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.
Benzimidazole is a benzo derivative of imidazole. It is a kind of bicyclic aromatic organic compounds, which is formed by fusing a six-membered benzene ring and five-membered imidazole at positions 4 and 5 of imidazole ring. It is an important pharmacophore of many biologically active heterocyclic compounds with various pharmacological activities. Benzimidazoles and their derivatives have developed into dynamic heterocyclic systems due to their potency in a variety of biologically active compounds such as anticancer, bactericidal and antiviral drugs. Benzimidazoles are a class of therapeutic motifs with broad relevance in medicinal chemistry.