Synthesis of core-2 branched tetrasaccharides 1-3, in which a fluorine atom was substituted at the 3 or 4-position of galactose residues is described. Glycosyl imidates 13, and 19 were prepared and used to provide novel glycosyl disaccharide donors 15 and 21, respectively. Coupling of acceptor 7 with glycosyl bromide 6 provides a disaccharide that was further converted into disaccharide acceptor 8. The coupling of acceptor 14 with donor 13, and acceptor 20 with donor 19 provided disaccharides that were converted to disaccharide donors 15 and 21, respectively. Regioselective glycosylation of acceptors 8, and 16 with donors 9, 15, and 21 provided tetrasaccharides 10, 17, and 22 respectively, which were systematically deprotected to targets 1-3.
描述了合成核心-2分支四糖 1-3,其中在半
乳糖残基的 3 位或 4 位上替代了一个
氟原子。准备了糖苷
亚胺 13 和 19,并用于提供新型糖苷二糖供体 15 和 21。受体 7 与糖苷
溴化物 6 的偶联提供了一种二糖,进一步转化为二糖受体 8。受体 14 与供体 13 的偶联,以及受体 20 与供体 19 的偶联,分别提供了二糖,转化为二糖供体 15 和 21。使用供体 9、15 和 21 对受体 8 和 16 进行区域选择性糖苷化,分别提供四糖 10、17 和 22,随后系统性去保护为目标 1-3。