Stereoselective synthesis of β-d-GlcNAc-(1→4)-d-Glc disaccharide starting from lactose
作者:Lorenzo Guazzelli、Giorgio Catelani、Felicia D’Andrea、Tiziana Gragnani
DOI:10.1016/j.carres.2014.01.020
日期:2014.3
a-d-talopyranosyl]-2,3 :5,6-di-O-isopropylidene-aldehydo-D-glucose dimethyl acetal (2), in turn easily obtained from lactose, is reported. Key steps of this new procedure, that avoids the glycosylation reaction, are (a) a first epimerization at C-4' through an unusual procedure involving a completely stereospecific hydroboration-oxidation of the enol ether group of the hex-4-enopyranoside 4, obtained
从已知的4-O- [6-O-(1-甲氧基-1-甲基乙基)-3,4-O开始立体选择性制备β-d-GlcNAc-(1→4)-D-Glc二糖据报道,[-异亚丙基-β-d-talopyranosyl] -2,3:5,6-二-O-异亚丙基-醛-D-葡萄糖二甲基乙缩醛(2)又容易从乳糖获得。避免糖基化反应的这一新程序的关键步骤是(a)通过不寻常的程序在C-4'上进行第一个差向异构化,该程序涉及对4--4-enopyranoside 4的烯醇醚基进行完全立体定向的硼氢化-氧化,由3通过碱促进的丙酮消除而获得的,(b)通过在酰亚胺酶中间体上的S(N)2反应转化而进行的胺化,最后是(c)N-乙酰化,然后完全脱保护。