A Bird's Eye View of Atropisomers Featuring a Five‐Membered Ring

Abstract

An atropisomer is a member of a subclass of restricted rotational conformers – this restricted rotation giving rise to stereogenic sigma bonds – that can be isolated as separate chemical species. Most atropisomer are six‐membered‐ring biaryl or heterobiaryl derivatives. The aim of this microreview is to shed light on a less common class of atropisomers, those containing at least one five‐membered hetero‐ or carbocycle and displaying variously a stereogenic C–N, C–C, or even N–N chemical bond. After a short introduction, the occurrence of atropisomers in nature is presented, as well as the synthetic efforts – encompassing non‐stereoselective and diastereoselective strategies, together with an update on very recent enantioselective approaches – devoted to such axially chiral compounds. Finally, a special focus is placed on their important utilization as original and efficient ligands for metal complexes.