Synthesis of carbon-11-labeled tariquidar derivatives as new PET agents for imaging of breast cancer resistance protein (ABCG2)

Carbon-11-labeled tariquidar derivatives were first designed and synthesized as new PET agents for imaging of breast cancer resistance protein. The target tracers were prepared by O-[11C]methylation of their corresponding acid precursors using [11C]CH3OTf under basic conditions and isolated by a simplified solid-phase extraction (SPE) method in 50–60% radiochemical yields based on [11C]CO2 and decay corrected to end of bombardment (EOB). The overall synthesis time from EOB was 15–20 min, the radiochemical purity was >99%, and the specific activity at end of synthesis (EOS) was 111–185 GBq/μmol.