University of Tehran Journal of Sciences, Islamic Republic of Iran 1016-1104 26 2 2015 06 01 Ultrasound Assisted One-pot Synthesis of Dihydropyrimidinones Using Holmium Chloride As Catalyst 117 123 54643 EN S. Kakaei 1 NFCRS, Nuclear Science and Technology Research Institute, P.O. Box 11365-3486, Tehran, Islamic Republic of Iran H. Sid Kalal 1 NFCRS, Nuclear Science and Technology Research Institute, P.O. Box 11365-3486, Tehran, Islamic Republic of Iran H. Hoveidi 2 Graduate Faculty of Environment, University of Tehran, Tehran, Islamic Republic of Iran Journal Article 2014 11 16 <span>A simple and green chemical procedure was reported for the synthesis of dihydropyrimidinones from various aldehydes, ethyl acetoacetate and urea or thiourea using  holmium chloride as catalyst. The reactions were performed under solvent free conditions with ultrasound irradiation as the energy source. The advantages of this protocol include the excellent yield, operational simplicity, short time and the avoidance of the use of organic solvents and friendly preparation. Products were identified by mp. and IR, NMR and Mass spectroscopies.</span> https://jsciences.ut.ac.ir/article_54643_2697fa36306ef65835e2a262449dd2a6.pdf