A visible-light-induced oxidation of diazenyl-protected tetrahydroisoquinolines and isoindolines for the synthesis of structurally diverse lactams is developed. The reaction was carried out with Eosin Y-Na 2 as an organic photocatalyst and molecular oxygen as an oxidant, and the desired functionalized N-aryldiazenyl-lactams were obtained under mild and transition metal-free conditions. The utility of this method is showcased by the gram-scale synthesis and deprotection of the Naryldiazenyl-lactam product.