The method for the synthesis of ethyl 4-[3-(ethoxycarbonyl)-1-phenyl-1H-pyrazol-4-yl]-2-oxo/thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxylates was developed, and the bioactivity of the obtained compounds against infectious agents was predicted. Docking studies of the synthesised compounds were performed on pteridine reductase 1 (PTR1) of Leishmania, dihydrofolate reductase–thymidylate synthase of Trypanosoma cruzi, and human dihydrofolate reductase. The results demonstrated that the investigated compounds exhibit high affinity for these enzymes. Moderate selectivity relative to human DHFR was also observed. In addition, the predicted drug-likeness, ADME-Tox parameters, and toxicity profiles suggest the potential of the synthesised compounds for further pharmacological development.

A sequence of thioxotetrahydropyrimidenes derivatives, N-(4-chloro/methoxyphenyl)-3-formyl-6-methyl-4-aryl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxamides (4a-l) were synthesized by the formylation of N-(4-chloro/methoxyphenyl)-6-methyl-4-aryl-2-thioxo-1,2,3,4-tetrahydropyrimidine-5-carboxamides (3a-l) by dry dimethyl formamide (DMF) and phosphorous oxychloride at room temperature. Formerly, compounds (3a-l) were synthesized by the condensation of N-(4-chloro/methoxyphenyl)-3-oxobutanamide (1), various aromatic aldehydes (2a-f) and thiourea with catalytic amount of concentrated hydrochloric acid under reflux temperature. The structures of the synthesized various thioxotetrahydropyrimidenes have been characterized by using elemental analysis, Infrared, ¹H-NMR, ¹³C-NMR spectroscopy and further supported by Mass spectroscopy. All the products have been screened for their in-vitro biological assay like antibacterial activity towards Gram-positive and Gram-negative bacterial strains and antifungal activity towards Aspergillus niger at a concentration of 40 µg/ml. It was showing that the compounds 4a, 4e, 4g, 4h, 4i and 4l displayed inspirational antibacterial and antifungal activity compared to the used reference standard.