Water-Mediated Radical Kinetic Resolution of Terminal Activated N-Carbamate Aziridines

Optically active terminal aziridines are fundamental building blocks for constructing complex nitrogen-containing molecules. Notably, the protecting group on the amino moiety critically governs not only the reactivity and enantioselectivity during aziridine formation but also the efficiency of downstream functionalization. While carbamates are among the most widely employed protecting groups in amine-related synthesis due to their versatility and orthogonality, their enantioselective incorporation into aziridines remains a long-standing challenge. Herein, we present the first radical approach for kinetic resolution of aziridines, enabling efficient access to a broad range of aziridines bearing diverse carbamate protecting groups and substituents. This transformation exploits the dual functionality of a dinuclear titanium radical catalyst, which enables enantiodiscriminative activation of racemic aziridines and coordinative activation of H₂O as a sustainable hydrogen-atom donor. Mechanistic studies reveal that the optimal distribution of the catalyst between aziridine and H₂O is crucial for sustaining the cooperative catalytic cycle.