C−C Coupling Reactivity of an Alkylgold(III) Fluoride Complex with Arylboronic Acids

Previously, alkylgold(III) fluorides have been proposed as catalytic intermediates that undergo C−C coupling with reagents such as arylboronic acids in Au(I)/Au(III) cross-coupling reactions. Here is reported the first experimental evidence for this elementary mechanistic step. Complexes of the type (NHC)AuMe (NHC = N-heterocyclic carbene) were oxidized with XeF2 to yield cis-(NHC)AuMeF2 products, which were found to be in equilibrium with their fluoride-dissociated, dimeric [(NHC)AuMe(μ-F)]2[F]2 forms. In one case, a monomeric cis-(NHC)AuMeF2 complex was favored exclusively in solution, and it was found to react with a variety of ArB(OH)2 reagents to yield Ar−CH3 products.