作者:Sunil V. Pansare、Rajendra P. Jain
DOI:10.1021/ol990372g
日期:2000.1.1
alkylidene morpholinone derived from (1R,2S)-ephedrine and 3-methyl-2-oxobutanoic acid proceeds with good diastereoselectivity to generate a spiro bis-acetal. Lewis acid mediated diastereoselective reductive cleavage of the spiro acetal and subsequent removal of the ephedrine portion generates a alpha-hydroxy-gamma-methoxy carboxamide which is readily converted to (S)-(+)-pantolactone with high enantiomeric
[反应:见正文]衍生自(1R,2S)-麻黄碱和3-甲基-2-氧代丁酸的手性亚烷基吗啉酮的Prins反应以良好的非对映选择性进行,生成螺双缩醛。路易斯酸介导的螺缩乙二醛的非对映选择性还原裂解和随后的麻黄碱部分的去除产生了α-羟基-γ-甲氧基羧酰胺,该α-羟基-γ-甲氧基羧酰胺易于转化为具有高对映体过量的(S)-(+)-泛内酯。