Fused Quinoline Heterocycles V. Synthesis of Novel 1,2,3,5,6-Pentaazaaceanthrylene Derivatives

Abstract

2,4-Dichloroquinoline-3-carbonitrile (1) with phenylhydrazine in DMF at room temperature gave the 3-amino-4-chloro-1-phenylpyrazolo[4,3- c]quinoline (2). Reaction of 2 with phenyl isothiocyanate afforded the novel fused tetracyclic ring system 1,5-diphenyl-1,5-dihydro-1,2,3,5,6-pentaazaaceanthrylene-4(3 H)-thione (7). Refluxing 2 with excess of a primary amines 8a-d in boiling DMF yielded the corresponding aminopyrazolo[4,3- c]quinolines 9a-d which react with an excess of triethyl orthoformate to furnish 5-substituted 1-phenyl-1,2,3,5,6-pentaaza-aceanthrylenes 11a-d. Reacting 9a with acetic anhydride does not give the expected tetracyclic compound 12, but instead the acetamide 13 is obtained. With triethyl orthoacetate the corresponding iminoester 14 is formed. When compound 14 was refluxed in DMF containing NaH it cyclised to the 4-methyl analogue 12.