Sequential C−F Bond Transformation of the Difluoromethylene Unit in Perfluoroalkyl Groups: A Combination of Fine‐Tuned Phenothiazine Photoredox Catalyst and Lewis Acid

Abstract

Abstract A sequential process via photoredox catalysis and Lewis acid mediation for C−F bond transformation of the CF 2 unit in perfluoroalkyl groups has been achieved to transform perfluoroalkylarenes into complex fluoroalkylated compounds. A phenothiazine‐based photocatalyst promotes the defluoroaminoxylation of perfluoroalkylarenes with (2,2,6,6‐tetramethylpiperidin‐1‐yl)oxyl (TEMPO) under visible light irradiation, affording the corresponding aminoxylated products. These products undergo a further defluorinative transformation with various organosilicon reagents mediated by AlCl 3 to provide highly functionalized perfluoroalkyl alcohols. Our novel phenothiazine catalyst works efficiently in the defluoroaminoxylation. Transient absorption spectroscopy revealed that the catalyst regeneration step is crucial for the photocatalytic aminoxylation.