A direct fixation of CO2 for isotopic labelling of hydantoins using iodine–phosphine charge transfer complexes

Abstract

Herein, we report a method for the isotopic labelling of hydantoins directly from CO₂ by means of trimethyl-λ⁵-phosphine diiodide mediated carbonyl insertion. The method is suitable for ¹³C-labelling of diverse substrates and was implementated for ¹¹C-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).