title: Stereoelectronic effects determine oxacarbenium vs β-sulfonium ion mediated glycosylations.
abstract: Activation of a glycosyl donor protected with a 2-O-(S)-(phenylthiomethyl)benzyl ether chiral auxiliary results in the formation of an anomeric β-sulfonium ion, which can be displaced with sugar alcohols to give corresponding α-glycosides. Sufficient deactivation of such glycosyl donors by electron-withdrawing protecting groups is, however, critical to avoid glycosylation of an oxacarbenium ion intermediate. The latter type of glycosylation pathway can also be suppressed by installing additional substituents in the chiral auxiliary.
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, 315 Riverbend Road, Athens, Georgia 30602, USA.
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Boltje
authors.forename: Jin-Hwan
authors.initials: JH
authors.lastname: Kim
authors.forename: Jin
authors.initials: J
authors.lastname: Park
authors.forename: Geert-Jan
authors.initials: GJ
authors.lastname: Boons
mesh_terms: D006027:Glycosides / Q000138:chemical synthesis* / Q000737:chemistry; D006031:Glycosylation; D015394:Molecular Structure; D019906:Nuclear Magnetic Resonance, Biomolecular; D013237:Stereoisomerism; D013452:Sulfonium Compounds / Q000138:chemical synthesis* / Q000737:chemistry
chemical_list: D006027:Glycosides; D013452:Sulfonium Compounds