Study of carbohydrate–carbohydrate interactions: total synthesis of 6d-deoxy Lewisx pentaosyl glycosphingolipid

This article describes total synthesis of 6d-deoxy Lewisx pentaosyl glycosphingolipid, a useful tool for study of the Lewisx–Lewisx interaction. A 6-deoxy galactose donor was condensed with a diol of glucosamine to provide regioselectively a β 1→4 linked disaccharide, which was further fucosylated to a protected deoxy Lewisx trisaccharide. Glycosylation of a lactoside diol with the 6d-deoxy Lewisx trisaccharide gave regio- and stereoselectively a pentasaccharide in excellent yield. After chemical modification, this pentasaccharide reacted with the 3-O-benzoylated azidosphingosine to form a glycosphingolipid, which, after azide reduction followed by condensation with stearic acid and deprotection, afforded the target compound.