(representing the two alpha-gluco linkages cleaved by alpha-Glucosidase II in N-glycan biosynthesis) in which the non-reducing-end sugar is replaced by a carbasugar and the inter-glycosidic oxygen by a sulfur were synthesised. The key coupling step was an S(N)2 displacement of an equatorial triflate at C-1 of the carbasugar by C-3 gluco or manno thiolates with inversion of configuration to give thioether pseudodisaccharides
α-Glcp-(1-> 3)-alpha-Glcp和α-Glcp-(1-> 3)-α-Manp二糖的类似物(代表两个被α-
葡萄糖苷酶II切割的α-
葡萄糖键合成了非还原末端的糖被碳糖代替,糖间的氧被
硫合成的N-聚糖
生物合成。关键的偶联步骤是通过C-3
葡萄糖或
甘露醇硫醇盐对Carbasugar的C-1处的赤道
三氟甲磺酸盐进行S(N)2置换,构型反转,得到在Carbasugar的C-1处具有轴向取代的
硫醚假二糖。脱保护的假二糖未能抑制α-
葡萄糖苷酶II的作用,无论是通过体外试验还是通过细胞研究中的游离
寡糖(FOS)分析进行测量。