A Simple and Efficient Regioselective and Chemoselective Synthesis of New Substituted 3‐Methyl‐6‐arylpyridazine‐4‐carboxamides and 5‐Oxo‐3‐aryl‐5,6‐dihydropyrido[4,3‐c]pyridazine‐8‐carbaldehydes

A facile, green, and one‐pot approach is described for the regioselective synthesis of new substituted 3‐methyl‐6‐arylpyridazine‐4‐carboxamides in water at room temperature. Subsequent treatment of these products with the Vilsmeier reagent led to chemoselective and regioselective production of new 5‐oxo‐3‐aryl‐5,6‐dihydropyrido4,3‐c]pyridazine‐8‐carbaldehydes in good to excellent yields.