Synthesis and structure of 1-methyl-2-(2-nitro-2-phenylethenyl)-1H- benzimidazole

Full text of DOI:10.1134/S1070428009040290

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2009, Vol. 45, No. 4, pp. 629–630. © Pleiades Publishing, Ltd., 2009.
Original Russian Text © E.S. Ostroglyadov, A.A. Nikonorov, O.S. Vasil’eva, M.M. Zobacheva, V.M. Berestovitskaya, 2009, published in Zhurnal
Organicheskoi Khimii, 2009, Vol. 45, No. 4, pp. 642–643.
SHORT
COMMUNICATIONS
Synthesis and Structure of 1-Methyl-2-(2-nitro-2-phenyl-
ethenyl)-1H-benzimidazole
E. S. Ostroglyadov, A. A. Nikonorov, O. S. Vasil’eva, M. M. Zobacheva,
and V. M. Berestovitskaya
Hertzen Russian State Pedagogical University, nab. r. Moiki 48, St. Petersburg, 191186 Russia
e-mail: kohrgpu@yandex.ru
Received December 5, 2008
DOI: 10.1134/S1070428009040290
1
Benzimidazole ring system is a pharmacophoric
fragment included into the structure of many natural
compounds and drugs, in particular psychostimulators
(Bemithyl), antihistaminic agents (Astemizol, Oxato-
mide), and spasmolytics (Dibazole) [1–3], as well as
antihelminthics (Mebendazole, Medamine) widely
used in veterinary [4]. Therefore, synthesis of new
potential biologically active compounds containing
a benzimidazole fragment is a promising line of
studies. A convenient starting material for the synthesis
of such compounds may be 1-methyl-2-(2-nitro-2-
phenylethenyl)-1H-benzimidazole (III) [5] which is
available from 1-methyl-1H-benzimidazole-2-carbal-
dehyde (I) [6] and phenylnitromethane.
The H NMR spectrum of nitroethene III in CDCl3
indicated the presence of only one stereoisomer; it
contained signals from protons in the benzimidazole
(δ 7.30, 7.80 ppm, 4H) and benzene rings (δ 7.50,
7.54 ppm, 5H) and methyl group (δ 3.88 ppm, 3H),
and the olefinic proton (HA) resonated at δ 6.83 ppm.
According to [7–10], upfield shift of the HA signal in
the spectrum of III as compared to model 1-methyl-2-
[(E)-2-nitroethenyl]benzimidazole (δ 8.15 ppm) [7]
suggests trans arrangement of the olefinic proton and
the nitro group at the double C=C bond, i.e., its Z con-
figuration.
The IR spectrum of nitroethene III contained ab-
sorption bands typical of stretching vibrations of C=S
and C=N bonds (1655, 1595, 1562 cm–1) and con-
jugated nitro group (1540, 1340 cm–1). Compound III
We have improved the procedure for dehydration of
nitro alcohol II by changing the order of mixing of the
reactants and stirring the reaction mixture both in the
course of heating and for 2 h after treatment with
water. As a result, compound III was isolated in a high
yield (83%). The melting point of nitroethenylbenz-
imidazole III thus obtained (mp 210–212°C) consider-
ably differed from that reported in [5] (mp 160–
161°C). Presumably, the melting point given in [5]
corresponds to another substance, the more so no data
in support of its structure were given. We were the first
displayed in the electronic absorption spectrum [λmax
,
nm (ε, l mol–1 cm–1): 205 (30000), 260 (11000), 335
(25000)] a blue shift of the long-wave absorption max-
imum (Δλmax = 33 nm) relative to that in the spectrum
of 1-methyl-2-[(E)-2-nitroethenyl]benzimidazole
[λmax, nm (ε, l mol–1 cm–1): 202 (23500), 368 (11500)],
which may be attributed to cis orientation of the benz-
imidazole fragment and the nitro group in molecule
III, unlike trans orientation of the same substituents in
1-methyl-2-[(E)-2-nitroethenyl]benzimidazole [7].
1
to record the H NMR and IR spectra of nitro alcohol
II (mp 160–161°C) and nitroethene III (mp 210–
212°C), which unambiguously confirm their structure.
1-(1-Methyl-1H-benzimidazol-2-yl)-2-nitro-2-
phenylethanol (II) was synthesized according to the
OH
HA
N
N
N
PhCH2NO2, NaOH
Ac2O
CHO
N
N
N
NO2
Ph
Ph
Me
Me
Me
O2N
I
II
III
629

OSTROGLYADOV et al.
630
procedure described in [5]. mp 160–162°C (from
MeOH); published data [5]: mp 160–161°C. IR spec-
REFERENCES
1
trum, ν, cm–1: 1375, 1555 (NO2). H NMR spectrum
1. Mashkovskii, M.D., Lekarstvennye sredstva (Drugs),
Moscow: Novaya Volna, 2007.
(DMSO-d6), δ, ppm: 5.83 m (1H, CHOH); 6.30 m
(2H, CHPh, OH); 7.20 m, 7.25 m, and 7.70 m (4H,
4-H, 5-H, 6-H, 7-H); 7.48 m and 7.60 m (5H, C6H5);
3.88 s (3H, NMe).
2. Registr lekarstvennykh sredstv Rossii. Entsiklopediya
lekarstv (Russian Registry of Drugs. Encyclopedia of
Drugs), OOO RLS-2002, 2002 (9).
3. Kopelevich, V.M., Bulanova, L.N., Marieva, T.D., and
Gunar, V.I., Pikamilon v sovremennoi nevrologicheskoi
i psikhiatricheskoi praktike (kliniko-eksperimental’nye
issledovaniya) (Pikamilon in Modern Neurologic and
Psychiatric Practice. Clinical and Experimental Studies),
Moscow: NPO Vitaminy, 1994, p. 13.
1-Methyl-2-(2-nitro-2-phenylethenyl)-1H-benz-
imidazole (III). Acetic anhydride, 2.1 ml, was added
to 0.9 g (3 mmol) of nitro alcohol II, and the mixture
was heated for 30 min on a boiling water bath under
stirring until it became homogeneous. The mixture was
then treated with 16.5 ml of ice water under stirring
and was stirred for 2 h more. The precipitate was
filtered off and washed on a filter with water, alcohol,
and diethyl ether. Yield 0.7 g (83%), mp 210–212°C
(from MeOH); published data [5]: mp 160–161°C.
1H NMR spectrum (CDCl3), δ, ppm: 6.83 (1H, HA),
7.50 and 7.54 (5H, C6H5), 7.30 and 7.80 (4H, 4-H,
5-H, 6-H, 7-H), 3.88 (3H, Me). Found, %: C 68.53,
68.78; H 4.27, 4.50; N 15.42, 15.40. C16H13N3O2. Cal-
culated, %: C 68.82; H 4.66; N 15.05.
The 1H NMR spectra were recorded on a Jeol JNM
ECX400A spectrometer at 400 MHz. The IR spectra
were measured on an InfraLYuM FT-02 instrument
from samples dispersed in mineral oil. The electronic
absorption spectra were obtained on a Shimadzu UV-
2401 spectrophotometer from solutions in acetonitrile.
4. Kuz’min, A.A., Antigel’mintiki v veterinarnoi meditsine
(Antihelminthics in Veterinary), Moscow: Akvarium,
2000.
5. Dolgatov, D.D. and Simonov, A.M., Zh. Obshch. Khim.,
1964, vol. 34, p. 3052.
6. Le-Bris, M., Wahl, H., and Jambu, T., Bull. Soc. Chim.
Fr., 1959, p. 343.
7. Berestovitskaya, V.M., Ishmaeva, E.A., Litvinov, I.A.,
Vasil’eva, O.S., Vereshchagina, Ya.A., Ostroglyadov, E.S.,
Fattakhova, G.R., Beskrovnyi, D.V., and Aleksandro-
va, S.M., Russ. J. Gen. Chem., 2004, vol. 74, p. 1108.
8. Dore, I.C. and Veil, C., Recl. Trav. Chim. Pays–Bas,
1975, vol. 94, p. 225.
9. Descotes, G., Bahurek, Y., Bourillot, M., and Ros-
traing, R., Bull. Soc. Chim. Fr., 1970, p. 282.
10. Trukhin, E.V., Makarenko, S.V., and Berestovits-
kaya, V.M., Russ. J. Org. Chem., 1998, vol. 34, p. 59.
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