title: A reagent-controlled SN2-glycosylation for the direct synthesis of β-linked 2-deoxy-sugars.
abstract: The efficient and stereoselective construction of glycosidic linkages remains one of the most formidable challenges in organic chemistry. This is especially true in cases such as β-linked deoxy-sugars, where the outcome of the reaction cannot be controlled using the stereochemical information intrinsic to the glycosyl donor. Here we show that p-toluenesulfonic anhydride activates 2-deoxy-sugar hemiacetals in situ as electrophilic species, which react stereoselectively with nucleophilic acceptors to produce β-anomers exclusively. NMR studies confirm that, under these conditions, the hemiacetal is quantitatively converted into an α-glycosyl tosylate, which is presumably the reactive species in the reaction. This approach demonstrates that use of promoters that activate hemiacetals as well-defined intermediates can be used to permit stereoselective glycosylation through an SN2-pathway.
authors.affiliation: Department of Chemistry, Tufts University , 62 Talbot Avenue, Medford, Massachusetts 02155, United States.
authors.forename: John Paul
authors.initials: JP
authors.lastname: Issa
authors.forename: Clay S
authors.initials: CS
authors.lastname: Bennett
mesh_terms: D002241:Carbohydrates / Q000138:chemical synthesis* / Q000737:chemistry; D006031:Glycosylation; D007202:Indicators and Reagents / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy
chemical_list: D002241:Carbohydrates; D007202:Indicators and Reagents