Palladium‐Catalyzed Enantioselective C−H Olefination to Access Planar‐Chiral Cyclophanes by Dynamic Kinetic Resolution

Abstract

AbstractPlanar‐chiral cyclophanes have received increasing attention for drug discovery and catalyst design. However, the catalytically asymmetric synthesis of planar‐chiral cyclophanes has been a longstanding challenge. We describe the first Pd(II)‐catalyzed enantioselective C−H olefination of prochiral cyclophanes. The low rotational barrier of less hindered benzene ring in the substrates allows the reaction to proceed through a dynamic kinetic resolution. This approach exhibits broad substrate scope, providing the planar‐chiral cyclophanes in high yields (up to 99 %) with excellent enantioselectivities (up to >99 % ee). The ansa chain length scope studies reveal that the chirality of the cyclophanes arises from the bond rotation constraint of the benzene ring around the macrocycle plane, rather than the C−N axis. The C−H activation approach is also applicable to the late‐stage modification of bioactive molecules and pharmaceuticals.