Horner-Emmons reaction of 1-benzyl-4-piperidone (I) with diethyl cyanomethylphosphonate (II) in the presence of K2CO3 provided the piperidinilydeneacetonitrile (III). Reduction of the double bond of (III) with magnesium in MeOH yielded the saturated nitrile (IV), which was further reduced to amine (V) using LiAlH4. Treatment of 6-phenyl-3-pyridazinone (VI) with POCl3 gave the chloropyridazine (VII). This was coupled with diamine (V) in the presence of ammonium chloride in refluxing butanol to furnish the title pyridazinamine, which was finally converted to the dihydrochloride salt.