Bimetallic Carbene Complexes as Reagents and Catalysts for Organic Synthesis

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This research involves the development of new methods for directing the powerful carbon-carbon bond-forming chemistry of Fischer carbene complexes for the purposes of organic synthesis. It will focus on the cyclopropanation of alkenes and several addition/insertion reactions of alkynes. The key intermediates are heterobimetallic Fischer carbene complexes, in which an electron-deficient metal center is attached to the heteroatom of a metallocarbenoxy moiety. By virtue of their electron-deficient nature and rapid ligand substitution chemistry, Lewis acidic metal substituents will play a fourfold role in the chemistry of these bimetallic systems: (1) as a template on which to attach substrate molecules bearing a ligand "handle" to achieve new and useful diastereoselectivity; (2) as a site for attachment of chiral auxiliaries to achieve asymmetric induction; (3) as a source of intramolecular nucleophilic reactivity, allowing stabilized Fischer carbenes to be activated by heteroatom displacement: and (4) as a means to regenerate the carbene moiety under mild conditions, allowing the target reactions to be performed under catalytic conditions. %%% With this award the Synthetic Organic Program of the Chemistry Division will support the research of Dr. M. G. Finn of the Department of Chemistry at the University of Virginia. The research is in the area of syntheic methodology and will develop new methods for directing carbon-carbon bond formation, one of the most important classes of reactions in organic chemistry. The key intermediates in the process are heterobimetallic Fischer carbene complexes, which are molecules containing two different metal atoms. These intermediates will enable shape-selective control of the reactions.