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-1 H -4,7-methanoisoindol-1-one. AgPF 6 (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.