Enantioselective synthesis of 6-[fluorine-18]-fluoro-L-dopa from no-carrier-added fluorine-18-fluoride.
METHODS
A trimethylammonium veratraldehyde triflate was synthesized and used as a precursor for the asymmetric synthesis of 6-[18F]fluoro-L-dopa.


RESULTS
Its nucleophilic fluorination with 18F-fluoride produced by the 18O(p,n)18F nuclear reaction on enriched 18O-water led to the corresponding no-carrier-added [18F]fluoroveratraldehyde (45 +/- 5% EOB). Diiodosilane was used to prepare the corresponding [18F]fluorobenzyl iodide (36.5 +/- 5.3% EOB). Akylation of (S)-1-tert-boc-2-tert-butyl-3-methyl-4-imidazolidinone with this electrophilic agent, hydrolysis and purification by preparative high-pressure liquid chromatography made 6-[18F]fluoro-L-dopa ready for human injection, in a 23% +/- 6% decay-corrected radiochemical yield. The enantiomeric purity and the specific activity were above 96% and 1 Ci/mumole respectively.


CONCLUSIONS
Through this procedure, starting from 250 mCi of 18F-fluoride, multimillicurie amounts (32 +/- 8.5 mCi) of no-carrier-added 6-[18F]fluoro-L-dopa are now available at the end of synthesis (90 min) with a good radiochemical purity (more than 98%).
Lemaire
C
C
Cyclotron Research Center, Liège University, Belgium.
Damhaut
P
P
Plenevaux
A
A
Comar
D
D
D002851:Chromatography, High Pressure Liquid; D004295:Dihydroxyphenylalanine / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000302:isolation & purification; D005462:Fluorine Radioisotopes; D007202:Indicators and Reagents; D007553:Isotope Labeling / Q000379:methods; D015394:Molecular Structure
D005462:Fluorine Radioisotopes; D007202:Indicators and Reagents; C043437:fluorodopa F 18; D004295:Dihydroxyphenylalanine