C(sp³)-O bond-forming reductive elimination from Pd(IV) with diverse oxygen nucleophiles.

This article describes an investigation of C(sp(3))-O bond-forming reductive elimination reactions from Pd(IV) complexes. Phenoxide, acetate, difluoroacetate, dimethylphosphate, tosylate, and nitrate nucleophiles are shown to participate in this reaction. In all cases, C(sp(3))-O bond formation occurs with high selectivity over potentially competing C(sp(2))-O coupling. Additives have a profound impact on the chemoselectivity of these reductive elimination reactions. An excess of RO(-) was found to limit competing C(sp(3))-C(sp(2)) bond-forming reductive elimination, while the presence of Lewis acidic cations was found to suppress competing C(sp(3))-F coupling. Mechanistic investigations were conducted, and the available data are consistent with a sequence involving pre-equilibrium dissociation of the oxyanion ligand (RO(-)) followed by nucleophilic attack of RO(-) on a cationic Pd(IV)-alkyl intermediate.