Chiral Acylsilanes in Organic Synthesis. Part 3. Silicon-directed stereoselective preparation and Ireland ester-enolate rearrangement of O-acyl-substituted α-silylated allyl alcohols

TLDR: In this article, the Me3Si groups in α-position to the COOH group of these compounds were removed chemoselectively in presence of the chiral silyl group in δ-position by treatment with Bu4NF · 3 H2O or Et3N · 3 HF.

Abstract: Stereocontrolled addition of alk-1-enylmetal reagents to the chiral (alkoxymethyl)-substituted acylsilanes (±)-6 gave rise to α-silylated allyl alcohols, which were converted to the corresponding acetates or propionates 11–16 (Scheme 2). Deprotonation and silylation with Me3SiCl afforded – in an Ireland ester-enolate-accelerated Claisen rearrangement – stereoselectively αδ-silylated γδ-unsaturated carboxylic acids 18–24 (Scheme 4). The Me3Si groups in α-position to the COOH group of these compounds were removed chemoselectively in presence of the chiral silyl group in δ-position by treatment with Bu4NF · 3 H2O or Et3N · 3 HF (→ 27–32; Scheme 5). The reaction sequence allows a novel stereocontrolled access to chiral C-frameworks possessing a vinylsilane moiety with its full reaction potential.