3(2H)-PYRIDAZINONE DERIVATIVES AND PROCESS FOR THE PREPARATION THEREOF

The invention relates to racemic or optically active new 3(2H)-pyridazinone derivatives, a process for the preparation thereof, pharmaceutical compositions comprising the same, to the use of the said 3(2H)-pyridazinone derivatives for the treatment of diseases and for the preparation of pharmaceutical compositions suitable for the treatment of diseases. The new 3(2H)-pyridazinone derivatives according to the invention correspond to the general formula (I), (see formula I) wherein R1 represents hydrogen; phenyl; methyl optionally carrying a benzyloxy substituent; C1-4 alkyl optionally carrying a substituent of the formula R8R9N-, wherein R8 and R9 are independently C1-4 alkyl, or R8 and R9 form, together with the adjacent nitrogen atom, a 6-membered heterocyclic group optionally containing an oxygen atom or a group of the formula R10N-, wherein R10 stands for C1-4 alkyl optionally carrying a phenoxy substituent, or C3-5 alkenyl carrying a phenyl substituent, furthermore said C1-4 alkyl is optionally substituted by a phenyl carrying a methoxy or a methanesulfonylamino substituent; or C3-5 alkenyl optionally carrying a phenyl or halophenyl substituent; A and B stand for hydrogen, halogen or a group of the general formula (II), (see formula II) wherein R2 and R3 are independently hydrogen or C1-4 alkyl, or together with the adjacent -N-(CH2)n N- group form a piperazine or homopiperazine ring; R4 represents hydrogen, C1-4 alkyl or phenyl, R5, R6 and R7 each stand for hydrogen, C1-4 alkoxy or amino optionally carrying a methanesulfonyl substituent; X is a single valency bond, an oxygen atom or a group of the formula -CH=CH-; m is 0 or 1, and n is 2 or 3, with the proviso that A and B are always different, and if one of A and B is hydrogen or halogen, the other stands for a group of the general formula (II), and acid addition salts thereof, and possess valuable antiarrhythmic effect.