Heterocycles are cyclic compounds in which one or more atoms of the ring are hetero atoms like O, N, S, P, etc. They are present in many biologically important molecules such as alkaloids, essential amino acids, vitamins, hemoglobin, nucleic acids, and hormones. Heterocyclics are also present in a large number of synthetic drugs like caffeine, acyclovir (antiviral), clopidogrel (anti-platelet), diazepam, carbamazepine (anti-epileptic), nicotine, etc. There are six main classification of heterocyclic compounds
Classification of Heterocyclic Compounds
These heterocycles may be classified on the basis of the number of atoms present in the ring. For example,
1. Five membered heterocyclic rings containing one heteroatom:
![Classification of Heterocyclic Compounds](https://pharmacyscope.com/wp-content/uploads/2022/06/Five-membered-heterocyclic-ring.png)
2. Five membered heterocyclic rings containing two heteroatoms (1, 2 – azoles):
![heterocyclic](https://pharmacyscope.com/wp-content/uploads/2022/06/heterocyclic.png)
- Pyrazole: X = N – H
- Isoxazole: X = O
- Isothiazole: X = S
3. Five membered heterocyclic rings containing two heteroatoms (1, 3 – azoles):
![](https://pharmacyscope.com/wp-content/uploads/2022/06/Hetero.png)
- Imidazole: X = N – H (Azole)
- Oxazole: X = O (Oxa)
- Thiazole: X = S (Thia)
4. Six membered heterocyclic rings containing one heteroatom:
![Six membered heterocyclic ring](https://pharmacyscope.com/wp-content/uploads/2022/06/Six-membered-heterocyclic-ring.png)
5. Six membered heterocyclic rings containing two heteroatoms:
![Six membered hetero cyclic ring](https://pharmacyscope.com/wp-content/uploads/2022/06/Six-membered-hetero-cyclic-ring-1024x211.png)
6. Polyclinic heterocyclic rings:
![Classification of Heterocyclic Compounds](https://pharmacyscope.com/wp-content/uploads/2022/06/Polyclic-heterocyclic-rings-1024x487.png)
Make sure you also check our other amazing Article on : Stereoselective and Stereospecific Reactionsa