L. V. Andriyankova, K. Belyaeva, L. Nikitina
Aug 1, 2010
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Journal
Synthesis
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.