The reaction of Ge-masked dienolates with Michaelacceptors in the presence of Lewis acids produced the 1,4-γ adduct regioselectively, whereas the reaction in the presence of Bu4NF gave the 1,4-α adduct exclusively.
Stabilization and activation of dienolates with germanium and tin. Stereo- and regioselective aldol reactions, regioselective coupling reactions, and regioselective synthesis of amino acid derivatives