Using MS/MS analysis, they deduced that ebselen (153) and 156 are irreversible inhibitors of Mpro by covalently attaching to Cys145 of the catalytic dyad. Molecular docking was used to illustrate how 151, 154, and 155 bind to Mpro. Antiviral activity assays, using real‐time reverse transcription‐PCR, indicated that ebselen and inhibitor “N3” (40; Figure 12) had the strongest antiviral effects. Ebselen displayed an EC50 value of 4.67 µM, and “N3” showed an EC50 value of 16.77 µM in a plaque‐reduction assay. Ebselen's IC50 value for SARS‐CoV‐2 Mpro was reported at 0.67 µM. The activity data of remaining compounds is summarized in Figure 35.