SARS‐CoV‐2 shares only 82% of its genome with its relative SARS‐CoV‐1. However, essential viral enzymes of both species show sequence similarities of greater than 90%. 137 ,  139 ,  140 ,  141 ,  142  SARS‐CoV‐2 3CLpro is highly similar to SARS‐CoV‐1 3CLpro, sharing 96% of its sequence. Therefore, one could expect that SARS‐CoV‐1 Mpro inhibitors are active against SARS‐CoV‐2 Mpro. Compound 40 was found to be active against SARS‐CoV‐2 Mpro and its value of kobs/[I] for the COVID‐19 virus Mpro was determined to be 11 300 ± 880 M−1·s−1. 143  Peptide N3 was co‐crystalized with SARS‐CoV‐1 Mpro at 2.1 Å resolution (see Figure 13). Its binding mode to SARS‐CoV‐2 Mpro is highly similar to that of other CoV main proteases. Some key features include the Cys‐His catalytic dyad and the substrate‐binding pocket situated in a gap between domain I and II.