- SYNTHESE EINES TRISACCHARIDES AUS N-ACETYLNEURAMINSAEURE UND N-ACETYLLACTOSAMIN
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The reaction of methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-2-chloro-2,3,5-trideoxy-D-glycero-β-D-galacto-2-nonulopyranosonate with benzyl 2-azido-3,6-di-O-benzyl-2-deoxy-4-O-(2,3-di-O-benzyl-β-D-galactopyranosyl)-β-D-glucopyranoside in the presence of mercury cyanide-mercuri bromide gave a 1:1 mixture of the two anomeric (2->6)linked trisaccharides containing N-acetylneuraminic acid.By chromatography, 22percent of benzyl O-(methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosylonate)-(2->6)-O-(2,3-di-O-benzyl-β-D-galactopyranosyl)-(1->4)-2-azido-3,6-di-O-benzyl-2-deoxy-β-D-glucopyranoside and 23percent of the corresponding β-(2->6)-linked isomer could be isolated.A deblocking sequence, consisting of hydrogen sulfide reduction, acetylation, deacetylation, ester hydrolysis and hydrogenolysis led to the deblocked O-(5-acetamido-3,5-dideoxy-D-glycero-α-D-galacto-2-nonulopyranosylonic acid)-(2->6)-O-β-D-galactopyranosyl-(1->4)-2-acetamido-2-deoxy-D-glucopyranose and to the corresponding β-(2->6)-linked compound.
- Paulsen, Hans,Tietz, Holger
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- SYNTHESIS OF 6-O-(5-ACETAMIDO-3,5-DIDEOXY-α-D-glycero-D-galacto-2-NONULOPYRANOSYLONIC ACID)-D-GALACTOSE
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Condensation of methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-2-chloro-2,3,5-trideoxy-β-D-glycero-D-galacto-2-nonulopyranosonate with benzyl 2,3,4-tri-O-benzyl-β-D-galactopyranoside, using silver salicylate as promoter, gave benzyl 2,3,4-tri-O-benzyl-6-O-(methyl-5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-α-D-glycero-D-galacto-2-nonulopyranosylonate)-β-D-galactopyranoside (11) as the main product in 65percent yield.Furthermore, the following by-products were formed: methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-3,5-dideoxy-2-O-salicyloyl-D-glycero-D-galacto-2-nonulopyranosonate, methyl 5-acetamido-4,7,8,9-tetra-O-acetyl-2,6-anhydro-3,5-dideoxy-D-glycero-D-galacto-non-2-enopyranosonate, and an impure compound that gave, after O-deacetylation and catalytic hydrogenolysis, 6-O-(methyl 5-acetamido-3,5-dideoxy-β-D-glycero-D-galacto-2-nonulopyranosylonate)-D-galactose.O-Deacetylation of 11 gave benzyl 2,3,4-tri-O-benzyl-6-O-(methyl 5-acetamido-3,5-dideoxy-α-D-glycro-D-galacto-2-nonulopyranosylonate)-β-D-galactopyranoside, which was converted into 6-O-(methyl 5-acetamido-3,5-dideoxy-α-D-glycero-D-galacto-2-nonulopyranosylonate)-D-galactose (13) by catalytic hydrogenolysis.Saponification of 13 gave the title compound as its potassium salt.
- Vleugel, Dominicus J. M. van der,Wassenburg, Fred R.,Zwikker, Jan W.,Vliegenthart, Johannes F. G.
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p. 221 - 234
(2007/10/02)
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