Asymmetric Aldol Reactions Using (<i>S</i>,<i>S</i>)-(<i>+</i>)-Pseudoephedrine-Based Amides: Stereoselective Synthesis of α-Methyl-β-hydroxy Acids, Esters, Ketones, and 1,3-Syn and 1,3-Anti Diols
作者:Jose L. Vicario、Dolores Badía、Esther Domínguez、Mónica Rodríguez、Luisa Carrillo
DOI:10.1021/jo000035h
日期:2000.6.1
reactions is reported. The reaction of (S, S)-(+)-pseudoephedrine-derived propionamide enolates with several aldehydes yielded exclusively one of the four possible diastereomers in good yields, although transmetalation of the firstly generated lithium enolate with a zirconium(II) salt, prior to the addition of the aldehyde, is necessary in order to achieve high syn selectivity. The so-formed syn-alpha-methyl-beta-hydroxy
报道了进行立体选择性醛醇缩合反应的非常有效的方法。(S,S)-(+)-伪麻黄碱衍生的丙酰胺烯醇化物与几种醛的反应仅以良好的收率仅产生了四种可能的非对映异构体之一,尽管先生成的烯醇酸锂与锆(II)盐进行了重金属化。为了获得高的顺式选择性,添加醛是必需的。如此形成的顺-α-甲基-β-羟基酰胺被转化为其他有价值的手性非外消旋合成子,例如α-甲基-β-羟基酸,酯和酮。最后,已经开发了一种立体控制的还原程序,该程序从如此获得的α-甲基-β-羟基酮开始,可以合成1,3-syn-或1,3-抗-α-甲基-1,