Nickel Chloride Hexahydrate Catalyzed Multicomponent Biginelli's Synthesis of 3,4-Dihydropyrimidin-2(1H)-Ones and Thiones

An efficient protocol is reported for the one-pot three-component Bignelli synthesis of a series of 3,4-dihydropyrimidine-2(1H)-ones and thiones in good yields (66-90%) from the aldehydes (4-benzyloxybenzaldehyde, 5-bromovanilin, 4-formyl-1-cyclohexene, and trans-cinnamaldehyde), -keto esters (ethyl acetoacetate, allyl acetoacetate, and t-butyl acetoacetate), and urea/thiourea in ethanol, using nickel chloride hexahydrate as a catalyst.