Studies on the syntheses of heterocyclic compounds—DLIX : A synthesis of benzocarbazole derivatives by thermolysis

A thermal reaction of indolylmagnesium bromide (5) with 1-cyano-4,5-dimethoxybenzocyclobutene (6) gave a mixture of 6-cyano-5a, 6,11,11a-tetrahydro-8,9-dimethoxy-5H-benzo [b] carbazole (8a) and 6-cyano-5a, 6, 11, 11a-tetrahydro-9-hydroxy-8-methoxy-5H-benzo [b] carbazole (10). Compound 8a was easily converted to 6-cyano-8, 9-dimethoxy-5H-benzo [b] carbazole (12) by dehydrogenation on 30% Pd-C.