Microfluidic reactions using [11C]carbon monoxide solutions for the synthesis of a positron emission tomography radiotracer

Abstract

Microfluidic technology has been used to perform [¹¹C]carbonylation reactions using solutions containing [¹¹C]CO in the form of the complex, copper(I)tris(3,5-dimethylpyrazolyl)borate-[¹¹C]carbonyl (Cu(Tp*)[¹¹C]CO). The synthesis of the model compound [¹¹C]N-benzylbenzamide and the known tracer molecule [¹¹C]trans-N-[5-(2-flurophenyl)-2-pyrimidinyl]-3-oxospiro[5-azaisobenzofurane-1(3H),1′-cyclohexane]-4′-carboxamide ([¹¹C]MK-0233), a ligand for the neuropeptide Y Y5 receptor, have been performed using this technique. Following semi-preparative HPLC purification and reformulation, 1262 ± 113 MBq of [¹¹C]MK-0233 was produced at the end of the synthesis with a specific activity of 100 ± 30 GBq μmol⁻¹ and a >99% radiochemical purity. This corresponds to a decay corrected radiochemical yield of 7.2 ± 0.7%. Using a 3 mL vial as the reaction vessel, and following semi-preparative HPLC purification and reformulation, 1255 ± 392 MBq of [¹¹C]MK-0233 was produced at the end of the synthesis with a specific activity of 100 ± 15 GBq μmol⁻¹ and a >99% radiochemical purity. This corresponds to a decay corrected radiochemical yield of 7.1 ± 2.2%.