C-O and C-N Bond Formation Using Metal-Based Reagents

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Metal-mediated atom- and group-transfer reactions play an important role in chemical biology and organic synthesis. These reactions serve to transfer groups containing heteroatoms such as nitrogen, oxygen phosphorus and sulfur to organic molecules. Many of these processes have been postulated to proceed via complexes that contain reactive metal-heteroatom bonds. However, an understanding of the chemistry of these functionalities and the mechanisms of their reactions lags substantially behind that which is known about analogous transformations involving metal-carbon and metal-hydrogen bonds. As a result, the development of catalysts and stoichiometric reagents based on isolable complexes that bear metal-heteroatom bonds is also in its infancy. The overall goals of this project are the systematic development of general methods for preparing transition metal complexes containing metal-heteroatom bonds, investigation of the scope and mechanisms of their reactions, and application of these reactions to problems in organic synthesis. Research proposed for the upcoming grant period focuses on reagents with metal-nitrogen (as well as -oxygen and -sulfur) multiple bonds, and builds on recent preliminary findings of the highly enantioselective reactions of some of these complexes with organic compounds. The specific goals are: (1) development of general methods for the synthesis of metal complexes with metal-nitrogen multiple bonds that are reactive toward organic compounds; (2) isolation and full characterization of such molecules where it is possible, and where it is not, their characterization by indirect methods; (3) synthesis of chiral, enantioresolved complexes with metal- nitrogen multiple bonds; (4) exploration of the reactions of these materials with organic compounds, with a particular focus on the search for processes that take place with high levels of asymmetric induction; (5) elucidation of the mechanisms of these reactions to uncover general concepts useful for the development of new catalytic and stoichiometric synthetic reagents; (6) extension of these developments to analogous reactions of metal- oxygen and metal-sulfur multiple bonds.