Enantioselective Allylmetal-Aldehyde, -Acetal and Aldol Reactions

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This project contains three subprojects, in the first of which three models will be used to probe the transition structure preferences in the reaction of enoxysilanes with aldehydes. Double bond orientation, the role of Lewis acids and facial preferences with chiral Lewis acids will be studied. The second subproject will develop general synthetic methodology involving the use of organotin reagents as nucleophiles for stereoselective opening of chiral acetals. The third area of study involves development of a new class of chiral Lewis acids based on strain-release Lewis acidity, the invention of a catalytic asymmetric aldol condensation, the study of a catalytic asymmetric allylation of aldehydes using metallacyclobutanes and preparation of a reagent for asymmetric allylation of aldehydes using pentacoordinate siliconate complexes. %%% With this renewal award, the Synthetic Organic Program is supporting the research of Dr. Scott E. Denmark of the Department of Chemistry at the University of Illinois, Urbana. The primary objectives of the research are: 1) to elucidate those factors responsible for stereochemical control in an important family of reactions of silicon compounds 2) to expand the synthetic utility of organotin reagents, and 3) to develop new catalytic reactions for asymmetric synthesis. Asymmetric synthesis leads to the preferential production of only one of the many products possible from reactions of a complicated set of starting materials, and is of critical importance for the efficient synthesis of large organic molecules.