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

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 sp 2 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.