Syntheses of β-d-GalpNAc4SO3-(1→4)-l-IdopA2SO3, a disaccharide fragment of dermatan sulfate, and of its methyl α-l-glycoside derivative

The syntheses of sodium (sodium 2-acetamido-2-deoxy-4-O-sulfonato-β-d-galactopyranosyl)-(1→4)-(sodium 2-O-sulfonato-l-idopyran)uronate, a disaccharide fragment of dermatan sulfate, and of its methyl α-l-glycoside derivative are reported for the first time. The use of 4-O-acetyl-3,6-di-O-benzyl-2-deoxy-2-trichloroacetamido-1-O-trichloroacetimidoyl-α-d-galactopyranose, readily prepared from a d-gluco precursor, allowed the stereocontrolled and high yielding coupling with the low reactive 4-hydroxyl group of l-iduronic acid ester derivatives. Classical transformation of the disaccharide products into the target molecules was achieved in high yield.