Medicinal Chemistry

8.1.6.1 Classification of Heterocycles

Structurally and functionally, there is a bewildering array of different heterocycles.
These may be classified as follows:

Simple heterocyclic compounds

Three-membered heterocycles containing one heteroatom

Oxiranes (epoxides), thiiranes (episulfides), aziridines

Three-membered heterocycles containing more than one heteroatom

Oxaziridines, dioxiranes, diazirines

Four-membered heterocycles containing one heteroatom

Oxetanes, thietanes, azetidines

Four-membered heterocycles containing more than one heteroatom

Dithietanes, dithietes, diazetidines

Five-membered non-aromatic heterocycles containing one heteroatom

Pyrrolidine

Five-membered non-aromatic heterocycles containing more than one heteroatom

1-Pyrazolines, 1,3-dioxolanes, 2-pyrazolines

Five-membered aromatic heterocycles containing one heteroatom

Pyrrole, furan, thiophene

478 MEDICINAL CHEMISTRY