Synthesis of dibenzo[e,g]isoindol-1-ones via photoinduced intramolecular annulation of 3,4-diphenyl-1H-pyrrol-2(5H)-ones

An efficient, oxidant and photocatalyst-free approach for the synthesis of polycyclic-fused isoindolinone derivatives is reported via annulation of 3,4-diphenyl-3-pyrrolin-2-ones along with release of the hydrogen gas under an argon atmosphere in EtOH by irradiation with a 500 W mercury lamp at room temperature. The described approach is atom-economic and environmentally friendly and tolerates various electron-donating and electron-withdrawing groups. In addition, selected annulation products, dibenzo[e,g]isoindole-1-ones, were successfully oxidized into dibenzo[e,g]isoindole-1,3(2H)- diones in DMSO in the presence of CH3ONa at room temperature.