| abstract |
3(2H)-Pyridazinone derivatives of the formula (I), <IMAGE> wherein R<1> represents hydrogen or one of various defined substituents, A and B stand for hydrogen, halogen or a group of the formula (II), <IMAGE> wherein R<2> and R<3> are independently hydrogen or C1-4 alkyl, or together with the adjacent -N-(CH2)n<N>- group form a piperazine or homopiperazine ring; R<4> represents hydrogen, C1-4 alkyl or phenyl.r |