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, NMeOC(CF), 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 (PR)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) as a Cr(CO) donor.