Short Communication MICROWAVE ASSISTED GREEN SYNTHESIS OF PHARMACEUTICALLY IMPORTANT DIHYDROPYRIMIDINONES IN FRUIT JUICE MEDIUM TANAY PRAMANIK *a , POULAMI MAJI a a Department of Chemistry, Faculty of Technology and Sciences, Lovely Professional University, Phagwara, P. O. Box 144411, India Email: tanay.pramanik@gmail.com Received: 24 Aug 2015 Revised and Accepted: 22 Sep 2015 ABSTRACT Objective: The objective of this research project was to perform the green synthesis of a series of Dihydropyrimidinone (DHPM) derivatives which are having immense importance in biological and pharmaceutical science, via microwave assisted Biginelli reaction in fruit juice medium. Methods: Urea and ethyl acetoacetate were made to react with different electron rich as well as electron deficient aromatic aldehydes in various fruit juice medium under microwave irradiation. After successful completion of the reaction the crude product was precipitated out of the reaction medium and after re-crystallization of the crude product the pure desired DHPMs were obtained with quite good percentage of yield. Results: It was observed that our green Biginelli reaction was completed successfully within few minutes duration and the microwave assisted Biginelli reaction in fruit juice medium was much faster, greener and cleaner compared to that of room temperature Biginelli reaction in the same fruit juice medium. The acidity of the fruit juices and the electronic effect of the aromatic aldehydes have shown significant influence on the rate of reaction. Conclusion: Thus an efficient, green, cost-effective and eco-friendly method has been developed and reported for the very first time for microwave assisted synthesis of dihydropyrimidinone using some common fruit juices as reaction medium. The fruit juices have served as the solvent cum catalyst in these Biginelli reactions. Our current approach of synthesizing DHPM via microwave assisted Biginelli reaction in fruit juice medium has given a new direction in the field of green chemistry. Keywords: Biginelli reaction, Fruit Juice, Microwave, Dihydropyrimidinone, Green synthesis. Due to wide range of promising and multifaceted biological activities of N-contained heterocyclic compound known as dihydro pyrimidinone (DHPM) as anticancer, anti-inflammatory, antibacterial, antifungal, anthelmintic and antitopoisomerase agents [1-4], the synthesis of DHPM derivatives bearing diverse substitution patterns has attracted much attention from the researcher for last few decades [5]. The most convenient and popular reaction that gives easy access to various derivatives of DHPM is the Biginelli reaction [6] which is a multi component condensation employing urea, ethyl acetoacetate and aromatic aldehydes [Scheme-1]. Scheme 1: Synthesis of DHPM via Biginelli reaction A large number of Lewis acids like BF3 [7], FeCl3 [8], InCl3 [9], BiCl3 [10], LaCl3 [11], LiClO4 [12], Mn-(OAc)3 [13], CAN [14] have already been explored as catalysts for performing this Biginelli reaction. Verities of solvents like EtOH, CH3CN, CH2Cl2, THF have also been employed by the researchers as the reaction medium for synthesis of DHPM via Biginelli reaction. Unfortunately none of these catalysts and solvents is completely safe for the environment and human health. The toxicity of these solvents and catalysts posed a serious threat to the environment and human health. Our growing concern for the environment has motivated the researchers to develop a green and eco friendly method for synthesis of DHPM. To avoid the toxic effects of solvents and catalysts, “a solvent free and catalyst free Biginelli reaction” has been reported in literature [15, 16]. But the reactants mixture needs to be stirred at a high temperature (100-105 °C) while performing the reaction in a “solvent-free and catalyst-free” condition. So the scope and need of developing a green methodology for synthesizing DHPM at room temperature was still there. So recently a green methodology has been developed by our group [17, 18] to synthesize DHPM at room temperature employing common fruit juices as reaction medium. According to our previous reports [17, 18] the DHPMs were synthesized without employing any toxic artificial solvents or catalyst, rather natural acids present in the common fruit juices were successfully employed as eco friendly, nontoxic and safe biocatalysts in our reaction. The room temperature Biginelli reactions used to take more than an hour to go for completion in fruit juice medium [17, 18]. So to make this reaction even more eco friendly and green, the reaction time need to be minimized by making the reaction faster and more efficient. Organic synthesis using microwave assisted heating method is considered to be much cleaner, greener and eco friendly compared to that of conventional heating method [19]. The energy efficiency of microwave (MW) irradiation and the ability of MW irradiation to speed up the chemical reaction [20] have made us think to employ this technique (MW irradiation) as a potential tool for our green synthesis of DHPM. Large verities of “Microwave assisted Biginelli reactions” have already been well explored by researchers and well documented in literature [21-23]. But unfortunately the solvents or catalysts like FeCl3 [21], CaCl2 [22], ZnI2 [23] those were used so far for those “Microwave assisted Biginelli reactions” are toxic, non eco friendly and unsafe for human health. The fruit juices are completely eco friendly, biodegradable, non- polluting and non toxic. Moreover they are completely safe for human health and environment. Some common fruit juices like amla, orange and lime juices have already been proven to be effective as green reaction medium for room temperature Biginelli reaction [17, 18]. Microwave assisted synthesis of DHPM in fruit juice medium is expected to be much efficient, faster and cleaner compared to that of room temperature but our extensive literature search has revealed that so far no attempt has been made by the researcher to synthesize DHPM in fruit juice medium using microwave (MW) irradiation. So based on the research gap stated above, the main aim of this work is to synthesize a series of DHPM derivates bearing both electron rich International Journal of Pharmacy and Pharmaceutical Sciences ISSN- 0975-1491 Vol 7, Issue 11, 2015 Innovare Academic Sciences