threo-3-Hydroxycarboxylic acids as key intermediates in a highly stereoselective synthesis of (Z)- and (E)-olefins and enol ethers

Abstract

threo-3-Hydroxycarboxylic acids, which are stereoselectively obtained from metallated carboxylic acids and aldehydes, are converted into (Z)-olefins and enol ethers with the triphenylphosphine–diethyl azodicarboxylate-adduct, whereas the corresponding (E)-isomers are prepared via the β-lactones.