121. Asymmetric and ‘anti’-Selective Aldolisations of Acetates and Propionates. Preliminary Communication
     Oppolzer, W.; Marco-Contelles, J.
     Helv. Chim. Acta 1986, 69, 1699-1703

Starting from acetates 1 and propionates 6, TiCl₄-mediated addition of their silyketene acetals 2 and 7 to aldehydes gave aldols 4 and 9, respectively, with high π-face and ‘anti’ differentiation (Schemes, and Tables 1 and 2). Alternation of the (E/Z)-enolate geometry led to reversed α- and β-inductions (7 → 9b, 8 → 10b). Non-destructive removal of the auxiliary yielded enantiomerically pure β-hydroxycarboxylic acids 13.

DOI : 10.1002/hlca.19860690725