C-2,6), 43.9(C-4), 103.2
(3,5-COOCH2CH3), 60.8 (3,5-COOCH2CH3), 14.4 (3,5-COOCH2CH3),
18.8 (2,6-CH3), 31.4 (C-4).
Ph-ring), 4.76 (s, 1H, C4eH), 4.18 (q, 4H, C3eOCH2CH3 and C5-
OCH2CH3), 2.21 (s, 6H, C2eCH3 and C6eCH3), 1.34 (t, 6H,
C2eOCH2CH3 and C6eOCH2CH3); 13C NMR (DMSO-d6
, d/ppm) :
131.4, 128.1, 130.8, 142.5 (Ph-Cl), 152.5 (C-2,6), 34.6 (C-4), 103.9 (3,5-
COOCH2CH3), 60.3 (3,5-COOCH2CH3), 15.2 (3,5-COOCH2 CH3), 18.6
(2,6-CH3), 32.1(C-4).
4.1.6. Diethyl 4-(4-methoxyphenyl)-2,6-dimethyl-
1,4-dihydropyridine-3,5-dicarboxylate (1f)
C20H25NO5; C, 66.83; H, 7.01; N, 3.90; Found: C, 66.87; H, 7.07; N,
3.97%; IR (KBr, cmꢀ1):
n
¼ 3352 (NeH str), 3026 (Ar-H), 2961(CeH
str of CH3), 1742 (C]O, ester), 823 (Ar-H); 1H NMR (DMSO-
d6):
4.1.4. Diethyl 4-(4-hydroxyphenyl)-2,6-dimethyl-
1,4-dihydropyridine-3,5-dicarboxylate (1d)
d
¼ 8.21 (s, 1H, NH of pyridine ring), 6.86e7.17 (m, 5H, Ph-ring),
C19H23NO5; C, 66.07; H, 6.71; N, 4.06; Found: C, 66.10; H, 6.75; N,
4.69 (s,1H, C4eH), 4.23 ( q, 4H, C3eOCH2CH3 and C5eOCH2CH3),
3.84 (s, 3H, eOCH3), 2.23 (s, 6H, C2eCH3 and C6eCH3), 1.30 (t, 6H,
4.01%; IR (KBr, cmꢀ1):
n
¼ 3342 (NeH str), 3024 (Ar-H), 2922 (CeH
str of CH3), 1764 (C]O, ester), 1447 (CeOH), 814 (Ar-H); 1H NMR
(DMSO-d6):
C2eOCH2CH3 and C6eOCH2CH3); 13C NMR (DMSO-d6
, d/ppm) :
d
¼ 9.47 (s, 1H, COH), 8.41 (s, 1H, NH of pyridine ring),
157.2, 114.6, 129.3, 135.9 (Ph), 158.3(C-2,6), 102.3(3,5-COOCH2CH3),
61.5(3,5-COOCH2CH3), 55.7 (Ph-OCH3), 43.6 (C-4), 14.8 (3,5-
COOCH2CH3), 18.0 (2,6-CH3).
6.34e7.07 (m, 4H, Ph-ring), 4.67 (s, 1H, C4eH), 4.28 (q, 4H,
C3eOCH2CH3 and C5eOCH2CH3), 2.12 (s, 6H, C2eCH3 and C6eCH3),
Fig. 4. Anticoagulant activity variation of compounds (2aeg) were used two concen-
Fig. 5. Anticoagulant activity variation of compounds (2aeg) were used two concen-
trations at 30 and 60 (
m
g/mL) by APPT assay.
trations at 30 and 60 (mg/mL) by PT assay.

R.S. Kumar et al. / European Journal of Medicinal Chemistry 46 (2011) 804e810
809
(m/z, (relative abundance %)): 419.20 (Mþ, 20.1), 301.34, 241.28,
185.2, 157.21, 81.11.
Table 4
Comparison of the anticoagulant activity of the compounds (2aeg) by different
coagulant assays of APTT, PT.
4.1.10. 2,20-{[4-(4-chlorophenyl)-2,6-dimethyl-
1,4-dihydropyridine-3,5-diyl]dicarbonyl}dihydrazineca-
rbothioamide (2c)
Clotting time (s) concentration 60 (mg/mL)
Compounds
no
APTT
Relative clotting
potency
PT
Relative clotting
potency
>1.000a
182.4
200.4
882.7
721.8
120.2
480.0
36.4
27.47
5.01
5.50
24.25
19.82
3.30
13.18
1.0
240.42
45.8
33.8
70.8
52.8
93.4
48.2
19.8
72.8
2.31
1.24
3.5
2.66
4.71
2.43
1.0
C17H20ClN7O2S2; C, 44.98; H, 4.40, N, 21.60, S, 14.13; Found: C,
2a
2b
2c
2d
2e
2f
2g
Control
44.92; H, 4.46; N, 21.64; S,14.18%; IR (KBr, cmꢀ1):
n
¼ 3325 (NH), 3231
(NH2), 3198 (NHeC¼O), 3024 (Ar-H), 1707 (C]O), 1265 (C]S), 1097
(NeCeN), 827 (CeCl); 1H NMR (DMSO-d6 ):
d
¼ 9.41 (s, 2H, NH2), 8.41
(bs,1H, NH of pyridine ring), 8.11 (d, 1H, C3eCONH and C5eCONH),
7.38e7.14 (m, 5H, Ph-ring), 5.10 (s, 2H, C4-H), 2.45 (s, 6H, C2eCH3 and
C6eCH3), 2.08 (d, 1H, NHCS); 13C NMR (DMSO-d6 ):
d
¼ 128.7, 108.3,
a
143.2,152.8 (4C in furyl ring),105.3 (3,5, C inpyridine ring),166.2 (C]
O), 182.1 (C]S), 148.9 (2,6-C in pyridine ring), 39.3 (4C in pyridine
ring), 18.2 (2,6-CH3 in pyridine ring); MS (m/z, (relative abundance
%)): 453.12 (Mþ, 12.3), 335.78, 275.73, 219.70, 157.21, 81.11.
Clotting time >1000 s considered as 1000 s to calculate the relative clotting
potency.
4.1.7. Diethyl 4-(4-(dimethylamino)phenyl)-2,6-dimethyl-
1,4-dihydropyridine-3,5-dicarbo xylate (1g)
4.1.11. 2,20-{[4-(4-Hydroxyphenyl)-2,6-dimethyl-
1,4-dihydropyridine-3,5-diyl]dicarbonyl} dihydrazinecar-
bothioamide (2d)
C19H23NO4; C, 67.72; H, 7.58; N, 7.52; Found: C, 67.77; H, 7.52; N,
7.58%; IR (KBr, cmꢀ1):
n
¼ 3348 (NeH str), 3027 (Ar-H), 2956 (CeH
str of CH3) 1761 (C]O, ester), 808 (Ar-H); 1HNMR (DMSO-d6):
C17H21N7O2S2; C, 46.88; H, 4.86; N, 22.51; S, 14.72; Found: C,
d
¼ 8.37 (s,1H, NH of pyridine ring), 7.28e7.21 (m, 5H, Ph-ring), 4.70
46.81; H, 22.57; N, 4.81; S, 14.77%; IR (KBr, cmꢀ1):
n
¼ 3342 (NH),
3220 (NH2), 3028 (Ar-H), 3192 (NHeC¼O), 1242 (C]S), 1472
(CeOH), 1717 (C]O), 1091 (NeCeN); 1H NMR (DMSO-d6):
(s, 2H, C4eH), 4.22 (q, 4H, C3eOCH2CH3 and C5eOCH2CH3), 3.12 (s,
6H, eN(CH3)), 2,2.28 (s, 6H, C2eCH3 and C6eCH3), 1.32 (t, 6H,
d
¼ 9.71
C2eOCH2CH3 and C6eOCH2CH3); 13C NMR (DMSO-d6
,
d
/ppm) :
(s, 2H, NH2), 9.41 (s, 1H, OH), 8.64 (bs, 1H, NH of pyridine ring), 8.01
(d, 1H, C3eCONH and C5eCONH), 7.33e7.27 (m, 5H, Ph-ring), 5.11
(s, 2H, C4eH), 2.25 (s, 6H, C2eCH3 and C6eCH3), 2.02 (d, 1H,
128.3, 112.9, 148.5, 133.9 (Ph), 151.8 (C-2,6), 43.8 (C-4), 102.8 (3,5-
COOCH2CH3), 60.5 (3,5-COOCH2CH3), 40.8 (eN(CH3)2), 13.9 (3,5-
COOCH2CH3), 18.9(2,6-CH3).
eNHCS); 13C NMR (DMSO-d6):
d
¼ 155.8, 137.1, 130.3, 114.2 (4C in
furyl ring), 102.9 (C in pyridine ring), 164.9 (C]O), 184.6 (3,5, C]S),
148.1(2,6-C in pyridine ring), 43.8 (4C in pyridine ring), 19.2 (2,6-
CH3 in pyridine ring); MS (m/z, (relative abundance %)): 434.52
(Mþ, 27.2), 257.28, 201.26, 173.21, 157.21, 81.11.
4.1.8. Synthesis of 2,20-{[4-(furan-2-yl)-2,6-dimethyl-
1,4-dihydropyridine-3,5-diyl]dicarbonyl}dihydrazinecarbothi-
oamide (2a)
A reaction mixture consisting of compound 1a (0.1 mol), thio-
semicarbazide (0.2 mol) dissolved in ethanol (30 mL) and a few
drops of DMSO was added. It was then heated under reflux for 10 h.
The obtained solid was cooled and then poured in to crushed ice.
The solid was collected by filtration, washed with water and re-
crystallized using ethanol. The above procedure was repeated for
the synthesis of compounds (2beg).
4.1.12. 2,20-{[4-(4-nitrophenyl)-2,6-dimethyl-1,4-dihydropyridine-
3,5-diyl]dicarbonyl}dihydrazinecarbothioamide (2e)
C17H20N8O4S2;C, 43.96;H, 4.34;N, 24.12;S,13.81;Found:C, 43.91;
H, 4.38; N, 24.17; S,13.87%; IR (KBr, cmꢀ1):
n
¼ 3310 (NH), 3241 (NH2),
3218 (NHeC¼O), 3041 (Ar-H), 1272 (C]S), 1710 (C]O), 1091
(NeCeN),1530 (CeNO2); 1H NMR (DMSO-d6 ):
d
¼ 9.77 (s, 2H, NH2),
C15H19N7O3S2; C, 48.00; H, 4.68; N, 23.94; S, 15.66; Found: C,
8.60 (bs, 1H, NH of pyridine ring), 8.15 (d, 1H, C3eCONH and
C5eCONH), 7.42e7.18 (m, 5H, Ph-ring), 5.17 (s, 2H, C4-H), 2.31 (s, 6H,
C2eCH3 and C6eCH3), 2.08 (d, 1H, eNHCS); 13C NMR (DMSO-d6 ):
48.64; H, 5.57; N, 23.31; S, 15.34%; IR (KBr, cmꢀ1):
n
¼ 3370 (NH),
3221 (NH2), 3192 (NHeC¼O), 3037 (Ar-H),1263 (C]S),1721 (C]O),
1095 (NeCeN), 811 (Ar-H); 1H NMR (DMSO-d6):
d
¼ 9.64 (s, 2H,
d
¼ 143.2,123.7,126.7 (4C in furyl ring),102.9 (3,5-C in pyridine ring),
NH2), 8.46 (s, 1H, NH of pyridine ring), 8.12 (d, 1H, C3eCONH and
C5eCONH), 7.22 (s, 5H, Ph-ring), 6.14e6.32 (d, 2H, furyl ring), 5.15
(s, 2H, C4eH), 2.33 (s, 6H, C2eCH3 and C6eCH3), 2.14 (d, 1H,
164.9 (C]O), 181.9 (C]S), 149.9 (2,6-C in pyridine ring), 44.5 (4C in
pyridine ring), 19.7 (2,6-CH3 in pyridine ring); MS (m/z, (relative
abundance %)): 464.52 (Mþ, 12.78), 346.34, 286.20, 258.23, 230.21,
202.20, 81.11.
eNHCS); 13C NMR (DMSO-d6):
d
¼ 110.37, 106.79, 142.11, 152.79 (4C
in furyl ring), 102.79 (3,5-C in pyridine ring), 168.66 (C]O), 182.10
(C]S), 149.86 (2,6-C in pyridine ring), 38.70 (4C in pyridine ring),
18.72 (2,6-CH3 in pyridine ring); MS (m/z, (relative abundance %)):
409.45 (Mþ, 30.2), 350.39, 291.30, 261.27, 175.22, 147.12.
4.1.13. 2,20-{[4-(4-methoxyhenyl)-2,6-dimethyl-
1,4-dihydropyridine-3,5-diyl]dicarbonyl} dihydrazineca-
rbothioamide (2f)
C18H23N7O3S2; C, 48.09; H, 5.16; N, 21.81; S, 14.27; Found: C,
4.1.9. 2,20-[(2,6-dimethyl-4-phenyl-1,4-dihydropyridine-3,5-diyl)
dicarbonyl]dihydrazine carbothioamide (2b)
48.05; H, 5.19; N, 21.88; S, 14.21%; IR (KBr, cmꢀ1):
n
¼ 3323 (NH),
3251 (NHeC¼O), 3231 (NH2), 3034 (Ar-H), 1717 (C]O),1251 (C]S),
1091 (NeCeN), 808 (Ar-H); 1H NMR (DMSO-d6):
C17H21N7O2S2; C, 48.67; H, 5.50; N, 23.37; S, 15.29; Found: C,
d
¼ 9.82 (s, 2H,
48.64; H, 5.57; N, 23.31; S, 15.34%; IR (KBr, cmꢀ1):
n
¼ 3372 (NH),
3200 (NHeC¼O), 3218 (NH2), 3034 (Ar-H), 1718 (C]O), 1260 (C]
S), 1091 (NeCeN), 808 (Ar-H); 1H NMR (DMSO-d6):
NH2), 8.57 (bs, 1H, NH of pyridine ring), 8.05 (d, 1H, C3eCONH and
C5eCONH), 7.33e7.27 (m, 5H, Ph-ring), 5.21 (s, 2H, C4eH), 3.81 (s,
3H, eOCH3), 2.10 (d, 1H, eNHCS) 2.25 (s, 6H, C2eCH3 and C6eCH3);
d
¼ 9.62 (s, 2H,
NH2), 8.43 (s,1H, NH of pyridine ring), 8.09 (d, 1H, C3eCONH and
C5eCONH), 7.39e7.22 (m, 5H, Ph-ring), 5.17 (s, 2H, C4eH), 2.37 (s,
6H, C2eCH3 and C6eCH3), 2.12 (d, 1H, eNHCS); 13C NMR (DMSO-
13C NMR (DMSO-d6 ):
d
¼ 111.8, 108.3, 143.2, 152.8 (4C in furyl ring),
105.3 (3,5, C in pyridine ring), 166.2 (3,5, C]O), 181.7 (3,5, C]S),
147.7 (2,6-C in pyridine ring), 44.7 (4C in pyridine ring), 18.8 (2,6-
CH3 in pyridine ring), 55.9 (eOCH3); MS (m/z, (relative abundance
%)): 449.21 (Mþ, 29.12), 331.36, 271.31, 243.25, 215.29, 185.26,
157.21.
d6):
d
¼ 131.3, 128.5, 130.9, 141.8 (4C in furyl ring), 106.8 (3,5-C in
pyridine ring), 164.6 (C]O), 182.8 (C]S), 147.9 (2,6-C in pyridine
ring), 34.6 (4C in pyridine ring), 18.9 (2,6-CH3 in pyridine ring); MS

810
R.S. Kumar et al. / European Journal of Medicinal Chemistry 46 (2011) 804e810
4.1.14. 2,20-{[4-(4-dimethylnitrophenyl)-2,6-dimethyl-
1,4-dihydropyridine-3,5-diyl]dicarbonyl}dihydrazinecarbothi-
oamide (2g)
Where, APTTs and PTs were APTT and PT at determined sample
concentrations, respectively, while APTTc and PTc were those of the
control assays.
C19H26N8O2S2; C, 49.33; H, 5.67; N, 24.22; S, 13.86; Found: C,
49.37; H, 5.69; N, 24.27; S, 13.82%; IR (KBr, cmꢀ1):
n
¼ 3321 (NH),
3211 (NH2), 3118 (NHeC]O), 3021 (Ar-H),1712 (C]O),1248 (C]S),
1091 (NeCeN), 808 (Ar-H); 1H NMR (DMSO-d6):
5. Conclusion
d
¼ 9.66 (s, 2H,
We have synthesized a new series of 1,4-dihydropyridine
derivatives (1aeg) and (2aeg). The synthesized compounds (2aeg)
were screened for anticoagulant activity. Among these compounds,
2a was found to have highly response anticoagulation action (time
720.35 s) at a concentration of 30
compounds.
NH2), 8.52 (s, 1H, NH of pyridine ring), 8.03 (d, 1H, C3eCONH and
C5eCONH), 6.62e7.07 (m, 4H, Ph-ring), 5.13 (s, 2H, C4eH), 3.06 (s,
1H, eN(CH3)2)2, 19 (s, 6H, C2eCH3 and C6eCH3), 2.07 (d, 1H,
eNHCS); 13C NMR (DMSO-d6):
d
¼ 112.8, 134.8, 128.3, 148.2, 152.8
mg/mL compared with the other
(4C in furyl ring), 106.3 (3,5-C in pyridine ring), 165.2 (C]O), 181.1
(C]S), 147.9 (2,6-C in pyridine ring), 39.3 (4C in pyridine ring), 40.8
(N(CH3)2), 46.5 (4C in pyridine ring), 18.2 (2,6-CH3 in pyridine ring),
MS (m/z, (relative abundance %)): 462.22 (Mþ, 16.24), 432.56,
344.41, 284.35, 256.29, 213.23, 199.24, 185.26.
Acknowledgements
We wish to thank one of the authors, Dr. J. Selvin, Department of
Microbiology, Bharathidasan University, for his help in the antico-
agulant activity. We sincerely thank the Principal and management
committee of Jamal Mohamed College for providing laboratory
facilities and financial help.
4.2. Human blood plasma preparation
Human blood was collected from healthy individual donors in
conical tubes with 2.5% sodium citrate solution. The plasma was
separated from the blood cells by centrifuging at 5400 rpm at 4 ꢁC
for 20 min. The blood plasma was stored at ꢀ70 ꢁC until use.
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m
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APTT index ¼ APTTs=PTTc
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