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

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.