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.
Fluorene is a polycyclic aromatic hydrocarbon insoluble in water and soluble in many organic solvents. Fluorenes are one of the most important fluorescent molecules with applications in polymers, electronic devices, sensors, and photochromic materials.