The effects of substituents on the aryl ring were studied by the preparation and testing of several PD173955 analogs. Inserting a single carbon atom into the C–N bond in the aniline subunit (PDC) reduced the kinase inhibition by a factor of 200. Despite its decreased affinity for Abl compared with PD173955, PDC exhibits a Ki very similar to that reported for Imatinib. Increased water solubility is also gained by replacing the thiomethyl group with an amino ...