Synthesis of<i>β</i>-D-Ribofuranosyl-(1→3)-<i>α</i>-L-rhamnopyranosyl-(1→3)-L-rhamnopyranose by in situ Activating Glycosylation Using 1-OH Sugar Derivative and Me<sub>3</sub>SiBr–CoBr<sub>2</sub>–Bu<sub>4</sub>NBr–Molecular Sieves 4A System
β-d-Ribofuranosyl-(1→3)-α-l-rhamnopyranosyl-(1→3)-l-rhamnopyranose, the trisaccharide repeating unit of the C. freundii O28,1c O-specific polysaccharide, was synthesized using in situ activating glycosylation of the 1-OH sugar derivatives and a reagent mixture of trimethylsilyl bromide, cobalt(II) bromide, tetrabutylammonium bromide, and molecular sieves 4A. Regioselective tritylation was useful for synthesizing the 3-OH derivatives of methyl, allyl, and benzyl α-l-rhamnosides.
Synthesis of structural elements of the capsular polysaccharides of Streptococcus pneumoniae types 6A and 6B
作者:Ted M. Slaghek、Anita H. van Oijen、Augustinus A.M. Maas、Johannis P. Kamerling、Johannes F.G. Vliegenthart
DOI:10.1016/0008-6215(90)84051-u
日期:1990.10
copyranosyl-(1----3)- O-alpha-L-rhamnopyranosyl-(1----4)-D-ribitol (27), which are structural elements of the capsularpolysaccharides of Streptococcuspneumoniaetypes6A and 6B ([----2)-alpha-D-Galp-(1----3)-alpha-D-Glcp-(1----3)-alpha-L-Rhap- (1----X)- D-Rib-ol-(5-P----]n; 6A X = 3, 6B X = 4), have been synthesised. Ethyl 3-O-allyl-2,4,6-tri-O-benzyl-1-thio-beta-D-glucopyranoside (3) was coupled