Substituent-controlled selective synthesis of 1,2-diketones and internal alkynes from terminal alkynes and arylboronic acids via α-stilbene radicals obtained from heteroleptic Cu(i) complexes under visible light

Abstract

Herein, we report a substituent-controlled synthesis of 1,2-diketones and internal alkynes from terminal alkynes and arylboronic acids via α-stilbene radicals obtained from heteroleptic Cu(I) complexes under visible-light irradiation. The in situ generated α-stilbene radical Cu(II)-complex was achieved by photoinduced C_sp–C_sp² coupling of copper(I) acetylides and aryl radicals catalysed by heteroleptic Cu(I) complexes. This photochemical approach offered high atom economy with a low E-factor and functional group tolerance under mild reaction conditions. Mechanistic insights clearly show that the reaction proceeded via copper(I) acetylides and the phenyl radical intermediate pathway.