Highly optimized β-mannosylation via p-methoxybenzyl assisted intramolecular aglycon delivery
Highly optimized β-mannosylation via p-methoxybenzyl assisted intramolecular aglycon delivery
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DOI：
10.1055/s-1998-1894
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发表时间：
1998-10-01
期刊：
影响因子：
2
通讯作者：
Nakahara, Y
中科院分区：
文献类型：
--
作者：
Ito, Y;Ohnishi, Y;Nakahara, Y
利用甘露糖基巯基苷5和19实现了高效、立体选择性的-甘露糖基化。在MeOSO2CF3的作用下，从混合缩醛12、15和20中获得糖基分子内传递（IAD），通过糖基与C-2位置携带对甲氧基苄基（PMB）基团的甘露糖基硫苷进行氧化偶联，产生-甘露糖苷13/16/21。值得注意的是，通过将先前使用的4-和6-位置的保护基团从苄基改为环己基(5)或TIPDS（19）基团，大大提高了IAD的效率。因此，现在有可能以高度优化的方式进行-甘露糖基化，以75-85%的产率获得与天冬酰胺连接的低聚糖相对应的骨架结构的二糖和三糖作为单一立体异构体。
Highly efficient and stereoselective beta-mannosylation was achieved by using mannosyl thioglycosides 5 and 19. Intramolecular aglycon delivery (IAD) from mixed acetal 12, 15 and 20, obtainable by oxidative coupling of aglycon onto mannosyl thio-glycosides which carry p-methoxybenzyl (PMB) group at C-2 position, was performed by the action of MeOSO2CF3 to afford beta-mannosides 13/16/21. It is to be noted that efficiency of IAD was substantially improved by changing the protecting group at the 4- and 6- positions from previously utilized benzylidene to cyclohexylidene (5) or TIPDS (19) group. As a result, it is now possible to perform the beta-manno glycosylation in a highly optimized manner to afford di- and trisaccharides with a backbone structure corresponding to asparagine-linked oligosaccharides in 75-85% yield as single stereoisomers.