Simple Synthesis of Benzazoles by Substrate-Promoted CuI-Catalyzed Aerobic Oxidative Cyclocondensation of o-Thio/Amino/Hydroxyanilines and Amines under Air

摘要

By catalyst and condition screening, a simple method for the synthesis of benzazole and quinoxaline heterocycles via Cu-catalyzed direct aerobic oxidative cyclocondensation of o-thio/hydroxy/aminoanilines and amines was developed by using air as the safe, cheap, effective, and clean oxidant. Due to the observed great promoting effect of the substrates on the reaction, single CuI can be used as the efficient catalyst without requiring additional oxidation co-catalysts. This method provides a simple and practical way for preparation of the useful benzothiazoles, benzimidazoles and benzoxazoles from amines.