title: Electrochemical synthesis and X-ray crystal structures of beta-D-2-phenylselenyl-1,3,4,6-tetra-O-acetylglucopyranose and alpha-D-2-phenylselenyl-1,3,4,6-tetra-O-acetylmannopyranose.
abstract: Electrochemical acetoxyphenylselenation of 3,4-dihydro-2H-pyran and D-3,4,6-tri-O-acetylglucal was studied. The constant current electrolysis (50mA) of dihydropyran and diphenyl diselenide in an acetic acid solution of tetramethylammonium chloride was performed at room temperature in an undivided cell using a graphite anode and an aluminum cathode and yielded trans-DL-2-acetoxy-3-phenylselenyltetrahydropyran (27%), in agreement with Markovnikov's rule. The analysis of the 1H NMR spectral data showed that the acetoxy and phenylselenyl groups adopt axial positions in the most stable conformation of this compound due to the anomeric effect. Under the same conditions D-3,4,6-tri-O-acetylglucal afforded D-2-phenylselenyl-1,3,4,6-tetra-O-acetylglucopyranose and D-2-phenylselenyl-1,3,4,6-tetra-O-acetylmannopyranose, which were separated by column chromatography and isolated in 87% overall yield (isomer ratio 60:40). The structures of these compounds were established by spectral data. Single crystal X-ray structure determinations of the diastereomers are reported.
authors.affiliation: Department of Chemistry, Faculty of Science, University of Kragujevac, R. Domanovića 12, P.O. Box 60, YU-34000 Kragujevac, Serbia, Yugoslavia.
authors.forename: Jasmina
authors.initials: J
authors.lastname: Predojević
authors.forename: Mirjana D
authors.initials: MD
authors.lastname: Vukićević
authors.forename: Klaus
authors.initials: K
authors.lastname: Wurst
authors.forename: Karl-Hans
authors.initials: KH
authors.lastname: Ongania
authors.forename: Gerhard
authors.initials: G
authors.lastname: Laus
authors.forename: Rastko D
authors.initials: RD
authors.lastname: Vukićević
mesh_terms: D018360:Crystallography, X-Ray; D004563:Electrochemistry; D006027:Glycosides / Q000138:chemical synthesis*; D008362:Mannosides / Q000138:chemical synthesis*; D008968:Molecular Conformation; D009844:Oligosaccharides / Q000138:chemical synthesis* / Q000737:chemistry; D011714:Pyrans / Q000737:chemistry*; D012643:Selenium / Q000737:chemistry*; D013237:Stereoisomerism
chemical_list: D006027:Glycosides; D008362:Mannosides; D009844:Oligosaccharides; D011714:Pyrans; D012643:Selenium