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

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.