为了阐明导致选择蛋白介导的细胞粘附事件的分子因素,作为产生这些过程的有效和特异性抑制剂的基础,我们合成了三糖识别表位Lewis a [Le a]的多种硫酸盐类似物。:Galβ1→3(Fucα1→4)GlcNAc]和Lewis x [Le x:Galβ1→4(Fucα1→3)GlcNAc]。我们多样化的合成路线允许从常见中间体以10–20%的总产率(不超过15个线性步骤)合成克量的这些硫酸三糖。此外,我们还固定了Le a和Le x的还原端 β-烯丙基糖苷配基的三糖前体,提供每个最终产物的单一端基,并允许进一步修饰成多价衍生物。
为了阐明导致选择蛋白介导的细胞粘附事件的分子因素,作为产生这些过程的有效和特异性抑制剂的基础,我们合成了三糖识别表位Lewis a [Le a]的多种硫酸盐类似物。:Galβ1→3(Fucα1→4)GlcNAc]和Lewis x [Le x:Galβ1→4(Fucα1→3)GlcNAc]。我们多样化的合成路线允许从常见中间体以10–20%的总产率(不超过15个线性步骤)合成克量的这些硫酸三糖。此外,我们还固定了Le a和Le x的还原端 β-烯丙基糖苷配基的三糖前体,提供每个最终产物的单一端基,并允许进一步修饰成多价衍生物。
5,7-Dihydroxy-3-[beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl-(1-->2)-beta-D-glucopyranosyl]-2-(3,4-dihydroxy- phenyl)-4H-1-benzopyran-4-one (quercetin 3-sophorotrioside), a flavonol triglycoside, isolated from Pisum sativurn shoots and showing protective effects on liver injury induced by chemicals, was synthesized for the first time. The target compound was successfully synthesized in eight linear steps and in 39% overall yield through a combination of phasetransfer-catalyzed (PTC) quercetin C-3 glycosylation and silver triflate (AgOTf) promoted carbohydrate chain elongation using both sugar bromide and trichloroacetimidate donors.
Stereoselective, Lewis acid-catalyzed glycosylation of alcohols by glucose 1,2-cyclic sulfites
作者:William J. Sanders、Laura L. Kiessling
DOI:10.1016/0040-4039(94)85307-x
日期:1994.10
alpha-D-Glucopyranose-1,2-cyclic sulfites (1a-c) have been prepared by reaction of a suitably protected glucose residue and thionyl diimidazole. Reaction of these compounds with alcohols in the presence of Yb(OTf)(3) or Ho(OTf)(3) stereoselectively affords beta-O-glycosides