Asymmetric Michael Additions via 2,2-Dimethyl-1,3-dioxan-5-one SAMP-Hydrazone. Distereo- and Enantioselective Synthesis of Protected 3-Substituted 4,6-Dihydroxy-5-oxo Esters - Enders, Dieter; Kownatka, Dagmar; Hundertmark, Thomas; Prokopenko, Oleg F; Runsink, Jan (Synthesis, 1997)