Pyridazine, also known as o-diazobenzene, is a six-membered heterocyclic compound containing two nitrogen heteroatoms in the 1 and 2 positions with a special structure and a wide biological activity. Pyridazine is more and more popular in drug development, and a variety of pyridazine drugs have been developed and marketed. From the perspective of the therapeutic field, pyridazine drug molecules are mainly used for tumor treatment, but also involve in many therapeutic fields such as inflammation, hypertension and cardiovascular disease. With the increase and in-depth of research, pyridazine drugs will play more roles in the treatment of diseases.
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.