A Redox Transmetalation Step in Nickel-Catalyzed C–C Coupling Reactions

Ni-catalyzed C–H functionalization reactions are
becoming
efficient routes to access a variety of functionalized arenes, yet
the mechanisms of these catalytic C–C coupling reactions are
not well understood. Here, we report the catalytic and stoichiometric
arylation reactions of a nickel(II) metallacycle. Treatment of this
species with silver(I)–aryl complexes results in facile arylation,
consistent with a redox transmetalation step. Additionally, treatment
with electrophilic coupling partners generates C–C and C–S
bonds. We anticipate that this redox transmetalation step may be relevant
to other coupling reactions that employ silver salts as additives.