Iridium(III)-Catalyzed Direct Arylation of C–H Bonds with Diaryliodonium Salts

By developing a new Ir­(III)-catalyzed
C–C cross-coupling,
a versatile method for direct arylation of sp2 and sp3 C–H bonds in ketoximes, nitrogen-containing heterocycles,
various arenes, and olefins has been established. The key to this
arylation depends on the appropriate choice of catalyst and the use
of diaryliodonium triflate salts as the coupling partners. This transformation
has good functional group compatibility and can serve as a powerful
synthetic tool for late-stage C–H arylation of complex compounds.
Mechanistic studies by density functional theory calculations suggested
that the sp3 C–H activation was realized by a triflate-involved
concerted metalation–deprotonation process, and the following
oxidation of Ir­(III) to Ir­(V) is the most favorable when a bistriflimide
is contained in the diaryliodonium salt. Calculations indicated that
both steps are enabled by initial anion exchange between the reactant
complexes.