Synthesis 2010(16): 2828-2840  
DOI: 10.1055/s-0030-1258152
PAPER
© Georg Thieme Verlag Stuttgart ˙ New York

Stereospecific Synthesis of (Z)-1,3-Oxazolobenzimidazoles from Imidazole- and Benzene-Ring-Substituted Benzimidazoles and α,β-Acetylenic γ-Hydroxynitriles

Ludmila V. Andriyankova, Kseniya V. Belyaeva, Lina P. Nikitina, Anastasiya G. Mal’kina, Andrei V. Afonin, Boris A. Trofimov*
A. E. Favorsky Irkutsk Institute of Chemistry, Siberian Branch, Russian Academy of Sciences, 1 Favorsky Str., 664033 Irkutsk, Russian Federation
Fax: +7(3952)419346; e-Mail: boris_trofimov@irioch.irk.ru;
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Publikationsverlauf

Received 16 April 2010
Publikationsdatum:
07. Juli 2010 (online)

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Abstract

A stereospecific, facile synthesis of (Z)-1,3-oxazolobenz­imidazoles from imidazole- and benzene-ring-substituted benzimidazoles and α,β-acetylenic γ-hydroxynitriles has been elaborated. The reaction proceeds smoothly in acetonitrile without catalyst (room temperature, 3-5 days or 35-40 ˚C, 20-72 h) to afford the target compounds in 33-90% yields. The annulation involves an intermediate vinyl carbanion with zwitterionic character, which, after transformation into an O-centered zwitterion, is further inserted into the aromatic system of the imidazole ring. The synthesis contributes to the basic benzimidazole and acetylene chemistry and drug design.