Cyclopropane is the smallest cyclic compound with unique structural features and physicochemical properties, which is widely used in the design of small molecule drugs. In drug design, it is often used to increase activity, fix conformation and improve PK and water solubility. The introduction of cyclopropyl groups into drugs can change various properties of molecules, such as improving metabolic stability; increasing biological activity; enhancing drug efficacy; limiting polypeptide conformation and slowing down its hydrolysis; reducing plasma clearance; improving drug dissociation and many more. Cyclopropane rings are widely found in marketed drugs, including cardiovascular drugs, central nervous system (CNS) drugs, anticancer drugs, autoimmune and anti-inflammatory drugs.
Isothiazole or 1,2-thiazole is an organic compound containing a five-membered aromatic ring consisting of three carbon atoms, one nitrogen atom and one sulfur atom. In contrast to isomeric thiazoles, the two heteroatoms are in adjacent positions. The ring structure of isothiazoles is incorporated into larger compounds that are biologically active, such as the drugs ziprasidone and piperone. Isothiazoles are an important class of five-membered sulfur heterocyclic compounds that are widely used in medicinal chemistry and organic synthesis due to the unique properties of two electronegative heteroatoms in the 1,2-relationship.