A novel versatile precursor suitable for 18 F-radiolabeling via "click chemistry"

• Published in: Journal of labelled compounds & radiopharmaceuticals 2017-08, Vol.60 (10), p.466-480
• Main Authors: Lugato, B, Stucchi, S, Ciceri, S, Iannone, M N, Turolla, E A, Giuliano, L, Chinello, C, Todde, S, Ferraboschi, P
• Format: Article
• Language: English
• Subjects: Alkynes - chemistry; Azides - chemistry; Benzyl Alcohol - chemistry; Catalysis; Click Chemistry; Copper - chemistry; Fluorine Radioisotopes - chemistry; Isotope Labeling; Radiopharmaceuticals - chemistry
• ISSN: 0362-4803; 1099-1344
• DOI: 10.1002/jlcr.3529

As an effort to improve F-radiolabeling of biomolecules in method robustness and versatility, we report the synthesis and radiolabeling of a new azido precursor potentially useful for the so-called "click reaction," in particular the ligand-free version of the copper(I)-catalyzed alkyne-azide cycloaddition. The new azido precursor may help to overcome problems sometimes exhibited by most of the currently used analogues, as it is safe to handle and it displays long-term chemical stability, thus facilitating the development of new radiolabeling procedures. Moreover, the formed F-labeled 1,2,3-triazole is potentially metabolically stable and could enhance the in vivo circulation time. The above azido precursor was successfully radiolabeled with F, with 51% radiochemical yield (nondecay-corrected). As a proof of concept, the F-labeled azide was then tested with a suitable alkyne functionalized aminoacid (l-propargylglycine), showing 94% of conversion, and a final radiochemical yield of 27% (>99% radiochemical purity), nondecay-corrected, with a total preparation time of 104 minutes.