Synthesis of carbon-11-labeled casimiroin analogues as new potential PET agents for imaging of quinone reductase 2 and aromatase expression in breast cancer

Carbon-11-labeled casimiroin analogues were first designed and synthesized as new potential PET agents for imaging of quinone reductase (QR) 2 and aromatase expression in breast cancer. [11C]casimiroin (6-[11C]methoxy-9-methyl-[1,3]dioxolo[4,5-h]quinolin-8(9H)-one, [11C]11) and its carbon-11-labeled analogues 5,6,8-trimethoxy-1-[11C]methyl-4-methylquinolin-2(1H)-one ([11C]17), 8-methoxy-1-[11C]methyl-4-methylquinolin-2(1H)-one ([11C]21a), 6,8-dimethoxy-1-[11C]methyl-4-methylquinolin-2(1H)-one ([11C]21b), and 5,8-dimethoxy-1-[11C]methyl-4-methylquinolin-2(1H)-one ([11C]21c), were prepared from their corresponding precursors with [11C]methyl triflate ([11C]CH3OTf) under basic conditions (NaH) through either O- or N-[11C]methylation and isolated by semi-preparative HPLC method in 40–50% radiochemical yields decay corrected to end of bombardment (EOB), based on [11C]CO2, and 111–185 GBq/μmol specific activity at the end of synthesis (EOS).