Copper catalyzed radioiodination of 3-iodotyrosine and 4-iodophenyl alanine

Farah, K.; Farouk, N.

doi:10.1002/(sici)1099-1344(199711)39:11<915::aid-jlcr42>3.0.co;2-o

Cited by 5 publications

(2 citation statements)

References 15 publications

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“…No-carrier-added (n.c.a.) synthesis of 4-[*I]iodophenylalanine by copper-catalyzed iodo-debromination has been reported by several groups including that of Samnick (Farah et al, 1997; Samnick et al, 2001). Halodestannylation is the most facile route for radioiodination—the reaction can be conducted under very mild conditions, results in higher radiochemical yields, and the product can be isolated devoid of any carrier.…”

Section: Introductionmentioning

confidence: 99%

An alternative and expedient synthesis of radioiodinated 4-iodophenylalanine

Vaidyanathan

McDougald

Grasfeder

et al. 2011

Applied Radiation and Isotopes

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Radiolabeled amino acids have been used extensively in oncology both as diagnostic and therapeutic agents. In our pursuit to develop radiopharmaceuticals to target breast cancer, we were interested in determining the uptake of radioiodinated 4-iodophenylalanine, among other labeled amino acids, in breast cancer cells. In this work, we have developed an alternative method for the synthesis of this agent. The novel tin precursor, (S)-tert-butyl 2-(tert-butoxycarbonylamino)-3-(4-(tributylstannyl)phenyl)propanoate (3) was synthesized from the known, corresponding iodo derivative. Initially, the labeled 4-iodophenylalanine was synthesized from the above tin precursor in two steps with radiochemical yields of 91.6 ± 2.7% and 83.7 ± 1.7% (n = 5), for the radioiodination (first) and deprotection (second) step, respectively. Subsequently, it was synthesized in a single step with an average radiochemical yield of 94.8 ± 3.4% (n = 5). After incubation with MCF-7 breast cancer cells for 60 min, an uptake up to 49.0 ± 0.7% of the input dose was seen; in comparison, the uptake of [14C]phenylalanine under the same conditions was 55.9 ± 0.5%. Furthermore, the uptake of both tracers was inhibited to a similar degree in a concentration-dependent manner by both unlabeled phenylalanine and 4-iodophenylalanine. With [14C]phenylalaine as the tracer, IC50 values of 1.45 mM and 2.50 mM were obtained for Phe and I-Phe, respectively and these values for [125I]I-Phe inhibition were 1.3 and 1.0 mM. In conclusion, an improved and convenient method for the synthesis of no-carrier-added 4-[*I]phenylalanine was developed and the radiotracer prepared by this route demonstrated an amino-acid transporter-mediated uptake in MCF-7 breast cancer cells in vitro that was comparable to that of [14C]phenylalanine.

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Section: Introductionmentioning

confidence: 99%

An alternative and expedient synthesis of radioiodinated 4-iodophenylalanine

Vaidyanathan

McDougald

Grasfeder

et al. 2011

Applied Radiation and Isotopes

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“…215 Iodine-exchange which was Cu(II)catalysed has also been reported for 3-iodotyrosine and for (4-iodophenyl)alanine, together with activation energies for the exchange. 216 Farah and Farouk have also investigated the optimisation of yield of [I-131]-3-iodotyrosine and two of its derivatives, using NaI and either Chloramine-T or iodogen as the oxidising agent. Good yields were found with both the parent system and its a-methyl derivative (ca.…”

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Radiohalogen incorporation into organic systems

Bolton

2002

Labelled Comp Radiopharmac

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SummaryThis Review reports the more recent applications of radiohalogen labelling in organic compounds. Modern synthetic methods place more emphasis upon substitution at specific sites. Electrophilic substitution, especially at aromatic carbon atoms, involves displacement of halogen or of metals rather than the earlier popular halogen-deprotiation processes. Nucleophilic displacement, at either aliphatic or aromatic sites, has also become widespread since it may be made more selective by the inclusion of appropriate activating groups or suitable displaced groups. Microwave and thermally induced methods are both reported with a critical assessment of the value of each process.

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Evaluation of the reaction parameters and thermodynamics of the iodide-exchange preparation of radioiodinated 15-(p-iodophenyl) pentadecanoic acid by both solid phase and solution methods

Farah

1998

J Label Compd Radiopharm

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Two isotopic exchange procedures are described for the labelling of 15‐(p‐iodophenyl) pentadecanoic acid with radioiodine in the presence of ammonium sulphate and cuprous chloride as catalysts. The methods afforded regioselective and high specific activity products with radiochemical yields of 92% and 85% within relatively short reaction times. High pressure liquid chromatographic separation resulted in high radiochemically pure product suitable for medical application. Kinetic studies revealed second order iodine–iodine exchange reactions with an activation energy of 13.7 Kcal/mole for the solid state radioiodination with ammonium sulphate and 15.3 Kcal/mole for the copper catalyzed exchange reaction. © 1998 John Wiley & Sons, Ltd.

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Copper catalyzed radioiodination of 3-iodotyrosine and 4-iodophenyl alanine

Cited by 5 publications

References 15 publications

An alternative and expedient synthesis of radioiodinated 4-iodophenylalanine

An alternative and expedient synthesis of radioiodinated 4-iodophenylalanine

Radiohalogen incorporation into organic systems

Evaluation of the reaction parameters and thermodynamics of the iodide-exchange preparation of radioiodinated 15-(p-iodophenyl) pentadecanoic acid by both solid phase and solution methods

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