The crystal structures of 1,2,3,4,6-penta-O-trimethylacetyl- and 1,2,3,4,6-penta-O-dimethylacetyl-β-d-glucopyranose

The crystal structures of 1,2,3,4,6-penta-O-trimethylacetyl-β-d-glucopyranose (1) and 1,2,3,4,6-penta-O-dimethylacetyl-β-d-glucopyranose (2) have been determined by X-ray diffraction analysis and compared with that reported for 1,2,3,4,6-penta-O-acetyl-β-d-glucopyranose (3). Whereas 1 has a well ordered structure, the acyl groups in 2 at positions 1 and 2 of the pyranose ring show disorder with respect to the positions of the α-methyl groups. As with 3, the CO bonds of the acyl groups at positions 1-4 show a preference for near alignment with respective ring C-H bonds, but there are, nevertheless, significant differences in the torsional angles defining this arrangement. Intermolecular weak hydrogen bonding in the three compounds is not significantly different and involves carbonyl oxygen atoms as the acceptors.