Benzoxazole is an aromatic organic compound with a molecular formula of C7H5NO, a benzoxazole ring structure, and an odor similar to pyridine. Although benzoxazole itself has little practical value, many benzoxazole derivatives are commercially important. As heterocyclic compounds, benzoxazoles are used in research as starting materials for the synthesis of larger, often biologically active structures. Its aromaticity makes it relatively stable, although as a heterocycle it has an active site that enables it to be functionalized.
Thiadiazoles are a subfamily of azoles. Structurally, they are five-membered heterocyclic compounds containing two nitrogen atoms and one sulfur atom, and two double bonds, forming an aromatic ring. Depending on the relative positions of the heteroatoms, there are four possible structures; these forms do not interconvert and are therefore structural isomers rather than tautomers. These compounds themselves are rarely synthesized and have no particular utility, however, compounds that use them as structural motifs are fairly common in pharmacology.