Metal-free three-component reactions of alkynes for the construction of 3,4-difunctionalized benzo[h]coumarins

Abstract

Herein, we report a metal-free coupling cyclization reaction of alkyne ester with amines and quinones via multicomponent reactions to produce the target compounds with mild reaction conditions. This method provides a facile platform for the synthesis of 3,4-difunctionalized benzo[h]coumarin, through the formation of three new chemical bonds (C–C bond, C–O bond and C–N bond) in a single step, with broad substrate scope and high atom-economy. Furthermore, scale-up reactions highlight the potential synthetic utility of this methodology.