Imidazolines are a class of heterocycles derived from imidazoles by reduction of one of the two double bonds. Three isomers are known, 2-imidazoline, 3-imidazoline and 4-imidazoline. 2 and 3-imidazolines contain imine centers, while 4-imidazolines contain alkene groups. The 2-imidazoline group occurs in several drugs. Imidazolines are an important class of compounds found in many natural and medicinal products. These compounds are also used as intermediates in the synthesis of organic molecules. Furthermore, chiral imidazolines are widely used as organic catalysts for the synthesis of various natural and synthetic organic compounds.
Compared to quinolines, isoquinolines are also prominent structural motifs present in many biologically significant natural and synthetic compounds. Some well-known isoquinoline alkaloids include the anticancer and anticonvulsant berberine, the vasodilator and antispasmodic drugs papaverine and emetine. In addition to naturally occurring isoquinolines, synthetic analogs have also shown significant biological activity.