Methylation with 11C-methyl iodidehas historically been the preferred strategy towards site selective 11C-radiolabeling of small molecule radiotracers for imaging in Positron Emission Tomography (PET). In the recent years, however, metal-mediated carbonylation has emerged as a viable alternative for 11C-radiolabeling. Several systems for the production and delivery of the radiolabeled carbon monoxide have been reported and applied for the synthesis of simple structures displaying 11C-labeled carbonyl groups. The method serves as an appealing alternative to the radiolabeling of molecules, whereby 11C-methyl- or 18F-labeling is not feasible. Furthermore, the investigation of in vivo radiometabolite distribution is greatly facilitated by the possibility of site selective labeling. The main challenges remaining to further promote the carbonylation strategy as a reliable 11C-labeling method, therefore hinges on expansion of the substrate scope to include more complex pharmaceutical and bioactive molecules.Palladium-aryl oxidative addition complexes serve as excellent reagents for the [11C-carbonyl]- labeling of a selection of relevant PET-tracers. The isotope labeled carbonyl functionalities can be introduced by means of aminocarbonylation employing 11C-carbon monoxide. The method was applied to the generation of structurally challenging motifs, e.g. [11C-carbonyl]-Raclopride, a Dopamine-D2 receptor imaging agent. In general, excellent radiochemical purities are observed with this method, presumably owing to a shorter reaction route, when compared to coupling reactions from the parent aryl halides.

[<sup>11</sup>C-carbonyl] - labeling of positron emission tomography tracers by palladium catalyzed carbonylation with gaseous [<sup>11</sup>C]-carbon monoxide

248th National Meeting (2014)

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[11C-carbonyl] - labeling of positron emission tomography tracers by palladium catalyzed carbonylation with gaseous [11C]-carbon monoxide

[¹¹C-carbonyl] - labeling of positron emission tomography tracers by palladium catalyzed carbonylation with gaseous [¹¹C]-carbon monoxide