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.
Quinazolines belong to heterocyclic chemistry, also known as 1,3-naphthalenes. The backbone consists of two six-membered aromatic rings fused to each other, with two nitrogen atoms at positions 1 and 3 on the backbone. The presence of these two nitrogen atoms in quinazoline increases its importance in pharmaceutical and biological reactions. Quinazolines and their derivatives are among the most important heterocyclic compounds due to their diverse chemical reactivity and important range of biological activities.
Thiazolidine is a heterocyclic organic compound, which is a five-membered saturated ring with a thioether group and an amine group. It is the sulfur analog of oxazolidine. Thiazolidine derivatives have many uses and have a broad spectrum of biological activities. For example, the drug pioglitazone contains a thiazolidine ring. Thiazolidine has three isomers, 2-, 3-, and 4-. Derivatives with a 2-thiazoline ring are the most common.