Synthesis of various 1-alkylbenzimidazole derivatives directly from 2-alkylaminonitroarenes via a two-step, one-pot procedure

Abstract

N-Alkyl-2-nitroanilines deoxygenated with tributylphosphine form intermediate 2-(alkylamino)aryliminophosphoranes, which were subjected, without isolation, to various cyclocondensation reactions with CS₂, CO₂, alkyl isocyanates, acyl chlorides, anhydrides, or esters. A simple, convenient, one-pot procedure provided derivatives of unsymmetrically substituted 1-alkylbenzimidazoles functionalized at C2 in good to excellent yields. The method does not require the use of metals, sensitive catalysts, or pressure.