Visible-Light-Induced Palladium-Catalyzed Selective Defluoroarylation of Trifluoromethylarenes with Arylboronic Acids.

Selective functionalization of inactive C(sp3)-F bonds to prepare medicinally interesting aryldifluoromethylated compounds remains challenging. One promising route is the transition-metal-catalyzed cross-coupling through oxidative addition of the C(sp3)-F bond in trifluoromethylarenes (ArCF3), which are ideal precursors for this process due to their ready availability and low cost. Here, we report an unprecedented excited-state palladium catalysis strategy for selective defluoroarylation of trifluoromethylarenes with arylboronic acids. This visible-light-induced palladium-catalyzed cross-coupling proceeds under mild reaction conditions and allows transformation of a variety of arylboronic acids and ArCF3. Preliminary mechanistic studies reveal that the oxidative addition of the C(sp3)-F bond in ArCF3 to excited-state palladium(0) via a single electron transfer pathway is responsible for the C(sp3)-F bond activation.