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.
In addition to the nitrogen-based heterocycles presented so far, a number of others nitrogen-based scaffolds have also been reported as promising agents for GBM treatment, including pyrazolo-triazole, imidazotetrazine, piperidine, purine, imidazopyrazine, pyrazole, triazole among others.