Synthesis and antiarrhythmic activity of (1,3-dimethyl-5-nitro-5- hexahydropyrimidinyl)-propionic acid methyl ester

Article abstract of DOI:10.1007/s11094-006-0051-5

(1,3-Dimethyl-5-nitro-5-hexahydropyrimidinyl)propionic acid methyl ester (I) was obtained with a 83% yield using a Mannich type reaction of 4-nitrobutanoic acid methyl ester with excess formalin and methylamine. It was found that compound I possesses low toxicity and shows antiarrhythmic activity on models of arrhythmia induced by intravenous injections of calcium chloride and aconitine in rats.

Full text of DOI:10.1007/s11094-006-0051-5

Pharmaceutical Chemistry Journal
Vol. 40, No. 1, 2006
SYNTHESIS AND ANTIARRHYTHMIC ACTIVITY
OF (1,3-DIMETHYL-5-NITRO-5-HEXAHYDROPYRIMIDINYL)-
PROPIONIC ACID METHYL ESTER
1
1
1
R. R. Shakirov, N. N. Yarmukhamedov, L. I. Vlasova,
1
1
1
N. Z. Baibulatova, R. Yu. Khisamutdinova, S. F. Gabdrakhmanova,
1
1
L. T. Karachurina, and N. Zh. Baschenko
Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 1, pp. 29 – 30, January, 2006.
Original article submitted July 17, 2003.
(1,3-Dimethyl-5-nitro-5-hexahydropyrimidinyl)propionic acid methyl ester (I) was obtained with a 83% yield
using a Mannich type reaction of 4-nitrobutanoic acid methyl ester with excess formalin and methylamine. It
was found that compound I possesses low toxicity and shows antiarrhythmic activity on models of arrhythmia
induced by intravenous injections of calcium chloride and aconitine in rats.
Pyrimidine derivatives are known to exhibit high biolog-
3
CH NO2
CO CH3
O N
CO CH3
2
2
2
ical activity and are widely used in medicine as anti-
microbial, antiviral, antitumor, and other purposes [1, 2]. Un-
fortunately, there are practically no data on the antiar-
rhythmic properties of these compounds, although some
nitrous heterocycles with close chemical properties and
structures — such as pyrazines, 3-aza-, and 3,7-diaza-
bicyclo[3.3.1]nonanes — were reported to possess antiar-
rhythmic properties [1, 3, 4]. These data, as well as the fact
that the nitro group is an important structural element in
some drugs [1], allowed us to assume that nitrohexahydro-
pyrimidines can also possess antiarrhythmic properties.
In this study, we have synthesized (1,3-dimethyl-5-ni-
tro-5-hexahydropyrimidinyl)propionic acid methyl ester (I)
and characterized it with respect to the antiarrhythmic activ-
ity. Compound I was obtained with a yield of 83% using the
Mannich reaction of 4-nitrobutanoic acid methyl ester (II)
with methylamine and formalin in a molar ratio of 1 : 5 : 10.
The reaction proceeded in chloroform and took about 4 h at a
temperature of 20°C. The initial ester II was synthesized via
the Mannich reaction between methylacrylate and
nitromethane in tetrahydrofuran (THF) in the presence of
KF/Al O [5].
THF, 2 h
II, 71%
NO2
CO CH3
2
CH O, CH NH
2
2
3
CHCl , 4 h
3
N
N
H C
CH3
3
I, 83%
The proposed structure of hexahydropyrimidine I was
1
13
confirmed by the data of H and C NMR, IR spectroscopy,
13
and elemental analyses. Indeed, the one-dimensional
C
NMR spectrum measured in the regime of J-modulated CH
parameters unambiguously identify carbon atoms in the
functional groups CH N, CO CH , CO , and CNO with the
3
2
3
2
2
characteristic chemical shifts d = 42.25, 51.76, 171.99, and
6.48 ppm, respectively, and the characteristic signal from
8
carbon in the NCH N moiety is manifested at 78.13 ppm. In
2
1
the H NMR spectrum (measured at 50°C), it is also possible
to identify with sufficient precision the chemical shifts of ax-
ial and equatorial protons in the hexahydropyrimidine ring.
In particular, the signals from equatorial protons at the car-
bon atoms in 2NCH and NCH N groups are observed in
2
3
2
2
higher fields (d = 2.44 and 2.79 ppm) than the signals from
axial protons (3.20 and 3.26 ppm). The singlet signals at 2.29
and 3.66 ppm are due to protons of the methyl groups at ni-
trogen and the carboxy groups, respectively.
1
Institute of Organic Chemistry, Ufa Scientific Center, Russian Academy
of Sciences, Ufa, Bashkortostan, Russia.
29
0
091-150X/06/4001-0029 © 2006 Springer Science+Business Media, Inc.

3
0
R. R. Shakirov et al.
EXERIMENTAL CHEMICAL PART
was removed at a reduced pressure, and the residue was dis-
tilled in a 10-cm-long Vigreaux column to obtain 15.19 g
(75%) of compound II; b.p., 90 – 92°C/2 Torr. The physico-
chemical properties of the product coincide with the pub-
lished data [6].
1 13
The H and C NMR spectra of the synthesized com-
pounds were measured on a Bruker AM-300 spectrometer
(
1
Germany) operating at 300.13 MHz ( H mode) and
1
5.47 MHz ( C mode). The samples dissolved in CDCl and
3
7
1,3-Dimethyl-5-nitro-5-hexahydropyrimidinyl)pro-
pionic acid methyl ester (I). To a solution of 0.32 g
(2.17 mmole) of 4-nitrobutanoic acid methyl ester (II) in
3
the chemical shifts were determined using tetramethylsilane
Me Si) as the internal standard. The IR spectra were re-
(
4
corded with a Specord M-80 (Carl Zeiss Jena, Germany)
spectrophotometer using samples prepared as thin films or
Vaseline oil suspensions. The mass spectra were obtained us-
ing an MKh-1300 spectrometer (Russia) operating at an in-
jector temperature of 100°C and an electron-impact ioniza-
tion energy of 12 and 70 eV. The gas chromatography mea-
surements were carried out on a Khrom-5 (Russia)
chromatograph equipped with a plasma-ionization detector
and a 1200 ´ 5 mm stainless-steel column filled with 5%
SE-30 on Inerton N-AW DMCS (0.125 – 0.160). The carrier
gas was helium. TLC analyses were performed on Silufol
UV-254 plates (Czech Republic).
15 ml CHCl at 0 – 10°C was added with stirring a mixture
3
of 2.17 g (21.7 mmole) of a 30% aqueous formalin solution
and 1.40 g (10.85 mmole) of 24% aqueous methylamine so-
lution. The mixture was stirred for 4 h at room temperature,
washed with water (3 ´ 5 ml), and dried over Na SO . Then,
2
4
the solvent was distilled off at reduced pressure and the resi-
due was chromatographed on a column filled with silica gel
and eluted with petroleum ether – chloroform (9 : 1) mixture.
Finally, the solvent was distilled off to obtain compound I in
the form of white crystals; yield, 0.44 g (83%); C H N O ;
1
0
19
3
4
+
1
mass spectrum (m/z ): 245 [M] ; H NMR spectrum in
CDCl at T = 50°C (d, ppm; J, Hz): 2.20 – 2.36 (m, 4H,
3
H(CH CH CO )), 2.26 (s, 6H, 2CH N), 2.44 (d, 2H, J 12.2,
4
-Nitrobutanoic acid methyl ester (II) [6]. To a solu-
tion of 11.9 g (138 mmole) of methylacrylate and 34.18 g
560 mmole) nitromethane in 450 ml of anhydrous THF was
added 20 g of KF/Al O (base) and the reaction mass was
2
He (2CH N)), 2.79 (d, 1H, J 8.6, He (NCH N)), 3.20 (d, 1H,
2 2 2 3
2
J 8.6, Ha (NCH N)), 3.26 (d, 2H, J 12.2, Ha (2CH N)), 3.65
2
(
2
2
13
(s, 3H, CO CH ); C NMR spectrum in CDCl (d, ppm):
2
3
2 3 3
stirred for 2 h at 20°C. Upon cooling and filtration, the resi-
2
2
7.71 (t, CH CH CO ), 31.29 (t, CH CO ), 42.25 (q,
2 2 2 2 2
CH N), 51.75 (q, CO CH ), 58.95 (t, 2CH N), 78.13 (t,
due was washed with ethyl acetate (2 ´ 50 ml). The solvent
3
2
3
2
NCH N), 86.48 (s, CNO ), 171.99 (s, CO ).
2
2
2
EXPERIMENTAL PHARMACOLOGICAL PART
TABLE 1. Effect of Compound I on the Arrhythmia Induced by
Aconitine in Rats (n = 6)
The antiarrhythmic activity of the synthesized compound
I was studied on urethane-narcotized mongrel rats weighing
Percentage
Dose (i.v.),
Arrhythmia
Treatment
arrhythmia
incidence
1
60 – 200 g with model arrhythmia caused by intravenous
injections of aconitine (50 mg/kg) or calcium chloride
250 mg/kg, 10% aqueous solution). Compound I and the
mg/kg
duration, min
Control
—
100
50
120.6 ± 1.02
p2 < 0.001
(
reference drug allapinine were introduced into the tail vein
by single injections 1 – 2 min before introduction of the
arrhythmogenic agents, as recommended in [7]. The
antiarrhythmic activity was evaluated in terms of the de-
I
0.5
59.3 ± 3.40
p1 < 0.001
p2 < 0.001
0
0
.3
.2
50
67
83
65.8 ± 3.48
p1 < 0.001
p2 < 0.001
73.3 ± 14.11
p1 < 0.01
p2 < 0.01
TABLE 2. Effect of Compound I on the Arrhythmia Induced by
Calcium Chloride in Rats (n = 6)
0.15
91.5 ± 8.67
p1 < 0.01
p2 < 0.001
Percentage
Percentage
ventricular
Dose (i.v.),
Percentage
Treatment
arrhythmia
incidence
mg/kg
fibrillation loss of animals
incidence
Allapinine
0.15
33
50
83
26.5 ± 1.49
p1 < 0.001
Control
—
100
67
100
33
50
67
17
17
17
100
17
33
50
0
0
0
.05
.04
28.3 ± 1.66
p1 < 0.001
I
0.20
0.15
83
36.9 ± 0.95
0
.10
100
17
p1 < 0.001
Allapinine
0.35
0
0
.30
.25
50
0
Notes: p and p are confidence intervals for the difference from
control and reference (allapinine), respectively.
1
2
83
0

Synthesis and Antiarrhythmic Activity
31
2
3
. Comprehensive Heterocyclic Chemistry, A. J. Boulton and A.
McKillop (eds.), Pergamon Press, Oxford (1984), Vol. 3,
pp. 57 – 155.
crease in the arrhythmia onset rate and duration and in the
loss of animals.
As can be seen from the data presented in Tables 1 and 2,
compound I produce an antiarrhythmic action on both mod-
els, although the effect is less pronounced as compared to
that of the reference drug.
. A. M. Likhosherstov, O. V. Filippova, V. P. Peresada, et al.,
Khim.-Farm. Zh., 37(1), 8 – 11 (2003).
4. N. N. Yarmukhamedov, Author’s Abstract of Cand. Sci. (Chem.)
Thesis [in Russian], Ufa (2002).
5
. D. E. Bergbreiter and J. J. Lalonde, J. Org. Chem., 52,
1601 – 1603 (1987).
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6
. J. Colonge and J. M. Pouchot, Bull. Soc. Chim. Fr., 3, 596 – 598 (1962).
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pp. 209 – 217.
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1
. M. D. Mashkovskii, Drugs [in Russian], Torsing, Kharkov
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(