Treatment of 3,6-dichloro-4-isopropylpyridazine (I) with ethanolic ammonia in a sealed tube at 130-140 C provided aminopyridazine (II). Subsequent condensation of (II) with dimethylformamide dimethyl acetal in boiling toluene, followed by reaction with hydroxylamine hydrochloride furnished the formamide oxime (III). This was cyclized to the triazolopyridazine (IV) using polyphosphoric acid at 110 C. The remaining chloro atom of (IV) was finally displaced by 3-hydroxy-2,2-dimethyl-1-propanesulfonamide (V) in the presence of NaH in refluxing THF.