Pyrrolidine, also known as tetrahydropyrrole, is a saturated five-membered heterocyclic ring, which is miscible with water. Pyrrolidine exists in many alkaloids and drug molecules, such as kappa opioids, antagonists of dopamine D4 receptors, and HIV reverse transcriptase inhibitors.
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.