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Radiosynthesis and 'click' conjugation of ethynyl-4-[(18)F]fluorobenzene--an improved [(18)F]synthon for indirect radiolabeling.

Authors :
Roberts MP
Pham TQ
Doan J
Jiang CD
Hambley TW
Greguric I
Fraser BH
Source :
Journal of labelled compounds & radiopharmaceuticals [J Labelled Comp Radiopharm] 2015 Nov-Dec; Vol. 58 (13-14), pp. 473-8. Date of Electronic Publication: 2015 Nov 03.
Publication Year :
2015

Abstract

Reproducible methods for [(18)F]radiolabeling of biological vectors are essential for the development of new [(18)F]radiopharmaceuticals. Molecules such as carbohydrates, peptides and proteins are challenging substrates that often require multi-step indirect radiolabeling methods. With the goal of developing more robust, time saving, and less expensive procedures for indirect [(18)F]radiolabeling of such molecules, our group has synthesized ethynyl-4-[(18)F]fluorobenzene ([(18)F]2, [(18)F]EYFB) in a single step (14 ± 2% non-decay corrected radiochemical yield (ndc RCY)) from a readily synthesized, shelf stable, inexpensive precursor. The alkyne-functionalized synthon [(18)F]2 was then conjugated to two azido-functionalized vector molecules via CuAAC reactions. The first 'proof of principle' conjugation of [(18)F]2 to 1-azido-1-deoxy-β-D-glucopyranoside (3) gave the desired radiolabeled product [(18)F]4 in excellent radiochemical yield (76 ± 4% ndc RCY (11% overall)). As a second example, the conjugation of [(18)F]2 to matrix-metalloproteinase inhibitor (5), which has potential in tumor imaging, gave the radiolabeled product [(18)F]6 in very good radiochemical yield (56 ± 12% ndc RCY (8% overall)). Total preparation time for [(18)F]4 and [(18)F]6 including [(18)F]F(-) drying, two-step reaction (nucleophilic substitution and CuAAC conjugation), two HPLC purifications, and two solid phase extractions did not exceed 70 min. The radiochemical purity of synthon [(18)F]2 and the conjugated products, [(18)F]4 and [(18)F]6, were all greater than 98%. The specific activities of [(18)F]2 and [(18)F]6 were low, 5.97 and 0.17 MBq nmol(-1), respectively.<br /> (Copyright © 2015 John Wiley & Sons, Ltd.)

Details

Language :
English
ISSN :
1099-1344
Volume :
58
Issue :
13-14
Database :
MEDLINE
Journal :
Journal of labelled compounds & radiopharmaceuticals
Publication Type :
Academic Journal
Accession number :
26526606
Full Text :
https://doi.org/10.1002/jlcr.3354