X-ray diffraction and high-resolution NMR spectroscopy of methyl 3,4-di-O-acetyl-1,5-anhydro-2-deoxy-d-arabino-hex-1-enopyranuronate

Single-crystal X-ray diffraction and high-resolution 1H and 13C NMR spectral data for methyl 3,4-di-O-acetyl-1,5-anhydro-2-deoxy-d-arabino-hex-1-enopyranuronate are reported. The 5H4 conformation was found to be the preferred form for this glycal, both in the crystal lattice and in solution. The factors determining the 4H5 ⇄ 5H4 conformational equilibrium for acetylated glycals are discussed.