Dual ligand-enabled iron and halogen-containing carboxylate-based photocatalysis for chloro/fluoro-polyhaloalkylation of alkenes

Abstract

Herein, we demonstrate a practical dual ligand-enabled iron photocatalysis paradigm—converting all kinds of halogen-containing carboxylates (C_nX_mCOO⁻, X: F, Cl, Br) into C_nX_m radicals for the valuable chloro/fluoro-polyhaloalkylation of non-activated alkenes with easily available trichloroacetonitrile/Selectfluor as the electrophilic halogenation reagent. The modular in situ assembly of the effective iron and C_nX_mCOO⁻-based light-harvesting species using the two ligands—OMe/CF₃-substituted bipyridine and acetonitrile/trichloroacetonitrile is evidenced by detailed mechanistic studies. The late-stage modification, low loading amount of iron (TON: 257) and feasible gram-scale synthesis show the utility of this protocol. We thus anticipate that the dual ligand-enabled iron photocatalysis paradigm may facilitate activation and transformation of inert bulk chemicals.