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.
Pyrrolines, also called dihydropyrroles, are obtained from aromatic pyrroles by hydrogenation. 1-pyrroline is a cyclic imine, while 2-pyrroline and 3-pyrroline are cyclic amines.