Metallaphotoredox Synthesis of Axially Chiral Tetrasubstituted Allenes through Regio- and Enantioselective 1,4-Carbocyanation of 1,3-Enynes

Radical 1,4-difunctionalization of 1,3-enynes represents a promising approach for the rapid creation of allenes from readily available feedstocks. However, the enantioselective synthesis of tetra-substituted chiral allenes from 1,3-enynes via a radical pathway remains difficult. Herein, we disclose an enantioselective decarboxylative 1,4-carbocyanation of 1,3-enynes through photoredox and copper dual catalysis, affording a wide array of axially chiral tetra-substituted allenes in a highly chemoselective, regioselective, and enantioselective manner. This mild and redox-neutral protocol exhibits broad substrate scope and good functional group tolerance and enables late-stage allenyation of natural and drug-like molecules.