Synthesis of Sialic Acid Derivatives Having a C=C Double Bond Substituted at the C-5 Position and Their Glycopolymers.

Glycomonomers of sialic acid in which the acetamide group at C-5 was converted into two kinds of C=C double bond substituents were prepared and the fully protected glycomonomers were directly polymerized before deprotection steps. Radical polymerization with acrylamide in DMF in the presence of ammonium persulfate and N,N,N',N'-tetramethylethylenediamine proceeded smoothly and gave corresponding sialopolymers. Interestingly glycomonomers had hemagglutination inhibitory activities not only for H1N1 but also for H3N2 of human influenza virus strains.