Photoinduced Cross-Coupling Reactions of Diazoalkanes via a Selective Denitrogenation/Cyclization/Addition Cascade for Diversity-Oriented Synthesis of <i>N</i>-Acyl Pyrazolines

Herein, we present a coupling reaction of two-component diazoalkanes via a selective denitrogenation/cyclization/addition cascade under visible light irradiation for the diversity-oriented synthesis of <i>N</i>-acyl pyrazolines, using readily available diazoesters and diazoketones as substrates. The protocol features conditions that are free of photocatalysts, exhibit atomic economy, allow for simple operation, and demonstrate excellent chemoselectivity. These results, which suggest a reduction in the proliferation of T cells, indicate that <i>N</i>-acyl pyrazolines might have anti-inflammatory and immune-regulatory potential.