Metal-free photoinduced generation and alkynylation of carbamoyl radicals: a facile synthesis of alkynyl amides

Abstract

A metal-free photoinduced alkynylation of carbamoyl radical with hypervalent iodine(III) reagents for facile synthesis of alkynyl amides is described. This protocol features well functional group tolerance, and broad substrate scope, for direct synthesis of alkynyl amide derivatives in good to excellent yields under mild and redox-neutral reaction conditions. The synthetic application is demonstrated by the late-stage installation of alkynyl amides into the natural product and active pharmaceutical relevant molecules. The mechanistic studies indicated the simultaneous existance between photoredox catalytic and direct photoexcited processes, and quantum yield confirmed occurrence of radical chain propagation process.