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.
Isoxazole is a liquid heterocyclic compound C3H3NO isomeric with oxazole and having a penetrating odor like that of pyridine. Isoxazoles belong to an important class of five-membered aromatic heterocycles containing two electronegative heteroatoms, nitrogen and oxygen, in a 1,2-relationship and three regular sp2 carbon atoms. These molecules are found to be key components in various synthetic products in daily use and also present as a pharmacophore essential for biological activity in many drugs and bioactive natural products. In addition, isoxazoles have demonstrated their ability to exhibit hydrogen bond donor/acceptor interactions with a variety of enzymes and receptors.
The imidazothiazole, consisting of an imidazole ring fused with a thiazole ring, has been reported to have excellent immunostimulating and anti-inflammatory activities. Fused heterocyclic compounds are of great importance and are found in various types of synthetic and naturally occurring biologically important compounds. Imidazothiazoles and imidazopyridines possess a variety of applications such as dyes, pesticides, fungicides, antitumor, antiinflammatory, and analgesic activity.