A direct fixation of CO 2 for isotopic labelling of hydantoins using iodine-phosphine charge transfer complexes.

Herein, we report a method for the isotopic labelling of hydantoins directly from CO 2 by means of trimethyl-λ 5 -phosphine diiodide mediated carbonyl insertion. The method is suitable for 13 C-labelling of diverse substrates and was implementated for 11 C-labelling in PET-imaging facilities for the synthesis of radiotracers. Isolated yields of 90% and radiochemical yields of 89% were achieved for hydantoin containing drug candidates in formulation within 30 min with high molar activity (>400 MBq nmol -1 ).