Radical reactions are characterized by high reactivity, mild reaction conditions, and broad functional-group compatibility, yet precise stereocontrol of highly reactive radical intermediates remains a central challenge in asymmetric synthesis. Copper catalysts possess versatile capabilities for single-electron transfer, radical capture, and redox-state modulation, whereas chiral phosphoric acids (CPAs) can create well-defined chiral microenvironments through noncovalent interactions such as hydrogen bonding, ion-pairing, and spatial confinement. The synergistic integration of these two catalytic components therefore provides a powerful platform for asymmetric radical transformations that are difficult to achieve with either catalyst alone. Importantly, Cu/CPA cooperative catalysis does not represent a simple division of labor in which copper generates radicals and CPA controls stereochemistry; rather, the two components can cooperate dynamically at multiple stages of the catalytic cycle, including single-electron transfer, radical capture or oxidation, and stereoselective bond formation. According to the predominant stereodetermining step, Cu/CPA-catalyzed asymmetric radical reactions can be broadly classified into two principal mechanistic modes. In the first mode, copper and CPA jointly participate in the stereodetermining step: carbon-centered radicals are either trapped by chiral Cu(II)-phosphate species to form high-valent Cu(III) intermediates or undergo facially selective addition to copper-coordinated alkenes, with stereochemical differentiation occurring within the chiral environment established by the Cu/CPA catalytic system. In the second mode, radical-polar crossover generates carbocationic or iminium intermediates through single-electron oxidation of carbon radicals by Cu(II) species, after which stereoselective nucleophilic addition or rearrangement is governed predominantly by chiral phosphate ion pairing. In recent years, this cooperative catalytic strategy has been successfully applied to asymmetric radical 1,2-difunctionalization of alkenes, enantioselective radical functionalization of C(sp³)-H bonds, and enantioselective radical desymmetrization of olefinic 1,3-diols. These advances have enabled efficient access to structurally diverse chiral pyrrolidines, tetrahydrofurans, bridged and spirocyclic frameworks, including molecules bearing contiguous stereocenters and all-carbon quaternary stereocenters. In this review, we systematically summarize recent advances in Cu/CPA cooperative catalysis for asymmetric radical reactions, with particular emphasis on the mechanistic modes of stereocontrol across different reaction classes, and discuss current challenges and future perspectives of this emerging research field.

Key words: copper catalysis, CPA catalysis, cooperative catalysis, radical reaction, asymmetric transformation