Radical defluoroallylation of polyfluoroalkyl compounds with alkenes via synergistic photoredox/cobalt catalysis

Selective functionalization and high-value conversion of polyfluoroalkyl compounds is of paramount importance due to their widespread use in pharmaceuticals, agrochemicals, and advanced materials. However, the formidable stability of C(sp3)-F bonds, exacerbated by strong electron-withdrawing effects, steric hindrance, and the inherent challenge of achieving precise selectivity, has significantly hampered efforts toward their controlled activation and modification. Herein, we present a dual photoredox/cobalt catalytic strategy that enables redox-driven defluoroallylation of perfluoroalkylarenes and polyfluorinated aliphatic amides. Our approach leverages single-electron reduction to cleave robust C(sp3)-F bonds, generating reactive perfluoroalkyl radicals that couple efficiently with simple alkenes. Cobalt-mediated hydrogen atom transfer, with Lewis acidic fluorine scavengers serving primarily to trap the fluoride and suppress back-electron transfer, ensures precise regioselective allylation under mild conditions. Mechanistic investigations reveal that controlled radical generation and selective activation underpin the unique site selectivity observed. This dual catalytic platform offers an efficient strategy for the construction of complex fluorinated scaffolds and expands the toolkit for the selective transformation of polyfluorinated frameworks.