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
作者:Dieter Enders、Dagmar Kownatka、Thomas Hundertmark、Oleg F. Prokopenko、Jan Runsink
DOI:10.1055/s-1997-1397
日期:1997.6
The metalated 2,2-dimethyl-1,3-dioxan-5-one SAMP-hydrazone (S)-3 adds to enoate Michael acceptors 2 with high asymmetric induction. Oxidative cleavage of the SAMP auxiliary furnishes selectively protected 3-substituted 4,6-dihydroxy-5-oxo-esters (3S/R,4S)-5 in good yields (40-79%, two steps) with high diastereo- and enantiomeric excesses (de = 91-96%, ee = 89-97%). The relative configuration was determined by NMR spectroscopy and the absolute configuration by analogy with earlier results.
金属化的 2,2-二甲基-1,3-二恶烷-5-酮 SAMP-腙 (S)-3 以高不对称诱导作用加成烯酸 Michael 受体 2。 SAMP 辅助剂的氧化裂解以良好的产率(40-79%,两步)选择性保护 3-取代的 4,6-二羟基-5-氧代-酯 (3S/R,4S)-5,具有高非对映体和对映体过量(de = 91-96%,ee = 89-97%)。相对构型通过NMR光谱确定,绝对构型通过与早期结果类比确定。