formamido group replaced by a hydroxyl group, have been prepared as their methyl glycosides. Mono- and di-saccharide thioglycosides of D-rhamnose and 4-azido-4,6-dideoxy-D-mannose were used as glycosyl donors for the preparation of protected pentasaccharide derivatives with trisaccharides as intermediates. Glycosylations were performed by activation in situ of the thioglycosides with bromine in the presence
已制备了布鲁氏菌A抗原[---- 2)-alpha-D-Rhap4NFo-(1 ----)的三个五
糖类似物,每个类似物均被一个甲基取代,并带有一个甲酰胺基。用D-
鼠李糖和4-
叠氮基-4,6-二脱氧-
D-甘露糖的-和二糖
硫糖苷作为糖基供体,以三糖为中间体制备受保护的五糖衍
生物,通过原位活化糖基化来进行糖基化。在糖基受体和
三氟甲磺酸银作为助催化剂存在下,用
溴将
硫代糖苷与
溴化;用
硫化氢还原
叠氮基;用
甲酸乙酯进行N-甲酰化,然后氢解得到目标五糖。