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.
Benzotriazole is a bicyclic nitrogen heterocycle formed by the fusion of the benzene ring with the 4,5-positions or the “d” site of 1H-1,2,3-triazole. The benzotriazoles are known as important intermediates in the preparation of organic products such as β-amido ketones, aldehydes, β-ketoesters, ionic liquid, and as reagents for acylation and thioacylation reactions. 1H-Benzotriazoles are also known to exhibit broad spectrum of pharmacological activities. There are numerous benzotriazole-based clinically used drugs in the market for the treatment of various diseases.