To learn the criteria used to design the previously reported syntheses, we collected 47303 historical synthetic routes for various molecules from Journal of Medicinal Chemistry as the reference routes for these molecules. Reference routes were constructed by first grouping reactions in the Reaxys database by citation and then creating reaction networks from which routes could be extracted with a depth-first search . Journal of Medicinal Chemistry, years 2000 -2020, was used as the primary literature source in the Reaxys database.