CdS nanoparticles: An efficient, clean and reusable heterogeneous catalyst for one-pot procedure for synthesis of 3,4-Dihydropyrimidin-2(1H)-ones in solvent-free conditions

3,4-Dihydropyrimidinones and their derivatives are synthesized via Biginelli routes involving an aromatic aldehydes, ethylacetoacetates and urea in one-pot procedure by using CdS nanoparticles as efficient heterogeneous catalyst in solvent-free conditions. Compared with classical Biginelli reaction reported in 1893, this new method provides much improved modification in terms of simplicity. The present methodology offers several advantages such as a simple procedure with an easy work-up, short reaction times and excellent yields. Excellent yields and mild reaction conditions as well as the environmentally friendly character of CdS make it an important alternative to the classic acid catalyzed Biginelli's reactions. The catalysts could be recycled and reused for five times, without substantial reduction in their catalytic activities. The results are shown that electron-releasing group on aromatic ring causes reduced rate of reaction and electron with drawing group's causes increased the rate of reactions. The structure of products has been characterized by IR and 1HNMR spectra.