2-Dicyanomethylidene-3-ethoxymethylidene-2,3-dihydroindole in the synthesis of fused tri- and tetracyclic systems

The reactions of 2-dicyanomethylidene-3-ethoxymethylidene-2,3-dihydroindole with hydrazine hydrate and phenylhydrazine afforded 2,3-diamino-4-cyanopyrido4,3-b]indole and 3-amino-2-anilino-4-cyanopyrido4,3-b]indole, respectively, and the reactions of the latter compounds with dimethylformamide diethyl acetal were studied. The reactions of 2,3-diamino-4-cyanopyrido4,3-b]indole with benzaldehyde, ethyl acetoacetate, and acetylacetone were investigated. First representatives of new heterocyclic systems, viz., 1,2,4]triazolo1’,5’:1,6]-pyrido4,3-b]indole and pyrazolo1’,5’:1,2]pyrido4,3-b]indole, were synthesized. The structure of ethyl 6-cyano-5-(E)-(dimethylamino)methylideneamino]-2-methyl-7H-pyrazolo-1’,5’:1,2]pyrido4,3-b]indole-1-carboxylate was established by X-ray diffraction.