Abstract
Starting from the indole-fused pyridazinone 5, a series of new pyridazino[4,5-b] indoles of potential pharmaceutical interest (9-18), was prepared. Compounds 20 and 21 were obtained by nucleophilic displacement of the chlorine atom of 19. Thionation of the chloro derivative 19 gave the thione compound 23, while its reaction with sodium azide gave a tetracyclic system, namely the tetrazolopyridazinoindole 22. Dehalogenation of the chloro compound 19 gave a 3-aza analogue of the natural product, harman.