Steven W. Baldwin

The central themes of our research program are the development of methodology to accomplish the synthesis of optically pure materials and the subsequent application of the new methodology to the total synthesis of biologically significant natural products. At the present time there are several different approaches to a variety of targets in progress in our laboratories. The first is the transfer of chirality from optically active hydroxylamines (e.g.,1) employing intra-and intermolecular nitrone /alkene cycloaddition reactions in the chirality transfer step. Particular targets for this chemistry are several ''unusual'' alpha-amino acids (2) as well as alkaloids related to pretazettine (3). The synthesis of pretazettine is also being addressed in a different approach involving a chiral ring expansion of allylic alcohol (4). Recently, significant progress has been realized in the synthesis the alkaloid gelsemicine (7) based on the Diels-Alder reaction of chiral maleimides such as (5). It has been found, for instance, that diastereomeric ratios in excess of 50/1 can be realized when (5) is allowed to react with silicon substituted butadiene (6) in a Lewis-acid catalyzed reaction.