Synthesis of sulfonic acid analogues of the non-reducing end trisaccharide of the antithrombin binding domain of heparin

Three sulfonic acid trisaccharides related to the antithrombin-binding DEFGH domain of heparin were synthesised. Trisaccharides carrying the sulfonatomethyl moiety at position 2 or 6 were prepared in high yields by [DE+F] couplings using the same disaccharide uronate donor and the appropriate sulfonic acid acceptor, respectively. The trisaccharide with a 3-deoxy-3-sulfonatomethyl function could be obtained with high efficacy by a [D+EF] coupling where the carboxylic function of the EF uronate acceptor was created at a disaccharide level.