title: Acceptor reactivity in the total synthesis of alginate fragments containing α-L-guluronic acid and β-D-mannuronic acid.
abstract: The total synthesis of mixed-sequence alginate oligosaccharides, featuring both β-D-mannuronic acid (M) and α-L-guluronic acid (G), is reported for the first time. A set of GM, GMG, GMGM, GMGMG, GMGMGM, GMGMGMG, and GMGGMG alginates was assembled using GM building blocks, having a guluronic acid acceptor part and a mannuronic acid donor side to allow the fully stereoselective construction of the cis-glycosidic linkages. It was found that the nature of the reducing-end anomeric center, which is ten atoms away from the reacting alcohol group in the key disaccharide acceptor, had a tremendous effect on the efficiency with which the building blocks were united. This chiral center determines the overall shape of the acceptor and it is revealed that the conformational flexibility of the acceptor is an all-important factor in determining the outcome of a glycosylation reaction.
authors.affiliation: Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden (The Netherlands).
authors.forename: Qingju
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden (The Netherlands).
authors.forename: Erwin R
authors.initials: ER
authors.lastname: van Rijssel
authors.affiliation: Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden (The Netherlands).
authors.forename: Marthe T C
authors.initials: MT
authors.lastname: Walvoort
authors.affiliation: Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden (The Netherlands).
authors.forename: Herman S
authors.initials: HS
authors.lastname: Overkleeft
authors.affiliation: Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden (The Netherlands).
authors.forename: Gijsbert A
authors.initials: GA
authors.lastname: van der Marel
authors.affiliation: Leiden Institute of Chemistry, Leiden University, P.O. Box 9502, 2300 RA Leiden (The Netherlands). jcodee@chem.leidenuniv.nl.
authors.forename: Jeroen D C
authors.initials: JD
authors.lastname: Codée
mesh_terms: D000464:Alginates / Q000138:chemical synthesis* / Q000737:chemistry*; D020723:Glucuronic Acid / Q000138:chemical synthesis / Q000737:chemistry; D006031:Glycosylation; D006603:Hexuronic Acids / Q000138:chemical synthesis / Q000737:chemistry*; D015394:Molecular Structure; D009844:Oligosaccharides
chemical_list: D000464:Alginates; D006603:Hexuronic Acids; D009844:Oligosaccharides; C007896:guluronic acid; D020723:Glucuronic Acid; C008324:mannuronic acid
keywords: carbohydrates; conformation analysis; glycosylation; oligosaccharides; synthetic methods