Switchable Phenanthroline‐Cu Catalysts for Enantioselective Alkynylation and Amination of Cyclic Diaryliodonium Salts

Abstract Regio‐ and enantioselective ring‐opening alkynylation and amination of cyclic diaryliodoniums have been achieved through the development of conformationally switchable axially chiral phenanthroline‐Cu catalysts. A range of axially chiral biaryls bearing either an alkynyl substituent or an amide/oxalamide group were synthesized in good to excellent yield (up to 99%), with excellent regio‐ (up to >99:1) and enantioselectivity (up to 99.5:0.5 enantiomeric ratio [er]). Mechanistic studies revealed that the ion‐pairing interaction between the deprotonated phenolic hydroxy group within the ligand and the cyclic diaryliodonium cation played a significant role in controlling the enantioselectivity of the alkynylation reaction. In contrast, the switched conformation of the chiral phenanthroline‐Cu catalyst was found to be crucial to the high enantioselectivity obtained in the amination reaction.