Unusual Regioselective C–H Difluoroalkylation of Heteroarenes under Photoredox Catalysis

We disclose a new general strategy for the site-selective
difluoroalkylation
of nonprefunctionalized heteroarenes, such as quinoxaline at the C-8
position, and benzothiadiazole, benzoxadiazole, and benzothiazole
at the C-4 position via consecutive organophotoredox-catalyzed radical–radical
cross-coupling and base-assisted hydrogen abstraction reactions. The
current methodology represents a site-selective direct difluoroalkylative
strategy to allow broad functional group tolerance and a wide substrate
scope in good to excellent yields. Careful experimental investigations
and detailed DFT calculations revealed the exact site-selectivity
of the heteroarenes and a possible mechanistic pathway.