Castillo Meleán J, Ermert J, Coenen HH. A three-step radiosynthesis of 6-[(18) F]fluoro-L-meta-tyrosine starting with [(18) F]fluoride.
J Labelled Comp Radiopharm 2015;
58:133-40. [PMID:
25809710 DOI:
10.1002/jlcr.3273]
[Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2014] [Revised: 01/15/2015] [Accepted: 01/15/2015] [Indexed: 11/07/2022]
Abstract
The radiosynthesis of 6-[(18) F]fluoro-L-m-tyrosine has generally been performed by electrophilic radiofluorination, which exhibits several drawbacks. In the present work, a three-step radiochemical synthesis is described starting from [(18) F]fluoride. The synthetic sequence, including isotopic exchange, Baeyer-Villiger oxidation, and hydrolysis, were examined comparing four fluorobenzophenone derivatives as labeling precursors. Of those, (2S,5S)-tert-butyl 5-(5-acetyl-2-fluorobenzyl)-2-tert-butyl-3-methyl-4-oxoimidazolidine-1-carboxylate (1a) and (2S,5S)-tert-butyl 2-tert-butyl-5-(2-fluoro-5-(2,2,2-trifluoroacetyl)benzyl)-3-methyl-4-oxoimidazolidine-1-carboxylate (1d) proved to be the most suitable ones. 6-[(18) F]Fluoro-L-m-tyrosine was obtained with overall radiochemical yields of 8-13% and an enantiomeric excess of up to 98%.
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