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Synthesis 2004(16): 2736-2742  
DOI: 10.1055/s-2004-831244
PAPER
© Georg Thieme Verlag Stuttgart · New York

Silica-Assisted Reactions of Pyrroles with 1-Acyl-2-bromoacetylenes

Zinaida V. Stepanova, Lubov’ N. Sobenina*, Al’bina I. Mikhaleva, Igor’ A. Ushakov, Nina N. Chipanina, Valentina N. Elokhina, Vladimir K. Voronov, Boris A. Trofimov
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch of the Russian Academy of Sciences, 1 Favorsky Str., Irkutsk 664033, Russia
Fax: +7(3952)419346; e-Mail: sobenina@irioch.irk.ru;
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Publication History

Received 28 June 2004
Publication Date:
22 September 2004 (online)

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Abstract

Pyrroles react with 1-acyl-2-bromoacetylenes at room temperature on silica to give 2-acyl-1,1-di(pyrrol-2-yl)ethenes as major products in yields of up to 60%. Under reaction conditions employed, the intermediates (E)-2-(2-acyl-1-bromoethenyl)pyrroles (3-11% isolated yields) either readily exchange the bromine atom for the pyrrole molecule or eliminate HBr to afford 2-(2-acylethynyl)pyrroles, which can be isolated in 9-22% yields by chromatography of the reaction mixture on Al2O3.

Key words

pyrroles - 1-acyl-2-bromoacetylenes - 2-(2-acyl-1-bromoethenyl)pyrroles - 2-acyl-1,1-di(pyrrol-2-yl)ethenes - 2-(2-acylethynyl)pyrroles - silica