Visible-Light-Mediated α-Amino Alkylation of Azomethine Imines: An Approach to -(β-Aminoalkyl)pyrazolidinones.

Herein, a mild and robust photocatalytic protocol for the combination of amino and pyrazolidinone functionalities through a radical α-amino alkylation of azomethine iminium ions is demonstrated. This method presents a high functional group tolerance providing direct access to a large family of -(β-aminoalkyl)pyrazolidinones in good to excellent yields, including the late-stage incorporation of the pyrazolidinone moiety to pharmaceutical ingredients. We propose a plausible scenario for the C-C bond-forming step which involves radical addition followed by a spin-center-shift event.