Exploiting Imine Photochemistry for Masked N-Centered Radical Reactivity

This report details the development of a masked <i>N</i>-centered radical strategy that harvests the chemical potential of violet light to drive the conversion of cyclopropylimines to 1-aminonorbornanes. This process is initiated by the nitrogen-centered radical character of a photoexcited imine, facilitating the homolytic fragmentation of the cyclopropane ring followed by a radical cyclization sequence that forms two new C–C bonds en route to the norbornane core. Employing the excited state diyl of a Schiff base as a masked <i>N</i>‑centered radical is a unique mode of reactivity, the utility of which is amplified by the bathochromic shift into the visible spectrum imparted by the 4-nitrobenzimine. In addition to the intramolecular reactivity that generates 1‑aminonorbornanes, intermolecular formal [3+2] cycloadditions are also amenable to this strategy. This photochemical methodology operates in continuous flow, enhancing the potential to translate this approach beyond the academic sector.