Radiochemical and NMR spectroscopic investigation of the solvent effect onthe electrophilic elemental fluorination of L-DOPA: synthesis of [F-18]5-fluoro-L-DOPA

Differences in reactivity and selectivity of fluorine in the electrophilic fluorination of 3,4-dihydroxy phenyl-L-alanine (L-DOPA) in different solven ts have been exploited to produce mCi quantities of [F-18]5-fluoro-L-DOPA. Proton and C-13 NMR spectroscopy have been used to show that, while the ori entation of electrophilic fluorination of L-DOPA in weak acids (trifluoroac etic acid, 10% trifluoroacetic acid in glacial acetic acid and formic acid) is influenced by the electron donating OH groups on the ring, the orientat ion of electrophilic fluorination of L-DOPA in strong acids (HF and HF/BF3) is mainly influenced by the side-chain. (C) 1999 Elsevier Science S.A. All rights reserved.