Sonosynthesis of Pyrimidines as Antimicrobial Agents Using Nano-Fe3O4–L-cysteine

Nano-Fe3O4–L-cysteine as a superior catalyst was applied for the synthesis of pyrimidine-trions by three-component reactions of N,N-dimethylbarbituric acid, benzaldehydes and para-methyl aniline or para-methoxy aniline under ultrasonic irradiation in ethanol. The catalyst was characterized by SEM, FT-IR, XRD, TGA, EDS and VSM. In addition, screening diverse catalysts containing Et3N, p-TSA, nano NiO, nano Fe3O4, cysteine and nano-Fe3O4–L-cysteine revealed nano-Fe3O4–L-cysteine (4 mg) as the most effective catalyst to perform this reaction under ultrasonic irradiation in ethanol. Further, the compounds 4b (5-((2-amino-5-methoxyphenyl)(4-(methylthio)phenyl)methyl)-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-trione), 4c (5-((2-amino-5-methoxyphenyl)(4-chlorophenyl)methyl)-1,3- dimethylpyrimidine 2,4,6(1H,3H,5H)-trione) and 4f (5-((2-amino-5-methylphenyl)(2,4-dichlorophenyl)methyl)-1,3-dimethylpyrimidine-2,4,6 (1H,3H,5H)-trione) have moderate growth inhibitory effects on Gram positive bacteria (Staphylococcus aureus, Bacillus subtilis; and Staphylococcus epidermidis). The compound of 4b has moderate growth inhibitory effects on fungi. This technique provides  several benefits including the use of ultrasonic irradiation, great yields in concise times, retrievability the nanocatalyst and low nanocatalyst loading. The present catalytic method is extensible to a wide range of substrates for the preparation of a variety-oriented library of pyrimidines.