title: Stereoselective glycosylations of 2-azido-2-deoxy-glucosides using intermediate sulfonium ions.
abstract: TMSOTf-promoted glycosylations of 2-azido-2-deoxy-glucosyl trichloroacetimidates provide excellent alpha-anomeric selectivities when performed at a relatively high reaction temperature in the presence of PhSEt or thiophene. NMR and computation studies have shown that these glycosylations proceed through an equatorial anomeric sulfonium ion, which upon displacement by a sugar alcohol provides an axial glycoside. Computational studies have indicated that steric factors determine the selective formation of the beta-anomeric sulfonium ion.
authors: Complex Carbohydrate Research Center, University of Georgia, Athens, GA 30602, USA.
authors: Jin
authors: J
authors: Park
authors: Sameer
authors: S
authors: Kawatkar
authors: Jin-Hwan
authors: JH
authors: Kim
authors: Geert-Jan
authors: GJ
authors: Boons
mesh_terms: D001386:Azides / Q000737:chemistry*; D006027:Glycosides / Q000138:chemical synthesis / Q000737:chemistry*; D006031:Glycosylation; D007477:Ions / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D015394:Molecular Structure; D010100:Oxygen / Q000737:chemistry*; D013237:Stereoisomerism; D013452:Sulfonium Compounds / Q000737:chemistry*; D013876:Thiophenes / Q000737:chemistry
chemical_list: D001386:Azides; D006027:Glycosides; D007477:Ions; D013452:Sulfonium Compounds; D013876:Thiophenes; D010100:Oxygen