Dual Copper/Photoredox Catalysis: Photoreductive 1,4-Dicarbofunctionalization of 1,3-Enynes with Dibenzothiophenium Salts and Trimethylsilyl Cyanide.

A photoredox and copper dual-catalyzed 1,4-arylcyanation of 1,3-enynes has been established using aryldibenzothiophenium salts (Ar-DBT+) as aryl radical precursors, affording a wide array of tetra-substituted allenes with high chemo- and regioselectivity. This strategy exhibits a broad substrate scope with remarkable functional group tolerance, all under mild conditions. Notably, this process generates tetra-substituted allenes in a one-step reaction through the use of various electron-rich and electron-deficient aryldibenzothiophenium salts.