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 sp(2) and sp(3) 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 sp(3) 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.