New Transition Metal Catalysts for Organic Reactions

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DESCRIPTION (provided by applicant): The development of broadly useful and conceptually novel strategies for catalysis using high oxidation state transition metal complexes is proposed. In general, these reactions employ metal-oxo complexes, of rhenium and vanadium, as catalysts for a variety of organic transformations including reductions, substitution, additions and oxidations. Rhenium(V)-dioxo complexes can be employed as catalysts for chemoselective and enantioselective hydrosilylation of aldehydes, ketones and imines. This represents a reversal in the traditional role of this catalysts as oxidizing agents. The continued development of chiral versions of these rhenium(V)-oxo complexes for the enantioselective synthesis of alcohols and imines will be is proposed. More specifically, the unique ability of these complexes to enantio- and regioselectively reduce unsaturated imines will be exploited. Additionally, rhenium-oxo catalyzed addition of carbon (cyanide, allyl, trifluoromethyl) and metalloid (borane, stannane) nucleophiles is proposed. Metal-oxo catalyzed oxidations are also proposed. For example, studies on vanadium-catalyzed oxidative kinetic resolution and rhenium catalyzed enantioselective sulfoxidations are described. Additionally, novel rhenium-oxo catalyzed oxidative transformation (e.g. cleavage of olefins to imines) will be developed. Development of a number of new transformations that take advantage of the unique properties of metal-oxo complexes are proposed. Theses include unprecedented metal-oxo catalyzed de-racemization reactions, tandem oxidative cleavage/enantioselective additions and tandem rearrangements/enantioselective additions.