Visible-Light-Driven Palladium-Catalyzed 1,4-Difluoromethylative Functionalization of Conjugated Dienes Using Freon-22

We unveil a novel strategy that leverages cost-effective fluorine-containing sources for rapid synthesis of fluorinated com-pounds through multicomponent reactions. Our study introduces a visible light-driven palladium-catalyzed 1,4-difluoromethyl difunctionalization of conjugated dienes, capitalizing on the abundant industrial resource chlorodifluoro-methane (ClCF2H, Freon-22). Illuminated by blue LED light, the palladium catalyst orchestrates the efficient single electron reduction of Freon-22's C-Cl bond, yielding CF2H radicals. This versatile protocol accommodates an extensive array of amines, sulfinates, and enolates as nucleophiles, delivering regioselective difunctionalization products via SN2' substitution of the allylic palladium intermediate. Redox-neutral in nature, this transformation finds utility in late-stage functionalization of drug molecules, while the broad compatibility with diverse functional groups on conjugated dienes underscores its versa-tility. Initial insights suggest the involvement of a difluoromethyl radical intermediate, unveiling a direct and mild avenue to harness CF2H radicals from Freon-22.