Solvent-Free Synthesis of 3,4-dihydropyrimidin-2(1H)-ones under grauting heating with N,N-dihydroxydiphthalimideas Catalyst

Recently, the interest in synthesis of 3,4-dihydropyrimidin-2(1H)-ones (denoted as Biginelli compounds) andtheir derivatives is increasing tremendously because oftheir therapeutic and pharmacological properties andalso because of interesting biological activities of severalmarine alkaloids which contain the dihydropyrimidinenucleus [1-2].Synthetic strategies for thedihydropyrimidine nucleus involves One-Pot to multistepapproaches. The classical Biginelli synthesis is aOne-Pot condensation using dicarbonylcompoundswith aldehydes (aromatic and aliphatic aldehydes) andurea or thiourea in ethanol solution containing catalyticamounts of acid. [3].Here we report on a new procedure for preparing3,4- dihydropyrimidin-2(1H)-ones in thepresence of N,N-dihydroxydiphthalimide as organocatalyst. We obtained 3,4-dihydropyrimidinonesin high yield by thereaction of various aldehydes with ethyl acetoacetateand urea in the presence of N,N-diimideascatalyst under free solvent for 3 h at 120 OC(Figure 1).