%0 Journal Article
%T An Efficient One-Pot Multi-Component Synthesis of 3,4-Dihydropyrimidin-2-(1H)-Ones/Thiones Catalyzed by Bismuth (III) Sulfate Trihydrate under Solvent-Free Conditions
%A Farhad Hatamjafari
%J Organic Chemistry International
%D 2014
%I Hindawi Publishing Corporation
%R 10.1155/2014/761209
%X A convenient and efficient protocol for the one-pot synthesis of 3,4-dihydropyrimidin-2-(1H)-one/thione derivatives of aldehydes, and 1,3-dicarbonyl compounds with Bismuth (III) sulfate trihydrate as the catalyst was described. We had the advantages of good performance, simplicity, and short time reaction under solvent-free conditions. The catalyst can be repeatedly reused without loss of its activity. 1. Introduction Multi-component reactions play an important role in pharmaceutical industries. Pharmacies are trying to develop green chemistry reactions. Solvent-free synthesis of complex organic structures as drugs is the dream of every pharmacy. Multi-component reaction as a powerful tool for the rapid introduction of molecular diversity is evident and developed for the generation of heterocycles which receive growing interest [1¨C3]. Biginelli reaction is one of the most important multi-component reactions for the synthesis of dihydropyrimidinones/thiones. 3,4-Dihydropyrimidin-2(1H)-ones/thiones (DHPMs) reported the activity of many drugs as having antiviral, antibacterial, and antihypertensive effects, as calcium channel modulators [4¨C7], and as multidrug resistance reversal [8, 9]. Biological activity of some alkaloids isolated recently to 3,4 dihydropyrimidin-2(1H)-ones/thiones moiety [10, 11]. It was first synthesized by Biginelli in 1893 DHPMs as a pot condensation of an aldehyde, diketone, and urea under acidic conditions. These method has low yields, especially in the cases of some substituted aldehydes. To increase the efficiency of the reaction, Biginelli, various catalysts have been used [12]. Biginelli reaction suffers from low yields (20¨C50%) of products. Thus, in recent years, several methods to improve the use of Al(NO3)3¡¤9H2O [13], ZrCl4 [14], zeolites [15], silica sulfuric acid [16], BF3¡¤OEt2 [17], CuCl2¡¤2H2O [18], SbCl3 [19], RuCl3 [20], natural catalyst [21], and glutamic acid [22] have been reported in the literature. However, some of these methods are expensive and harmful to the environment; stoichiometrically, the amount of catalyst, low yields, and incompatibility with other functional groups including product isolation methods is difficult. Therefore, there is still a need for a simple and efficient method for the synthesis of a pot dihydropyrimidinone and thiones under mild conditions. In recent years, eco-friendly industrial application, using green and reusable catalyst, has been studied. Thus, green chemistry has been defined as a set of principles that reduces or eliminates the use or generation of hazardous chemical
%U http://www.hindawi.com/journals/oci/2014/761209/