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Reaction of [ 18 F]4‐fluorobenzenediazonium cations with cysteine or the cysteinyl group: preparation of 18 F‐labeled S‐aryl‐cysteine and a radiolabeled peptide
Author(s) -
Patt J. T.,
Patt M.
Publication year - 2002
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.635
Subject(s) - chemistry , tripeptide , yield (engineering) , nitrobenzene , dinitrobenzene , high performance liquid chromatography , methanol , aryl , cysteine , acetonitrile , fluoride , nuclear chemistry , medicinal chemistry , peptide , chromatography , catalysis , inorganic chemistry , organic chemistry , biochemistry , materials science , alkyl , metallurgy , enzyme
A reaction route for the preparation of no‐carrier‐added (n.c.a.) [ 18 F]S‐4‐fluorophenylcysteine 7 via the [ 18 F]‐4‐fluorobenzenediazonium ion 4 is described. The key step in this radiosynthesis is the reaction of 4 with cysteine forming [ 18 F]4‐fluorophenyldiazocysteine 6 , which is subsequently converted into 7 by irradiation with 366 nm light. 4 was synthesized by reacting 1,4‐dinitrobenzene 1 with [ 18 F]‐fluoride in acetonitrile in a PEEK‐capillary in a microwave oven. After dilution of the reaction mixture with methanol, the resulting [ 18 F]4‐fluoro‐1‐nitrobenzene 2 was submitted to reduction by means of H 2 with Pd on C catalyst. The resulting [ 18 F]4‐fluoroaniline 3 was purified by HPLC and diazotized to 4 . The preparation of 4 was optimized with regard to yield and purity. The radiochemical yield of 6 was >90% (based on 3 ) while after UV irradiation and HPLC purification 45% of 7 (based on 3 ) was obtained (yields corrected for decay). The suitability of this method for labeling peptides with fluorine‐18 was demonstrated by application to the tripeptide, glutathione (GSH; γ‐L‐glutamyl‐L‐cysteinyglycine) 8 . Copyright © 2002 John Wiley & Sons, Ltd.