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

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 halides using phenyl formate as a practical and safe in situ CO surrogate.By decoupling aryl halide 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 excellent 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 general and conceptually distinct approach to nickel-catalyzed carbonylation that bypasses the intrinsic limitations of conventional Ni-CO chemistry.CO Ni(0)L n CO CO CO CO Ni A) Conventional Ni-catalyzed carbonylation: fundamentally limited by Ni-CO binding, leading to Ni(CO) ₄ formation and suppressed aryl halide activation.favorable Ar-Ni(CO)nX Ar(CO)-Ni(CO)n-1 B) This Work: Radical-type carbonylation decouples aryl halide activation from Ni-CO binding.Ni Ar-X sluggish oxidative addition Ar-CO-Nu Strong Ni-CO binding and Ni(CO) 4 formation High temperature and/or stoichiometric reductants Catalyst sequestration suppresses oxidative addition Limited to activated aryl iodides Poor suitability for late-stage functionalization × × × × × Br Ar Ni Ⅲ L COAr L X Ar O Ar CO NuH Ar O Nu SET Ni Decoupling of aryl halide activation from low-valent nickel Compatibility with sterically hindered molecules Suitable for late-stage functionalization Radical carbonylation avoids Ni(0)/CO coexistence high-valent intermediate facile reductive elimination facile