| abstract |
There are provided novel pyridazinone derivatives having the general formula (I):n 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 C 1-5 alkyl, cyano, hydroxyl, C 1-5 alkoxyl, amino, C 1-5 alkylamino, C 2-6 dialkylamino, C 2 5 , acylamino, carboxyl, C 2-5 alkoxycarbonyl and carbamoyl, R 1 and R 2 independently represent hydrogen atom or C 1-5 alkyl or R 1 and R 2 may form together C 1-5 alkylene, and the dotted line represents either a single bond or a double bond, and salts thereof. |