Synthesis of a novel asparagine-linked heptasaccharide structure via p- methoxybenzyl-assisted β-mannosylation
RIKEN, Вако, Saitama, JapanCarbohydrate Research (Impact Factor: 1.93). 09/2000; 328(3):263-76. DOI: 10.1016/S0008-6215(00)00123-3
Synthesis of a core heptasaccharide asparagine N4-[alpha-D-mannopyranosyl-(1 --> 6)-[(alpha-D-mannopyranosyl)-(1 --> 3)]-[(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-(1 --> 2)]-(beta-D-mannopyranosyl)-(1 --> 4)-(2-acetamido-2-deoxy-beta-D-glucopyranosyl)-(1 --> 4)-[(alpha-L-fucopyranosyl)-(1 --> 6)]-2-acetamido-2-deoxy-beta-D-glucopyranosyl]-L-asparagine (1a) found from CHO glycosylation mutant cell LEC 14 is described. The structure of 1a is highly novel in terms of the presence of an extra GlcNAc residue linked to the 2-position of beta-linked mannose. The synthesis was performed using p-methoxybenzyl-assisted intramolecular aglycon delivery as the key transformation. 4,6-O-TIDPS-protected thiomannoside methyl 2-O-p-methoxybenzyl-4,6-O-(1,1,3,3-tetraisopropyl)disiloxanylid ene-3-O-trimethylsilyl-1-thio-alpha-D-mannopyranoside was adopted for this particular purpose, which afforded beta-mannoside p-methoxyphenyl 2,3-O-(p-methoxybenzylidene)-4,6-O-(1,1,3,3-tetraisopropyl)+ ++disiloxanylidene-beta-D-mannopyranosyl-(1 --> 4)-3,6-di-O-benzyl-2-deoxy-2-phthalimido-beta-D-glucopyranoside stereoselectively in 75% yield.
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ABSTRACT: The synthesis of a hexasaccharide from the inner part of an N-linked oligosaccharide portion of a glycoprotein from Haemonchus contortus is described. This hexasaccharide contains a novel fucosylation pattern with three α-linked fucosyl groups at O-3, O-6 and O-3′ of the two N-acetylglucosamine residues. In the synthesis two consecutive regioselective glycosylations were performed, thereby limiting protecting group manipulations, to yield a trisaccharide with β-(1⇄4) linkages. Subsequent trifucosylation in one step, followed by inversion of configuration via a displacement reaction at C-2′′ of the terminal glucosyl residue produced the resulting β-mannosyl linkage. The 2-acetamido-2-deoxy-glucosylamine residue was capped by an N-acetyl group and the hexasaccharide was deprotected. (© Wiley-VCH Verlag GmbH, 69451 Weinheim, Germany, 2002)European Journal of Organic Chemistry 04/2002; 2002(10):1614 - 1618. DOI:10.1002/1099-0690(200205)2002:10<1614::AID-EJOC1614>3.0.CO;2-1 · 3.07 Impact Factor
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ABSTRACT: Glycosphingolipids isolated from larvae of the green-bottle fly, Lucilia caesar, have quite unique structures containing GlcNAcbeta-(1 --> 3)-Man and GalNAcbeta-(1 --> 4)-GlcNAcbeta-(1 --> 3)-Man. We have synthesized two glycosphingolipids, beta-D-GlcNAcp-(1 --> 3)-beta-D-Manp-(1 --> 4)-beta-D-Glcp-(1 --> 1)-Cer and beta-D-GalNAcp-(1 --> 4)-beta-D-GlcNAcp-(1 --> 3)-beta-D-Manp-(1 --> 4)-beta-D-Glcp-(1 --> 1)-Cer. A key reaction in the synthetic sequence is the application of the intramolecular aglycon delivery (IAD) approach for the synthesis of the beta-mannopyranosidic linkages.Carbohydrate Research 11/2002; 337(21-23):2037-47. DOI:10.1016/S0008-6215(02)00295-1 · 1.93 Impact Factor
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