Slaghek T M, van Oijen A H, Maas A A, Kamerling J P, Vliegenthart J F
Department of Bio-Organic Chemistry, Utrecht University, The Netherlands.
Carbohydr Res. 1990 Oct 25;207(2):237-48. doi: 10.1016/0008-6215(90)84051-u.
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.
O-α-D-吡喃葡萄糖基-(1→3)-α,β-L-吡喃鼠李糖（15）、O-α-D-吡喃半乳糖基-(1→3)-O-α-D-吡喃葡萄糖基-(1→3)-α,β-L-吡喃鼠李糖（17）、O-α-D-吡喃半乳糖基-(1→3)-O-α-D-吡喃葡萄糖基-(1→3)-O-α-L-吡喃鼠李糖基-(1→3)-D-核糖醇（23）以及O-α-D-吡喃半乳糖基-(1→3)-O-α-D-吡喃葡萄糖基-(1→3)-O-α-L-吡喃鼠李糖基-(1→4)-D-核糖醇（27），它们是肺炎链球菌6A和6B型荚膜多糖的结构元件（[→2)-α-D-半乳糖-(1→3)-α-D-葡萄糖-(1→3)-α-L-鼠李糖-(1→X)-D-核糖醇-(5-P→]n；6A中X = 3，6B中X = 4），已被合成。3-O-烯丙基-2,4,6-三-O-苄基-1-硫代-β-D-吡喃葡萄糖苷乙酯（3）与2,4-二-O-苄基-α-L-吡喃鼠李糖苷苄酯（4）偶联，随后脱烯丙基（→14）和脱苄基得到15。14与2,3,4,6-四-O-苄基-1-硫代-β-D-吡喃半乳糖苷乙酯（2）缩合，随后脱苄基得到17。17乙酰化，然后除去AcO-1，转化为亚氨酸酯，与1,2,4,5-四-O-苄基-D-核糖醇（11）偶联，脱乙酰化，再脱苄基得到23。亚氨酸酯与1-O-烯丙氧羰基-2,3,5-三-O-苄基-D-核糖醇（12）偶联，随后脱烯丙氧羰基化、脱乙酰化和脱苄基得到27。
