Design, synthesis and anti-influenza virus activity of furan-substituted spirothiazolidinones

A new series of N-(3-oxo-1-thia-4-azaspiro[4.5]decan-4-yl)carboxamides have been designed, synthesized and evaluated as antiviral agents. The compounds were prepared by condensation of 2-methylfuran-3-carbohydrazide, appropriate carbonyl compounds and sulfanyl acids. The new molecules were characterized by IR, ¹H NMR, ¹³C NMR, mass spectrometry and elemental analysis. Six analogues proved to be active against influenza A/H3N2 virus, the two most protent analogues, 3c and 3d, having an EC₅₀ value of about 1 µM. These findings help to define the SAR of spirothiazolidinone-based inhibitors of the influenza virus membrane fusion process.