Pyridazines. XXXVII. Novel triazanaphthalene derivatives via intramolecular cyclization reactions of vic‐disubstituted pyridazines

Abstract
8‐Phenylpyrido[3,4‐d]pyridazines bearing various amino substituents at C‐5 (7a‐d, 8) were prepared from ethyl 5‐benzyl‐4‐pyridazinecarboxylate 1 via the fused pyridone 5. The isomeric 4‐phenylpyrido[2,3‐d]pyridazines having the amino functions attached to C‐2 (10a‐f) were obtained by a one‐pot cyclization of the amino ketone 1 with appropriate acetamide acetals. These novel triazanaphthalene derivatives are of interest as analogues of diuretic and antithrombotic agents.