Pyrrole

Pyrrolidine ranks among the most frequently occurring ring systems in approved pharmaceuticals, appearing in more than 35 FDA-approved drugs. The great interest in the pyrrolidine scaffold stems from the sp³-hybridised character of the ring, which allows efficient exploration of three-dimensional pharmacophore space, contributes well-defined stereocentres, and introduces non-planarity through pseudorotation. Unlike aromatic systems, pyrrolidine presents substituents at defined spatial positions determined by ring puckering and nitrogen inversion, allowing medicinal chemists to project pharmacophoric groups in orientations that are inaccessible to flat heterocycles and that can improve selectivity by matching the three-dimensional topology of binding sites. The basic nitrogen atom is readily protonated under physiological conditions, contributing to aqueous solubility and enabling salt formation, while also participating in hydrogen bonding and electrostatic interactions with enzyme active sites and receptor pockets.

Pyrrolidines are widely used in fragment-based drug design, peptidomimetic programmes, and structure-activity relationship campaigns across CNS disorders, metabolic disease, anti-infective, and oncology programmes. Nirmatrelvir (Paxlovid, Pfizer) is an FDA-approved first-in-class oral inhibitor of the SARS-CoV-2 main protease (Mpro) built around a peptidomimetic scaffold incorporating a pendant 2-oxopyrrolidin-3-yl group confirmed in the FDA label IUPAC name, granted Emergency Use Authorisation in December 2021 and full FDA approval in May 2023 for the treatment of mild-to-moderate COVID-19 in adults and adolescents at high risk of progression to severe disease, where the unfused pyrrolidinone occupies the S1 substrate recognition pocket of Mpro and mimics the glutamine P1 residue of the native viral polyprotein, positioning the nitrile warhead for reversible covalent engagement with the catalytic Cys145 residue. Trofinetide (Daybue, Acadia Pharmaceuticals) is an FDA-approved synthetic analogue of the brain tripeptide glycine-proline-glutamate containing a 2-methylpyrrolidine (methylproline) residue, approved in March 2023 as the first and only treatment for Rett syndrome in adults and children aged two years and older, representing the first therapy approved for this rare neurodevelopmental disorder.

Our range of Pyrrolidines features novel substitutions and the incorporation of synthetically tractable functional groups such as boronic acids and esters, amines, carboxylic acids, ketones, hydroxyls and halogens to enable expedient synthetic strategies.

Please examine a selection of Pyrrolidines in our catalogue. The full range can be found using the substructure feature of our Search tools.