Photocatalytic Iminyl Radical Cyclization for the Synthesis of Quinazolinones

An operationally simple protocol for the synthesis of medicinally relevant quinazolin-4(3H)-ones is described. This method employs an organic dye, ambient atmosphere, and visible light to activate α-azido benzamides through a photoinduced hydrogen atom transfer, generating iminyl radicals upon extrusion of dinitrogen. Cyclization to close the pyrimidinone ring then affords a variety of quinazolinone derivatives. This photocatalytic strategy establishes a foundation for iminyl radical-mediated heterocycle synthesis from alkyl azides under mild conditions.