One-pot synthesis of dihydropyrimidinones using facile and reusable polyoxometalate catalysts for the Biginelli reaction

The efficiency of various heteropoly compounds as well-known solid acids is investigated for the three-component condensation reaction of an aldehyde with beta-ketoester and urea in acetonitrile to afford the dihydropyrimidinones (DHPM). Compared to the classical Biginelli reaction conditions, this new method consistently has the advantage of excellent yields and short reaction times. Furthermore, the catalyst could be easily recovered after completion of the reaction and reused without a considerable change in its activity. (c) 2006 Elsevier B.V. All rights reserved.