The reaction of 6-(pyridin-2-yl)-2H-pyran-2-one (1) with hydrazine hydrate toward pyridazine derivatives was investigated. To elucidate the reaction pathway, an intermediary-formed α,δ-dihydrazonohydrazide derivative (3) was successfully isolated. Oxidations of the above compounds as well as of other pyridazine derivatives containing a carbohydrazido group, using ammonium cerium(IV) nitrate (CAN),