Table 3. Structure–Activity Relationships of the R⁴-Group-Substituted Pyridine and Pyrimidines.

^aData represent the geometric mean of at least three replicates. See Supporting Information Table S2 for full statistics.

^bKinetic solubility measured by NMR in HEPES buffer (containing 5% DMSO) at pH 8. Where this was <30 μM, solubility by HPLC in PBS buffer and 1% DMSO at pH 7.4 was measured and is shown in parentheses.