To complement this, WaterFLAP was used to calculate the pseudo-apo water network for each A 2A structure binding site as well as perturbation of the pseudo-apo water network upon ligand binding for the 427 molecules and predicted binding poses. This helped to de-prioritize molecules predicted to trap water molecules unfavourably in the lipophilic pockets without a sufficient supporting water network or hydrogen bond donors/acceptors. Based on these analyses, a panel of 41 predicted synthesisable de novo molecules were proposed for synthesis, of which 9 were synthesised for experimental validation based on synthetic route and diversity. The final 9 molecules are shown in Figure with their corresponding predicted binding pose in Figure . Four of these molecules contain known A 2A chemotypes, while the remained contain potentially novel bioactive chemotypes. None of the compounds were available for purchase from a commercial library, and none had a Tanimoto similarity (using ECFP4 fingerprints) greater than 0.6 to any compound in the training dataset.