Synthetic mucin fragments: methyl 3-O-(2-acetamido-2-deoxy-β-d-glucopyranosyl)-β-d-galactopyranoside and methyl 3-O-(2-acetamido-2-deoxy-3-O-β-d-galactopyranosyl-β-d-glucopyranosyl)-β-d-galactopyranoside

✍ Scribed by Katsunori Kohata; Saeed A. Abbas; Khushi L. Matta

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 608 KB
• Volume: 132
• Category: Article
• ISSN: 0008-6215
• DOI: 10.1016/0008-6215(84)85070-3

✦ Synopsis

Methyl 2,4,6-tri-O-benzyl-P-D-galactopyranoside (5) was obtained crystalline by way of its 3-O-ally] derivative, which was in turn obtained by ring-opening of a presumed 3,4-0-stannylene derivative of methyl p-D-galactopyranoside, followed by benzylation. Condensation of 5 with 2-methyl-(2-acetamido-3,4,6-tri-O-acetyl-l,2-dideoxy-P-D-glucopyrano)-[2,1-d]-2-oxazoline in 1,Zdichloroethane in the presence of p-toluenesulfonic acid afforded the disaccharide derivative methyl 3-0-(2-acetamido-3,4,6-tri-O-acety1-2-deoxy-~-~-glucopyranosy1)-2,4,6tri-0-benzyl-p-D-galactopyranoside (6). Deacetylation of 6 in methanolic sodium methoxide afforded the disaccharide derivative 7, which was acetalated with CY,(Ydimethoxytoluene to afford the 4',6'-0-benzylidene acetal (10). Catalytic hydrogenolysis of the benzyl groups of 7 afforded the title disaccharide 8. Glycosylation of 10 with 2,3,4,6-tetra-O-acetyl-cw-D-galactopyranosyl bromide in 1:l benzenenitromethane in the presence of mercuric cyanide gave the fully protected trisaccharide derivative 12. Systematic removal of the protecting groups of 12 then furnished the title trisaccharide 14. The structures of 5, 8, and 14 were all confirmed by 13C-n.m.r. spectroscopy. The 13C-n.m.r. chemical shifts for methyl a-and P-Dgalactopyranoside, and also those of their 3-O-ally1 derivatives, are recorded, for the sake of comparison, in conjunction with those of compound 5. *Synthetic Studiesin Carbohydrates, Part XLII, for Part XLI, see ref. 1.