Isoxazole is a liquid heterocyclic compound C3H3NO isomeric with oxazole and having a penetrating odor like that of pyridine. Isoxazoles belong to an important class of five-membered aromatic heterocycles containing two electronegative heteroatoms, nitrogen and oxygen, in a 1,2-relationship and three regular sp2 carbon atoms. These molecules are found to be key components in various synthetic products in daily use and also present as a pharmacophore essential for biological activity in many drugs and bioactive natural products. In addition, isoxazoles have demonstrated their ability to exhibit hydrogen bond donor/acceptor interactions with a variety of enzymes and receptors.
Pyrazoline is a heterocyclic chemical compound with the molecular formula C3H6N2. Pyrazolines are well-known and important nitrogen-containing five-membered ring heterocyclic compounds. Pyrazoline derivatives have numerous prominent pharmacological effects, such as antimicrobial, anti-inflammatory, analgesic, antidepressant and anticancer.