title: Synthesis of structural elements of the capsular polysaccharides of Streptococcus pneumoniae types 6A and 6B.
abstract: O-alpha-d-Glucopyranosyl-(1----3)-alpha, beta-L-rhamnopyranose (15), O-alpha-D-galactopyranosyl-(1----3)-O-alpha-D-glucopyranosyl-(1----3)-al pha, beta-L-rhamnopyranose (17), O-alpha-D-galactopyranosyl-(1----3)-O-alpha-D-glucopyranosyl-(1----3)- O-alpha-L-rhamnopyranosyl-(1----3)-D-ribitol (23), and O-alpha-D-galactopyranosyl-(1----3)-O-alpha-D-glucopyranosyl-(1----3)- O-alpha-L-rhamnopyranosyl-(1----4)-D-ribitol (27), which are structural elements of the capsular polysaccharides of Streptococcus pneumoniae types 6A 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 with benzyl 2,4-di-O-benzyl-alpha-L-rhamnopyranoside (4), and subsequent deallylation (----14) and debenzylation gave 15. Condensation of 14 with ethyl 2,3,4,6-tetra-O-benzyl-1-thio-beta-D-galactopyranoside (2) followed by debenzylation gave 17. Acetylation of 17 followed by removal of AcO-1, conversion into the imidate, coupling with 1,2,4,5-tetra-O-benzyl-D-ribitol (11), deacetylation, and debenzylation gave 23. Coupling of the imidate with 1-O-allyloxycarbonyl-2,3,5-tri-O-benzyl-D-ribitol (12) followed by deallyloxycarbonylation, deacetylation, and debenzylation yielded 27.
authors.affiliation: Department of Bio-Organic Chemistry, Utrecht University, The Netherlands.
authors.forename: T M
authors.initials: TM
authors.lastname: Slaghek
authors.forename: A H
authors.initials: AH
authors.lastname: van Oijen
authors.forename: A A
authors.initials: AA
authors.lastname: Maas
authors.forename: J P
authors.initials: JP
authors.lastname: Kamerling
authors.forename: J F
authors.initials: JF
authors.lastname: Vliegenthart
mesh_terms: D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D008969:Molecular Sequence Data; D015394:Molecular Structure; D011135:Polysaccharides, Bacterial / Q000138:chemical synthesis*; D013296:Streptococcus pneumoniae / Q000276:immunology*
chemical_list: D011135:Polysaccharides, Bacterial