Carbon-11-labeled chromen-4-one derivatives were synthesized as new potential PET agents for imaging of DNA repair enzyme DNA-dependent protein kinase (DNA-PK) in cancer. The target tracers, X-[(11)C]methoxy-2-morpholino-4H-chromen-4-ones (X=8, 7, 6, 5; [(11)C]4a-d), were prepared from their corresponding precursors, X-hydroxy-2-morpholino-4H-chromen-4-ones (X=8, 7, 6, 5; 5a-d), with [(11)C]CH(3)OTf through O-[(11)C]methylation and isolated by a simplified solid-phase extraction (SPE) method using a C-18 Sep-Pak Plus cartridge. The radiochemical yields decay corrected to end of bombardment (EOB), from [(11)C]CO(2), were 40-60%. The specific activity at end of synthesis (EOS) was 185-370 GBq/μmol.
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