(<i>S</i>,<i>S</i>)-(<i>+</i>)-Pseudoephedrine as Chiral Auxiliary in Asymmetric Conjugate Addition and Tandem Conjugate Addition/α-Alkylation Reactions
作者:Efraim Reyes、Jose L. Vicario、Luisa Carrillo、Dolores Badía、Uxue Uria、Ainara Iza
DOI:10.1021/jo061205e
日期:2006.9.1
Organolithium reagents undergo highly regio- and diastereoselective 1,4-addition to (S,S)-(+)-pseudoephedrine enamides furnishing the corresponding β-alkyl-substituted adducts in excellent yields and diastereoselectivities. In addition, the intermediate lithium enolates generated after the conjugate addition step undergo a highly diastereoselective alkylation reaction, furnishing α,β-dialkyl-substituted
有机锂试剂对(S,S)-(+)-伪麻黄碱酰胺进行高度的区域和非对映选择性1,4-加成,从而以优异的收率和非对映选择性提供相应的β-烷基取代的加合物。另外,在共轭加成步骤之后产生的中间烯醇锂经历高度非对映选择性烷基化反应,以高收率提供α,β-二烷基取代的酰胺。使用非常简单和高产率的方法,将获得的加合物转化为手性非外消旋的β-烷基和α,β-二烷基取代的羧酸以及γ-烷基和β,γ-二烷基取代的醇。