Synthesis of [11C]FEDAA1106 as a new PET imaging probe of peripheral benzodiazepine receptor expression

Peripheral benzodiazepine receptor (PBR) is associated with neuroinflammation and tumor progression. [11C]DAA1106 and [18F]FEDAA1106 are two promising radioligands for positron emission tomography (PET) imaging of PBR. This study was designed to develop a new radiolabeled analog of [11C]DAA1106 and [18F]FEDAA1106, [11C]FEDAA1106, for PET imaging of PBR expression in brain and cancer. Precursor N-(5-fluoro-2-phenoxyphenyl)-N-(2-(2-fluoroethoxy)-5-hydroxybenzyl)acetamide (9) was synthesized in multiple steps with moderate to high chemical yields. Precursor 9 was labeled by [11C]CH3OTf and isolated by high pressure liquid chromatography (HPLC) purification to provide target radioligand N-(5-fluoro-2-phenoxyphenyl)-N-(2-(2-fluoroethoxy)-5-[11C]methoxybenzyl)acetamide ([11C]FEDAA1106, [11C]10) in 60–70% radiochemical yields, decay corrected to end of bombardment (EOB), based on [11C]CO2. The specific activity of the target radiotracer [11C]10 was in a range of 111–185 GBq/μmol at the end of synthesis (EOS).

This paper reports the synthesis of a new radioligand, [11C]FEDAA1106, for PET imaging of peripheral benzodiazepine receptor expression in brain and tumor.Figure optionsDownload as PowerPoint slide