Nitrogen Heterocycles
Nitrogen Heterocycles
Cyclic compounds which contain atoms from at least two different elements in the ring are called heterocyclic compounds or simply heterocycles. Most of the heterocycles contain carbon atoms. Nitrogen heterocycles contain at least one nitrogen atom in the ring. Nitrogen heterocycles can be aromatic, saturated or unsaturated. They are also grouped on the basis of ring size, as the ring size is related to their features, reactivity and stability. Examples of saturated nitrogen heterocycles, in order of increasing ring size, starting at the three-membered ring size are: aziridines, azetidines, pyrrolidines, piperidines, and azepanes.
Some of the aromatic nitrogen heterocycles are pyrroles, pyridines, imidazoles, pyrazoles, pyrazines, pyrimidines, pyridazines, 1,2,3-triazoles, 1,2,4-triazoles, 1,3,5-triazines, 1,2,4-triazines, and tetrazoles. Other than these single ring systems, nitrogen heterocycles are also fused with other ring systems, forming condensed ring nitrogen heterocycles, such as, indoles, isoindoles, indazoles, carbazoles, quinolines, isoquinolines, benzimidazoles, and acridines.
