Visible-Light Photoredox-Catalyzed C(sp²)-H Difluoromethoxylation of (Hetero)arenes Utilizing a Shelf-Stable Pyridinium Reagent.

Difluoromethoxyarene moieties have been demonstrated to impart desirable physio-chemical properties to organic molecules. Presented herein is a shelf-stable radical difluoromethoxylating reagent that enables facile and direct C(sp²)-H difluoromethoxylation of (hetero)arenes under blue light photoredox catalysis. 4-Cyano-1-(difluoromethoxy)pyridin-1-ium trifluoromethanesulfonate is prepared in one simple step from the parent pyridine <i>N</i>-oxide. The current protocol tolerates a variety of synthetically and pharmacologically relevant functional groups. Applicability toward the late-stage functionalization of APIs and druglike molecules is also demonstrated.