Gram scale synthesis of A (type 2) and B (type 2) blood group tetrasaccharides through 1,6-anhydro-N-acetyl-β-D-glucosamine
作者:Tatiana V. Tyrtysh、Elena Yu. Korchagina、Ivan M. Ryzhov、Nicolai V. Bovin
DOI:10.1016/j.carres.2017.06.014
日期:2017.9
Fuc-Gal-anhydroGlcNAc with single free 3'-OH group. Its standard α-galactosylation gave protected B (type 2) tetrasaccharide. For synthesis of correspondent A tetrasaccharide seven different 2-azido-2-deoxygalactosyl (GalN3) donors were tested: 6-O-acetyl-3,4-O-isopropylidene-GalN3 thioglycoside was shown to provide the best yield (89%) and stereoselectivity (α/β = 24:1). Further 1,6-anhydro cycle opening
从3-O-苯甲酰基-1,6-脱水-N-乙酰基葡糖胺开始,提出了以3-氨基丙基糖苷形式的A(2型)和B(2型)四糖的革兰氏合成。其半乳糖基化,然后再保护,得到具有单个游离2'-OH基团的乳糖胺衍生物,总产率为75%。标准岩藻糖基化和下一轮再保护的总产率为88%,得到具有单个游离3'-OH基团的三糖Fuc-Gal-anhydroGlcNAc。其标准的α-半乳糖基化得到保护的B(2型)四糖。为了合成对应的A四糖,测试了七个不同的2-叠氮基-2-脱氧半乳糖基(GalN3)供体:6-O-乙酰基-3,4-O-异亚丙基-GalN3硫代糖苷提供了最佳收率(89%),立体选择性(α/β= 24:1)。进一步打开1,6-脱水循环,