Ag/Pd Cocatalyzed Direct Arylation of Fluoroarene Derivatives with Aryl Bromides

Diverse C–H functionalizations catalyzed by Pd employ Ag­(I) salts added as halide abstractors or oxidants. Recent reports have shown that Ag can also perform the crucial C–H activation step in several of these functionalizations. However, all of these processes are limited by the wasteful requirement for (super)­stoichiometric Ag­(I) salts. Herein, we report the development of a Ag/Pd cocatalyzed direct arylation of (fluoroarene) chromium tricarbonyl complexes with bromoarenes. The small organic salt, NMe₄OC­(CF₃)₃, added as a halide abstractor, enables the use of a catalytic amount of Ag, reversing the rapid precipitation of AgBr. We have shown through H/D scrambling and kinetic studies that a (PR₃)­Ag-alkoxide is responsible for C–H activation, a departure from previous studies with Ag carboxylates. Furthermore, the construction of biaryls directly from the simple arene is achieved via a one-pot chromium tricarbonyl complexation/C–H arylation/decomplexation sequence using (pyrene)­Cr­(CO)₃ as a Cr­(CO)₃ donor.