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.
When the ends of the chains are joined together into a ring, cyclic compounds result; such substances often are referred to as carbocyclic or alicyclic compounds. Substitution of one or more of the ring carbon atoms in the molecules of a carbocyclic compound with a heteroatom gives a heterocyclic compound.
Benzene is an important organic compound with the chemical formula C6H6, and its molecule consists of a ring of 6 carbon atoms, each with 1 hydrogen atom. Benzene is a sweet, flammable, colorless and transparent liquid with carcinogenic toxicity at room temperature, and has a strong aromatic odor. It is insoluble in water, easily soluble in organic solvents, and can also be used as an organic solvent itself. The ring system of benzene is called benzene ring, and the structure after removing one hydrogen atom from the benzene ring is called phenyl. Benzene is one of the most important basic organic chemical raw materials. Many important chemical intermediates can be derived from benzene through substitution reaction, addition reaction and benzene ring cleavage reaction.