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Efficient automated syntheses of high specific activity 6‐[ 18 F ]fluorodopamine using a diaryliodonium salt precursor
Author(s) -
Neumann Kiel D.,
Qin Linlin,
Vāvere Amy L.,
Shen Bin,
Miao Zheng,
Chin Frederick T.,
Shulkin Barry L.,
Snyder Scott E.,
DiMagno Stephen G.
Publication year - 2016
Publication title -
journal of labelled compounds and radiopharmaceuticals
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.432
H-Index - 47
eISSN - 1099-1344
pISSN - 0362-4803
DOI - 10.1002/jlcr.3367
Subject(s) - chemistry , toluene , acetonitrile , salt (chemistry) , fluoride , solvent , pet imaging , nuclear chemistry , radiochemistry , positron emission tomography , organic chemistry , inorganic chemistry , nuclear medicine , medicine
6‐[ 18 F]Fluorodopamine (6‐[ 18 F]F‐DA) is a positron emission tomography radiopharmaceutical used to image sympathetic cardiac innervation and neuroendocrine tumors. Imaging with 6‐[ 18 F]F‐DA is constrained, in part, by the bioactivity and neurotoxicity of 6‐[ 19 F]fluorodopamine. Furthermore, routine access to this radiotracer is limited by the inherent difficulty of incorporation of [ 18 F]fluoride into electron‐rich aromatic substrates. We describe the simple and direct preparation of high specific activity (SA) 6‐[ 18 F]F‐DA from no‐carrier‐added (n.c.a.) [ 18 F]fluoride. Incorporation of n.c.a. [ 18 F]fluoride into a diaryliodonium salt precursor was achieved in 50–75% radiochemical yields (decay corrected to end of bombardment). Synthesis of 6‐[ 18 F]F‐DA on the IBA Synthera® and GE TRACERlab FX‐FN automated platforms gave 6‐[ 18 F]F‐DA in >99% chemical and radiochemical purities after HPLC purification. The final non‐corrected yields of 6‐[ 18 F]F‐DA were 25 ± 4% ( n = 4, 65 min) and 31 ± 6% ( n = 3, 75 min) using the Synthera and TRACERlab modules, respectively. Efficient access to high SA 6‐[ 18 F]F‐DA from a diaryliodonium salt precursor and n.c.a. [ 18 F]fluoride is provided by a relatively subtle change in reaction conditions – replacement of a polar aprotic solvent (acetonitrile) with a relatively nonpolar solvent (toluene) during the critical radiofluorination reaction. Implementation of this process on common radiochemistry platforms should make 6‐[ 18 F]F‐DA readily available to the wider imaging community.