Methyl 4-O-beta-D-galactopyranosyl alpha-D-glucopyranoside (methyl alpha-lactoside)

Acta Crystallogr C. 2005 Dec;61(Pt 12):o674-7. doi: 10.1107/S0108270105033706. Epub 2005 Nov 11.

Abstract

Methyl alpha-lactoside, C13H24O11, (I), is described by glycosidic torsion angles varphi (O5gal-C1gal-O1gal-C4glc) and psi (C1gal-O1gal-C4glc-C5glc), which have values of -93.52 (13) and -144.83 (11) degrees, respectively, where the ring atom numbering conforms to the convention in which C1 is the anomeric C atom and C6 is the exocyclic hydroxymethyl (-CH2OH) C atom in both residues. The linkage geometry is similar to that observed in methyl beta-lactoside methanol solvate, (II), in which varphi is -88.4 (4) degrees and psi is -161.3 (4) degrees. As in (II), an intermolecular O3glc-H...O5gal hydrogen bond is observed in (I). The hydroxymethyl group conformation in both residues is gauche-trans, with torsion angles omegagal (O5gal-C5gal-C6gal-O6gal) and omega(glc) (O5glc-C5glc-C6glc-O6glc) of 69.15 (13) and 72.55 (14) degrees, respectively. The latter torsion angle differs substantially from that found for (II) [-54.6 (2) degrees; gauche-gauche]. Cocrystallization of methanol, which is hydrogen bonded to O6glc in the crystal structure of (II), presumably affects the hydroxymethyl conformation in the Glc residue in (II).

MeSH terms

  • Carbohydrate Conformation
  • Crystallography, X-Ray
  • Hydrogen Bonding
  • Methylglycosides / chemistry*
  • Models, Molecular

Substances

  • Methylglycosides
  • methyl lactoside