Synthesis of oxindole fused 1,3-oxazepanes via hydride transfer initiated ring expansion of pyrrolidine

Abstract

An efficient B(C₆F₅)₃ catalyzed protocol for the synthesis of oxindole fused 1,3-oxazepanes from pyrrolidine-substituted aryl alkynones has been developed. A ring expansion of pyrrolidine and dual hydride transfer were involved in the cascade reactions. Transition metal-free conditions, good functional group tolerance and operational simplicity make this C(sp³)–H functionalization methodology attractive.