Reaction of Silyllithium, α‑Keto <i>N</i>-<i>tert</i>-Butanesulfinyl Imidates and Aldehydes for Asymmetric Synthesis of α‑Substituted β‑(Silyloxy)-α-hydroxy Acid Derivatives

A single-flask reaction of silyllithium, α-keto N-tert-butanesulfinyl imidates and aldehydes has been developed for the diastereoselective synthesis of α,β-dihydroxy acid derivatives. In this reaction, the nucleophilic addition of silyllithium to chiral α-keto imidates followed by silyl migration forms chiral aza-enolates, which react diastereoselectively with aldehydes. Subsequent [1,4]-O → O silyl migration affords α-substituted β-(silyoxy)-α-hydroxy imidates.