Novel quinolizidine salicylamide influenza fusion inhibitors

A novel series of quinolizidine salicylamides was synthesized as specific inhibitors of the H1 subtype of influenza A viruses. These inhibitors inhibit the pH-induced fusion process, thereby blocking viral entry into host cells. Compound 16 was the most active inhibitor in this series with an EC50 of 0.25 μg/mL in plaque reduction assay. The synthesis and the SAR of these compounds are discussed.