The focus of this research is the development of new stereoselective syntheses of specifically fluorinated molecules. The work studies the reactivity and selectivity of various fluorinated building blocks and how these factors are effected by the presence of fluorine. Toward this end the stereoselective reactivity of fluorinated ketenes, ketene equivalents or products derived from them will be explored. Specific aspects include a study of the reactivity of fluoroketenes in cycloaddition reactions, preparation of fluorinated transition metal organometallic complexes as fluoroketene surrogates, use of optically pure fluorinated beta-lactams as building blocks, use of optically pure fluorinated cyclobutanones as intermediates, and use of fluorinated C,O- disilylketenes as building blocks for the synthesis of fluorinated olefins. With this award, the Synthetic Organic Program is supporting the research of Dr. John T. Welch of the Department of Chemistry at the SUNY Albany. Professor Welch will focus his work on the development of new stereoselective syntheses of specifically fluorinated molecules. This strategy will use the construction of reactive, functionalized fluorinated intermediates that can undergo a variety of further stereoselective transformations. Such systems include fluorinated ketenes, beta-lactams and cyclobutanones. The methodology developed will allow the synthesis of optically pure fluorinated compounds that can be used as probes in a variety of mechanistic and biological problems, as well as materials applications.