Markovnikov Hydroheteroarylation of Styrenes with Quinoxalinones via Dual Photoredox and Cobalt Catalysis

A visible-light-driven dual photoredox/cobaloxime system enables Markovnikov-selective intermolecular hydroheteroarylation of alkenes without an external photocatalyst or oxidants. Alkyl radicals generated via cobalt–hydride hydrogen atom transfer add to electron-deficient N-heteroarenes. This method exhibits broad functional group tolerance and allows the late-stage diversification of complex molecules. Mechanistic studies reveal that photoreduction to Co(I) and subsequent protonation form the key Co(III)–H intermediate, initiating the hydrogen atom transfer process and governing selectivity.