Chiral rare earth metal complex-catalyzed conjugate addition of O-alkylhydroxylamines. An efficient synthetic entry into optically active 2-acyl aziridines

The conjugate addition of O-alkylhydroxylamines to α,β-unsaturated ketones is effectively catalyzed by chiral rare earth metal complexes to afford the corresponding β-amino ketones with high enantioselectivities (up to 99% ee) in almost quantitative yields, which are, upon treatment with a base catalyst, quantitatively converted into the 2-acyl aziridines without losing their enantiopurities. The protocol is highly practical thus providing an easy access to enantiopure 2-acyl aziridines and their derivatives in good quantities.