Synthesis and biological screening of pyrazole moiety containing analogs of podophyllotoxin

Abstract

The pyrazole moiety containing analogs of podophyllotoxin as potential antimitotic agents were synthesized in five step reactions via chalcone route. The first step is the synthesis of chalcone (2a–d) by the reaction of substituted acetophenones with p-tolualdehyde in the presence of sodium hydroxide in water–ethanol mixture. The cyclopropyl ketones (3a–d) were prepared by the reaction of chalcones (2a–d) with trimethylsulfoxonium iodide (TMSOI) in dry DMSO. The key intermediate tetralones (4a–d) were prepared by the intramolecular cyclization reaction of cyclopropyl ketones (3a–d) in the presence of anhyd. stannic chloride and acetic anhydride in dry dichloromethane. These compounds (4a–d) on formylation give substituted hydroxylmethylene tetralones (5a–d). Further, pyrazole moiety containing analogs of podophyllotoxin (6a–d) were synthesized in high yields by the condensation of hydroxylmethylene tetralones (5a–d) with hydrazine hydrate in absolute ethanol. The structures of the synthesized compounds were confirmed by spectral and elemental analysis data. The synthesized compounds were also screened for their antimitotic activity. It is noteworthy that compounds 6d possessed excellent antimitotic activity, 6b and 6c showed considerable activity, and remaining 6a possessed least activity. Compound 6d was immense to show high antibacterial and antifungal activity against all bacterial and fungal strains compared with standard chloramphenicol and nystatin, respectively.