A concise synthesis of the 6-o- and 6′-o-sulfated analogues of the sialyl lewis X tetrasaccharide

The octyl glycoside of the sialyl Lewis X tetrasaccharide and its 6-O-sulfated and 6′-O-sulfated analogues were chemically synthesized in a concise manner starting from readily accessible monosaccharide intermediates. The synthesis involved formation of an orthogonally protected tetrasaccharide intermediate from which all three materials were prepared. A selective catalytic hydrogenolysis of four O-benzyl ethers in presence of a 4,6-O-benzylidene group was the key step in the synthetic scheme.