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.
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.
Predojević
Jasmina
J
Department of Chemistry, Faculty of Science, University of Kragujevac, R. Domanovića 12, P.O. Box 60, YU-34000 Kragujevac, Serbia, Yugoslavia.
Vukićević
Mirjana D
MD
Wurst
Klaus
K
Ongania
Karl-Hans
KH
Laus
Gerhard
G
Vukićević
Rastko D
RD
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
D006027:Glycosides; D008362:Mannosides; D009844:Oligosaccharides; D011714:Pyrans; D012643:Selenium