title: Investigations of glycosylation reactions with 2-N-acetyl-2N,3O-oxazolidinone-protected glucosamine donors.
abstract: NIS/AgOTf-promoted glycosylations with ethyl 2,3-N,O-carbonyl-2-deoxy-1-thio-beta-D-glucopyranoside donors can be performed with either alpha- or beta-selectivity by tuning the reaction conditions. Small amounts of AgOTf (0.1 equiv) and short reaction times give beta-selectivity, whereas 0.4 equiv of AgOTf and prolonged reaction times afford alpha-linked products. NMR-monitored glycosylation and anomerization experiments show initial formation of exclusively the beta-linkage, which anomerizes, through an intramolecular mechanism involving an endocyclic C-O bond cleavage, to the alpha-linkage.
authors: Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, S-106 91 Stockholm, Sweden.
authors: Johan D M
authors: JD
authors: Olsson
authors: Lars
authors: L
authors: Eriksson
authors: Martina
authors: M
authors: Lahmann
authors: Stefan
authors: S
authors: Oscarson
mesh_terms: D002236:Carbohydrate Conformation; D018360:Crystallography, X-Ray; D004187:Disaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D005944:Glucosamine / Q000737:chemistry*; D006031:Glycosylation; D008698:Mesylates / Q000737:chemistry; D008958:Models, Molecular; D015394:Molecular Structure; D023303:Oxazolidinones / Q000138:chemical synthesis* / Q000737:chemistry; D013997:Time Factors
chemical_list: C532723:2-N-acetyl-2N,3O-oxazolidinone; D004187:Disaccharides; D008698:Mesylates; D023303:Oxazolidinones; C012077:trifluoromethanesulfonic acid; D005944:Glucosamine