Design, synthesis and spectroscopic and crystallographic characterisation of novel functionalized pyrazole derivatives: biological evaluation for their cytotoxic, angiogenic and antioxidant activities

The current study presents the synthesis of functionalized pyrazoles (18–29) through 3 + 2 annulation reaction of ethyl 2-(arylidene)-3-oxobutanoates (8–13) with phenylhydrazine hydrochlorides (14–17) in acetic acid under reflux conditions. Structures of the synthesized new compounds were characterized by spectral and single-crystal X-ray diffraction studies. Preliminary assessment on their biological activities showed that compounds 19, 23 and 28 have anticancer and antiangiogenic properties and compounds 20, 24 and 26 have excellent diphenylpicrylhydrazyl (DPPH) radical scavenging activities. Detailed quantitative structure–activity relationship (QSAR) analysis provided insights into the molecular features that might have contributed towards increasing potency of inhibition. In summary, we present a study that has successfully demonstrated the synthesis of novel pyrazole analogues that display anticancer, antiangiogenic and DPPH free radical scavenging activities, making them lead molecules of choice for further development.