Novel 2,3-unsaturated O-glycosides containing an alkynyl function in their aglycones

Abstract

This paper describes the synthesis of seven D-glucosides, 3a-g, and six D-galactosides, 4a-f, all containing an alkynyl function in their aglycones. The reaction was performed using dichloromethane as solvent in the presence of Montmorillonite K-10. The structure of all compounds were confirmed employing IR, 1H NMR and 13C NMR spectroscopic techniques. The aim was to study their conformational energies using ab initio Hartree Fock method with 6-31G as basis set. Two compounds, namely, (R)-(+)-3-butyn-2-yl 4,6-di-O-acetyl-2,3-dideoxy-α-D-erythro-hex-2-enopyranoside, 3d, and (R)-(+)-3-butyn-2-yl 4,6-di-O-acetyl-2,3-dideoxy-α-D-threo-hex-2-enopyranoside, 4d, were subjected to X-ray diffraction analyses and their experimental values compared with the calculated values obtained by molecular orbital calculations. Our studies have found a good correlation between the two types of glycosides.

Keywords

• 2,3-Unsaturated D-glucosides
• 2,3-Unsaturated D-galactosides
• NMR-Spectroscopy