Methyl 3-O-α-l-fucopyranosyl α-d-gal-acto-pyran-oside: a synchrotron study.

The title compound, C(13)H(24)O(10) is the methyl glycoside of a structural element α-l-Fucp-(1→ 3)-α-d-Galp making up two thirds of the repeating unit in the capsular polysaccharide of Klebsiella K63. The conformation of the title compound is described by the glycosidic torsion angles ϕ(H) = 55 (1)° and ψ(H) = -24 (1)°. The hy-droxy-methyl group in the galactose residue is present in the gauche-trans conformation. In the crystal, O-H⋯O hydrogen bonds connect the disaccharide units into chains along the a-axis direction and further hydrogen bonds cross-link the chains.