Compounds useful in inhibiting endo-exonuclease activity and treating cancer have the formula (I) wherein R3 is selected from the group consisting of loweralkyl, oxyalkyl, cycloalkyl, aryl, heteroaryl, heterocycloalkyl, aminoalkyl or a halogen； R4 is selected from the group consisting of H, loweralkyl, oxyalkyl, cycloalkyl, aryl, heteroaryl, heterocycloalkyl, aminoalkyl or a halogen； and wherein R5 is a loweralkyl； or formula (II) wherein R1 is selected from the group consisting of loweralkyl, oxyalkyl, cycloalkyl, aryl, heteroaryl, heterocycloalkyl, aminoalkyl or halogen； R2 is selected from the group consisting of H, loweralkyl, oxyalkyl, cycloalkyl, aryl, heteroaryl, heterocycloalkyl, aminoalkyl or halogen； and wherein R5 is a loweralkyl comprising a linear carbon chain of at least two carbons connecting the first "O" to the second "O".
