Understanding Internal Chirality Induction of Triarylsilyl Ethers Formed from Enantiopure Alcohols

Chirality transmission from point chirality to helical chirality was explored using triarylsilyl ethers. Circular dichroism (CD) spectroscopy was employed to show that the alcohol stereocenter of silylated, enantiopure secondary alcohols can transmit chirality to the aryl groups on the silicon resulting in a higher population of one helical conformation over another. Cotton effects characteristic of the aryl groups organized into one preferred conformation were observed for all of the compounds examined, which included both triphenyl- and trinaphthylsilyl groups. Alcohols with an R configuration typically induced a PMP helical twist, while an S configuration induced a MPM helical twist. Molecular modeling combined with solid-state structures also gave evidence signifying that point chirality adjacent to triphenylsilyl groups could bias the conformation of the phenyl groups. This work helps in our understanding of the origin of selectivity in our silylation-based kinetic resolutions and a role the phenyl groups play in that selectivity.