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), β‐keto esters (ethyl acetoacetate, allyl acetoacetate, and t‐butyl acetoacetate), and urea/thiourea in ethanol, using nickel chloride hexahydrate as a catalyst.