Crystal and molecular structure of (−)-1,2-O-isopropylidene-3-O-methyl-7,8-dideoxy-β-l-glycero-d-gluco-non-7-enofuranurono-9,6-lactone, C₁₃H₁₈O₇

Abstract

The crystal structure of the title lactone, C₁₃H₁₈O₇, has been determined by single crystal diffraction methods. The compound crystallizes in the monoclinic space groupP2₁ witha=13.231(2),b=10.248(2),c=5.348(1) Å,β=96.66(2)°, andZ=2. A total of 1055 reflection intensities were recorded on a Siemens AED single-crystal diffractometer (CuKα radiation) at room temperature. The structure was solved by direct methods and electron density calculations. Full-matrix least-squares refinement gaveR=0.055 for 946 unique reflections above 2σ(I). The absolute configuration of the six chiral carbon atoms was deduced as 4S, 5R, 6R, 7S, 9R, 10R (crystallographic numbering corresponds to C-6, 5, 4, 3, 2, 1 in the title compound). An intermolecular O-H⋯O hydrogen bond joins the molecules in chains which run along the twofold screw axis.