Synthesis of the 2"-hydroxy, 4"-deoxy and 4"-epi analogues of beta-D-GalNAc-(1-->3)-alpha-D-Gal-(1-->4)-beta-D-Gal, the terminal trisaccharide of globotetraose.
Radical deoxygenation of methyl 3,6-di-O-benzoyl-2-deoxy-4-O-imidazol-1-yl-thiocarbonyloxy-2-phtha limido-beta-D - glucopyranoside 5 gave methyl 3,6-di-O-benzoyl-2,4-dideoxy-2-phthalimido-beta-D-glucopyranoside 6, which was converted into the corresponding methyl thioglycoside donor 9. Methylsulfenyl trifluoromethane-sulfonate-promoted glycosylation of 2-(trimethylsilyl)ethyl 2,3,6-tri-O-benzyl-4-O-(2,4,6-tri-O-benzyl-alpha-D-galactopyranosyl)-bet a-D- galactopyranoside 10, followed by removal of protecting groups gave the 4"-deoxy analogue 12 of the terminal trisaccharide of globotetraose. Silver trifluoromethanesulfonate-promoted glycosylation of the same disaccharide alcohol 10 with 3,4,6-tri-O-acetyl-2-deoxy-2- phthalimido-alpha/beta-D-glucopyranosyl bromide 13 and 2,3,4,6-tetra-O-acetyl-alpha-D-galactopyranosyl bromide 16, followed by deblocking, gave the 2"-hydroxy and 4"-epi analogues 15 and 18, respectively.
Lund Institute of Technology, University of Lund, Sweden.
U
U
Nilsson
A
A
Wendler
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G
Magnusson
D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002853:Chromatography, Liquid; D005915:Globosides / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D014312:Trisaccharides / Q000138:chemical synthesis* / Q000737:chemistry
D005915:Globosides; D014312:Trisaccharides; C088208:2-(trimethylsilyl)ethyl 4-O-(3-O-(2-acetamido-2,4-dideoxy-xylohexopyranosyl)galactopyranosyl)galactopyranoside; C088209:2-(trimethylsilyl)ethyl 4-O-(3-O-(2-deoxy-2-acetamido-glucopyranosyl)galactopyranosyl)galactopyranoside; C088210:2-(trimethylsilyl)ethyl 4-O-(3-O-(galactopyranosyl)galactopyranosyl)galactopyranoside; C035968:globotetraose