title: Efficient and stereoselective synthesis of methyl 3-O-(3,6-anhydro-beta-D-galactopyranosyl)-alpha-D-galactopyranoside and methyl 3,6-anhydro-4-O-beta-D-galactopyranosyl-alpha-D-galactopyranoside.
abstract: Methyl 3-O-(3,6-anhydro-beta-D-galactopyranosyl)-alpha-D-galactopyranoside (3) and methyl 3,6-anhydro-4-O-beta-D-galactopyranosyl-alpha-D-galactopyranoside (4) have been synthesised stereoselectively using three coupling procedures. Acceptable yields were achieved using acetylated derivatives as donors and trimethylsilyl triflate as the catalyst. Intramolecular tosylate displacement to form 3,6-anhydro rings proceeded in methanolic sodium methoxide.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Leeds, Great Britain.
authors.forename: A
authors.initials: A
authors.lastname: Rashid
authors.forename: W
authors.initials: W
authors.lastname: Mackie
mesh_terms: D002236:Carbohydrate Conformation; D002240:Carbohydrate Sequence; D002351:Carrageenan / Q000138:chemical synthesis*; D004187:Disaccharides / Q000138:chemical synthesis*; D007202:Indicators and Reagents; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009904:Optical Rotation; D013237:Stereoisomerism
chemical_list: D004187:Disaccharides; D007202:Indicators and Reagents; C068275:methylcarrabioside; C074937:methyl 3-O-(3,6-anhydrogalactopyranosyl)galactopyranoside; D002351:Carrageenan