Fluoride‐Coupled Electron Transfer and Hydrogen‐Atom‐Transfer‐Mediated Synthesis of Difluoromethylarenes

The difluoromethyl group is a bioisostere of hydroxy and sulfanyl groups. The photocatalytic reduction of trifluoromethyl groups is one of the most important methods for the synthesis of difluoromethyl compounds. We have developed a photoinduced synthesis of difluoromethyl compounds using a combined method of fluoride‐coupled electron transfer and hydrogen atom transfer. Utilizing benzimidazoline derivatives as photoreductant and hydrogen atom donor, difluoromethylarenes were synthesized through the C–F bond reduction of trifluoromethylarenes. Mechanistic studies indicated that the photoreduction proceeded via an electron‐donor–acceptor complex between trifluoromethylarenes and benzimidazoline derivatives.