Asymmetric Synthesis\nof Azahelicenes via CPA-Catalyzed\nKinetic Resolution

The azahelicenes are structurally fascinating and practically\nuseful\nchiral scaffolds, but their synthesis, especially in a catalytically\nasymmetric manner, is rather challenging. Herein, we report a CPA-catalyzed\ntransfer hydrogenation process, which enables a rapid kinetic resolution\nof aza[6]helicenes. The established strategy provides facile access\nto enantioenriched aza[6]helicenes and tetrahydro[6]helicenes from\neasily available starting materials. A gram-scale reaction and facile\nconversion of the helical products into a promising chiral Lewis base\ncatalyst, a chiroptical switch material, and monophosphine ligands\nfurther highlight the potential application of this protocol.