Crystal and molecular structures of substituted β-D-glucofuranosidurono-6,3-lactones

Abstract

The crystal and molecular structures of methyl β- d-glucofuranosidurono-6,3-lactone ( 1), 5- O-pivaloyl-β- d-glucofuranurono-6,3-lactone ( 2), and methyl 2- O-acetyl-5- O-pivaloyl-β- d-glucofuranosidurono-6,3-l ( 3) were determined by X-ray analysis. Crystals of compound 1 are orthorhombic, space group P2 12 12 1 with the unit cell a = 7.074(1), b = 7.448(1), c = 14.995(2) Å, Z = 4. Crystals of 2 and 3 are monoclinic, space group P2 1. The unit-cell parameters are a = 6.315(1), b = 9.307(2), c = 10.612(2) Å, β = 98.68(1)°, Z = 2 for 2; and a = 13.337(1), b = 10.296(1), c = 13.544(1) Å, β = 118.24(1)°, Z = 4 for 3. The structures were solved by MULTAN-80 and refined by a full-matrix procedure to final values of R = 0.042(1), 0.048(2), and 0.093(3). The furanoid rings in 1, 2, and conformer B of 3 appear in twisted. 1 T 2 conformation, and the lactone rings adopt conformations between T and E. The lactone ring of conformer A of 3 adopts a T conformation and that of the furanoid ring is E 2. The molecular packing is through the hydrogen bonds involving hydroxyl groups HO-2 · ⋯ O-1 [2.812(2) Å] in 1. A hydrogen bond between a hydroxyl group and the pivaloyl carbonyl group, HO-1 · ⋯ O-7 [2.855(3) Å], connects the molecules of 2. There are no free hydroxyl groups in 3 and molecular packing reflects van der Waals interactions only.