Asymmetric Synthesis Based on Chiral Heterobicyclo{2.2.1}heptanes

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With the support of the Organic Synthesis Program, Professor Xumu Zhang, of the Department of Chemistry at the Pennsylvania State University, explores the use of chiral heterobicyclo(2.2.1) heptanes as catalysts and auxiliaries for enantioselective organic transformations. Phosphine-catalyzed (3+2) cycloaddition reactions afford chiral cyclopentenes with a high degree of regio- and enantioselectivity when mediated by chiral phosphabicyclo(2.2.1)heptanes. Related asymmetric catalysts are explored for their applicability in nucleophilic gamma addition reactions with alkynes bearing electron withdrawing groups, the Baylis-Hillman reaction, and thioether-mediated epoxidation and aziridination of aldehydes. Chiral azabicyclo(2.2.1)heptanes are employed as chiral auxiliaries for asymmetric deprotonation, enamine alkylation, and cycloaddition reactions. It has become increasingly important to develop synthetic methods which allow precise control over the three-dimensional form of organic molecules, since even the seemingly minor difference in structure displayed by two molecules related to one another as mirror images not infrequently leads to a dramatic difference in chemical properties. Professor Xumu Zhang, of the Department of Chemistry at the Pennsylvania State University, with the support of the Organic Synthesis Program, explores methods to effect such highly controlled syntheses of organic molecules. By exploring and developing reactions which are mediated by specifically designed and tailored phosphorus- or nitrogen-containing molecules, Professor Zhang is able to impart specific three-dimensional forms to the products of these reactions. In addition to developing practical synthetic methods, Professor Zhang explores the mechanisms by which these molecular transformations take place and targets important drugs and pharmaceutical intermediates to demonstrate their synthetic utility.