Hofmann-Type Elimination in the Efficient<i>N</i>-Alkylation of Azoles: Imidazole and Benzimidazole

Abstract

A simple and efficient preparation of 1-substituted 1H-azoles (imidazole and benzimidazole) has been developed, which involves a selective Hofmann-type elimination of the 2-cyanoethyl group from the azolium salts obtained by the reaction of halides with 1H-imidazole-1-propanenitrile and 1H-benzimidazole-1-propanenitrile. Overall yields of 1-substituted 1H-azoles decreased in the order: primary alkyl halides ≥ allylhalides ≥ secondary alkyl halides > benzyl halides > α-keto halides, in relation to the alkylating agent, and imidazole > benzimidazole, in relation to the azole, respectively.