Syntheses of model oligosaccharides of biological significance. Synthesis of methyl 3,6-di-O-(alpha-D-mannopyranosyl)-alpha-d-mannopyranoside and the corresponding mannobiosides.
Methyl 2-O-allyl-4,6-O-benzylidene-3-O-(2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranosyl) -alpha-D-mannopyranoside (12) was prepared in 90% yield by Helferich glycosylation of methyl 2-O-allyl-4,6-O-benzylidene-alpha-D-mannopyranoside (9) with tetra-O-acetyl-alpha-D-mannopyranosyl bromide (11). Removal of the benzylidene group and second Helferich glycosylation with 11 led to methyl 2-O-allyl-3,6-di-O-(2,3,4,6-tetra-O-acetyl-alpha-D-mannopyranosyl)-alpha-D-mannopyranoside (14) which, after deallylation and Zemplén deacetylation, gave the title compound 5. The disaccharides methyl 3-O-(alpha-D-mannopyranosyl)-alpha-mannopyranoside (7) and methyl 6-O-(alpha-D-mannopyranosyl)-alpha-D-mannopyranoside (6) have also been synthesized. Complete assignments of the 1H-n.m.r. spectra of the compounds 5, 6, and 7 are given.
D002236:Carbohydrate Conformation; D006023:Glycoproteins; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008565:Membrane Proteins; D009844:Oligosaccharides / Q000138:chemical synthesis*
D006023:Glycoproteins; D007202:Indicators and Reagents; D008565:Membrane Proteins; D009844:Oligosaccharides