A Chiral Phenanthroline Ligand with a Hydrogen-Bonding Site: Application to the Enantioselective Amination of Methylene Groups

A silver-catalyzed amination is reported that occurs at the aliphatic C3-substituent of various quinolones and pyridones. The C-H amination reaction proceeded with high site- and enantioselectivity (14 examples, 83-97% ee). The key to its success is the use of a chiral phenanthroline ligand that is attached via an ethynyl linker to the 8-position of octahydro-1H-4,7-methanoisoindol-1-one. AgPF6 (10 mol %) served as the silver source, PhI=NNs as the nitrene precursor, and 1,10-phenanthroline as the coligand. The reaction outcome can be understood by assuming a nitrene C-H insertion within a hydrogen-bonded silver complex in which a single C-H bond is exposed to the catalytic reaction center.