Photoinduced Copper-Catalyzed Enantioselective Deoxygenative Alkynylation

Deoxygenative coupling provides an attractive strategy for converting abundant alcohol feedstocks into value-added molecules. Despite recent advances, the enantioselective synthesis of chiral alkynes from alcohols and their derivatives remains elusive. Herein, we report a photoinduced copper-catalyzed asymmetric deoxygenative alkynylation of alcohol-derived xanthates with terminal alkynes. This strategy employs aryl iodides as aryl radical precursors to activate xanthate esters, with both the electronic and steric properties of the aryl iodide being critical for efficient aryl radical generation and productive transformation. The reaction proceeds under mild conditions and exhibits good functional-group tolerance. Mechanistic studies support a radical relay pathway involving aryl-radical-mediated xanthate activation and copper-catalyzed asymmetric alkynylation, wherein the photoexcited chiral copper acetylide serves a dual role as the photoactive species for aryl radical generation and the enantioselective catalyst for C(sp3)–C(sp) bond formation.