DOWEX 50W IN AQUEOUS MEDIUM: HIGHLY EFFICIENT BIGINELLI CONDENSATION PROCEDURE FOR THE SYNTHESIS OF 4-ARYL-3,4-DIHYDROPYRIMIDONES

摘要

We report here Dowex 50W-mediated efficient synthesis of 4-aryl 3,4-dihydropyrimidones in water for the first time in a one-pot operation. In recent years, 4-aryl dihydropyrimidones have shown immense interest as calcium channel blockers, antihypertensive agents, alpha-la-antagonists and neuropeptide Y (NPY) antagonists.Dihydropyrimidone-5-carboxylate moiety is also present in biologically active marine alkaloids. In this series the most important examples are batzelladine alkaloids which are potent HIV group-120-CD4 inhibitors. As a result of their biological properties, synthesis of the dihydropyrimidone nucleus has received much attention. The initial synthesis of dihydropyrimidone following Biginelli condensation has proved to be inefficient with 20-50% yield. Better methods have been discovered, but through multiple sequences and hazardous conditions. A few other attractive methods are known, but most of them employ anhydrous reaction conditions and Lewis acids. Therefore, an efficient and operationally simple method is necessary for the synthesis of this type of multifunctionalized rings.