This work will focus on the total synthesis of a diverse group of important natural products and on the development of new synthetic methodology. Synthetic targets include: oleanolic acid, miroestrol, paeoniflorin, prostaglandin H2, lactacystin, ovalicin, cassioside, epibatidine and brefeldin A. The methodology topics chosen include: enantioselective addition of vinyl and alkynyl groups to aldehydes and ketones, enantioselective reduction of ketones, syntheses of chiral oxiranes, catalytic syntheses of new chiral controller groups, exploratory chemistry of chiral oxazaaluminolidines and chiral cationc oxazaborolidines, exploratory research on new titanium (IV) complexes as enantioselective catalysts, use of amino-acid derived catalysts for enantioselective synthesis and new methodology for the preparation of medium- and large-ring terpenoids. %%% With this Renewal award, the Synthetic Organic Program is supporting the research of Dr. Elias J. Corey of the Department of Chemistry at Harvard University. Professor Corey will focus his work on the synthesis of several naturally occurring and biologically active complex organic molecules. He will also pursue the development of new synthetic methodology