%0 Journal Article
%T Three Component Reaction: An Efficient Synthesis and Reactions of 3,4-Dihydropyrimidin-2(1H)-Ones and Thiones Using New Natural Catalyst
%A A. M. Elmaghraby
%A I. A. Mousa
%A A. A. Harb
%A M. Y. Mahgoub
%J ISRN Organic Chemistry
%D 2013
%R 10.1155/2013/706437
%X Synthesis of 3,4-dihydropyrimidin-2(1H)-one and 3,4-dihydropyrimidin-2(1H)-thione derivatives from aldehydes, 1,3-dicarbonyl derivatives and urea or thiourea using granite and quartz as new, natural and reusable catalysts. Some of the 3,4-dihydropyrimidin-2(1H)-thione derivatives were used to prepare new heterocyclic compounds. The antimicrobial activity of selected examples of the synthesized compounds was tested and showed moderate activity. 1. Introduction Aryl-3,4-dihydropyrimidines derivatives have recently received great attention because of their wide range of therapeutic and pharmacological properties, such as antiviral [1], antitumor, antibacterial and antifungal [2], anti-inflammatory [3], antihypertensive agents, and neuropeptide Y (NPY) antagonists [4]. Furthermore, these compounds have emerged as the integral backbones of several calcium-channel blockers [5]. Also, several alkaloids containing the dihydropyrimidine were isolated from marine sources, for example, of these are the batzelladine alkaloids, which are found to be potent HIVgp-120-CD4 inhibitors [6, 7]. In general, the classic Biginelli approach to 3,4-dihydropyrimidinones is based on the condensation of ethyl acetoacetate, aromatic aldehyde, and urea under strong acidic conditions; this suffers, however, from low yields of products, particularly in case of substituted aromatic and aliphatic aldehydes [8, 9]. This problem has led to the development of multistep synthetic strategies that produce relatively higher yields, but lack the simplicity of the original one-pot-Biginelli protocol. Thus, the Biginelli reaction has received renewed interest from researchers interested in discovering milder and more efficient procedures that are applicable to a wide range of substituents in all three components and proceed in better yields. So, the one-pot-Biginelli protocol for 3,4-dihydropyrimidines synthesis was explored by varying all components and catalysts [10¨C18] in protic, aprotic solvents, and solvent free conditions [19] using either classical heating, microwave [20, 21], ultrasound [22, 23], and visible light (100£¿W Lamp, THF) irradiations [24]. Also several improved procedures have been reported recently using not only acidic media such as Lewis acids, protic acids, and ionic liquids as promoters [25, 26] but also nonacidic substances such as baker¡¯s yeast [27], graphite [28], and iodine [29, 30]. Heterogeneous solid acids are used also; however, these are advantageous over conventional homogeneous acid catalysts as they can be easily recovered from the reaction mixture by simple
%U http://www.hindawi.com/journals/isrn.organic.chemistry/2013/706437/