[en] The NCA asymmetric synthesis of L-6-[F-18]fluorodopa starting from (1R,2R,5R)-[(+)-2-hydroxypinanyl-3-idene]glycine t-butyl ester as chiral agent has been developed. After F-18-fluorination of the two commercially available aldehydes either 6-nitroveratraldehyde or 6-nitropiperonal, the required alkylating [F-18]fluorobenzyl bromide derivative can be easily prepared by treatment with NaBH4 followed by SOBr2. Alkylation of the Schiff base was carried out with the lithium salt of 2,2,6,6-tetramethylpiperidine as base in anhydrous THF at -78-degrees-C. Following hydrolysis of the protecting groups with hydroxylamine and Hl, the L-amino acid was obtained in 75% L form (ee 50%) with a 10% decay corrected (120 min) radiochemical yield.
Centre de Recherches du Cyclotron - CRC
Fonds de la Recherche Scientifique (Communauté française de Belgique) - F.R.S.-FNRS