Synthetic oligosaccharides related to Group B streptococcal polysaccharides. The rhamnotriose moiety of the common antigen
作者:
Vince Pozsgay,
Jean-Robert Brisson,
Harold J. Jennings,
期刊:
Canadian Journal of Chemistry
(NRC Available online 1987)
卷期:
Volume 65,
issue 12
页码: 2764-2769
ISSN:0008-4042
年代: 1987
DOI:10.1139/v87-459
出版商: NRC Research Press
数据来源: NRC
摘要:
The methyl glycoside (1) of the α-L-Rhap-(1 → 2)-α-L-Rhap-(1 → 2)-α-L-Rhap-(1 → portion of the group-specific, common antigen polysaccharide of Group B Streptococci has been synthesized. The key compound of the synthesis was methyl 3,4-di-O-benzyl-α-L-rhamnopyranoside (4). Controlled acetolysis of4gave 1,2-di-O-acetyl-3,4-di-O-benzyl-α-L-rhamnopyranose (10), which upon reaction with4under catalysis by trimethylsilyl trifluoromethanesulfonate (TMS-Tf) yielded the α-(1 → 2)-linked dirhamnoside. Subsequent rhamnosylation followed by deprotection gave1. TMS-Tf was also used in rhamnosylation reactions with tetra-O-acetyl-α-L-rhamnopyranose. Acetylation of acceptor alcohols was found to be a major side reaction in the TMS-Tf assisted glycosylations. One-dimensional nuclear Overhauser enhancement differential spectroscopy indicated that, in solution,1takes up a bent instead of an extended conformation.
点击下载:
PDF
(426KB)
返 回