Conformations and structure studies of sugar lactones in the solid state. Part II. The molecular structure of alpha-D-glucosaccharino-gamma-lactone: 2-C-methyl-D-ribo-pentono-1,4-lactone.

ABSTRACT

The crystal structure of 2-C-methyl-D-ribo-pentono-1,4-lactone (alpha-D-glucosaccharino-gamma-lactone, 1) has been determined by single-crystal X-ray diffraction. The crystals are orthorhombic, space group P2(1)2(1)2(1) with a = 7.7429(6), b = 8.3373(7), c = 11.3258(7) A, V = 731.1(2) A3 (CuK alpha, lambda = 1.54184 A), mu = 10.82 cm-1, Dc = 1.473 g cm-3, and Z = 4. The structure was refined to R = 0.0307 and Rw = 0.0424 for 876 observed reflections. Compound 1 has the D-ribo configuration, in agreement with an earlier deduction from chemical evidence. The lactone ring adopts the 3T2 conformation, with puckering parameters psi = 279.8(9) degrees and q = 0.32(5) A. The orientation of the methyl group about the C-2-C-3 bond is gauche-trans, with the C-6-C-2-C-3-O-3 and C-6-C-2-C-3-C-4 torsion angles being -81.3(2) degrees and 154.7(1) degree, respectively. The molecules are linked in the crystal in a two-dimensional intermolecular hydrogen bonding network that involves all hydroxyl groups as well as the carbonyl oxygen atom.