Thiophene is a five-membered heterocyclic compound containing a sulfur heteroatom with the molecular formula C4H4S. Thiophene is aromatic and is very similar to benzene; electrophilic substitution reaction is easier than benzene, and it is mainly substituted at the 2-position. Thiophene ring system has certain stability to oxidant.
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.
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.