Novel effective antivirals against SARS-CoV-2 are needed because of the emergence of novel variants and the potential risk of SARS-CoV-2/MERS-CoV recombination. The SARS-CoV-2 main protease (Mpro) is a promising antiviral target. Mpro presents a His41-Cys145 catalytic dyad in the central part of its active site, which confers a natural advantage for developing covalent drugs.