C(sp3)–O Bond-Forming Reductive Elimination from PdIV with Diverse Oxygen Nucleophiles

This article describes an investigation of C­(sp3)–O bond-forming reductive elimination reactions from PdIV complexes. Phenoxide, acetate, difluoroacetate, dimethylphosphate, tosylate, and nitrate nucleophiles are shown to participate in this reaction. In all cases, C­(sp3)–O bond formation occurs with high selectivity over potentially competing C­(sp2)–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(sp3)–C­(sp2) bond-forming reductive elimination, while the presence of Lewis acidic cations was found to suppress competing C­(sp3)–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 PdIV–alkyl intermediate.