Synthesis, antimicrobial activity, and molecular docking studies of new fused pyrimidinethiones

2-Cyano-3-(methylsufany)-3-(phenylamino)prop-2-enethioamide (3) was treated with dimethylformamide-dimethylacetals (DMF-DMA), dimedone, isatin, and/or 3-iminobutanenitrile to give prop-2-enethioamide 4, N-substituted thioamides 9, 10, and 5,6-dihydropyridine 12, respectively. While, the reaction of bis-thioamide 5 with DMF-DMA gave 4-thioxo-1,4-dihydropyrimidine 6. Cyclization of compound 4 using different conditions afforded pyrimidinethione 15, which reacted with guanidine, cyanothioacetamide, and/or 2-cyanomethylpyrazole to yield the corresponding fused pyridopyrimidine 17 and pyrimidopyrimidines 18 and 20, respectively. Structures of the newly compounds were characterized by using their infrared (IR), nuclear magnetic resonance (NMR) data and elemental analysis. The synthesized compounds were in vitro evaluated for their antibacterial activity through the zone of inhibition measurement. The results revealed promising antibacterial activity for compounds against the used pathogenic bacterial strains. Moreover, the antibacterial activity of the active compounds (4, 6, 9, 10, 12, 15, 17, 18, and 20) was interpreted using molecular docking against E. coliFabH-CoA complex (PDB ID: 1HNJ) to determine the binding energy, binding interactions, and molecules' orientations inside the active site of the target protein.