title: Oligosaccharides from "standardized intermediates". The 2-amino-2-deoxy-D-galactose analog of the blood-group O(H) determinant, type 2, and its precursors.
abstract: The selectively benzylated glycoside allyl 2-acetamido-4,6-di-O-benzyl-2-deoxy-beta-D-galactopranoside (4) was prepared from the corresponding derivative of 2-acetamido-2-deoxy-D-glucose via the p-bromobenzenesulfonate and the benzoate. 2-O-Benzoyl-3,4,6-tri-O-benzyl-alpha-D-galactopyranosyl (10) was obtained from allyl 6-O-benzyl-2-O-(2-butenyl)-alpha-D-galactopyranoside via known intermediates. To complete the sequence, the 1-propenyl 3,4,6-tri-O-benzyl galactoside was successively converted into the 2-benzoate, the free sugar, and the chloride 10. A fully protected form (11) of the trisaccharide alpha-L-Fucp-(1 leads to 2)-beta-D-Galp-(1 leads to 4)-D-GalNAc was then synthesized by coupling 10 to 4, partially deblocking the disaccharide product, and L-fucosylating the resulting intermediate. Cleavage of the O-benzyl groups from 11, with concomitant saturation of the allyl group, gave the propyl beta-glycoside of the unsubstituted trisaccharide.
mesh_terms: D000017:ABO Blood-Group System / Q000276:immunology*; D000939:Epitopes; D005688:Galactosamine / Q000031:analogs & derivatives*; D006801:Humans; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000276:immunology; D009904:Optical Rotation
chemical_list: D000017:ABO Blood-Group System; D000939:Epitopes; D007202:Indicators and Reagents; D009844:Oligosaccharides; D005688:Galactosamine