Photoredox/Cobalt Dual Catalysis Enabled Regiospecific Synthesis of Distally Unsaturated Ketones with Hydrogen Evolution

In this report, we present a photoredox/cobalt dual catalytic system for the synthesis of distally unsaturated ketones. Upon a cooperative utilization of an organo photoredox catalyst and a cobaloxime catalyst, sequential ring-opening C–C bond scission and dehydrogenation of nonstrained tertiary cycloalkanols of variable ring sizes are achieved under visible-light irradiation, producing a wide range of γ,δ-, δ,ε-, and even more distally unsaturated ketones in good yields, with hydrogen gas as the sole byproduct. The produced distally unsaturated ketones are versatile building blocks, which can be easily converted to other valuable molecules.