NbCl5-catalyzed Rapid and Efficient Synthesis of 3,4-Dihydropyrimidinones Under Ambient Conditions

Three-component condensation of an aldehyde, 1,3-dicarbonyl compound and urea or thiourea proceeds smoothly at room temperature in the presence of 5 mol % of NbCl5 under extremely mild conditions to afford the corresponding 3,4-dihydropyrimidines in high to quantitative yields. This method is very useful for the synthesis of a wide range of dipyrimidinones at room temperature from aromatic, heterocyclic, and aliphatic aldehydes.