Synthesis and characterization Some 3,4-Dihydropyrimidin-2(1H)ones using diimide as novel organocatalyst under free solvent

Dihydropyrimidinones attract growing interest dueto their therapeutical and pharmacological activity [1]. 4-aryldihydropyrimidinones are powerfulblockators of calcium channels and antihypertonic,drenergicand neuropeptide antagonists [2]. The simplest and direct route to dihydropyrimidinones,suggested for the first time by Biginelliandinvolving ternary condensation of an aldehyde, aketo ester, and urea, often gives the desired productin a low yield, especially with aliphatic aldehydes [3].Therefore,theBiginelli reaction continues to attract the attentionof researchers looking for facile and efficient proceduresfor preparing dihydropyrimidinones. Here we report on a new procedure for preparing3,4- dihydropyrimidin-2(1H)-ones in thepresence of N,N-diimide 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 solvent free for 3 h at 120 OC(Figure 1).