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

The single-crystal X-ray diffraction and high-resolution 1H and 13C NMR spectral data for methyl 2,5-di-O-acetyl-β-d-glucofuranosidurono-6,3-lactone and 1,2,5-tri-O-acetyl-β-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 1T2-like conformation was found to be the preferred form for these lactones in both the crystal lattice and in solution.