Formation of 5-phenyl-1-vinyl-1H-pyrrole-2-carbonitrile in the vinylation of 5-phenyl-1-vinyl-1H-pyrrole-2-carbaldehyde oxime with acetylene

Full text of DOI:10.1134/S1070428008090261

ISSN 1070-4280, Russian Journal of Organic Chemistry, 2008, Vol. 44, No. 9, pp. 1395–1396. © Pleiades Publishing, Ltd., 2008.
Original Russian Text © E.Yu. Shmidt, A.I. Mikhaleva, E.Yu. Senotrusova, A.M. Vasil’tsov, A.V. Ivanov, B.A. Trofimov, 2008, published in Zhurnal
Organicheskoi Khimii, 2008, Vol. 44, No. 9, pp. 1412–1413.
SHORT
COMMUNICATIONS
Formation of 5-Phenyl-1-vinyl-1H-pyrrole-2-carbonitrile
in the Vinylation of 5-Phenyl-1-vinyl-1H-pyrrole-2-carbaldehyde
Oxime with Acetylene
E. Yu. Shmidt, A. I. Mikhaleva, E. Yu. Senotrusova, A. M. Vasil’tsov,
A. V. Ivanov, and B. A. Trofimov
Favorskii Irkutsk Institute of Chemistry, Siberian Division, Russian Academy of Sciences,
ul. Favorskogo 1, Irkutsk, 664033 Russia
e-mail: boris_trofimov@irioch.irk.ru
Received February 11, 2008
DOI: 10.1134/S1070428008090261
It is known that ketone oximes react with acetylene
in the superbasic system KOH–DMSO to give
O-vinyloximes which readily undergo rearrangement
into pyrroles (Trofimov reaction [1–3]). However,
vinylation of 5-phenyl-1-vinyl-1H-pyrrole-2-carbalde-
hyde oxime (I) under analogous conditions gave
exclusively 5-phenyl-1-vinyl-1H-pyrrole-2-carbonitrile
(III, yield 67%) instead of expected O-vinyloxime II.
It could be presumed that compound III was formed
via dehydration of initial oxime I. Dehydration of
aldehyde oximes to the corresponding nitriles in the
system KOH–DMSO was described in [4]. However,
oxime I almost did not undergo dehydration in the
absence of acetylene (the yield of nitrile III did not
exceed 4%). Therefore, we concluded that 5-phenyl-1-
vinyl-1H-pyrrol-2-carbonitrile (III) is formed as a re-
sult of elimination of vinyl alcohol (acetaldehyde)
from O-vinyloxime II.
carbaldehyde oxime (I) with acetylene can be used
to obtain 1-vinyl-1H-pyrrole-2-carbonitriles from
1-vinyl-1H-pyrrole-2-carbaldehyde oximes.
Pyrrolecarbonitriles are widely used as nonsteroidal
progesterone receptor agonists (e.g., Tanaproget [9]),
precursors of conducting polypyrroles with tetrazine
spacers, which are characterized by a narrow forbidden
zone [10], and intermediate products in fine organic
synthesis for the preparation of the corresponding
alcohols, acids, esters, amides [11], and heterocyclic
compounds [12]. Introduction of a vinyl groups into
pyrrolecarbonitrile molecules should further extend
their synthetic potential. However, such 1-vinyl-1H-
pyrrole-2-carbonitriles were previously unknown. The
discovered transformation provides a synthetic route to
such derivatives.
5-Phenyl-1-vinyl-1H-pyrrole-2-carbonitrile (III).
A 0.25-l steel rotating high-pressure reactor was
charged with 0.50 g (2.4 mmol) of 5-phenyl-1-vinyl-
1H-pyrrole-2-carbaldehyde oxime (I), 0.16 g
(2.4 mmol) of KOH·0.5H2O, and 50 ml of DMSO,
and the mixture was saturated with acetylene at room
temperature to a pressure of 14 atm. The mixture was
then heated to 70°C and was kept for 10 min at that
temperature, the maximal acetylene pressure being
Pyrrole-2-carbonitriles are usually synthesized by
dehydration of the corresponding pyrrole-2-carbalde-
hyde oximes by the action of acid reagents, e.g., acetic
anhydride, p-toluenesulfonic acid, epichlorohydrin [5],
or diethyl chlorophosphate [6]). However, the vinyl
group is sensitive to acids [7, 8]; therefore, the ob-
served reaction of 5-phenyl-1-vinyl-1H-pyrrole-2-
NOH
N
CH2
O
HC CH, KOH–DMSO
≡
Ph
H2C
Ph
H2C
Ph
H2C
CN
N
N
N
–HOCH=CH2
(–MeCHO)
I
II
III
1395

SHMIDT et al.
1396
~20–22 atm. After cooling to room temperature, the
mixture was diluted with 100 ml of water and ex-
tracted with methylene chloride (6×20 ml). The com-
bined extracts were washed with water (4×30 ml) and
dried over potassium carbonate. Removal of the sol-
vent gave 0.68 g of a brown tarry material which was
subjected to flash chromatography on basic aluminum
oxide using hexane as eluent to isolate 0.31 g (67%) of
compound III as colorless crystalline substance which
turned yellow on exposure to air. mp 40–42°C. IR
spectrum, ν, cm–1: 2924, 2853, 2214 (C≡N), 1648,
1636, 1458, 1415, 1402, 1329, 1299, 964, 909, 761,
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This study was performed under financial support
by the Russian Foundation for Basic Research (project
no. 06-03-39003-GFEN_a) and by the Foundation for
Support of Russian Science.
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RUSSIAN JOURNAL OF ORGANIC CHEMISTRY Vol. 44 No. 9 2008