Pyridones as potential antitumor agents II: 4-Pyridones and bioisosteres of 3-acetoxy-2-pyridone.

Pyridone structural requirements for activity against murine P-388 leukemia have been extended to isosteric analogs of 3-hydroxy-4-pyridone, a compound previously found to have activity. An amino group can be substituted for the 3-hydroxyl function with retention of activity. A sulfur, but not an amino function, can replace the lactam oxygen in the 2-position. Relocation of the lactam oxygen from the 2- to the 4-position in the pyridine ring also produces active pyridones, including 2-methyl-3-acetoxy-4-pyridone. This compound, which has a T/C value of 179%, is the most active material discovered thus far in the pyridone studies.