alpha-Oxygenation of N-aryl/alkyl heterocyclic compounds via ruthenium photocatalysis

We herein report ruthenium(iii) photocatalyzed oxidation of N-aryl tertiary amines to the corresponding amides. More specifically, various N-aryl tetrahydroisoquinolines were converted to analogous N-aryl dihydroisoquinolinones under an oxygen atmosphere. Molecular oxygen is utilized for alpha-oxidation in the presence of benzylic proton abstracting base DBU to get oxidized products in good to excellent yields. Quenching experiments confirmed the radical pathway of the reaction through the formation of O-2(-) reactive oxygen species (ROS).