Opening a Pandora's Flask on a Prototype Catalytic Direct Arylation Reaction of Pentafluorobenzene: The AgCO/Pd(OAc)/PPh System.

Direct C-H functionalization reactions have opened new avenues in catalysis, removing the need for prefunctionalization of at least one of the substrates. Although C-H functionalization catalyzed by palladium complexes in the presence of a base is generally considered to proceed by the CMD/AMLA-6 mechanism, recent research has shown that silver(I) salts, frequently used as bases, can function as C-H bond activators instead of (or in addition to) palladium(II). In this study, we examine the coupling of pentafluorobenzene to 4-iodotoluene (and its analogues) to form 4-(pentafluorophenyl)toluene catalyzed by palladium(II) acetate with the commonplace PPh ligand, silver carbonate as base, and DMF as solvent.