This is mainly because of drug-and lead-likeness concepts prioritizing physicochemical properties of the compounds that were in the focus of the medicinal chemistry community in the 2000s and partiallyin 2010s, and which still widely used today. In other words, the Enamine screening collection focuses on structures of smaller size, making the compounds suitable as primary hits that can be further functionalized and structurally evolved. This is also reflected by the distributions of NumHA. The distributions of NumHA and MW for the subset selected for CPA (Enamine-PNP CPA) are shifted towards smaller molecules. Compared to the larger olle tions, pra ti ally all ompounds in the sele ted set have a MW ≤ 400 g/mol.