Access to Alkylative/Hydrodefluorination of Trifluoromethyl Ketones Using Photoexcited Dihydropyridines

A convenient strategy for selective and challenging single
C–F
bond functionalization of trifluoromethyl ketones has been introduced
under visible light irradiation. Photoexcited 1,4-DHP serves a dual
purpose as a reductant and a source of alkyl radicals (or H atoms)
in the alkylative defluorination and hydrodefluorination processes.
The solvent hexafluoroisopropyl alcohol (HFIP) plays a crucial role
in the selective single C–F bond cleavage. Overall, a transition-metal-
and photocatalyst-free, mild protocol for accessing a broad range
of functionalized fluorinated products of high pharmaceutical interest
is presented here. Operational simplicity and mechanistic evidence
for photoinduced alkyl (or HAT) radical generation highlight the effectiveness
of this strategy as a reliable toolbox for selective defluorinative
C–C cross-coupling and a hydrodefluorination protocol.