The focus of this research is the preparation and synthetic use of allenylmetallic reagents of tin, boron, titanium and chromium. Particular attention will center on SE' additions to aldehydes as a route to enantioenriched propargylic and allenic carbinols. Among the issues to be addressed include: the configurational and regiochemical stability of chiral allenyl and propargyl organometallics, the stereochemistry and regiochemistry of the SE' additions of these reagents, the effect of chiral ligands on the enantioselectivity of the SE' process, and possible applications of these reagents in natural product synthesis. %%% With this Renewal award, the Synthetic Organic Program is supporting the research of Dr. James A. Marshall of the Department of Chemistry at the University of South Carolina. Professor Marshall will focus his work on developing optically active organometallic reagents for possible use in the synthesis of a variety of natural products.