Exploring Potential Coplanar Chiral Bipyridine Ligands for Asymmetric Catalysis

Bipyridines represent a class of ligands renowned for their versatility and efficacy in numerous transition metal-catalyzed reactions. Chiral bipyridine ligands are noted for their distinctive reactivity and stereoselectivity. In this work, we have designed and synthesized a class of bipyridine ligands endowed with an axially chiral scaffold. These ligands feature: (a) a precisely aligned coplanar bipyridine framework that is beneficial for metal chelation; (b) a spacious environment around the metal-bipyridine complexes, capable of hosting substrates with substantial steric bulk; (c) a chiral pocket induced by the axially chiral architecture. These atropochiral planar bipyridine ligands were successfully applied in copper-catalyzed ring-opening reactions of cyclic diaryliodoniums with bulky secondary amines, achieving high efficiency and stereoselectivity that were unsuccessful in our previous efforts.