Synthesis of C-5-thioglycopyranosides and their sulfonium derivatives from 1-C-(2′-oxoalkyl)-5-S-acetylglycofuranosides
作者:Tian Yi、Shih-Hsiung Wu、Wei Zou
DOI:10.1016/j.carres.2004.11.014
日期:2005.2
D-xylose were converted to 1-C-(2'-oxoalkyl)-5-thioglycopyranosides by base treatment. The transformation was achieved through beta-elimination to an acyclic alpha,beta-conjugated aldehyde (ketone or ester), followed by an intramolecular hetero-Michael addition by the 5-thiol group. The cycloaddition was highly stereoselective in favor of an equatorial 1-C-substitution. The resultant C-5-thioglycopyranosides
通过碱处理将L-阿拉伯糖,D-核糖和D-木糖的1-C-(2'-氧代烷基)-5-S-乙酰基呋喃糖苷转化为1-C-(2'-氧代烷基)-5-硫代吡喃果糖苷。通过β-消除成无环α,β-共轭醛(酮或酯),然后通过5-硫醇基团进行分子内杂-迈克尔加成,实现了转化。环加成是高度立体选择性的,有利于赤道1-C取代。通过用环状硫酸盐和甲基碘处理,将所得的C-5-硫代糖吡喃果糖苷进一步转化为the盐。由于存在S-轴和S-赤道取代基,获得了两种sulf异构体。