Spin-Controlled Inner-Sphere Radical Coupling Enables Enantioinduction for Ni-Catalyzed C─C Couplings Involving Bulky Groups

Reductive elimination (RE) is the prevailing mechanism for Ni-catalyzed C–C couplings, yet it often encounters difficulties when sterically bulky components are involved. The bimolecular homolytic substitution (SH2) mechanism offers an alternative pathway that alleviates this steric limitation but typically lacks effective enantiocontrol. Herein, we found that the interaction between the alkyl radical and the Ni(III) center can be governed by spin states, resulting in a spin-controlled inner-sphere radical coupling (SIRC) manifold facilitated by exchange-enhanced reactivity. This mechanism can rectify the wrong enantioselectivity predicted by the RE manifold, enabling enantioinduction for C–C coupling with bulky components that is challenging for both the RE and SH2 mechanisms. The current finding of the SIRC mechanism may open an avenue for the development of a spin-controlled asymmetric coupling mechanism using cost-effective first-row transition metal catalysis.