MW-assisted synthesis of new polysubstituted tetrahydropyrimidines

Pyrimidines are important in the area of bioorganic and medicinal chemistry since they showed a variety of biological activities such as anticonvulsant, antidepressant, antioxidant, anti-inflammatory, antiviral, anti-HIV, antimicrobial and antitumor and also, the vital biomolecules DNA is composed of the pyrimidine bases. A fused heterocyclic analog of pyrimidines, the thiazolo[3,2-c]pyrimidines with their biological activities were reported by our group in 2014, 2015 and 2018. In order to elaborate the chemistry and biology of pyrimidine compounds, synthesis of new polysubstituted nitropyridimines were aimed in the current study. To achieve this goal, first of all, aryl substituted β-nitroenamines as suitable precursors were prepared by the reaction of anilines with α-nitroketones and characterized by IR, NMR and HRMS analyses. In the second part of the study, nitrotetrahydropyrimidines were efficiently synthesized through Mannich cyclizations of nitroenamines with formaldehyde and aniline derivatives under microwave heating in 30-40 minutes. The structures of all the nitropyrimidine products were fully characterized by IR, NMR and HRMS analyses. In the last part of the study, an antioxidant study was conducted for nitropyrimidine products using DPPH radical scavenging activity assay. Two of the nitropyrimidine products exhibited moderate percentage inhibition effect and three of the derivatives exhibitied moderate-low percentage inhibition effects in DPPH radical solution. Also, a preliminary antibacterial activity study was performed for five of the nitropyrimidine derivatives against S.Epidermidis and S.Aureus bacterial strains using disc diffusion method. It was observed that only one nitropyrimidine derivative exhibited moderate antibacterial activity against S.Epidermidis bacteria.