Synthesis and antiviral activity of novel 3-substituted pyrazolinium salts

For the first time, convenient methods for the preparation of pyrazoline N-alkylidene salts based on terpene (camphor, camphorquinone, carvone) ketones, cage (adamantanone and norcamphor) ketones, and natural aldehydes (carvone and myrtenal) allowing the isolation of stable pyrazolinium salts in individual form were proposed. Optimization of the conditions for the synthesis of the target products was carried out. The antiviral activity of the synthesized salts was studied; among the tested compounds 1-bornylidene-3-phenylpyrazolinium tetrafluoroborate (IC50 6.2 μM, SI 107) exhibited the greatest activity against influenza A/Puerto Rico/8/34 (H1N1) virus.