Photoredox-Enabled Chromium-Catalyzed Alkene Diacylations

Transition-metal-catalyzed cross-coupling reactions are a powerful tool to construct carbon-carbon bonds in modern synthetic chemistry. Chromium catalysis is much less developed compared with the widely used palladium and nickel catalysis. Herein, we reported an efficient and flexible chromium-catalyzed radical diacylation of alkenes with the help of visible-light photoredox catalysis, giving access to valuable 1,4-, 1,6-, and 1,7-diones under mild conditions. The synthetic utility of this methodology was proven by converting diones to diverse heterocycles. Furthermore, the same dual catalysis system can be successfully applied to dienes and vinyl cyclopropanes. A possible mechanism of alkene diacylation via dual photoredox/chromium catalysis was proposed according to control experiments and DFT calculations.