To predict a comprehensive impurity map, we outlined different possible reactions, other than the intended major reaction (Figure ). First, we noted impurities arising from possible side reactions with the same set of reactants, reagents, and solvent, but resulting in different products . Second, we captured the impurities when additional reagents or solvents are added, as a part of the work-up or isolation processes, such as crystallization . Lastly, we outlined the impurities arising from reactions with known impurities in the starting materials . Overall, we enumerated three different types of possible reactions, other than the major reaction, for a single step.