Stereoretentive radical-based alkyl-alkyl cross-coupling

The construction of stereogenic C(sp³)-C(sp³) bonds through cross-coupling remains a formidable challenge owing to competing β-hydride elimination and homocoupling as well as the poor inherent stereocontrol of radical pathways. In this work, we report a scalable stereoretentive radical-radical cross-coupling of two distinct, transient alkyl radicals, derived from enantioenriched sulfonylhydrazides and achiral primary and secondary alkyl halides, achieved without chiral ligands, directing groups, or exogenous redox agents. This substrate-controlled approach leverages a nickel-catalyzed, redox-neutral manifold, which enables precise kinetic matching of diazene-mediated radical generation and halogen atom transfer. The reaction produced enantiospecificities of 80 to 96% and synthetically useful yields (up to 90%) across diverse piperidine and pyrrolidine scaffolds while tolerating ethers, free amines, aryl halides, heterocycles, olefins, and other sensitive motifs. Mechanistic studies support caged radical rebound at nickel to preserve chirality, followed by nickel(I)-nickel(III)-mediated radical capture and reductive elimination.