title: Double diastereoselection explains limitations in synthesizing mannose-containing beta-(1,3)-glucans.
abstract: It is known that 3-O-glycosylation of glucosidic acceptors bearing acyl groups in the 4 and 6 positions instead of a 4,6-O-benzylidene ring mainly affords alpha-glycosides. Described here is an unexpected stereochemical outcome for elongation at glucose O-3 of a beta-d-Glcp-(1-->3)-alpha-d-Manp disaccharide using peracetylated ethyl thioglucoside as a donor. This unexpected reaction was correlated with match-mismatch effects, as shown by efficient coupling of the same acceptor by a donor of l-configuration.
authors.affiliation: Ecole Nationale Supérieure de Chimie de Rennes, CNRS, UMR 6226, Avenue du Général Leclerc, CS 50837, 35708 Rennes Cedex 7, France.
authors.forename: Balla
authors.initials: B
authors.lastname: Sylla
authors.forename: Karine
authors.initials: K
authors.lastname: Descroix
authors.forename: Christophe
authors.initials: C
authors.lastname: Pain
authors.forename: Cédric
authors.initials: C
authors.lastname: Gervaise
authors.forename: Frank
authors.initials: F
authors.lastname: Jamois
authors.forename: Jean-Claude
authors.initials: JC
authors.lastname: Yvin
authors.forename: Laurent
authors.initials: L
authors.lastname: Legentil
authors.forename: Caroline
authors.initials: C
authors.lastname: Nugier-Chauvin
authors.forename: Richard
authors.initials: R
authors.lastname: Daniellou
authors.forename: Vincent
authors.initials: V
authors.lastname: Ferrières
mesh_terms: D002236:Carbohydrate Conformation; D005936:Glucans / Q000138:chemical synthesis* / Q000737:chemistry*; D006031:Glycosylation; D008358:Mannose / Q000737:chemistry*; D008958:Models, Molecular; D013237:Stereoisomerism; D013379:Substrate Specificity
chemical_list: D005936:Glucans; D008358:Mannose