Sulfur [18F]Fluoride Exchange Click Chemistry Enabled Ultrafast Late-Stage Radiosynthesis

The lack of efficient [F-18]fluorination processes and target-specific organofluorine chemotypes remains the major challenge of fluorine-18 positron emission tomography (PET). We report here an ultrafast isotopic exchange method for the radiosynthesis of novel PET agent aryl [F-18]fluorosulfate enabled by the emerging sulfur fluoride exchange (SuFEx) click chemistry. The method has been applied to the fully automated F-18-radiolabeling of 25 structurally and functionally diverse aryl fluorosulfates with excellent radiochemical yield (83-100%, median 98%) and high molar activity (280 GBq mu mol(-1)) at room temperature in 30 s. The purification of radiotracers requires no time-consuming HPLC but rather a simple cartridge filtration. We further demonstrate the imaging application of a rationally designed poly(ADP-ribose) polymerase 1 (PARP1)-targeting aryl [F-18]fluorosulfate by probing subcutaneous tumors in vivo.

Automated summary

Efficient and target-specific fluorination processes remain the main challenge in fluorine-18 PET, but a new ultrafast isotopic exchange method has been developed for the synthesis of novel PET agent aryl [F-18]fluorosulfate. This method enables automated F-18-radiolabeling of diverse aryl fluorosulfates with high yield and molar activity in just 30 seconds at room temperature, without the need for time-consuming HPLC purification steps. Additionally, the imaging application of a designed PARP1-targeting aryl [F-18]fluorosulfate has been successfully demonstrated in vivo.