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-α-d-glucopyranosyl)-l-idopyranuronic acid, 4-O-(2-amino-2-deoxy-α-d-glucopyranosyl)-d-glucopyranose, and 4-O-α-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-α-d-glucopyranosyl)-aldehydo-d-glucose dimethyl acetal. It was subjected to a sequence of transformations 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. © 1990.