Nucleophilic asymmetric substitution at silicon

CHED 309

Chad A. Meece, MEECEC@student.gvsu.edu and William R. Winchester, winchesr@gvsu.edu. Department of Chemistry, Grand Valley State University, 1 Campus Drive, Allendale, MI 49401
This poster will present our progress toward the synthesis of chiral at silicon asymmetric molecules using nucleophilic asymmetric substitution. Chiral silanes have potential as resolving agents, chiral ligands, chiral auxiliaries and in chiral polymers. While there are many naturally occurring chiral organic molecules, there are no naturally occurring chiral at silicon asymmetric molecules. We have made significant progress in our studies of the reactions of organolithium compounds with prochiral silanes in the presence of sparteine. Specifically, we have observed that there is a regular increase in enantioselectivity as the size of the groups attached to silicon increases for the subsititution of hydrides. Also, the size of the nucleophile does not seem to influence the enantioselectivity. Substitution of alkoxy groups at silicon has the potential to increase selectivity, but is less regular in its dependence on size of the groups attached to silicon.