Versatile intermediates for the syntheses of cell-surface oligosaccharides bearing N-acetyllactosamine units have been prepared from a readily available 1,6-anhydro-β-lactose as a key starting material. Regioselective chemical manipulations of 1,6-anhydro-β-lactose were carried out in a stepwise procedure and gave fully-protected lactosamine derivatives. It was clearly suggested that modification at C-3′ position of the galactose residue and the following introduction of a sterically hindered leaving group at C-2 position of the reducing glucose remarkably accelerated and facilitated further derivatization of this potential disaccharide material. Selective generation of hydroxyl groups at C-3, C-3′, and/or C-6′ positions proceeded smoothly in mild conditions and afforded a series of fully-functionalized disaccharide-acceptors in high yields.
我们以容易获得的 1,6-脱
水-
β-乳糖为关键起始原料,制备出了用于合成含有 N-乙酰半
乳糖胺单元的细胞表面低聚糖的多功能中间体。通过逐步对 1,6-脱
水-
β-乳糖进行区域选择性
化学处理,得到了完全保护的
乳糖胺衍
生物。研究清楚地表明,在半
乳糖残基的 C-3′ 位上进行修饰,然后在还原
葡萄糖的 C-2 位上引入一个立体受阻的离去基团,可显著加速和促进这种潜在
双糖材料的进一步衍生。在温和的条件下,在 C-3、C-3′和/或 C-6′ 位选择性地生成羟基的过程进展顺利,并以高产率获得了一系列全官能化的二糖受体。