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Free keywords:
PROTECTED GLYCOSYL DONORS; ORGANIC-SOLVENTS; NEUTRAL CONDITIONS; CONCENTRATED-SOLUTIONS; STEREOCONTROLLED SYNTHESIS; OLIGOSACCHARIDES; LICLO4; ANTIGENS; DERIVATIVES; PHOSPHITES
Abstract:
Trisaccharides embodying the Fuc-alpha-(1-2)-Gal or the Fuc-alpha-(1-2)-Glc substructure can be built up under neutral conditions by glycosylation of selectively deprotected glycosyl acceptor disaccharides with 2,3,4-tri-O-benzyl fucosyl fluoride in 0.07 M solutions of LiClO4 in CH2Cl2. The glycosyl and the galactosyl trisaccharides, which are stereoisomers of the carbohydrate determinant of the human blood group H, are obtained in high yield and with complete alpha-selectivity. The glycosyl acceptor disaccharides with a deblocked 2-OH group in the saccharide unit are obtained by treatment of the respective 1,2-anhydro carbohydrates with glycosyl acceptors in 0.07 M LiClO4/CH2Cl2.
