Carbazole benzocarbazole derivs

Typical examples are the N-methylacridone derivative (19), the carbazole-and benzocarbazole derivatives (20) and (21), in which the fluorescent, heterocyclic part of the molecule is linked with the phthalhydrazide structure via a bridging methylene group. 

When naphthyl amines e.g. 23) are used in the Bucherer carbazole synthesis, they are converted by the catalytic action of aqueous bisulfite into tetralonesulfonic acid derivative 13 by the Bucherer reaction. Addition of NaHSOs gives an enamine, which tautomerises to the imine 24 24 is hydrolysed to keto form 13 and subsequent Bucherer carbazole synthesis follows to afford the benzocarbazole product 20. ... 

Indoles substituted at C-3 with butadienyl or styryl groups undergo electrocyclic reactions to give carbazole derivatives. The silyl enol ether (275) can be converted thermally directly into the carbazole (276), as the result of ready elimination of methanol this sequence is crucial for a hyellazole synthesis (Equation (96)) <89CC43>. Several related 3-styrylindole sequences have been developed and differ with respect to the placement of ethyl carbonate groups on the alkene. Both the substrates (277) and (279) undergo photocyclization to the respective benzocarbazoles (278) and (280) as a result of... 

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