Visible Light Photoredox Catalysis: Synthesis of Indazolo[2,3-a]quinolines from 2-(2-Nitrophenyl)-1,2,3,4-tetrahydroquinolines

The synthesis of indazolo[2,3-a]quinoline derivatives in moderate to good yields from 2-(2-nitrophenyl)-1,2,3,4-tetrahydroquinolines via visible light photoredox catalysis is reported. The reaction involves a novel ruthenium-catalyzed intramolecular formation of the N-N bond of the indazole ring.