A new three-component condensation of aryl glyoxals, acetylacetone and urea in the presence of a small amounts of tungstate sulfuric acid (TSA) leads to novel functionalized 5-acetyl-4-(aryloyl)3,4-dihydropyrimidinones which these heterocycles can undergo the Knorr condensation with hydrazines to produce newpyrimido[4,5-d]pyridazines in good yields. These approaches are consistent with principles