An improved and convenient procedure for the synthesis of 1-substituted imidazoles.

Abstract

1-Protected imidazoles, such as 1-acetyl-and 1-benzoylimidazoles, react with various halides, such as benzyl, allyl, α-keto, and alkyl halides, to give 1-protected-3-substituted imidazolium salts in high yields. The resultant imidazolium salts are easily deprotected by treatment with water or alcohols to give the corresponding 1-substituted imidazoles in excellent yields. In this reaction the yields of 1-substituted imidazoles in excellent yields. In this reaction the yields of 1-substituted imidazoles vary with the kinds of halides used and/or with the protecting groups, and the yields increase in the following order : benzyl halides g allyl halides∼α-keto halides < alkyl halides, and acetyl g benzoyl < ethoxycarbonyl < diethoxymethyl < trimethylsilyl < tosyl.