Design, synthesis, characterization, structure-activity relationship, and molecular docking studies of novel 2,3-dihydropyrimidin-4(5H)-one and pyrimido[5,4–c] pyridazine-4-carbonitrile derivatives with biological evaluation

• Published in: Journal of molecular structure 2024-12, Vol.1318, p.139113, Article 139113
• Main Authors: Reheim, Mohamed A.M. Abdel, Ghazal, Basma, Hafiz, Ibrahim S. Abdel, Rady, HendS. Abdel, Elhagalic, Gameel A.M., El-Gaby, Mohamed S.A.
• Format: Article
• Language: English
• Subjects: 3,4-dihydropyrimidin-4(5H)-one,pyrimido [5,4–c]pyridazine-4-carbonitrile; Heterocyclization,antimicrobial; Molecular docking
• ISSN: 0022-2860
• DOI: 10.1016/j.molstruc.2024.139113

•New molecules of pyridazine-4-carbonitriles were synthesized and characterized.•Quantum chemical calculations were carried out by DFT method using B3LYP functional and 6–31 G(d,p) basis set.•Molecular Electrostatic Potential (MEP) analysis of the synthesized compounds was performed over the optimized structures.•Molecular docking studies were performed to explain the interaction between target compounds and the PDB code: 3ACX.•Structure-activity relationship (SAR) was reported based on their electronic structures. The key starting material, 2-imino-6-phenyl-2,3-dihydropyrimidin-4(5H)-one 1, was the focus of our approach due to the fact that it has an endocyclic active methylene group adjacent to the carbonyl function at position-5. We also further investigated the heterocyclization of the target products 3a–d with diverse carbon nucleophiles to generate fused pyrimidines. The authors provide a simple synthesis of heretofore unreported findings from two series of the novel 2,3,5,6-tetrahydropyrimido [5,4-c]pyridazine-4-carbonitriles 4a–d and 6a–c. The structures of the newly synthesized compounds have been confirmed via analytical and spectroscopic data. All compounds were screened against bacterial species (Escherichia coli, Bacillus megaterium, and Bacillus subtilis), and their antifungal activity was also tested against fungal species (Fusariumproliferatum, Trichodermaharzianum, and Aspergillus niger). Moreover, the minimum inhibitory concentration (MIC) was detected for all the studied compounds and revealed that all compounds had good to moderate results compared to the standby ones. Density function theory (DFT) at B3LYP via the 6–31 G (d,p) basis set has been calculated to explore the electronic properties of all studied compounds. Structure-activity relationship (SAR) was reported based on their electronic structure. Furthermore, molecular docking studies were conducted to evaluate the DFT results and visualize the activity of the compounds. The results displayed that those compounds (3b and 4a-d) were excellent scaffolds acting as antimicrobial agents. [Display omitted]