The COVID Moonshot project, a crowd-sourced initiative to accelerate the development of a COVID antiviral, was announced in mid-March 2020. The organizers of the project provided several crystal structures of the COVID-19 main protease (M Pro ) in complex with several small fragments (Figure ) and invited the scientific community use this data to construct and submit potential M Pro inhibitors for 7/16 further experimental verification. Though we were in a relatively early stage of this project we decided to build upon our methodology as it was then, to construct candidates for the second and third rounds of submissions.