[en] Asymmetric nucleophilic synthesis of 6-[¹⁸F]fluoro-L-dopa was investigated in order to reach an enantiomeric excess of close to 100% of the L form of this amino acid. The radiochemical synthesis required [¹⁸F]fluoride as fluorinating agent and regioselective nucleophilic substitution of commercially available 6-nitroveratraldehyde. The [¹⁸F]fluorobenzaldehyde thus obtained was easily converted to the corresponding 2-[¹⁸F]fluoro-4,5-dimethoxybenzyl bromide. This alkylating agent was added to the lithium enolates of 1-(S)-(-)camphor imine of t-butyl glycinate and (S)-(-)-1-Boc-2-t-butyl-3-methyl-4-imidazolidinone [(S)- Boc-BMI] in order to compare the enantiomeric excess of the L form obtained in each case with these two chiral inductors. The L-isomer of fluorodopa was isolated after H1 hydrolysis and HPLC purification in 5-10% radiochemical yield (decay corrected). The overall synthesis time was of 110 min. Through this synthetic pathway, the L-isomer of fluorodopa was obtained in 83% e.e with 1 and 96% e.e with 2 respectively, as determined by chiral HPLC. A practical three step preparative scale synthesis of 6-[¹⁹F]fluoro-D,L-dopa is also presented. (Author)

[en] Owing to the difficulties occurring in the nitroprecursor synthesis of altanserine and regarding to the biological data in the literature of the N-alkylfluorospiperone derivatives compared to those of spiperone, the authors have prepared an N-ω-[¹⁸F]-fluoroethyl analog of this radioligand via alkylation of the thioamide function

[en] 6-¹⁸F-fluoro-L-dopa appears as a fundamental tracer for cerebral PET studies of dopaminergic system in humans. The main synthetic routes so far reported for the preparation of this radiopharmaceutical were based on the electrophilic labeling of precursors such as dopa itself or partially blocked dopa derivatives. As an alternative to the electrophilic routes, the authors have recently developed two different nucleophilic syntheses of this radiotracer. These no-carrier-added methods of preparation of 6-¹⁸F-fluoro-L-dopa are a multi-step synthesis based on the nucleophilic displacement of nitro groups of two commercially available compounds: 6-nitroveratraldehyde and 6-nitropiperonal

[en] The authors have developed a new iodinated radioligand: iodine-131 labelled tropapide. Tropapride, iodotropapride, and bromotropapride are substituted benzamide antagonists which have shown high affinity and selectivity to dopamine receptors. The iodine labelled compound was synthesized by nucleophilic substitution on the corresponding brominated analog. Preliminary animal studies were conducted to evaluate the binding properties of [¹³¹I]iodotropapride as an in vivo dopaminergic tracer. Biodistribution studies in rats are discussed

[en] A simple wet chemical procedure has been developed, optimized, and used for preparation of no-carrier-added selenium-73 in high chemical and radiochemical purities. A recovery procedure for the target material has been developed to allow the use of germanium-70 enriched material. The entire process has been used to prepare L-[⁷³Se]selenomethionine for human study

[en] Short communication

[en] Published in summary form only; 1 reference

[en] N.c.a. (S)-L-([α-¹¹C]methyl)-tryptophan was prepared by treatment at -78^oC of (2S,3aR,8aS)-1,2-bis(-methoxycarbonyl)-1,2,3,3a,8,8a-hexahydropyrrolo [2,3 -b]-indole with lithium diisopropylamide and [¹¹C]CH₃I. After hydrolysis with HI and HPLC purification, the title compound was isolated with a radiochemical yield of 36% (EOB corrected) within 22 min; e.e. was shown >97% (n 20); specific activity was ranging between 0.8 and 1.2Ci (30-45 GBq)/μmol EOB. (Author)

[en] Short communication

[en] The synthesis of no-carrier-added 3-[¹⁸F]fluoroanisole, 2-[¹⁸F]fluoroanisole, [¹⁸F]fluorobenzene and 4-[¹⁸F]fluoroveratrole are reported. The strategy consists of amino-polyether supported nucleophilic substitution with [¹⁸F]F^- on activated nitro aromatic aldehyde precursors followed by decarbonylation using Tris(triphenylphosphine) rhodium (I) chloride. The experimental parameters for this reaction have been studied and optimized with 2-[¹⁸F]fluoro-4-methoxybenzaldehyde and then successfully applied to four other ¹⁸F-fluorinated aromatic aldehydes. The decarbonylation yields obtained were 84±5% (corrected for decay) within 15 min at 150^oC in 1,4-dioxan. (author)