Ligand-enabled Pt(II)-C(sp3) bond functionalization with dioxygen as a direct oxidant.
This feature article summarizes the progress achieved in the field of aerobic functionalization of Pt(II) monoalkyl complexes in protic solvents, water and alcohols. These functionalization reactions are possible in the presence of tripodal semi-labile ligands such as di(2-pyridyl)methanesulfonate (dpms). The reactions include two subsequent transformations: (i) direct (mediatorless) oxidation of a Pt(II) monoalkyl or a Pt(II)-oxetane to produce a Pt(IV)(OH) alkyl or a Pt(IV)(OH)-oxetane, respectively, and (ii) reductive elimination from the Pt(IV) center of an oxygenated organic derivative with a new C-O bond such as alcohols (MeOH, HOC2H4OH), ethers (Me2O), or olefin (ethylene, cis-cyclooctene, norbornene) oxides. All the reactions are highly chemo- and stereoselective. Mechanisms of dioxygen activation with (dpms)Pt(II) alkyls and C-O reductive eliminations from a Pt(IV) center are discussed, including the direct C-O elimination of epoxides from Pt(IV) oxetanes previously undocumented for this metal. Modification of the "slow" Pt(II)-based systems led to the discovery of a "fast" dioxygenase-like acetoxylation of benzylic C-H bonds catalyzed by homogeneous Pd complexes with O2 as the sole oxidant.
Vedernikov
Andrei N
AN
Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA. avederni@umd.edu