title: 3,4-anhydro-1,2-O-isopropylidene-beta-D-tagatopyranose and 4,5-Anhydro-1,2-O-isopropylidene-beta-D-fructopyranose.
abstract: 3,4-Anhydro-1,2-O-isopropylidene-beta-D-tagatopyranose (8) and 4,5-anhydro-1,2-O-isopropylidene-beta-D-fructopyranose (10) have been prepared by treatment of 3,5-di-O-acetyl-1,2-O- isopropylidene-4-O-toluene-p-sulfonyl-beta-D-fructopyranose with methanolic sodium methoxide. The structures of 8 and 10 were assigned by 1H and 13C NMR spectroscopy and that of 10 by X-ray crystallography; both exist in half-chair conformations. Compounds 8 and 10 interconvert in aqueous sodium hydroxide, giving a ratio of 1:2 at equilibrium. The monoacetates of 8 and 10 (5-O-acetyl-3,4-anhydro-1,2-O-isopropylidene-beta-D-tagatopyranose and 3-O-acetyl-4,5-anhydro-1,2-O-isopropylidene-beta-D-fructopyranose) undergo stereospecific epoxide ring opening in 80% acetic acid to give mainly the axial monoacetates 5-O-acetyl-1,2-O-isopropylidene-beta-D-fructopyranose and 4-O-acetyl-1,2-O-isopropylidene-beta-D-tagatopyranose, respectively.
authors.affiliation: Department of Chemistry, Heriot-Watt University, Riccarton, Edinburgh, UK.
authors.forename: M
authors.initials: M
authors.lastname: Ataie
authors.forename: J G
authors.initials: JG
authors.lastname: Buchanan
authors.forename: A R
authors.initials: AR
authors.lastname: Edgar
authors.forename: R G
authors.initials: RG
authors.lastname: Kinsman
authors.forename: M
authors.initials: M
authors.lastname: Lyssikatou
authors.forename: M F
authors.initials: MF
authors.lastname: Mahon
authors.forename: P M
authors.initials: PM
authors.lastname: Welsh
mesh_terms: D002244:Carbon / Q000737:chemistry; D018360:Crystallography, X-Ray; D004852:Epoxy Compounds / Q000737:chemistry; D005632:Fructose / Q000031:analogs & derivatives* / Q000138:chemical synthesis*; D006027:Glycosides / Q000138:chemical synthesis*; D006859:Hydrogen / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular
chemical_list: C410146:4,5-anhydro-1,2-O-isopropylidenefructopyranose; C410145:4,5-anhydro-1,2-O-isopropylidenetagatopyranose; D004852:Epoxy Compounds; D006027:Glycosides; D005632:Fructose; D002244:Carbon; D006859:Hydrogen