Enantioselective Synthesis of 2-Substituted Alcohols Using (+)-(1<i>S</i>,2<i>S</i>)-Pseudoephedrine as Chiral Auxiliary
作者:Lutz Tietze、Christian Raith、C. Brazel、Sören Hölsken、Jörg Magull
DOI:10.1055/s-2008-1000851
日期:2008.1
An improved method for the selective synthesis of enantiopure 2-substituted alcohols is described. Highly diastereoselective alkylation of pseudoephedrine-derived amides and subsequent oxidation of the hydroxyl group in the amide side chain, leads to oxoamides. These oxoamides can be purified by crystallization or preparative HPLC to obtain diastereomeric ratios of >99:1. The following reductive cleavage of the modified auxiliary allows the epimerization-free formation of enantiopure 2-substituted alcohols with up to 99.9% ee.
本研究介绍了一种选择性合成对映体纯 2-取代醇的改进方法。对来源于伪麻黄碱的酰胺进行高非对映选择性烷基化,然后氧化酰胺侧链中的羟基,从而得到草酰胺。这些草酰胺可通过结晶或制备型高效液相色谱法进行提纯,以获得大于 99:1 的非对映比率。随后对改性助剂进行还原裂解,可形成无对映异构的 2-取代醇,ee 值高达 99.9%。