Regio- and Stereoselective Synthesis of the Biotin-Conjugated Keratan Sulfate Hexa- and Octasaccharides [-3)βGal6S(1–4)βGlcNAc6S(1-] _3and4 in the Repeating Disaccharide Region

Keratan sulfate (KS) is an acidic linear polysaccharide belonging to the glycosaminoglycan family. The repeating disaccharide unit of KS consists of the sequence -4)-βGlcNAc(1→3)-βGal(1→, with varying sulfation patterns at the primary hydroxy groups. L4 is a subclass of KS in which both primary hydroxy groups are sulfated. Herein, we report an efficient synthesis of KS L4 hexa- and octasaccharides as biotin conjugates through coupling reactions employing partially protected glycosyl acceptors.