96016-67-0Relevant articles and documents
SYNTHESIS OF STRUCTURAL ELEMENTS OF THE CAPSULAR POLYSACCHARIDE OF STREPTOCOCCUS PNEUMONIAE TYPE 14
Koeman, Franciscus A. W.,Meissner, Johannes W. G.,Ritter, Hendrik R. P. van,Kamerling, Johannis P.,Vliegenthart, Johannes F. G.
, p. 1 - 26 (2007/10/02)
The synthesis is reported of methyl O-β-D-galactopyranosyl-(1->4)-O-β-D-glucopyranosyl-(1->6)-O-4)>-O-2-acetamido-2-deoxy-β-D-glucopyranoside (13), methyl O-β-D-galactopyranosyl-(1->4)-O-β-D-glucopyranosyl-(1->6)-O-4)>-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-(1->3)-O-β-D-galactopyranosyl-(1->4)-β-D-glucopyranoside (28), and O-β-D-galactopyranosyl-(1->4)-O-β-D-glucopyranosyl-(1->6)-O-4)>-O-(2-acetamido-2-deoxy-β-D-glucopyranosyl)-(1->3)-O-β-D-galactopyranosyl-(1->4)-D-glucopyranose (38), representing fragments of the capsular polysaccharide of Streptococcus pneumoniae type 14 (3)-β-D-Galp-(1->4)-β-D-Glcp-(1->6)-4)>-β-D-GlcpNAc-(1->>n). 4-O-(2,3,4,6-Tetra-O-acetyl-β-D-galactopyranosyl)-2,3,6-tri-O-acetyl-α-D-glucopyranosyl trichloroacetamidate (6) was coupled regio- and stereoselectively with HO-6 of methyl 3-O-benzyl-2-deoxy-2-phthalimido-β-D-glucopyranoside (4) in dichloromethane, using boron trifluoroetherate as a promoter.Coupling of 2,3,4,6-tetra-O-acetyl-α-D-galactopyranosyl trichloroacetimidate (8) with HO-4 of the resulting trisaccharide derivative (9) in dichloromethane, using boron trifluoroetherate as a promoter, afforded methyl 4-O-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl)-6-O--3-O-benzyl-2-deoxy-2-phthalimido-β-D-glucopyranoside (10).Debenzylation of 10, followed by dephthaloylation, N,O-acetylation, and de-O-acetylation gave tetrasaccharide methyl glycoside 13.Disaccharide derivative 6 was also coupled with HO-6 of allyl 3-O-benzyl-2-deoxy-2-phthalimido-β-D-glucopyranoside (16) in dichloromethane using trimethylsilyl trifluoromethanesulfonate as a promoter.Coupling of 8 with HO-4 of the resulting trisaccharide derivative (17) in dichloromethane, using trimethylsilyl trifluoromethanesulfonate as a promoter, afforded allyl-4-O-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl)-6-O--3-O-benzyl-2-deoxy-2-phthalimido-β-D-glucopyranoside (18).Deallylation of 18, followed by imidation gave an activated tetrasaccharide (20), which was coupled to both methyl (24) and benzyl (33) 2,3,6-tri-O-benzyl-4-O-(2,4,6-tri-O-benzyl-β-D-galactopyranosyl)-β-D-glucopyranoside in dichloromethane, using trimethylsilyl trifluoromethanesulfonate as a promoter, to give the corresponding hexasaccharide derivatives 25 and 34.Debenzylation of 25, followed by dephthaloylation, N,O-acetylation, and de-O-acetylation gave hexasaccharide methyl glycoside 28.Dephthaloylation of 34, followed by N,O-acetylation, debenzylation, re-O-acetylation and de-O-acetylation gave hexasaccharide 38.
