Fluorine is the most electronegative element in the periodic table, and the fluorine atom has a small atomic radius, so fluorine-containing organic compounds have many wonderful properties. For example, the introduction of fluorine atoms or fluorine-containing groups into drug molecules can improve the permeability to cell membranes, metabolic stability and bioavailability; in addition, the introduction of fluorine atoms will improve the lipid solubility of the compound and promote its absorption in the body. The speed of delivery changes the physiological effect. In the field of medicinal chemistry, the introduction of fluorine atoms into organic molecules is an important direction for the development of new anticancer drugs, antitumor drugs, antiviral agents, anti-inflammatory drugs, and central nervous system drugs.
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.
The molecular structure of cyclobutane has four carbon atoms, and its four carbon atoms are not in the same plane, which is the folded conformation of cyclobutane. Cyclobutane itself is not of commercial or biological interest, but more complex derivatives are important in biology and biotechnology. Currently, nine FDA-approved drugs contain the cyclobutane structure. From the perspective of therapeutic areas, cyclobutyl drugs are mainly distributed in popular areas such as tumors, neurological diseases, infectious diseases, endocrine and metabolic diseases.
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.