Palladium-Catalyzed Synthesis of α-Trifluoromethyl Benzylic Amines via Fluoroarylation of gem-Difluoro-2-azadienes Enabled by Phosphine-Catalyzed Formation of an Azaallyl-Silver Intermediate.

We report the synthesis of α-trifluoromethyl benzylic amines through the vicinal fluoroarylation of gem-difluoro-2-azadienes. Our studies indicate that XPhos plays an important role as a phase transfer catalyst that promotes the addition of AgF to the difluoroazadiene, generating an α-trifluoromethyl azaallyl-silver intermediate that we have characterized by NMR spectroscopy. This intermediate likely transmetallates to Pd, coupling several aryl iodides to deliver products in up to 90% yield. Modification of the azadiene's activating group facilitates challenging cross-couplings.