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

Abstract

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(9 H)-one, [ 11C] 11) and its carbon-11-labeled analogues 5,6,8-trimethoxy-1-[ 11C]methyl-4-methylquinolin-2(1 H)-one ([ 11C] 17), 8-methoxy-1-[ 11C]methyl-4-methylquinolin-2(1 H)-one ([ 11C] 21a), 6,8-dimethoxy-1-[ 11C]methyl-4-methylquinolin-2(1 H)-one ([ 11C] 21b), and 5,8-dimethoxy-1-[ 11C]methyl-4-methylquinolin-2(1 H)-one ([ 11C] 21c), were prepared from their corresponding precursors with [ 11C]methyl triflate ([ 11C]CH 3OTf) 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]CO 2, and 111–185 GBq/μmol specific activity at the end of synthesis (EOS).