Phosphoramidates as Transient Precursors of Nitrogen‐Centered Radical Under Visible‐Light Irradiation: Application to the Synthesis of Phthalazine Derivatives
Maxime De Abreu, Mohamed Selkti, Philippe Belmont, Etienne Brachet
Abstract
Abstract Phosphoramidates are for the first time presented as efficient N‐Centered Radical (NCR) precursors under visible‐light irradiation. More precisely among this class of phosphorus‐derived compounds, we studied the radical reactivity of phosphonohydrazones, under mild reaction conditions, which allowed the synthesis of a wide and diversified library of the scarcely reported phthalazine scaffold. Mechanistic investigations confirmed the formation of a NCR from these brand‐new phosphonohydrazones (derivatived from phosphoramidates), which were further engaged in an intramolecular 6‐ exo ‐dig cyclization to provide phthalazines. Compared to other pre‐activated moieties, the phosphoramidate group is self‐immolative, thus enhancing its attractiveness for the C−N bond formation. magnified image