Synthesis of carbazoles from N-(N,N-diarylamino)phthalimides with aluminum chloride via diarylnitrenium ions

Generation of diarylnitrenium ions from N-(N,N-diarylamino)phthalimides by treatment with AlCl3 in benzene or in 1,2-dichloroethane leads to formation of carbazoles by intramolecular C-C bond formation. The reaction proceeds in synthetically useful yields.