van Steijn A M, Kamerling J P, Vliegenthart J F
Bijvoet Center, Department of Bio-Organic Chemistry, Utrecht University, The Netherlands.
Carbohydr Res. 1992 Mar 2;225(2):229-45. doi: 10.1016/s0008-6215(00)90498-1.
The synthesis is reported of methyl 3-O-(4-O-beta-D-galactopyranosyl-alpha-D- glucopyranosyl)-alpha-L-rhamnopyranoside (1), methyl 2-O-alpha-D-glucopyranosyl-4-O-beta-D-glucopyranosyl-beta-D- galactopyranoside (3), methyl 3-O-(4-O-beta-D-galactopyranosyl-alpha-D-glucopyranosyl)-alpha-L- rhamnopyranoside 3"-(sn-glycer-3-yl sodium phosphate) (2), and methyl 2-O-alpha-D-glucopyranosyl-4-O-beta-D- glucopyranosyl-beta-D-galactopyranoside 3-(sn-glycer-3-yl sodium phosphate) (4), which are trisaccharide methyl glycosides related to fragments of the capsular polysaccharide of Streptococcus pneumoniae type 18C ([----4)-beta-D- Glcp-(1----4)-[alpha-D-Glcp-(1----2)]-[Glycerol-(1-P----3)]-beta-D-Galp - (1----4)-alpha-D-Glcp-(1----3)-alpha-L-Rhap-(1----]n). Ethyl 4-O-acetyl-2,3,6-tri-O-benzyl-1-thio-beta-D-glucopyranoside (10) was coupled with benzyl 2,4-di-O-benzyl-alpha-L-rhamnopyranoside (6). Deacetylation of the product, followed by condensation with 2,4,6-tri-O-acetyl-3-O-allyl-alpha-D-galactopyranosyl trichloroacetimidate (18), gave benzyl 2,4-di-O-benzyl-3-O-[2,3,6-tri-O- benzyl-4-O-(2,4,6-tri-O-acetyl-3-O-allyl-beta-D-galactopyranosyl)-alpha- D- glucopyranosyl]-alpha-L-rhamnopyranoside (19). Acetolysis of 19, followed by methylation, deallylation (----22), and further deprotection afforded 1. Condensation of methyl 2,4-di-O-benzyl-3-O-[2,3,6-tri-O-benzyl-4-O-(2,4,6-tri- O-acetyl-beta-D-galactopyranosyl)-alpha-D-glucopyranosyl]-alpha-L- rhamnopyranoside (22) with 1,2-di-O-benzyl-sn-glycerol 3-(triethyl-ammonium phosphonate) (24), followed by oxidation and deprotection, yielded 2. Condensation of ethyl 2,3,4,6-tetra-O-benzyl-1-thio-beta-D-glucopyranoside (27) with methyl 3-O-allyl-4,6-O-benzylidene-beta-D-galactopyranoside (28), selective benzylidene ring-opening of the product, coupling with 2,3,4,6-tetra-O-acetyl-alpha-D-glucopyranosyl trichloroacetimidate (31), and deallylation afforded methyl 6-O-benzyl-4-O-(2,3,4,6-tetra-O-acetyl-beta-D-glucopyranosyl)-2-O- (2,3,4,6-tetra-O-benzyl-alpha-D-glucopyranosyl)-beta-D-galactopyranoside (33). Deprotection of 33 gave 3, and condensation of 33 with 24, followed by oxidation and deprotection, gave 4.
报道了3 - O -（4 - O -β - D -吡喃半乳糖基-α - D -吡喃葡萄糖基）-α - L -吡喃鼠李糖苷甲酯（1）、2 - O -α - D -吡喃葡萄糖基-4 - O -β - D -吡喃葡萄糖基-β - D -吡喃半乳糖苷甲酯（3）、3 - O -（4 - O -β - D -吡喃半乳糖基-α - D -吡喃葡萄糖基）-α - L -吡喃鼠李糖苷3″-（甘油-3 -磷酸钠）（2）和2 - O -α - D -吡喃葡萄糖基-4 - O -β - D -吡喃葡萄糖基-β - D -吡喃半乳糖苷3 -（甘油-3 -磷酸钠）（4）的合成，它们是与18C型肺炎链球菌荚膜多糖片段相关的三糖甲基糖苷（[----4）-β - D -葡萄糖-(1----4)-[α - D -葡萄糖-(1----2)]-[甘油-(1 -磷酸----3)]-β - D -半乳糖 - (1----4)-α - D -葡萄糖-(1----3)-α - L -鼠李糖-(1----]n）。4 - O -乙酰基-2,3,6 -三-O -苄基-1 -硫代-β - D -吡喃葡萄糖苷乙酯（10）与2,4 -二-O -苄基-α - L -吡喃鼠李糖苷（6）偶联。产物脱乙酰化，然后与2,4,6 -三-O -乙酰基-3 - O -烯丙基-α - D -吡喃半乳糖基三氯乙酰亚胺酯（18）缩合，得到2,4 -二-O -苄基-3 - O -[2,3,6 -三-O -苄基-4 - O -（2,4,6 -三-O -乙酰基-3 - O -烯丙基-β - D -吡喃半乳糖基）-α - D -吡喃葡萄糖基]-α - L -吡喃鼠李糖苷（19）。19进行乙酰解，然后甲基化、脱烯丙基化（----22）并进一步脱保护得到1。2,4 -二-O -苄基-3 - O -[2,3,6 -三-O -苄基-4 - O -（2,4,6 -三-O -乙酰基-β - D -吡喃半乳糖基）-α - D -吡喃葡萄糖基]-α - L -吡喃鼠李糖苷甲酯（22）与1,2 -二-O -苄基-甘油-3 -（三乙铵膦酸酯）（24）缩合，然后氧化和脱保护，得到2。2,3,4,6 -四-O -苄基-1 -硫代-β - D -吡喃葡萄糖苷乙酯（27）与3 - O -烯丙基-4,6 - O -亚苄基-β - D -吡喃半乳糖苷甲酯（28）缩合，产物进行选择性亚苄基开环，与2,3,4,6 -四-O -乙酰基-α - D -吡喃葡萄糖基三氯乙酰亚胺酯（31）偶联，然后脱烯丙基化得到6 - O -苄基-4 - O -（2,3,4,6 -四-O -乙酰基-β - D -吡喃葡萄糖基）-2 - O -（2,3,4,6 -四-O -苄基-α - D -吡喃葡萄糖基）-β - D -吡喃半乳糖苷甲酯（33）。33脱保护得到3，33与24缩合，然后氧化和脱保护得到4。
