Asymmetric synthesis of heterocyclic chloroamines and aziridines by enantioselective protonation of catalytically generated enamines

We report a method for the synthesis of chiral vicinal chlo-roamines via asymmetric protonation of catalytically gener-ated prochiral chloroenamines using chiral Brønsted acids. The process is highly enantioselective, with the origin of asymmetry and catalyst substituent effects elucidated by DFT calculations. We show the utility of the method as an approach to the synthesis of a broad range of heterocycle-substituted aziridines by treatment of the chloroamines with base in a one-pot process, as well as the utility of the process to allow access to vicinal diamines.