A Photochemical Route to Benzo[a]carbazoles via Domino Elimination/Electrocyclization of 2-Aryl-3-(1-tosylalkyl)indoles

The photochemical synthesis of benzo[a]carbazoles from easily synthesizable 2-aryl-3-(1-tosylalkyl)indoles is presented. Irradiation of these substrates in polar aprotic solvents (acetone or THF) gives selectively the target products in satisfactory yields. This versatile and efficient procedure promises to be a useful alternative to the multistep strategies reported in the literature.