Construction of tetrasubstituted silicon-stereogenic silanes via conformational isomerization and N‑heterocyclic carbenecatalyzed desymmetrization

Abstract

Disclosed here is a catalytic strategy for asymmetric access to chiral tetrasubstituted silicon-stereogenic silanes. Our reaction starts with a (covalently) symmetric silane bearing two aldehyde moieties as the substrate. Single-crystal structural analysis shows that the substrate exists as a racemate of two conformational enantiomers because of the presence of a Si/O weak interaction. Mechanistic studies assisted by DFT calculation indicate that the two conformational enantiomers can readily isomerize to each other, and one of the conformational enantiomers of the substrate is favorably activated by a N-heterocyclic carbene catalyst via an overall desymmetrization process to eventually afford optically enriched tetrasubstituted silicon-stereogenic silanes as the products. Our chiral silanes' products can be readily transformed to a diverse set of silicon stereogenic functional molecules.