A series of 3-aryl-6, 8-dialkyl-7-thioxo-7, 8-dihydropyrimido [4, 5-c] pyridazine-5 (6 H)-one derivatives have been regioselectively synthesized via the one-pot three-component reaction of 1, 3-dimethylthiobarbituric acid and 1, 3-diethylthiobarbituric acid with various arylglyoxals in the presence of hydrazinium dihydrochloride in warm ethanol. These new substituted pyrimidopyridazines may be potential monoamine oxidase inhibitors.
