Radical Carbonylation of Aryl Bromides Enabled by Decoupling Nickel–CO Binding

Abstract Nickel-catalyzed carbonylation represents an attractive alternative to palladium-based methods but has long been constrained by the strong affinity of low-valent nickel for carbon monoxide, leading to formation of catalytically inactive Ni(CO)4 species. As a result, mild nickel-catalyzed carbonylation of aryl bromides has remained largely inaccessible. Here, we report a photoredox-enabled nickel-catalyzed carbonylative esterification of aryl bromides using phenyl formate as a practical and safe in situ CO surrogate. By decoupling aryl bromide activation from nickel–CO binding and relocating CO incorporation to a radical pathway, this strategy enables efficient carbonylation of aryl bromides under ambient conditions. The method exhibits broad substrate scope, high functional-group tolerance, and good compatibility with sterically hindered and complex molecular architectures. Mechanistic studies reveal a pathway involving aryl radical generation, radical carbonylation, nickel capture, and oxidation-enabled C(O)–O bond formation. This work establishes a conceptually distinct strategy to nickel-catalyzed carbonylation that bypasses the intrinsic limitations of conventional Ni–CO chemistry.