| abstract |
There are provided novel pyridazinone derivatives having the general formula (I): <IMAGE> (I) wherein A represents 5- or 6-membered heterocyclic ring having 1-3 nitrogen atoms, which may be substituted by at least one member selected from the group consisting of C1-5 alkyl, cyano, hydroxyl, C1-5 alkoxy, amino, C1-5 alkylamino, C2-6 dialkylamino, C2-5 acylamino, carboxyl, C2-5 alkoxycarbonyl and carbamoyl, and R1 and R2 independently represent hydrogen atom or C1-5 alkyl or R1 and R2 may form together C1-5 alkylene, and salts thereof. |