Cyclization Reaction of 2-Azido-1-(2-hydroxyphenyl)ethanones with Terminal Alkynoates Catalyzed by 4-Dimethylaminopyridine (DMAP): Synthesis of 2-Aminobenzofuran-3(2H)-one Derivatives

An unexpected cyclization reaction of 2-azido-1-(2-hydroxyphenyl)ethanones with terminal alkynoates catalyzed by 4-dimethylaminopyridine (DMAP) was developed, and 2-aminobenzofuran-3(2H)-one derivatives were obtained in moderate to good yields under mild reaction conditions within 2 h. The scope and limitations of the cyclization reactions were also investigated.