The Sialyl Tn disaccharide, Neu5Acα2-6GalNAc, is a common O-linked glycan structure found on glycoproteins. These building blocks can be used as ligands of glycan binding proteins, standards or for the precise synthesis of glycopeptides containing the Sialyl Tn disaccharide. We offer a variety of Sialyl Tn modified glycoamino acids.