Catalytic Enantioselective Macrocyclization for the Synthesis of Planar‐Chiral Cyclophanes: Recent Updates

The planar chirality of macrocycles is a fascinating research topic. Locking the configurational flip between the benzene ring and macrocycle leads to planar chirality, which can significantly enhance the biological activity of cyclophanes. Planar‐chiral cyclophanes are widely used in pharmaceuticals, chiral catalysts, and functional materials. However, accessing planar‐chiral cyclophanes via asymmetric catalysis has remained challenging. Among the various strategies, asymmetric macrocyclization provides a powerful tool for accessing planar‐chiral cyclophanes. This method allows for control of the planar chirality when constructing the macrocycle and greatly improves the efficiency. There are three types of macrocyclization reactions: transition metal‐catalyzed, organocatalyzed, and biocatalyzed. In addition, the chiral confinement strategy breaks through conservative synthetic approaches. This review summarizes these achievements, aiming to highlight the catalytic asymmetric synthesis of cyclophanes and inspire interested researchers.