Pyridazinylpiperazine (III) was prepared from 3,6-dichloropyridazine (I) and N-methylpiperazine (II) according to a literature method. Subsequent quaternization of piperazine (III) with methyl iodide gave the title ammonium salt.
The condensation of 3,6-dichloropyridazine (I) with piperazine (II) by means of TEA in refluxing toluene gives 3-chloro-6-(1-piperazinyl)pyridazine (III), which is methylated with HCHO/ HCOOH at 110 C, yielding 3-chloro-6-(4-methylpiperazin-1-yl)pyridazine (IV). Finally, this compound is quaternized with methyl iodide in ethyl ether to provide the target dimethylpiperidinium salt.