Synthesis of the globotetraose tetrasaccharide and terminal tri- and di-saccharide fragments.
The 2-(trimethylsilyl)ethyl (TMSEt) beta-glycosides of globotetraose [beta-D-GalNAc-(1-->3)-alpha-D-Gal-(1-->4)-beta-D-Gal-(1-->4)-D-Glc] and the terminal trisaccharide, as well as the methyl alpha-glycoside 1 of the terminal disaccharide, were synthesised by silver trifluoromethanesulfonate-promoted beta-glycosylation of suitably protected galactoside, galabioside, and globotrioside alcohols with 3,4,6-tri-O-acetyl-2-deoxy-2-phthalimido-beta-D-galactopyranosyl chloride, followed by removal of protecting groups. Removal of the anomeric TMSEt group of the globotetraoside and of the terminal trisaccharide, using trifluoroacetic acid-dichloromethane, gave the corresponding hemiacetal sugars 8 and 3. The TMSEt glycoside of the terminal trisaccharide was converted, via the 1-acetate, into the corresponding isobutyl (4) and 3-butylsulfonyl-2-[(butylsulfonyl)methyl]propyl (5) glycosides and into the TMSEt thioglycoside 6 via the glycosyl bromide.
Nilsson
U
U
Organic Chemistry 2, Chemical Center, Lund Institute of Technology, University of Lund, Sweden.
Ray
A K
AK
Magnusson
G
G
D000941:Antigens / Q000737:chemistry; D002240:Carbohydrate Sequence; D004187:Disaccharides / Q000138:chemical synthesis*; D005915:Globosides / Q000737:chemistry*; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000138:chemical synthesis*; D014312:Trisaccharides / Q000138:chemical synthesis*
D000941:Antigens; D004187:Disaccharides; D005915:Globosides; D009844:Oligosaccharides; D014312:Trisaccharides; C035968:globotetraose