Direct Evidence for Competitive C–H Activation by a Well-Defined Silver XPhos Complex in Palladium-Catalyzed C–H Functionalization

Increasing evidence indicates that silver salts can play a role in the C–H activation step of palladium-catalyzed functionalization. Here we isolate silver(I) complex by bond and demonstrate its catalytic competence for We how carbonate, common but highly insoluble additive, reacts with pentafluorobenzene presence bulky phosphine, XPhos, to form product Ag(C6F5)(XPhos). By isolating fully characterizing this related carbonate iodide complexes, [Ag(XPhos)]2(?-?2,?2-CO3) [AgI(XPhos)]2, show well-defined Ag(I) complexes operate conjunction palladium achieve functionalization even at ambient temperature. Reactions are tested against standard cross-coupling C6F5H 4-iodotoluene, catalyzed acetate 60 °C Xphos. Key observations (a) PdI(C6H5)(XPhos) stoichiometrically Ag(C6F5)(XPhos) Ph–C6F5 instantly room temperature; (b) cross coupling be achieved using 5% as sole source; (c) (typical precatalyst) replaced expected oxidative addition compound PdI(C6H5)(XPhos). These investigations lead cycle which plays role. Moreover, phosphine exchanged between ensuring it is recycled though consumed during cross-coupling.