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
Radiochemical and NMR spectroscopic investigation of the solvent effect on the electrophilic elemental fluorination of L-DOPA: synthesis of []5-fluoro-L-DOPA
作者:Raman Chirakal、Neil Vasdev、Gary J. Schrobilgen、Claude Nahmias
DOI:10.1016/s0022-1139(99)00123-2
日期:1999.10
Differences in reactivity and selectivity of fluorine in the electrophilicfluorination of 3,4-dihydroxy phenyl-L-alanine (L-DOPA) in different solvents have been exploited to produce mCi quantities of []5-fluoro-L-DOPA. Proton and spectroscopy have been used to show that, while the orientation of electrophilicfluorination of L-DOPA in weak acids (trifluoroacetic acid, 10% trifluoroacetic acid in
Remarkable differences in the human in vivo behaviour of each of the three [F-18]-labelled ring fluorinated isomers of L-dihydroxyphenylalanine (L-DOPA) are presented. Unlike [F-18]2-fluoro-L-DOPA, which did not appear to cross the blood brain barrier, [F-18]5-fiuoro-L-DOPA appears to be taken up and cleared from the cerebellum and the striata. In contrast with the 2- and 5-fluoro isomers of L-DOPA, radioactivity derived after injection of [F-18]6-fluoro-L-DOPA is specifically retained in the striata. The present study is the first direct comparison of the time course and distribution of radioactivity in the human brain after intravenous injections of [F-18]2-, [F-18]5- and [(18)]F6-fluoro-L-DOPA. (C) 2002 Elsevier Science B.V. All rights reserved.