Methyl 2-O-beta-D-glucopyranosyl-alpha-L-rhamnopyranoside.
The overall conformation of the title compound, C(13)H(24)O(10), is described by the glycosidic torsion angles phi(H) (H1(g)[bond]C1(g)[bond]O2(r)[bond]C2(r)) and psi(H) (C1(g)[bond]O2(r)[bond]C2(r)[bond]H2(r)), which have values of 13.6 and 16.1 degrees, respectively. The former is significantly different from the value predicted by consideration of the exo-anomeric effect (phi(H) approximately 60 degrees ) and from that in solution (phi(H) approximately 50 degrees ), as determined previously by NMR spectroscopy. An intramolecular O3(r)[bond]H...O2(g) hydrogen bond may help to stabilize the conformation in the solid state. The orientation of the hydroxymethyl group of the glucose residue is gauche-gauche, with a torsion angle omega (O5(g)[bond]C5(g)[bond]C6(g)[bond]O6(g)) of -70.4 (4) degrees. Both pyranose rings are in their expected chair conformations, i.e. (4)C(1) for D-glucose and (1)C(4) for L-rhamnose.
Eriksson
Lars
L
Division of Structural Chemistry, Arrhenius Laboratory, Stockholm University, SE-106 91 Stockholm, Sweden. lerik@struc.su.se
Stenutz
Roland
R
Widmalm
Göran
G