N. Vasdev, R. Chirakal, G. Schrobilgen
Sep 28, 2001
Citations
0
Influential Citations
7
Citations
Journal
Journal of Fluorine Chemistry
Abstract
Abstract Fluorinated derivatives of l -tyrosine and l -α-methyltyrosine ( l -α-MT) are known to be useful tracers for medical imaging with positron emission tomography. Direct fluorination of l -tyrosine and l -α-MT with [ 18 F ]F 2 in different acidic media show increases in the radio-chemical yield of the 3-fluoro isomers as the acidity of the reaction medium is increased. Lower radiochemical yields and increased production of the 3,5-difluoro isomers of the tyrosine derivatives resulted when solvent mixtures containing BF 3 added to anhydrous HF (aHF) were used. Lower yields in BF 3 /aHF have been studied by use of low-temperature (−70°C) 1 H and 13 C NMR spectroscopy of l -α-MT, which showed deactivation of the aromatic ring in BF 3 /aHF. Improved isocratic preparative and analytical HPLC methods for the separation of the fluorinated tyrosine derivatives were also developed. All compounds synthesized in this study were characterized by NMR spectroscopy and mass spectrometry.