Metallaphotoredox‐Catalyzed Acceptorless Dehydrogenative Carbonylation Employing Benzylic C─H Bonds as Limiting Substrates

We report a visible light‐driven, metallaphotoredox‐catalyzed acceptorless dehydrogenative carbonylation of benzylic C─H bonds with carbon monoxide and nucleophiles. Enabled by a long‐chain diphosphine ligated nickel(II) bromide complex, this protocol uniquely employs C(sp 3 )─H bonds as limiting reagents under ambient temperature and CO atmosphere, affording esters and related carbonyls under oxidant‐free conditions with H 2 as the sole byproduct. The reaction exhibits broad substrate scope, tolerating diverse functional groups and complex bioactive scaffolds. Mechanistic studies are consistent with a pathway involving photoinduced hydrogen atom transfer and nickel‐mediated carbonylation.