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.
Thienopyridines are similar in structure to quinoline and isoquinoline, and are a class of heterocyclic compounds with important physiological activity and medicinal value. Thienopyridines are a subclass of antiplatelet drugs that prevent platelet aggregation by binding to selected extracellular cysteine residues on the P2Y12 receptor located on the platelet membrane.