Difluoromethyl phenoxathiinium salt: A new general and versatile difluoromethylating reagent with divergent ·CF2H, CF2H+, and:CF2 reactivities

Development of practical and versatile electrophilic difluoromethylating reagent is still a grand challenge so far due to its inherent instability or low reactivity. Herein, we report the design and synthesis of difluoromethyl phenoxathiinium tetrafluoroborate (PT-CF2H+BF4−) as a novel difluoromethylating reagent, which proves to be a bench-stable, general, powerful and versatile reagent with divergent ·CF2H, CF2H+, and:CF2 reactivities. Making use of this reagent, we demonstrated a vast array of difluoromethyl radical transfer reactions via diverse pathways involving photocatalyst-free visible-light induction, visible-light photoredox catalysis and visible-light mediation single electron transfer of EDA complex. Moreover, the green and highly effective CF2H+ and:CF2 transfer reactions were also readily accomplished.