Catalytic conversion of conjugated enones into optically active α-keto aziridines using chiral rare earth metal complexes

Optically active N-unsubstituted α-keto aziridines 2 were synthesized from conjugated enones 1 via the Sc[(R)-BNP]3-catalyzed enantioselective Michael addition of O-methylhydroxylamine followed by the La(O-i-Pr)3-catalyzed ring closure of the corresponding β-methoxyamino ketones 3. A remarkably high asymmetric amplification was observed during the Michael addition, and notable kinetic resolution was also realized during the ring closure reaction when a La(O-i-Pr)3–(R)-BINOL catalyst system was employed.