Pyrolytic Generation of 3-Phenylindol-2-ylmethylene-carbene and Its Cyclization to 7H-Benzo[c]carbazole

Abstract

Flash vacuum pyrolysis of the 3-phenylindol-2-ylmethylene derivative (12) of Meldrum's acid at 600° and at 750°/0.03 mm gives 9-phenyl-3H-pyrrolo[1,2-a]indol-3-one (14) (97%). At 900°/0.3 mm (14) (49%) is accompanied by 7H-benzo[c] carbazole (6) (10%). The latter is formed by intramolecular C-H insertion in the title carbene (5).