Labeling of amino acids with carbon-11 and fluorine-18 for PET.

in Journal of Nuclear Biology and Medicine (Turin, Italy : 1991) (1993), 37

Asymmetric synthesis of n.c.a. L-[2-11C]-4-chlorophenylalanine.

in Journal of Labelled Compounds & Radiopharmaceuticals (1993), 32

NUCLEOPHILIC ENANTIOSELECTIVE SYNTHESIS OF 6-[F-18]FLUORO-L-DOPA VIA 2 CHIRAL AUXILIARIES

in Applied Radiation & Isotopes (1993), 44(4), 737-744

Asymmetric nucleophilic synthesis of 6-[F-18]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 ... [more ▼]

Asymmetric nucleophilic synthesis of 6-[F-18]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 [F-18]fluoride as fluorinating agent and regioselective nucleophilic substitution of commercially available 6-nitroveratraldehyde. The [F-18]fluorobenzaldehyde thus obtained was easily converted to the corresponding 2-[F-18]fluoro-4,5-dimethoxybenzyl bromide. This alkylating agent was added to the lithium enolates of 1-(S)-(-)camphor imine of t-butyl glycinate (1) and (S)-(-)- 1 -Boc-2-t-butyl-3-methyl-4-imidazolidinone [(S)- Boc-BMI] (2) 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-[F-19]fluoro-D,L-dopa is also presented. [less ▲]

Feasibility of multumillicurie preparation of L-6-[18F]fluorodopa by nucleophilic asymmetric synthesis.

in European Journal of Nuclear Medicine (1992), 19

2- and 4-[18F]fluorotropapride, two specific D2 receptor ligands for positron emission tomography: N.C.A. syntheses and animal studies.

in International Journal of Radiation Applications and Instrumentation. Part A : Applied Radiation and Isotopes (1992), 43(10), 1265-74

Tropapride, (exo)-2,3-dimethoxy-N-[8-(phenylmethyl)-8- azabicyclo[3.2.1]oct-3-yl]benzamide hydrochloride, has been labeled with fluorine-18 at the 2- and 4-positions of its benzylic group. Two synthetic ... [more ▼]

Tropapride, (exo)-2,3-dimethoxy-N-[8-(phenylmethyl)-8- azabicyclo[3.2.1]oct-3-yl]benzamide hydrochloride, has been labeled with fluorine-18 at the 2- and 4-positions of its benzylic group. Two synthetic pathways were investigated: the first one required the alkylation of the norbenzyl precursor with 2- or 4-[18F]fluorobenzyl bromide (radiochemical yield of 5% EOB, 180 min); the second method consisted of a reductive amination of norbenzyl tropapride with 2- or 4-[18F]fluorobenzaldehyde (20% EOB, 110 min). In both cases, the specific activity was found to be greater than 1 Ci/mumol (EOS). Animal studies in rats showed the percentage of the injected dose localizing in the whole brain to be 0.6 +/- 0.09 and 0.2 +/- 0.03 at 2 h post injection for the para- and the ortho-[18F]fluoro analogs of tropapride respectively. Cerebral biodistribution studies showed at 4 h a striatum uptake of 5 +/- 0.7% of the injected dose per gram of striatum for the para derivative with a low fixation into the frontal cortex and the cerebellum (% ID/g FC < 0.4 and % ID/g Cb < 0.3). The selectivity of 4-[18F]fluorotropapride for D2 dopaminergic sites was demonstrated through blocking experiments with ketanserin, spiperone and halopemide. The saturability was confirmed by the use of variable specific activities. These preliminary results showed that 4-[18F]fluorotropapride can be considered as a potent radiopharmaceutical for the study of the dopaminergic system with PET. [less ▲]

NCA synthesis of an N-w-[18F]fluoroethyl analog of altanserine, a serotonine S2 receptor ligand.

in Journal of Labelled Compounds & Radiopharmaceuticals (1991), 30

NCA asymmetric synthesis of 6-[18F]fluoro-L-dopa.

in Journal of Labelled Compounds & Radiopharmaceuticals (1991), 30

Synthesis and preliminary animal studies of [131I]iodotropapride: a cerebral dopamine D2 receptor ligand.

in Journal of Labelled Compounds & Radiopharmaceuticals (1991), 30

Serotonine-S2 receptor imaging with [18F]altanserin and PET. Results in young normal controls.

in Journal of Nuclear Medicine : Official Publication, Society of Nuclear Medicine (1991), 32

2 and 4-[18F]fluorotropapride, two specific D2 receptor ligand for PET.

in European Journal of Nuclear Medicine (1991), 18