One pot multi-component synthesis of novel functionalized pyrazolo furan-2(5H)-one derivatives: in vitro, DFT, molecular docking, and pharmacophore studies, as coronavirus inhibitors.

New and facile one-pot approach for the syntheses of 12 derivatives of 3,5-disubstituted furane-2(5H)-one (4a-l) from easily available starting materials. The suitable synthetic procedures for selective synthesis of diverse furane-2(5H)-one derivatives were achieved via multi-component condensation of 1,3-diphenyl-1H-pyrazole-4-carbaldehyde (1), pyruvic acid and different aromatic amines 3a-l in good to high yields and short reaction time by refluxing in acetic acid as well as obtained by another method (method B) when unsaturated arylidene pyruvic acid 6 was refluxed with different aromatic amines in acetic acid but in smaller yield than method A. Structures of the prepared compounds were elucidated by elemental analysis and spectral data as mass, IR, H-NMR and C-NMR spectroscopy. The antiviral efficacy of compounds 4a-l against SARS-CoV-2 was evaluated using the MTT assay. It was demonstrated that synthetic compounds 4c-e and 4h-j have a potent and selective inhibitory effect on SARS-CoV-2, a strain obtained from Egyptian patients. We utilized density-functional theory (DFT) analyses to deduce the molecular structures and topologies of the more energetic molecules. Molecular docking studies were performed against the SARS-CoV-2 main protease (PDB ID: 6Y84) and the SARS-CoV-2 Nsp9 RNA binding protein (PDB ID: 6W4B) to study the binding mechanism, non-bonding interactions, and binding affinity. Lastly, a hypothetical pharmacophore model was constructed by applying the Molecular Operating Environment (MOE) tool and eleven pharmaceuticals with proven antiviral activity.