Formation of disaccharides related to heparin and heparan sulfate by chemical modification of maltose.

Maltose has been converted into 4-O-(2-amino-2-deoxy-alpha-D-glucopyranosyl)-L-idopyranuronic acid, 4-O-(2-amino-2-deoxy-alpha-D-glucopyranosyl)-D-glucopyranose, and 4-O-alpha-D-glucopyranosyl-L-idopyranose, the first two disaccharides being related structurally to biose sequences in heparin and heparan sulfate. Used as the starting material was a major product of the kinetic acetonation of maltose, namely, 2,3:5,6-di-O-isopropylidene-4-O-(4,6-O-isopropylidene-alpha-D-glucopyran osyl)-aldehydo-D-glucose dimethyl acetal. It was subjected to a sequence of transformation that included the introduction of a 2'-amino-2'-deoxy function into the glucosyl group, the inversion of C-5 in the glucose residue to give the L-ido configuration, oxidation at position 6, and cyclisation of the acyclic dimethyl acetal to give the desired pyranuronic acid. In the formation of the latter, the 5-O-levulinoyl substituent was found to be less prone to acyl migration to O-6 than more conventional ester groups. The relative acid labilities of the O-isopropylidene and dimethyl acetal groups are compared, and conformations of the acyclic residues of some disaccharide derivatives are discussed.