LMCT Photocatalysis Coupled with Halogen‐Atom Transfer (XAT) for Difunctionalizing Alkene Fluoroalkylation

Ligand‐to‐metal charge transfer (LMCT) photocatalysis, which utilizes simple transition metal salts to enable redox‐potential‐independent conversion of anions into radicals, has recently gained significant interest in organic synthesis. Radical relay, which transforms primary radicals generated via LMCT into secondary radicals through atom transfer, expands the synthetic utility of LMCT photocatalysis. However, the high reactivity of LMCT‐derived radical species strongly limits the reaction modes and applicable substrates. In this study, we successfully couple copper LMCT photocatalysis with halogen atom transfer (XAT) and demonstrate efficient gem‐difluoro‐γ‐lactone synthesis via difunctionalizing fluoroalkylation of alkenes using bromodifluoroacetic anhydride (BDFAA) and LiCl. Key steps include chlorine radical formation via the LMCT of [CuCl 3 ]Li and bromine atom transfer from BDFAA to generate a fluoroalkyl radical. Although theoretical calculations suggest that chlorine radical addition to alkenes is significantly faster than XAT, the desired yet energetically unfavorable XAT proceeds through solubility‐modulated proximity between the catalyst and BDFAA, as well as a solvent‐mediated radical relay involving hydrogen atom transfer from acetonitrile. This study reveals a novel application of LMCT photocatalysis and proposes a general strategy for tuning radical reactivity through the entire reaction system.