The focus of this research is the development of new synthetic methodology based on radical anion intermediates, specifically samarium or tin associated ketyls which have a distinct free radical component as well as an accompanying anionic behavior. The ketylmediated opening of oxygen and nitrogen heterocycles and carbocyclic rings with samarium iodide and tin hydride will be studied. In each case, one or two new bonds will be formed at the expense of either a carbon-oxygen, carbon-nitrogen, or carbon-carbon bond. Mechanistic studies will determine the nature of the tethered atom in terms of its ionic or free radical nature as well as the influence of ring size on the fragmentation process. Subsequent reactions of intermediates will allow tandem processes to occur such as "moving the ring down the chain." Applications of this methodology will be used on optically active carbohydrate templates and to synthesize portions of two natural products, capsimycin and X-206. With this award, the Synthetic Organic Program is supporting the research of Dr. Eric J. Enholm of the Department of Chemistry at the University of Florida. Professor Enholm will focus his work on the development of new synthetic methodology. The emphasis of the research will be on the use of radical anion intermediates to initiate fragmentation reactions of cyclic systems, the products of which in turn can undergo further reactions. In this way, one or two new bonds will be formed at the expense of either a carbon-oxygen, carbon-nitrogen or carbon- carbon bond.
