As in the ChEMBL dataset, the linear connection (connection monopodal (cm)) is the most common connection type found for the fragment combinations within the Enamine-PNPs (83%), followed by fusion edge (fe; 12%), fusion spiro (fs; 2.5%), fusion bridge (fb; 1.8%) and connection bipodal edge (cbe; 0.3%). The relative distribution of the different connection and fusion types is cm:fe:fb:fs:cbe ≈ 100:15:3.0:2.2:0.1. Thus, in the Enamine library PNPs with monopodal connectivity are significantly more prevalent than in the ChEMBL dataset. This is due to synthesis reasons, since compounds with monopodal fragment connectivity are more straightforward to synthesize than for instance fragment combinations with spiro or bridged fusion. Fig. and D show the 10 most common fragments found in the NP fragment combinations of the PNPs and the 6 most common fragment combinations, respectively. The full list of fragments and fragment combinations found in Enamine PNPs is available as Supporting Information. To assess how the Enamine library in general, and the identified PNPs more specifically, compare to each other, we generated the following three datasets: