Abstract
For the preparation of both N-linked and O-linked sialylglycopeptides and their glycoprotein form, the critical points in these syntheses are the preparation of an appropriate amount of sialyloligosaccharyl-amino acid and isolation of the sialylglycopeptides. In particular, it have been difficult to isolate O-linked sialylglycopeptides in which the sialyl linkage is labile to acid treatment and the N-acetyl-galactosaminyl linkage is labile to base-treatment. For the preparation of target glycoproteins by the use of such sialylglycopeptide thus obtained, an efficient coupling method should be essential. In this review, we introduce our new sialyl donors for the synthesis of sialyl-TN epitope and O-linked sialyl-TN-glycopeptides, and a new concept for a glycopeptide coupling reaction in the synthesis of glycoproteins.
