Synthesis and caracterization of 3,4 dihyoropyrimidin-2-ones by heteregeneous acid catalysts

Key words: 3,4-Dihydropyrimidin-2-ones, Biginelli condensation, Zirconium phosphate, Alumina sulfuric acid, Solid acid catalyst, Solvent-free reactions. Dihydropyrimidinones and their derivates have attracted considerable interest because of their pharmaceutical and therapeutic properties, such as antibacterial, antiviral, anti-tumor, anti-inflammatory activities. Some of them have been successfully used as calcium channel blockers, antihypertensive agents, ?1a-antagonists and neuropeptide Y antagonists. Additionally, their particular structure has been found in Batzelladine A and B which are the first low molecular weight natural products reported in the literature to inhibit the binding of HIV gp-120 to CD4 cells. The original procedure was reported by Biginelli in 1983, often provides low yields of the products, when substituted aromatic or aliphatic aldehyes are employed. Due to the importance of Biginelli reaction products, the discovery and introduction of better and milder conditions using new catalysts has been under attention. In this study, two different heterogeneous acid catalysts are used in solvent free conditions, the first catalyst is zirconium phosphate, and the second is alumina sulfuric acid. The synthesis of various 3,4-dihydropyrimidinines at 90 Celcius in the presence of zirconium phosphate were performed in good yields. And the catalyst was recovered easily and reused without loss of its activity. The same reactions were also carried out at room temperature by using alumina sulfuric acid as a catalyst and the catalyst exhibited remarkable reactivity. These methods not only afforded the products in high yield but also avoided the problems associated with catalyst cost, handling, safety and pollution. 1H-NMR, 13C-NMR and Mass spectrum of all the final products were elucidated.