Transformations of 1,2,4-triazine 4-oxides to pyridazines and triazolo[4,3-b]pyridazines by the action of substituted acetonitriles

Two types of ring transformations of 1,2,4-triazine to pyridazine were found: 1,2,4-triazine 4-oxides bearing ortho-halophenyl in the 3-position react with phenylacetonitrile under basic conditions to form 3-(2-oxyphenyl)[1,2,4]triazolo[4,3-b]pyridazines, while the reactions of 3,6-diaryl-1,2,4-triazin 4-oxides with sodium ethyl cyanoacetate afforded 2-aminopyridazines.