Syntheses of Three Interglycosidic Isomers of N-Acetyl-.BETA.-D-mannosaminyl-L-rhamnoses Associated with O-Antigens of Several Gram-Negative Opportunistic Pathogens.
作者:Eisuke KAJI、Noriko ANABUKI、Shonosuke ZEN
DOI:10.1248/cpb.43.1441
日期:——
We achieved practical, highly stereoselective syntheses of three interglycosidic isomers of N-acetyl-β-D-mannosaminyl-L-rhamnoses, among which a β(1→4)-isomer corresponds to the repeating unit of the O-antigen of lipopolysaccharide (LPS) from the opportunistic pathogens Pseudomonas cepacia O5 and Pseudomonas aeruginosa X (Meitert). The other isomers are a β(1→2)-disaccharide, a constituent of LPS from Escherichia coli O1A, and an artificial β(1→3)-isomer. The disaccharides were obtained by simple three-step reaction sequences from 2-(benzoyloxyimino)-2-deoxyglycosyl halides (mannosamine progenitor). β-Selective glycosylations of appropriately protected L-rhamnosyl acceptors were performed. Subsequent reduction of the 2-acyloxyimino function to an amino group, N-acetylation, and removal of the protecting groups provided the target disaccharides. 13C-NMR and nuclear Overhauser effect spectra proved to be useful for stractural determination of the positional isomers of the disaccharides.
我们实现了N-乙酰基-β-D-甘露糖胺酰-L-鼠李糖三种糖苷间异构体的实用、高度立体选择性合成,其中β(1→4)异构体对应于机会性病原体铜绿假单胞菌O5和铜绿假单胞菌X(Meitert)的脂多糖(LPS)O抗原的重复单元。其他异构体是β(1→2)二糖(大肠杆菌O1A的LPS的成分)和人工β(1→3)异构体。二糖是通过简单的三步反应序列从2-(苯甲酰氧亚氨基)-2-脱氧糖基卤化物(甘露糖胺前体)获得的。对适当保护的L-鼠李糖基受体进行了β选择性糖基化。随后将2-酰氧亚氨基官能团还原为氨基,进行N-乙酰化,并去除保护基团,从而得到目标二糖。13C-NMR和核Overhauser效应谱被证明可用于确定二糖位置异构体的结构。