The Organic Synthesis Program will provide support to Dr. Hans J. Reich in the Department of Chemistry at the University of Wisconsin in Madison. The work will develop the synthetic potential of the main group by unraveling the nature of some of the intermediates and applying this knowledge to develop greater synthetic control. The synthesis of the complex molecules utilized by modern agriculture and medicine requires highly sophisticated synthetic methodology. This research is in several areas of main group organometalloid and organometallic chemistry. Specifically, experiments aimed at elucidating the mechanism of some important metathesis reactions of organolithium reagents, the metal-halogen exchange and the transmetallation reaction of organotin compounds, are described. Since these reactions are widely used in preparative organic chemistry it is important to understand them mechanistically. The experiments described will clarify the role that ate complexes play in the chemistry of organolithium reagents, and will establish whether the complexes themselves are useful carbanion donors. A new technique for determining geometry of nucleophilic attack at non-stereogenic centers (divalent tellurium) will be examined. An exploratory study will establish whether a dynamic NMR technique which has provided detailed information concerning the mechanism of the degenerate Li/I exchange between phenyllithium and iodobenzene, can also be used to study enolate reactions. The second part concerns the design of a chiral electrophilic selenenylation agent. The reagent is designed to utilize the geometry of hypervalent organoselenium species thought to be intermediates in the electrophilic addition of R-Se+ species to olefins. The process, if successful, would provide a method for asymmetric oxidation of olefins to nonracemic allyl alcohols or lactones. A third part involves the continuation of ongoing research to investigate the potential of using silyl ketones as precursors to carbonyl ylides.
