Three-component synthesis of 5:6 and 6:6 fused pyrimidines using KF–alumina as a catalyst

A series of fused pyrimidine derivatives were synthesized by the three-component reaction of an aryl aldehyde, urea, or guanidine in ethyl alcohol/dioxane in presence of 1-methyl-1H-pyrrol-2(3H)-one 1, 1-methylpiperidin-2-one 2, 1-methylindolin-2-one 3, or 1,3-dimethyl-dihydropyrimidine-2,4-dione 9 at 80 °C catalyzed by KF–Al2O3. For example, when 1-methyl-1H-pyrrol-2(3H)-one 1, arylaldehyde 4, and urea 5 were treated with KF–Al2O3 in ethyl alcohol at 80 °C for 3–5 h, we obtained pyrrolo[2,3-d]pyrimidine derivatives in good yield.