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 (1)H and (13)C NMR spectral data for methyl 3,4-di-O-acetyl-1,5-anhydro -2-deoxy-D -arabino-hex-1-enopyranuron ate are reported. The 5 H(4) conformation was found to be the preferred form for this glycal, both in the crystal lattice and in solution. The factors determining the (4)H(5) reversible arrow (5)H(4) conformational equilibrium for acetylated glycals are discussed. (C) 2007 Elsevier Ltd. All rights reserved.