Bausteine von Oligosacchariden, XLVII. Synthese von Tri‐ und Tetrasaccharid‐Sequenzen von N‐Glycoproteinen mit β‐D‐mannosidischer Verknüpfung

Abstract

Building Units of Oligosaccharides, XLVll 'I. -Synthesis of Tri-and Tetrrsaccharide Sequences of N-Glycoproteins Including a P-o-Mannosidic LinkageThe trisaccharides a-

Control of O-glycan synthesis: specificity and inhibition of O-glycan core 1 UDP-galactose:N-acetylgalactosamine-α-R β3-galactosyltransferase from rat liver

“…The following oligosaccharides were synthesized as described: GlcNAcPl-3GalNAca-Bn and GlcNAcBl-6GalNAca-Bn, Abbas et al (198 1); GlcNAc/31-6(Gal~l-3)GalNAca-Bn, Piscorz et 41. et a1 (1988); GlcNAcpl-3Galp-M, Kohata et al (1984); Mana6(Mana3)Manfl4GIcNAc, Paulsen and Lebuhn (1983); G~INAC~-(CH~),NHCO(CH~)~COOCH~, Paulsen et al (1982); 3-deoxy-, 4-deoxy-, and 6-deoxy-GalNAca-Bn, 3-0-ethylGalNAm-Bn, 3-0-propyl-GalNAca-Bn, 3-0-methyl-GalNAccu-Bn, 3-0-(2.3-epoxy)propyI-GalNAca-Bn, 6-0-(2,3-epoxy)propylGalNAca-Bn, 6-0-(4,5-epoxy)pentyI-GalNAm-Bn, 6-0-(4,4-azo)-pentyl-GalNAca-Bn, and 3-0-acetyl-GalNAca-Bn (V. Rutz, in preparation). 6-Fluoro-GalNAca-Bn was prepared by treatment of benzyl2-acetamido-2-deoxy-3,4-O-isopropylidene-a-~-galactopyranoside with diethylaminosulfur trifluoride in diethyleneglycol dimethylether to give benzyl2-acetamido-2,6-dideoxy-6-fluoro-3,4-0-isopropylidene-a-D-galactopyranoside (Sharma et al 1987).…”

Strategies of Synthetic Methodologies for Constructing β-Mannosidic Linkage

“…Thus, 4-O-acyl functions increased the β/α ratio in the coupling products as shown in 29d and 29e, whereas 3-O and 6-O acyl functions decreased this ratio. Inductive effects are responsible for this influence; an electron-withdrawing substituent at 4-O has suppressed the formation of a mannosyl oxocarbonium ion, thus pushing the reaction to be more S N 2 type, while the electronwithdrawing substituents at the 3-O and 6-O positions hindered the S N 2 reaction more than the formation of a glycosyl oxocarbonium ion [45,46] (Scheme 6).…”

Chemical Synthesis of Asparagine‐Linked Glycoprotein Oligosaccharides: Recent Examples

“…3,6-O-Allyl-2,4-O-benzyl-mannosyl bromide 8 was treated with the acceptor 9 to provide b-linked product 10 [23]. The stereoselectivity of this type of reaction can be interpreted as follows ( Fig.…”