Photoredox Nickel-Catalyzed Dehydrogenative Alkoxycarbonylation of Benzylic C─H Bonds.

Radical-mediated transition-metal-catalyzed C─H carbonylation represents a direct and powerful approach for the synthesis of carbonyl compounds; however, the stoichiometric oxidants typically required for hydrogen atom abstraction hamper the extensive application of these protocols and raise environmental concerns. In this study, we report a photoredox Ni-catalyzed acceptorless dehydrogenative alkoxycarbonylation of alkylarenes with releasing hydrogen gas (H2) as the sole byproduct. A variety of benzylic carboxylates, benzofuranones, and lactones with different frameworks were obtained with high selectivity through intermolecular and intramolecular alkoxycarbonylation. The reaction is distinguished by broad functional-group compatibility with radical-quenching phenolic hydroxyl group applicable. Notably, the use of biphosphine ligand promotes the reductive elimination of acylnickel(II) intermediate with alcohols while suppressing undesired single-electron oxidative addition with benzylic radical.