Dual Ligand-Tuned Iron and Halogen-Contained Carboxylates-based Photocatalysis for Chloro/Fluoro-Polyhaloalkylation of Alkenes

Abstract Herein, we demonstrate a practical dual ligand-tuned iron-based photocatalyzed decarboxylation paradigm—translating all kinds of halogen-contained carboxylates (CnXmCOO⁻, X: F, Cl, Br) into CnXm radical for the valuable chloro/fluoro-polyhaloalkylation of non-activated alkenes through utilizing easily available trichloroacetonitrile and selectfluor as electrophilic halogenation reagents, respectively, in which the modular assembly of the dual ligand—bipyridines and acetonitriles to in situ-generated ferric halogen-contained carboxylates to produce the effective iron and CnXmCOO⁻-based light-harvesting species for CnXm radical release in visible light conditions 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 dual ligand-tuned iron photocatalysis may have an aptitude for activation and transformation of inert bulk chemicals.