The synthesis and properties of pyridazino[4,3‐e] ‐as‐triazines and pyridazino[4,5‐e] ‐as‐triazines, two novel condensed pyridazine ring systems

Abstract The compounds prepared in the novel pyridazino[4,3‐e]‐as‐triazine ring system are: 8‐chloro‐4‐methyl‐3,4‐dihydropyridazino[4,3‐e]‐as‐triazine (21), 8‐chloro‐2,4‐dimethyl‐3,4‐dihydropyridazino[4,3‐e]‐as‐triazine (23), 8‐chloro‐2‐ethyl‐4‐methyl‐3,4‐dihydropyridazino[4,3‐e]‐as‐ triazine (24), 4‐methyl‐3,4‐dihydropyridazino[4,3‐e]‐as‐triazine‐8‐thione (25), 4‐methyl‐3,4‐dihydropyridazino[4,3‐e]‐as‐triazine (26), 2,4‐dimethyl‐3,4‐dihydropyridazino[4,3‐e]‐as‐triazine (27), and 2‐ethyl‐4‐methyl‐3,4‐dihydropyridazino[4,3‐e]‐as‐triazine (28). In the novel pyridazino[4,5‐e]‐as‐triazine ring system the following compounds were prepared: 1,2‐dihydropyridazino[4,5‐e]‐as‐triazine (31), 3‐methyl‐1,2‐dihydropyridazino[4,5‐e]‐as‐triazine (32), 3‐ethyl‐1,2‐dihydropyridazino[4,5‐e]‐as‐triazine (33), and 1‐methyl‐1,2‐dihydropyridazino[4,5‐e]‐as‐triazine (35). The preparation of a number of previously unreported intermediates and compounds for structure proof are also described.