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

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