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.
Cyclohexane is an organic compound with a chemical formula C6H12. It is a colorless liquid with a pungent odor, insoluble in water, and soluble in most organic solvents such as ethanol, ether, benzene, and acetone. Cyclohexyl fragments are a common structure in both natural and synthetic drugs. It can be used as both core structure and part of achiral side chain.
Tetrahydroisoquinoline is an organic compound with the chemical formula C9H11N. It is classified as a secondary amine, obtained from isoquinoline by hydrogenation. The tetrahydroisoquinoline moiety forms the backbone of several natural, synthetic and semi-synthetic drugs approved for the treatment of cancer, pain, gout and various neurodegenerative diseases.