Acid Catalyzed One-pot Three-component Biginelli-type Synthesis of Some New Symmetrical Bis 3,4-dihydropyrimidin-2(1H)-ones/thiones

Biologically important 21 new symmetrical bis 3,4-dihydropyrimidin-2(1H)-ones/thiones were synthesized by reacting 4,4 '-diaminodiphenyl ether/4,4 '-ethylenedianiline with tert-butyl acetoacetate to produce diphenyl ether-bridged bis beta-keto amide/diphenyl ethane-bridged bis beta-keto amide then treated with urea or thiourea and an appropriate aldehyde with either a catalytic amount of p-TSA center dot H2O or conc. HCl in ethanol afforded the title compounds.