Crystal and molecular structures of the pentaacetates of d-gluconic acid and derived tert-butyl- and tert-butylperoxyesters and the tetra-O-acetyl-1,2-O-tert-butyl-peroxyorthoacetyl derivative

The crystal structures of 2,3,4,5,6-penta-O-acetyl-d-gluconic acid (1), 2,3,4,5,6-penta-O-acetyl-d-gluconic acid tert-butylester (2), 2,3,4,5,6-penta-O-acetyl-d-gluconic acid tert-butylperoxyester (3) and 3,4,5,6-tetra-O-acetyl-1,2-(tert-butylperoxyorthoacetyl)-d-gluconic acid (4) were determined by X-ray crystallography, using direct methods, and refined to final conventional residual parameters of R = 0.050, 0.037, 0.042 and 0.042, respectively. In all cases, a planar zigzag conformation of the carbon chain is adopted with a resulting 1,3-parallel interaction between O-2 and O-4. In 2, a second 1,3-parallel alignment between O-3 and the esterified oxygen at C-1 is observed. The peroxycarbonyl group in 3 is essentially planar with a torsion angle about the OO bond of −119° for 3 and 145° for 4.