Efficient and stereocontrolled synthesis of chondroitin mono- and disaccharide linked to variously sulfated biotinylated trisaccharides of the linkage region of proteoglycans

Efficient and stereocontrolled preparation of a library of variously sulfated biotinylated tetra- and pentasaccharides possessing the backbone of the partial linkage region plus the first chondroitin sulfate mono- or disaccharide unit (D-GlcA)_n-β-D-(1,3)-GalNAc-β-D-(1,4)-GlcA-β-D-(1,3)-Gal-β-D-(1,3)-Gal (n = 0 or 1) is reported herein for the first time. The synthesis of these compounds was achieved using common key intermediates and a disaccharide building block obtained by semisynthesis. Stereoselective glycosylation, selective protection/deprotection steps, efficient reduction of the N-trichloroacetyl group into the corresponding N-acetyl group, efficient sulfation strategy, deprotection and biotinylation afforded target oligomers in good yield with high purity.