Macrocyclic substructure of tricolorin A – The first crystal structure of a resin glycoside

The structure of a tricolorin A derivative (11S)-11-[[4,6-O-benzylidene-β-D-glucopyranosyl-(1 → 2)-3,4-O-isopropylidene-β-D-fucopyranosyl]oxy]hexadecanoic acid 3gluc-lactone 2, a member of the resin glycosides, has been determined. This crystal structure is the first example for this class of natural products. At 100 K the lattice parameters in monoclinic space group P21 are: a = 22.502 (5)Å, b = 17.339( 4)Å, c= 25.011( 5)Å, β= 92.49(3)°, V = 9749(3)Å3 , Z = 10. M = 705.67, ρ= 1.202 Mg m -3 , μ = 0.087 mm-1 , F (000)= 3824. The five crystallographically independent molecules show upon superpositioning the expected preservation of the glycosidic link geometry, however the alkyl part of the macrocyclic ring expresses a larger degree of freedom while conserving gauche and anti conformations in six of nine torsion angles.