Synthesis and sulfation of branched dextrans.

2,4-Di-O-benzyl-(1→6)-α-d-glucopyranan, which was synthesized by ring-opening polymerization of 1,6-anhydro-2,4-di-O-benzyl-3-O-tert-butyldimethylsilyl-β-d-glucopy-ranose and subsequent desilylation, was β-glucosylated or α-mannosylated by the orthoester method. Deprotection of glycosylated polysaccharides with sodium in liquid ammonia was performed to give branched dextrans with free hydroxyl groups. Sulfation of the branched dextrans was carried out with piperidine N-sulfonic acid in dimethylsulfoxide to give new heparinoids. The Polymers were characterized by NMR spectroscopy, gel permeation chromatography, and optical rotation.