[Synthesis of aminopropylglycoside Neu5Acalpha2-6GalNAcalpha, the SiaTn antigen].

The synthesis of the SiaTn disaccharide, hapten of a tumor-associated antigen, as a derivative convenient for condensation with a polymer carrier was described. Selective sialylation of the primary hydroxyl group in (3-trifluoroacetamidopropyl)-2-azido-2-deoxy-alpha-D-galactopyr ano side with a derivative of ethylthioglycoside of N-acetylneiraminic acid promoted with N-iodosuccinimide-trifluoromethanesulfonic acid (or its trimethylsilyl ester) pair provided alpha 2-->6- and beta 2--> 6-sialylgalactosides with 41 and 23% yields, respectively. Catalytic hydrogenolysis of the azido group, N-acetylation, and subsequent O- and N-deacetylation provided the target aminopropylglycoside Neu5Ac alpha 2-6GalNAc alpha 1-O(CH2)3NH2. The use of 3,4-isopropylidene derivative with the only free C6 hydroxyl group as a glycosyl acceptor shifted stereoselectivity of the sialylation towards the formation of the beta-disaccharide.