CycloSiFA: The Next Generation of Silicon‐Based Fluoride Acceptors for Positron Emission Tomography (PET)

Abstract

The ring‐opening Si‐fluorination of a variety of azasilole derivatives cyclo‐1‐(iPr2Si)‐4‐X‐C6H3‐2‐CH2NR (4: R = 2,6‐iPr2C6H3, X = H; 4a: R = 2,4,6‐Me3C6H2, X = H; 9: R = 2,6‐iPr2C6H3, X = tBuMe2SiO; 10: R = 2,6‐iPr2C6H3, X = OH; 13: R = 2,6‐iPr2C6H3, X = HCCCH2O; 22: R = 2,6‐iPr2C6H3, X = tBuMe2SiCH2O) with different 19F‐fluoride sources was studied, optimized and the experience gained was used in a translational approach to create a straightforward 18F‐labelling protocol for the azasilole derivatives [18F]6 and [18F]14. The latter constitutes a potential clickable CycloSiFA prosthetic group which might be used in PET tracer development using Cu‐catalysed triazole formation. Based on our findings, CycloSiFA has the potential to become a new entry into non‐canonical labelling methodologies for radioactive PET tracer development.

(SiFA)SeFe: A Hydrophilic Silicon-Based Fluoride Acceptor Enabling Versatile Peptidic Radiohybrid Tracers

“…21−25 Recently, a potential clickable CycloSiFA prosthetic group based on an azasilole five-membered ring scaffold has been reported, which might be used in PET tracer development using Cucatalyzed triazole formation, potentially enabling straightforward linkage to biomolecules on demand. 26 However, the compound is still highly lipophilic and its implementation into radiotracer scaffolds needs to be further demonstrated.…”