Conformations of methyl 2,5-di-O-acetyl-beta-D-glucofuranosidurono-6,3-lactone and 1,2,5-tri-O-acetyl-beta-D-glucofuranurono-6,3-lactone in the crystal structure and in solution

摘要

The single-crystal X-ray diffraction and high-resolution ~1H and ~(13)C NMR spectral data for methyl 2,5-di-O-acetyl-beta-D-glucofuranosidurono-6,3-lactone and 1,2,5-tri-O-acetyl-beta-D-glucofuranurono-6,3-lactone are reported.The lactones were synthesized as byproducts of reactions carried out to obtain methyl 1,2,3,4-tetra-O-acetyl-D-glucopyranuronate.The conformations of these lactones in the crystal structure and in solution are discussed.A ~1T_2-like conformation was found to be the preferred form for these lactones in both the crystal lattice and in solution.