CONFORMATIONAL FLEXIBILITY IN HIGHLY SULFATED BETA-D-GLUCOPYRANOSIDE DERIVATIVES

Triggered by findings on heparin-like disaccharides, the conformation of sulfated glucopyranosides was investigated. Sodium (methyl ,3,4-tri -O-sulfonato-beta-D-glucopyranosid)uronate tetrasodium salt is in a co nformational equilibrium, to which a non-chair conformation contribute s. The same is true for methyl (methyl ,3,4-tri-O-sulfonato-beta-D-glu copyranosid)uronate trisodium salt, methyl 2,3,4,6-tetra-O-sulfonato-b eta-D-glucopyranoside tetrasodium salt, and octa-O-sulfonato-beta,beta -trehalose octasodium salt, with less obvious non-chair contributions. The effect is charge related. The conformational effect, which does n ot occur in analogous alpha-D-glucopyranoside derivatives, is discusse d in terms of the anomeric effect.