Synthesis, X-ray crystal structure, Hirshfeld surface analysis and computational investigation into the potential inhibitory action of novel 6-(-tolyl)-2-((-tolyl)thio)methyl-7-[1.2.4]triazolo[5,1-][1,3,4]thiadiazine inhibits the main protease of COVID-19.

In recent times, the novel coronavirus disease (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has now become a worldwide pandemic. With over 71 million confirmed cases, even though the effectiveness and side effects of the specific drugs and vaccines approved for this disease are still limited. Scientists and researchers from all across the world are working to find a vaccine and a cure for COVID-19 by using large-scale drug discovery and analysis.

Synthesis, reactions, and biological activities of some new thieno[3,2-c]quinoline and pyrrolo[3,2-c]quinoline derivatives.

2-Bromo-4-fluoroaniline (1) was condensed with ethyl 2-cyano-3-ethoxyacrylate (2) in ethanol to afford 3, which upon refluxing in paraffin oil at 250°C gave 8-bromo-3-cyano-6-fluoroquinoline-4(1H)-one (4). Then, compound 4 was taken as a versatile building block that allows the synthesis of thieno[3,2-c]quinoline, pyrrolo[3,2-c]quinoline, and N-methylpyrrolo[3,2-c]quinoline systems. The newly synthesized compounds and their derivatives were characterized by elemental analysis and spectroscopy (IR, (1)H NMR, (13)C NMR, and mass).