Synthesis and reactions of some substituted heterocyclic systems as anti-arrhythmic agents

Article abstract of DOI:10.1007/s00706-007-0739-6

A series of substituted heterocyclic systems were prepared from N ¹-[4-(2-thienylmethylene)phenyl]-5-chloro-2-methoxybenzamide, which was prepared from the corresponding 5-chloroanisic acid (2-methoxy-4- chlorobenzoic acid) as starting material. Condensation of the thienylmethylene derivative with guanidine hydrochloride, urea, or thiourea afforded the aminopyrimidine, pyrimidinone, and thioxopyrimidine derivatives. The latter was condensed with chloroacetic acid to yield a thiazolopyrimidine, which was condensed with 2-thiophenealdehyde to yield the arylmethylene derivative, however, it was also prepared directly from thiopyrimidine by the action of chloroacetic acid, 2-thiophenealdehyde, and anhydrous sodium acetate. Treating of the thienylmethylene derivative with phenylhydrazine or hydrazine hydrate in dioxane afforded N-phenylpyrazoline and a pyrazoline, which was reacted with acetyl chloride in dioxane affording the N-acetyl analogue. The thienylmethylene derivative was reacted with malononitrile or ethyl cyanoacetate in the presence of ammonium acetate to yield the corresponding cyanoaminopyridine and cyanopyrimidone derivatives. Also, it was reacted with hydroxylamine hydrochloride in pyridine to give the oxime derivative, which was cyclized with acetic anhydride. On the other hand, condensation of the thienylmethylene derivative with ethyl cyanoacetate in the presence of sodium ethoxide or cyanothioacetamide gave the cyanopyrane and pyridine thione derivative, which was treated with ethyl chloroacetate affording the ethyl carboxylate derivative. The pharmacological screening showed that many of these compounds have good anti-arrhythmic activity and low toxicity.

Full text of DOI:10.1007/s00706-007-0739-6

Monatshefte fu¨r Chemie 139, 69–76 (2008)
DOI 10.1007/s00706-007-0739-6
Printed in The Netherlands
Synthesis and Reactions of Some Substituted Heterocyclic Systems
as Anti-arrhythmic Agents
ꢀ
Mohamed M. Abdulla
Research Units, Hi-Care Pharmaceutical Co., Cairo, Egypt
Received June 7, 2007; accepted June 12, 2007; published online November 14, 2007
# Springer-Verlag 2007
Summary. A series of substituted heterocyclic systems were
Introduction
prepared from N1-[4-(2-thienylmethylene)phenyl]-5-chloro-
In previous work our group has reported that certain
2-methoxybenzamide, which was prepared from the corre-
sponding 5-chloroanisic acid (2-methoxy-4-chlorobenzoic
acid) as starting material. Condensation of the thienylmethyl-
ene derivative with guanidine hydrochloride, urea, or thiourea
afforded the aminopyrimidine, pyrimidinone, and thioxopyr-
imidine derivatives. The latter was condensed with chloroace-
tic acid to yield a thiazolopyrimidine, which was condensed
with 2-thiophenealdehyde to yield the arylmethylene deriva-
tive, however, it was also prepared directly from thiopyrimi-
dine by the action of chloroacetic acid, 2-thiophenealdehyde,
and anhydrous sodium acetate. Treating of the thienylmethy-
lene derivative with phenylhydrazine or hydrazine hydrate in
dioxane afforded N-phenylpyrazoline and a pyrazoline, which
was reacted with acetyl chloride in dioxane affording the N-
acetyl analogue. The thienylmethylene derivative was reacted
with malononitrile or ethyl cyanoacetate in the presence of
ammonium acetate to yield the corresponding cyanoaminopy-
ridine and cyanopyrimidone derivatives. Also, it was reacted
with hydroxylamine hydrochloride in pyridine to give the
oxime derivative, which was cyclized with acetic anhydride.
On the other hand, condensation of the thienylmethylene de-
rivative with ethyl cyanoacetate in the presence of sodium
ethoxide or cyanothioacetamide gave the cyanopyrane and
pyridine thione derivative, which was treated with ethyl chloro-
acetate affording the ethyl carboxylate derivative. The phar-
macological screening showed that many of these compounds
have good anti-arrhythmic activity and low toxicity.
substituted pyridines and their chiral macrocyclic
derivatives have antidepressant, antimicrobial, anti-
cancer, analgesic, and anticonvulsant activities [1–7].
It has been reported that substituted heterocyclic
derivatives act as anti-inflammatory [8, 9] and an-
ticancer agents [10–12] and they are also used as
antimicrobial agents, in particular, their 3-substituted
derivatives [13–15]. Recently, some new substituted
pyrimidine and thiazolopyrimidine derivatives have
been synthesized, which exhibit analgetic, anti-inflam-
matory, antiparkinsonian, and androgenic-anabolic
activities [16, 17]. On the other hand, substituted
heterocyclic derivatives showed promising biolo-
gical activities [18–20]. In view of these observa-
tions and in continuation of our previous work in
heterocyclic chemistry, we synthesized some new
heterocyclic compounds containing pyridone, pyri-
dinethione, pyrazoline, and pyrimidine rings and
tested their anti-arrhythmic activities.
Results and Discussion
Keywords. 5-Chloroanisic acid; 2-Thiophenealdehyde; Thiox-
opyrimidine; Thiazolopyrimidine; Anti-arrhythmic activity.
Synthesis
The N1-[4-(2-thienylmethylene)phenyl]-5-chloro-
2-methoxybenzamide (2) was synthesized from
treating of N1-(4-acetylphenyl)-5-chloro-2-methoxy-
benzamide (1) with 2-thiophenealdehyde. Condensa-
tion of 2 with diamino reagents, namely, guanidine
ꢀ
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Corresponding author. E-mail: Mohamed_mostafa211@

70
M. M. Abdulla
hydrochloride, urea, or thiourea in methanolic sodi-
um methoxide afforded the corresponding aminopy-
rimidine 3, pyrimidinone 4, and thioxopyrimidine 5.
Also, 5 was condensed with chloroacetic acid in
a mixture of acetic acid=acetic anhydride in the
presence of anhydrous sodium acetate to yield the
corresponding thiazolopyrimidine 6, which was con-
densed with 2-thiophenealdehyde in the presence of
anhydrous sodium acetate and a glacial acetic acid=
acetic anhydride mixture to yield arylmethylene de-
rivative 7. However, the latter compound was also
prepared directly from 5 by the action of chloroace-
Scheme 1

Substituted Heterocyclic Systems as Anti-arrhythmic Agents
71
tic acid, 2-thiophenealdehyde, and anhydrous sodi-
um acetate in the presence of an acetic acid=acetic
anhydride mixture (Scheme 1).
Cyclocondensation of 2 with phenylhydrazine gave
N-phenylpyrazoline 8, but treatment with hydrazine
hydrate in refluxing dioxane afforded the pyrazoline
9, which was treated with acetyl chloride in dioxane
to yield the 1-acetylpyrazoline 10, which was also pre-
pared directly from 2 by the action of hydrazine hy-
drate in the presence of an acetic acid=acetic anhydride
Scheme 2

72
M. M. Abdulla
mixture. While, condensation of 2 with malononitrile
or ethyl cyanoacetate in the presence of ammonium
acetate in ethanol gave cyanoaminopyridine 11 and
cyanopyridone 12. A one-step synthesis of 11 and 12
could be achieved by condensation of 1 with 2-thio-
phenealdehyde and malononitrile or ethyl cyanoace-
tate in the presence of ammonium acetate (Scheme 2).
Condensation of 2 with hydroxylamine hydro-
chloride in pyridine afforded the corresponding 3-
ꢀ-(2-thienyl)acryloylpyridine oxime 13. The latter
was cyclized with refluxing acetic anhydride to the
oxazole 14, which was also prepared directly from 2
by reaction with hydroxylamine hydrochloride in the
presence of anhydrous sodium acetate in refluxing
acetic acid. Condensation of 2 with ethyl cyanoace-
tate in ethanol in the presence of sodium ethoxide
gave cyanopyridone 15. But, 2 was condensed with
cyanothioacetamide in the presence of ammonium
acetate in n-butanol to yield pyridinethione 16, which
was treated with ethyl chloroacetate in the presence
of EtONa to give the ethyl-3-aminothieno[2,3-b]pyr-
idine-2-carboxylate (17) (Scheme 3).
Pharmacological Screening
Procaine amide, 5 mg=kg i.v. and lidocaine 5 mg=kg
i.v. led to an increase in LD100 by 65%, which cor-
responds to a LD100 of approximately 9 ꢁg=100 mg.
All the tested compounds showed potent activities
and the degree of potency in descending order is
10, 9, 8, 14, 17, 7, 6, (4 and 14), (3, 5, and 13), 16,
12, and 11 (cf. Table 1).
Scheme 3

Substituted Heterocyclic Systems as Anti-arrhythmic Agents
73
Table 1. Anti-arrhythmic activities of the newly synthesized
compounds
Determination of Acute Toxicity (LD50)
The LD50 was determined by using rats. They were
injected with different increasing doses of the syn-
thesized compounds. The dose that killed 50% of
the animals (cf. Table 2) was calculated according
to Austen and Brocklehurst [21].
Compound
in (5 mg=kg)
Percentage increase
in LD100=%
3
4
5
6
7
75 ꢅ 0.091
76 ꢅ 0.081
75 ꢅ 0.071
81 ꢅ 0.063
83 ꢅ 0.064
93 ꢅ 0.071
94 ꢅ 0.061
95 ꢅ 0.082
71 ꢅ 0.093
73 ꢅ 0.090
75 ꢅ 0.089
92 ꢅ 0.091
76 ꢅ 0.090
74 ꢅ 0.091
85 ꢅ 0.099
Experimental
8
9
All melting points were taken on Electrothermal IA 9000
series digital melting point apparatus. Elemental analytical
data (in accord with the calculated values) were obtained from
the microanalytical unit, Cairo University, Cairo, Egypt. The
IR spectra (KBr) were recorded on a Shimadzu CVT-04 spec-
trophotometer. The 1H NMR spectra were measured with Jeol
270 MHz in DMSO-d6 or CDCl3. The chemical shifts were
recorded in ꢂ (ppm) relative to TMS. The mass spectra were
obtained using a Varian MAT CH-5 spectrometer (70 eV). All
reactions were followed by TLC (silica gel, aluminum sheets
60 F254, Merck).
10
11
12
13
14
15
16
17
All data were significantly different from the normal control
value at P ꢆ 0.05
N1-[4-(2-Thienylmethylene)phenyl]-5-chloro-2-
Table 2. Acute toxicity (LD50) of the synthesized compounds
methoxybenzamide (2, C21H16NO3ClS)
A mixture of 0.303 g acetyl derivative 1 (1mmol), 0.112 g 2-
thiophenealdehyde (1mmol) in 20cm3 absolute ethanol, and
0.5 cm3 piperdine was refluxed for 30min. The reaction mix-
ture was left overnight at room temperature, the obtained solid
was filtered off, and crystallized to give 0.26g 2 (66%). Mp
258–259ꢂC (MeOH); IR (film): ꢃꢀ¼ 3336–3230 (NH), 1692,
LD50
Compound no.
mg=kg
3
4
5
6
7
341 ꢅ 0.19
454 ꢅ 0.18
561 ꢅ 0.21
741 ꢅ 0.11
842 ꢅ 0.13
951 ꢅ 0.17
743 ꢅ 0.18
681 ꢅ 0.11
727 ꢅ 0.11
751 ꢅ 0.19
762 ꢅ 0.19
734 ꢅ 0.19
772 ꢅ 0.18
709 ꢅ 0.17
753 ꢅ 0.18
1
1680 (2 CO) cmꢃ1; H NMR (CDCl3): ꢂ ¼ 3.56 (s, OCH3),
6.90 (d, CH-arylidene), 7.12–7.82 (m, Ar–H þ CH-arylidene),
10.64 (s, NH, exchangeable with D2O) ppm; MS (EI, 70 eV):
m=z ¼ 398 (Mþ, 22) and at 267 (100, base peak).
8
9
10
11
12
13
14
15
16
17
Substituted Pyrimidine Derivatives 3, 4, and 5
A solution of 0.398 g 2 (1mmol), 1.2mmol diamino reagents,
namely, guanidine hydrochloride, urea, or thiourea and ꢄ0.1 g
sodium methoxide (1.5mmol) in 25 cm3 absolute methanol
was refluxed for 2–4 h. The reaction mixture was evaporated
to dryness under reduced pressure, dried, and crystallized to
give 0.3g 3 (72%), 0.29g 4 (65%), and 0.39g 5 (86%).
N1-{4-[2-Amino-6-(2-thienyl)-4-pyrimidinyl]phenyl}-5-
chloro-2-methoxybenzamide (3, C22H19ClN4O2S)
All data were significantly different from the normal control
value at P ꢆ 0.05
Mp 198–199ꢂC (AcOH); IR (film): ꢃꢀ¼ 3455–3210 (NH, NH2),
1694 (CO) cmꢃ1; 1H NMR (CDCl3): ꢂ ¼ 3.57 (s, OCH3), 5.20
(d, Ha-pyrimidine), 5.44 (s, NH2, exchangeable with D2O),
6.75–7.94 (m, Ar–H þ Hb-pyrimidine), 10.44 (s, NH, ex-
changeable with D2O) ppm; MS (EI, 70eV): m=z ¼ 439
(Mþ, 6) and 198 (100, base peak).
Structural Activity Relationship (SAR)
ꢁ The five membered ring derivatives (namely pyr-
azolines and isoxazoles) showed more potent anti-
arrhythmic activities than the six membered ring
derivatives (namely pyridines, pyrimidines, and
pyrans).
N1-{4-[6-(2-Thienyl)-2-oxo-4-pyrimidinyl]phenyl}-5-chloro-
2-methoxybenzamide (4, C22H18ClN3O3S)
ꢁ Hetero-aromaticity increases the anti-arrhythmic
Mp 205–207ꢂC (AcOH); IR (film): ꢃꢀ¼ 3455–3215 (NH),
activity.
ꢁ Fused ring systems give anti-arhythmic activity
but to a lower extent.
1
1695 (CO), 1226 (CS) cmꢃ1; H NMR (CDCl3): ꢂ ¼ 3.55 (s,
OCH3), 5.19 (d, Ha-pyrimidine), 7.16–8.05 (m, Ar–H þ Hb-
pyrimidine), 8.40 and 8.52 (2s, 2NH, exchangeable with

74
M. M. Abdulla
D2O), 10.58 (s, NH, exchangeable with D2O) ppm; MS (EI,
70eV): m=z ¼ 440 (Mþ, 100, base peak).
mixed m.p., and Rf value on TLC by comparison with an
authentic sample from method A.
N1-{4-[1-Phenyl-5-(2-thienyl)-4,5-dihydro-1H,3-pyrazolyl]-
phenyl}-5-chloro-2-methoxybenzamide (8, C27H22ClN3O2S)
A solution of 0.398 g 2 (1mmol) and 0.108g phenyl hydrazine
(1.5mmol) in 15cm3 absolute ethanol was refluxed for 5 h.
The reaction mixture was poured onto ice, the obtained solid
was collect by filtration, dried, and crystallized to give 0.41 g
8 (82%). Mp 212ꢂC (BuOH); yield 62%; IR (film): ꢃꢀ¼ 3358–
N1-{4-[6-(2-Thienyl)-2-thioxo-4-pyrimidinyl]phenyl}-5-
chloro-2-methoxybenzamide (5, C22H18ClN3O2S2)
Mp 218–220ꢂC (AcOH); IR (film): ꢃꢀ¼ 3465–3218 (NH),
1
1696 (CO), 1228 (CS) cmꢃ1; H NMR (DMSO-d6): ꢂ ¼ 3.56
(s, OCH3), 5.18 (d, Ha-pyrimidine), 7.05–8.00 (m, Ar–H þ
Hb-pyrimidine), 8.44 and 8.55 (2s, 2NH, exchangeable with
D2O), 10.62 (s, NH, exchangeable with D2O) ppm; MS (EI,
70eV): m=z ¼ 456 (Mþ, 100, base peak).
3155 (NH), 1695 (CO) cmꢃ1
;
1H NMR (CDCl3): ꢂ ¼
1.96–2.18 (d, CH2-pyrazoline), 3.56 (s, OCH3), 3.92 (m,
CH-pyrazoline), 7.10–7.94 (m, Ar–H), 10.55 (s, NH, ex-
changeable with D2O) ppm; MS (EI, 70eV): m=z ¼ 488
(Mþ, 100, base peak).
7-{4-[4-(5-Chloro-2-methoxybenzoyl)amino]phenyl}-3-oxo-
5-(2-thienyl)-2,3-dihydro-5H-thiazolo[3,2-a]pyrimidine
(6, C24H18ClN3O3S2)
A mixture of 0.456 g 5 (1mmol) and 0.1 g chloroacetic acid
(1mmol) was dissolved in 40 cm3 of a mixture of AcOH:
Ac2O (1:3) in the presence 1.5 g anhydrous sodium acetate,
and was refluxed for 6 h. The reaction mixture was cooled and
poured onto cold water with stirring, the formed solid was
filtered off, and crystallized to give 0.40g 6 (82%). Mp 192–
194ꢂC (EtOH); IR (film): ꢃꢀ¼ 3358–3310 (NH), 1732 (CO),
N1-{4-[5-(2-Thienyl)-4,5-dihydro-1H-3-pyrazolyl]phenyl}-
5-chloro-2-methoxybenzamide (9, C21H18ClN3O2S)
A solution of 0.398g 2 (1mmol) and 0.4cm3 hydrazine hydrate
(8mmol) in 20cm3 dioxane was refluxed for 2 h. The solvent
was evaporated under reduced pressure, the residuewas washed
with n-hexane, and crystallized to give 0.3g 9 (72%). Mp 198–
200ꢂC (EtOH); IR (film): ꢃꢀ¼ 3445–3295 (NH), 1698 (CO)
1692 (CONH) cmꢃ1
;
1H NMR (DMSO-d6): ꢂ ¼ 3.56 (s,
1
cmꢃ1; H NMR (CDCl3): ꢂ ¼ 2.12–2.25 (d, CH2-pyrazoline),
OCH3), 3.70 (s, CH2-thiazole), 5.54 (d, Ha, pyrimidine), 7.22–
7.66 (m, Ar–H þ Hb-pyrimidine), 10.35 (s, NH, exchangeable
with D2O) ppm; 13C NMR (CDCl3): ꢂ ¼ 56.22 (OCH3), 164.85
(CONH2), 115.65, 119.7, 121.50, 126.05, 126.7, 128.55, 132.5,
133.21, 135.05, 156.84 (Ph-C), 45.65, 114.04, 142.10, 162.75
(pyrimidinyl-C), 123.56, 126.70, 126.90, 139.40 (thionyl-C),
171.45 (CO, thiazole), 30.86 (CH2, thiazole) ppm; MS (EI,
70eV): m=z ¼ 496 (Mþ, 24) and 230 (base peak, 100).
3.54 (s, OCH3), 3.85 (m, CH-pyrazoline), 6.94 (s, NH, ex-
changeable with D2O), 7.25–7.95 (m, Ar–H), 10.54 (s, NH,
exchangeable with D2O) ppm; 13C NMR (CDCl3): ꢂ ¼ 56.18
(OCH3), 165.05 (CONH2), 45.70, 62.64, 156.00 (pyrazoline-
C), 115.68, 118.57, 122.95, 128.34, 129.36, 131.34, 133.80,
133.92, 139.38, 141.51, 147.92, 148.10 (Ar–C) ppm; MS (EI,
70eV): m=z ¼ 412 (Mþ, 36) and 314 (100, base peak).
N1-{4-[1-Acetyl-5-(2-thienyl)-4,5-dihydro-1H-3-pyrazolyl]-
phenyl}-5-chloro-2-methoxybenzamide (10, C23H20ClN3O3S)
Method A: A mixture of 0.412g 9 (1mmol) and ꢄ0.1g acetyl
chloride (1mmol) in 30 cm3 dioxane was stirred at room tem-
perature for 5 h. The reaction mixture was evaporated under
reduced pressure, the product was extracted with dichloro-
methane, washed with aqueous sodium bicarbonate, dried over
anhydrous Na2SO4, evaporated under reduced pressure, and
crystallized to give 0.26 g 10 (58%). Mp 264–266ꢂC (EtOH);
IR (film): ꢃꢀ¼ 3336–3150 (NH), 1722, 1698 (2 CO) cmꢃ1; 1H
NMR (CDCl3): ꢂ ¼ 1.82 (s, CH3), 2.05–2.21 (m, CH2-pyrazo-
line), 3.55 (s, OCH3), 3.86 (m, CH-pyrazoline), 7.23–7.96 (m,
Ar–H), 10.42 (s, NH, exchangeable with D2O) ppm; MS (EI,
70eV): m=z ¼ 454 (Mþ, 188) and 278 (100, base peak).
Method B: A mixture of 0.398 g 2 (1mmol) and 0.4 cm3
hydrazine hydrate (8mmol) in 40cm3 of a mixture of
AcOH:Ac2O (3:1) was refluxed for 3 h, allowed to cool, and
then poured onto water. The obtained solid was filtered off and
crystallized to give 0.36g 10 (74%).
7-{4-[4-(5-Chloro-2-methoxybenzoyl)amino]phenyl}-2-(2-
thienylmethylene)-3-oxo-5-(2-thienyl)-2,3-dihydro-5H-
thiazolo[3,2-a]pyrimidine arylidine (7, C29H20ClN3O3S3)
Method A: A mixture of 0.456 g 5 (1mmol), 0.1 g chloroacetic
acid (1mmol), 1.5g anhydrous sodium acetate in 40cm3 of a
mixture of AcOH:Ac2O (1:3) and 0.112 g 2-thiophenealdehyde
(1mmol) was refluxed for 6 h. The reaction mixture was
cooled and poured onto ice-water, the obtained solid was col-
lected by filtration, and crystallized to give 0.40 g 7 (68%). Mp
210–212ꢂC (AcOH); IR (film): ꢃꢀ¼ 3365–3315 (NH), 1708
(CO, this shift to lower frequency is due to conjugation with
1
the exocyclic double bond), 1688 (CONH) cmꢃ1; H NMR
(DMSO-d6): ꢂ ¼ 3.55 (s, OCH3), 5.54 (d, Ha, pyrimidine),
7.28–7.72 (m, Ar–H þ Hb-pyrimidine þ benzylic proton),
10.22 (s, NH, exchangeable with D2O) ppm; 13C NMR
(CDCl3): ꢂ ¼ 56.08 (OCH3), 164.88 (CONH2), 115.62, 119.65,
121.45, 126.10, 126.72, 128.54, 132.56, 133.24, 135.15,
156.80 (Ph–C), 45.60, 114.12, 142.15, 162.95 (pyrimidinyl-
C), 123.52, 126.46, 126.86, 127.00, 128.10, 130.05, 137.66,
139.35 (thionyl-C), 165.90 (CO, thiazole), 121.66 (CH-aryli-
dine) ppm; MS (EI, 70 eV): m=z ¼ 590 (Mþ, 100, base peak).
Method B: A mixture of 0.496 g 6 (1mmol) and 0.112 g 2-
thiophenealdehyde (1mmol) in 40 cm3 of a mixture of AcOH:
Ac2O (1:3) was refluxed for 5 h, allowed to cool, then poured
onto water, the solid formed was collected by filtration, and
crystallized to yield 0.44g 7 (75%), as identified by its mp,
N1-{4-[6-Amino-5-cyano-2-(2-thienyl)-4-pyridyl]phenyl}-
5-chloro-2-methoxybenzamide (11, C24H17ClN4O2S)
Method A: A solution of 0.398g 2 (1mmol), ꢄ0.1 g malono-
nitril (1.2mmol), and 0.616 g ammonium acetate (8mmol) in
25cm3 n-butanol was refluxed for 3 h. After cooling, the pre-
cipitate was filtered off, dried, and crystallized to give 0.4g 11

Substituted Heterocyclic Systems as Anti-arrhythmic Agents
75
(88%). Mp 186–188ꢂC (acetone=MeOH); IR (film): ꢃꢀ¼
oxazole), 3.54 (s, OCH3), 4.2 (m, CH-oxazole), 7.10–7.96
(m, Ar–H), 10.57 (s, NH, exchangeable with D2O) ppm; MS
(EI, 70 eV): m=z ¼ 413 (Mþ, 100, base peak).
3462–3254 (NH, NH2), 2222 (CN), 1698 (CO) cmꢃ1 1H
;
NMR (CDCl3): ꢂ ¼ 3.54 (s, OCH3), 5.46 (s, NH2, exchange-
able with D2O), 7.12–7.95 (m, Ar–H), 10.58 (s, NH, ex-
changeable with D2O) ppm; 13C NMR (CDCl3): ꢂ ¼ 56.22
(OCH3), 116.15 (CN), 164.70 (CONH), 111.42, 137.40,
145.05, 163.74, 176.05 (pyridine-C), 111.64, 113.08, 117.85,
125.65, 127.44, 129.00, 130.21, 134.15, 141.12, 141.84,
143.18, 154.70 (Ar–C) ppm; MS (EI, 70 eV): m=z ¼ 461
(Mþ, 100, base peak).
Method B: A mixture of 0.303 g 1 (1mmol), ꢄ0.10g mal-
ononitrile (1mmol), and 0.616 g ammonium acetate (8mmol)
in 20 cm3 n-butanol was refluxed for 5 h. After cooling, the
formed product was collected by filtration, dried, and crystal-
lized to give 0.35g 11 (75%).
Method B: A mixture of 0.398 g 2 (1mmol), ꢄ0.1 g
NH2OHꢇ HCl (1 mmol), and 0.082 g anhydrous sodium ace-
tate (1mmol) in 30cm3 glacial acetic acid was refluxed for
6 h. The reaction mixture was cooled, poured into ice-water,
the obtained solid was collected by filtration, washed with
water, dried (under vacuum), and crystallized to give 0.24g
(58%) 14 as identified by mp and TLC in comparison with an
authentic sample.
N1-{4-[3-Cyano-2-oxo-6-(2-thienyl)-2H-4-pyranyl]phenyl}-
5-chloro-2-methoxybenzamide (15, C24H15ClN2O4S)
A solution of 0.398 g 2 (1mmol), 0.13 cm3 ethyl cyanoacetate
(1.2mmol), and 68mg sodium ethoxide (1mmol) in 20cm3
absolute ethanol was refluxed for 2 h. The reaction mixture
was evaporated under reduced pressure, the residue was solid-
ified with n-hexane, the obtained solid was filtered off, and
crystallized to give 0.36 g 15 (77%). Mp 276–278ꢂC (MeOH);
IR (film): ꢃꢀ¼ 3425–3250 (NH), 2226 (CN), 1718, 1697 (2
N1-{4-[3-Cyano-2-oxo-6-(2-thienyl)-1,2-dihydro-4-pyridinyl]-
phenyl}-5-chloro-2-methoxy-benzamide (12, C24H16ClN3O3S)
Method A: A solution of 0.398 g 2 (1mmol), 0.13cm3 ethyl
cyanoacetate (1.2mmol), and 0.616 g ammonium acetate
(8mmol) in 20cm3 n-butanol was refluxed for 2 h. The formed
precipitate after cooling was filtered off, dried and crystallized
to give 0.36 g 12 (79%). Mp 158–160ꢂC (AcOH); IR (film):
1
CO) cmꢃ1; H NMR (CDCl3): ꢂ ¼ 3.54 (s, OCH3), 7.05 (s,
pyrane-H), 7.08–7.95 (m, Ar–H), 10.49 (s, NH, exchangeable
with D2O) ppm; 13C NMR (CDCl3): ꢂ ¼ 56.36 (OCH3), 117.84
(CN), 163.72 (CONH), 106.05, 131.10, 145.15, 154.72,
157.76 (pyrane-C), 114.70, 116.46, 117.78, 128.25, 129.45,
129.80, 133.88, 134.10, 139.88, 144.92, 144.96, 153.15 (Ar–
C) ppm; MS (EI, 70 eV): m=z ¼ 463 (Mþ, 46) and 352 (100,
base peak).
ꢃꢀ¼ 3450–2678 (NH), 2220 (CN), 1694, 1676 (2 CO) cmꢃ1
;
1H NMR (CDCl3): ꢂ ¼ 3.56 (s, OCH3), 7.16–7.98 (m, Ar–H),
8.70 (s, NH exchangeable with D2O), 10.54 (s, NH, exchange-
able with D2O) ppm; MS (EI, 70eV): m=z ¼ 462 (Mþ, 22) and
238 (100, base peak).
Method B: A mixture of 0.303 g 1 (1mmol), ꢄ0.13g ethyl
cyanoacetate malononitrile (1mmol), and 0.6g ammonium
acetate (8mmol) in 20cm3 n-butanol was refluxed for 4 h.
After cooling, the formed product was collected by filtration,
dried, and crystallized to give 0.35 g 12 (75%).
N1-{4-[3-Cyano-2-thioxo-6-(2-thienyl)-1,2-dihydro-4-
pyridinyl]phenyl}-5-chloro-2-methoxy-benzamide
(16, C24H16ClN3O2S2)
A solution of 0.398 g 2 (1mmol), 0.12 g cyanothioacetamide
(1.2mmol), and 0.616 g ammonium acetate (8mmol) in
25cm3 n-butanol was refluxed for 3 h. After cooling the pre-
cipitated was filtered off, dried, and crystallized to give 0.36 g
16 (76%). Mp 245–247ꢂC (EtOH); IR (film): ꢃꢀ¼ 3455–3258
N1-{4-[(2-Thienyl)acryloylphenyl] oxime}-5-chloro-2-
methoxy-benzamide (13, C21H17ClN2O3S)
A mixture of 0.398 g 2 (1mmol) and ꢄ0.1 g NH2OHꢇ HCl
(1mmol) in 30 cm3 dry pyridine was refluxed for 6 h. The
reaction mixture was cooled, poured into ice-water, and neu-
tralized with 1 N HCl. The obtained solid was collected by
filtration, dried (under vacuum), and crystallized to give 0.26g
(NH), 2222 (CN), 1695 (CO), 1240 (CS) cmꢃ1 1H NMR
;
(CDCl3): ꢂ ¼ 3.55 (s, OCH3); 4.54 (s, CSNH, exchangeable
with D2O), 7.15–8.10 (m, Ar–H), 10.61 (s, NH, exchangeable
with D2O) ppm; 13C NMR (CDCl3): ꢂ ¼ 56.18 (OCH3),
117.76 (CN), 164.90 (CONH), 112.88, 138.94, 145.37,
163.76, 171.54 (pyridine-C), 112.92, 118.12, 126.84, 127.79,
129.72, 129.89, 134.10, 134.20, 140.91, 141.21, 145.38,
153.12 (Ar–C) ppm; MS (EI, 70eV): m=z ¼ 478 (Mþ, 16)
and 230 (100, base peak).
(64%) 13. Mp 236–238ꢂC (AcOH); IR (film): ꢃꢀ¼
3536–
1
3265 (OH, NH), 1678 (C¼N), 1610 (C¼C) cmꢃ1; H NMR
(DMSO-d6): ꢂ ¼ 2.46 (s, OH, exchangeable with D2O), 3.56
(s, OCH3), 6.36 (d, J ¼ 14.55 Hz, CH-olefinic), 6.76 (d,
J ¼ 14.60 Hz, CH-olefinic), 7.14–7.98 (m, Ar–H), 10.55 (s,
NH, exchangeable with D2O) ppm; MS (EI, 70 eV): m=z ¼
413 (Mþ, 100, base peak).
Ethyl 3-amino-4-{4-[(5-chloro-2-methoxybenzoyl)amino]-
phenyl}-6-(2-thienyl)thieno[2,3-b]-pyridine-2-carboxylate
(17, C28H22N3O4ClS2)
N1-{4-[5-(2-Thienyl)oxazolyl]phenyl}-5-chloro-2-methoxy-
benzamide (14, C21H17ClN2O3S)
Method A: A solution of 0.413 g 13 (1mmol) in 50cm3 acetic
anhydride was refluxed for 10h. After cooling, the reaction
mixture was poured into ice-water, the obtained solid was
filtered off, washed with water, dried (under vacuum), and
crystallized to give 0.27 g (65%) 14. Mp 211–213ꢂC (EtOH);
IR (KBr): ꢃꢀ¼ 3348–3235 (NH), 1666 (C¼N), 1608–1600
A solution of 0.478 g 16 (1mmol), 0.122g ethyl chloroacetate
(1mmol), and 0.68g sodium ethoxide (10 mmol) in 10cm3
ethanol was refluxed for 4 h. The reaction mixture was evapo-
rated under reduced pressure, the obtained solid was filtered
off, dried, and crystallized to give 0.33g 17 (58%). Mp 296–
298ꢂC (MeOH); IR (film): ꢃꢀ¼ 3492–3268 (NH, NH2), 1732,
1696 (2 CO) cmꢃ1; 1H NMR (CDCl3): ꢂ ¼ 1.13 (t, CH3), 3.57
1
(C¼C) cmꢃ1; H NMR (DMSO-d6): ꢂ ¼ 1.6–1.9 (m, CH2-

76
M. M. Abdulla: Substituted Heterocyclic Systems as Anti-arrhythmic Agents
(s, OCH3), 4.52 (q, OCH2), 5.73 (s, NH2, exchangeable with
D2O), 7.10–7.98 (m, Ar–H), 10.62 (s, NH, exchangeable with
D2O) ppm; MS (EI, 70 eV): m=z ¼ 564 (Mþ, 25) and 528
(100, base peak).
[4] Amr AE (2005) Z Naturforsch 60b: 990
[5] Amr AE, Sayed HH, Abdulla MM (2005) Arch Pharm
Chem Life Sci 338: 433
[6] Abo-Ghalia MH, Amr AE (2004) Amino Acids 26: 283
[7] Hammam AG, Fahmy AFM, Amr AE, Mohamed AM
(2003) Ind J Chem 42B: 1985
Pharmacological Assay
[8] Bunker AM, Edmund JJ, Berryman KA, Walker DN,
Flynn MA, Welch KM, Doherty AM (1996) Bioorg Med
Chem Lett 6: 1061
[9] Yao-Chang X, Johnson KW, Phebus LA, Cohen M,
Nelson DL, Schenk K, Walker CD, Fritz JE, Kolder
SW, Letourneau NE, Murff RE, Zgombick JM, Calligaro
DO, Audia JE, Schaust JM (2001) J Med Chem 44: 4031
[10] Bailly C, Dassonneville L, Colson P, Houssier C,
Fukasawa K, Nishimura S, Yoshinari T (1999) Cancer
Res 59: 2853
Anti-arrhythmic Activity [22–27]
Animals obtained from the animal house colony of the National
Research Center, Cairo, Egypt. All animals were allowed free
access to water and kept on a constant standard diet.
Purpose and Rational
The plant alkaloid aconitine persistently activates sodium
channel. Infusion of aconitine in the anesthetized rat causes
ventricular arrhythmias. Drugs considered to have anti-arrhy-
thmic properties can be tested in aconitine-intoxicated rats.
[11] van Hattum AH, Pinedo HM, Schluper HNM, Erkelens
CAM, Tongo A, Boven E (2002) Biochem Pharm 64:
1267
Procedure
[12] He L, Chang X, Chou TC, Savaraj N, Cheng CC (2003)
Eur J Med Chem 38: 101
[13] Sugiyama H, Yokokawa F, Aoyama T, Shiori T (2001)
Tetrahedron Lett 42: 7277
[14] Yang CG, Liu G, Jiany B (2002) J Org Chem 67: 9392
[15] Min Y, Borgne M, Pagnez F, Baut G, Pape P (2003) Eur J
Med Chem 38: 75
Nineteen groups of male Ivanovas rats weighing 300–350 g
are used, each group of 12 animals. The first group represents
the control group and received no drug, while the second
received aconitine and groups 3–17 received the tested newly
synthesized agents, group 18 received the standard reference
drug procaine amide, while group 19 received the second
standard reference drug lidocaine.
[16] Amr AE, Hegab MI, Ibrahim AA, Abdalah MM (2003)
Monatsh Chem 134: 1395
[17] Amr AE, Abdulla MM (2002) Ind J Heterocycl Chem
12: 129
[18] Attia A, Abdel-Salam OI, Abou-Ghalia MH, Amr AE
(1995) Egypt J Chem 38: 543
[19] Attia A, Abdel-Salam OI, Amr AE (2000) Egypt J Chem
43: 297
The animals are anesthetized by intra peritoneal injection of
1.25g=kg urethane: 5 mg=kg aconitine dissolved in 0.1 N nitric
acid is adminstered by continuous infusion into the saphenous
vein of 0.1 cm3=min and the ECG in lead II is recorded every
30 sec. The test compound is injected i.v. at a screening dose
of 3 mg=kg 5 min before the start of the aconitine infusion, 24
animals are used per compound.
[20] Attia A, Abdel-Salam OI, Amr AE (1997) Egypt J Chem
40: 317
[21] Austen KF, Brocklehurst WE (1961) J Exp Med 113:
521
[22] Walker MJA, Curtius MJ, Hearse DJ, Campbell RWF,
Jams MJ, Yellon DM, Coker SM, Harness JB, Harron
DWG, Miggins AJ, Julian DG, Lab MJ, Manning AS,
Northover BJ, Parratt JR, Riemrsma RA, Riva E, Russell
DC, Sheridan DJ, Winslow E, Woodward B (1988)
Cardiovasc Res 22: 447
Evaluation
The anti-arrhythmic effect of a test compound is measured by
the amount of aconitine=100 g animal.
Duration of infusion which induces, ventricular extra
systoles, ventricular tachycardia, and ventricular fibrillation.
Higher doses of aconitine in the treated group as compared
to an untreated control group are an indication of anti-arrhyth-
mic activity. The statistical significance between the groups is
assessed by the Student’s T-test.
[23] Vaille A, Scotto di Tella AM, Maldonado J, Vanelle P
(1992) Meth Find Exp Clin Pharmacol 14: 183
[24] Bazzani C, Genedani S, Tugliavini S, Bertolini A (1989)
J Pharm Pharmacol 41: 651
[25] DeClerk FLUHR (1993) J Cardiovasc Pharmacol 22:
120
References
[1] Abdel-Latif NA (2005) Scientia Pharmaceutica 74: 193
[2] Amr AE, Abdel-Latif NA, Abdalla MM (2006) Acta
Pharm 56: 203
[3] Amr AE, Abdel-Latif NA, Abdalla MM (2006) Bioorg
Med Chem 14: 273
[26] Winslow E (1980) Br J Pharmac 71: 615
[27] Winslow E (1981) J Cardiovasc Pharmac 3: 87
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