Nickel-Catalyzed Radical-Radical Cross-Coupling Reactions

Over the past several years, nickel-catalyzed radical cross-coupling has emerged as a versatile platform for constructing carbon-carbon and carbon-heteroatom bonds from open-shell intermediates under mild conditions. This review summarizes recent advances in nickel-catalyzed radical cross-coupling, with a particular emphasis on dual radical sorting as a unifying mechanistic framework. Across C(sp²)-C(sp³), C(sp³)-C(sp³), and C(sp³)-heteroatom bond-forming manifolds, nickel catalysts enable selective differentiation and cross-coupling of multiple radical species through the interplay of inner-sphere organonickel pathways and outer-sphere processes, most notably bimolecular homolytic substitution (S_H2). We further highlight the recent emergence of triple radical sorting for multicomponent alkene difunctionalization. Remaining challenges, including asymmetric radical sorting and selective primary-primary radical coupling, are discussed.