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RESEARCH PRODUCT

ChemInform Abstract: Reaction of 2,2′-Bis(N-methylindolyl) with Dimethyl Acetylenedicarboxylate and Thermally and Photochemically Induced Cyclizations of the Product.

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2,2′-Bis(N-methylindolyl) 1 reacts with dimethyl acetylenedicarboxylate to furnish the 3-dimethyl maleoyl-substituted 2,2′-bisindolyl 2. Compound 2 cyclizes under aluminum trichloride catalysis according to a polar process to give a cyclopenta[2,1-b:3,4-b′]diindole derivative 4. Reaction of compound 4 with benzyl-amine yields the spiro derivative 5. Photochemically-induced 1,6-electrocyclization of compound 2 gives rise to the indolo[2,3-a]carbazole 6 directly, which is readily transformed to the pyrrolo-annelated carbazole 7 by treatment with benzylamine.