A simple, and efficient procedure for the synthesis of novel 2,5-diaryl-1-hydroxy-1H-imidazol-4-yl derivatives via a one-pot, four-component reaction between hydroxylamine, benzonitriles, arylglyoxals and cyclic 1,3dicarbonyl compounds (Melrum's acid or dimedone) in ethanol under reflux conditions without using bases and catalysts is reported. All the products were obtained in good yields and their structures were established from their spectroscopic data.

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applications in the field of drug research have stimulated the development of a wide range of synthetic methods for their preparation and chemical transformations. Out of the five major bases in nucleic acids, three (i.e. cytosine, uracil, and thymine) are pyrimidine derivatives, which are found in DNA and RNA [6][7][8]. Because of their involvement as bases in DNA and RNA, they have become very important in the world of synthetic organic chemistry. The best known method for making DHPMs is the classical Biginelli synthesis [9]. Although, it has been known for more than a century, it is still the most useful method for the preparation of this class of compounds. The simple and direct method for the synthesis of DHPMs reported by Biginelli in 1893 involves a one-pot condensation of an aldehyde, a β-diketone and urea under strong acidic conditions [9].Dihydropyrimidine-2,4,5(3H)-triones that from a structural standpoint are the same as dihydropyrimidin-2-(1H)-ones were considered as a lead analog for subsequent structural optimization as a potential agent for the treatment of breast cancer [10]. To the best of our knowledge, only in the one work the novel resveratrol analogs dihydropyrimidine-2,4,5(3H)-triones were prepared by aldol condensation of resveratrol-2-carboxaldehyde with the appropriate active methylene compound, utilizing a variety of reaction conditions, i.e., ammonium acetate in acetic acid under microwave irradiation (MWI), by refluxing the reactants in ethanol, or by stirring the reaction at ambient temperature in methanol [11].We herein report a hitherto unknown three-component reaction of appropriate amines, phenyl isocyanate or phenyl isothiocyanate, and ethyl bromopyruvate after stirring at reflux conditions in DMF for 24 h to afford substituted dihydropyrimidine-2,4,5(3H)-triones and tetrahydro-2-thioxopyrimidine-4,5-diones without any using bases and catalysts.Abstract Novel heterocyclic dihydropyrimidine-2,4,5(3H)-triones and tetrahydro-2-thioxopyrimidine-4,5-diones were synthesized via three-component reaction between appropriate amines, phenyl isocyanate or phenyl isothiocyanate, and ethyl bromopyruvate in DMF under reflux conditions without using additional bases or catalysts. All the products were obtained in good yield by simple and efficient procedure. The structures of all the synthesized compounds were established from advanced spectroscopic data.

A simple and efficient synthesis of pyrimido [2,1-b][1,3]benzothiazoles and [1,3]benzothiazolo[3,2a]quinazolines has been developed by using a one-pot, three-component reaction between arylglyoxals, 2-aminobenzothiazole, and various 1,3-dicarbonyl compounds in acetic acid. All the products were obtained in good yields and their structures were established from their spectroscopic data.