Galactose-conjugates of the oseltamivir pharmacophore--new tools for the characterization of influenza virus neuraminidases.

We describe the synthesis of mimetics of the alpha2-3 and alpha2-6 sialogalactoside substrates of influenza neuraminidase which include the oseltamivir pharmacophore, and report the sub-nanomolar affinities for these novel neuraminidase inhibitors. The challenge of synthesizing a Phospha-Oseltamivir/Tamiphosphor monoester involving the secondary 3-hydroxy group of galactose required to mimic the alpha2-3 sialogalactoside has been overcome by palladium-promoted coupling of the oseltamivir-derived vinyl iodide with a protected galactose-3-phosphonate. The difference in binding of these two inhibitors to a given influenza neuraminidase should be a function of its alpha2-3/alpha2-6-selectivity, an important, but not yet fully understood factor in the adaptation of highly pathogenic avian influenza viruses to human hosts.