Trifluoromethanesulfonic acid, an alternative solvent medium for the direct electrophilic fluorination of DOPA: new syntheses of 6-[18F]fluoro-L-DOPA and 6-[18F]fluoro-D-DOPA

✍ Scribed by Babak Behnam Azad; Raman Chirakal; Gary J. Schrobilgen

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: French
• Weight: 133 KB
• Volume: 50
• Category: Article
• ISSN: 0022-2135
• DOI: 10.1002/jlcr.1454

✦ Synopsis

Previous work from this laboratory has shown that the direct fluorination of 3, 4-dihydroxy-phenyl-lalanine (l-DOPA) in anhydrous HF (aHF) or BF 3 /HF with F 2 is an efficient method for the synthesis of 6-fluoro-l-DOPA. Since then, 18 F-labeled 6-fluoro-l-DOPA ([ 18 F]6-fluoro-l-DOPA) has been used to study presynaptic dopaminergic function in the human brain and to monitor gastrointestinal carcinoid tumors. This work demonstrates that the reactivity and selectivity of F 2 toward l-DOPA in CF 3 SO 3 H is comparable with that in aHF. This new synthetic procedure has led to the production of [ 18 F]fluoro-l-DOPA and [ 18 F]fluoro-D-DOPA isomers in 17 AE 2% radiochemical yields (decay corrected with respect to [ 18 F]F 2 ). The 2-and 6-FDOPA isomers were separated by HPLC and subsequently characterized by 19 F NMR spectroscopy. The corresponding [ 18 F]-FDOPA enantiomers have been obtained in clinically useful quantities by a synthetic approach that avoids the use of aHF.