Conformational features of idopyranose derivatives. The molecular structure of methyl 1,2,3,4-tetra-O-acetyl-α-L-idopyranuronate

Abstract

The molecular structure of the title compound has been determined by X-ray analysis. The structure was solved with the multisolution technique and the atomic parameters were refined by full-matrix least-squares refinement to an R value of 0.08 for 2 819 observed reflections. There are two molecules in the asymmetric unit. The bond lengths and bond angles of the pyranose rings are in good agreement within the limits of errors, except for the anomeric bond lengths. This is related to distinct conformations about the exocyclic anomeric bond which result in different respective orientations of the carbonyl O(62) and pyranic oxygen atoms. The conformation of each molecule is a normal ¹C₄(L) chair slightly deformed towards the ⁵H_o half chair. The molecular conformation of the title compound is compared to that of other idopyranose derivatives observed in the solid state.