Synthesis of benzo[b]benzo[2,3-d]thiophen-6,9-diones via palladium(II) acetate-mediated cyclization of 5-arylthiocyclohexa-2,5-diene-1,4-diones

Palladium(II)-mediated oxidative cyclization of 5-arylthiocyclohexa-2,5-diene-1,4- diones 4 giving biologically important benzo[b] benzo[2,3-d] thiophene-6,9-diones 2 has been performed with a stoichiometric amount of palladium( II) acetate in distillated acetic acid.