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Synthesis of <sup>11</sup>C-labelled Alkyl Iodides : Using Non-thermal Plasma and Palladium-mediated Carbonylation Methods

<p>Compounds labelled with <sup>11</sup>C (<i>β</i><sup>+</sup>, t<sub>1/2</sub> = 20.4 min) are used in positron emission tomography (PET), which is a quantitative non-invasive molecular imaging technique. It utilizes computerized reconstruction methods to produce time-resolved images of the radioactivity distribution in living subjects. </p><p>The feasibility of preparing [<sup>11</sup>C]methyl iodide from [<sup>11</sup>C]methane and iodine via a single pass through a non-thermal plasma reactor was explored. [<sup>11</sup>C]Methyl iodide with a specific radioactivity of 412 ± 32 GBq/µmol was obtained in 13 ± 3% decay-corrected radiochemical yield within 6 min via catalytic hydrogenation of [<sup>11</sup>C]carbon dioxide (24 GBq) and subsequent iodination, induced by electron impact. </p><p>Labelled ethyl-, propyl- and butyl iodide was synthesized, within 15 min, via palladium-mediated carbonylation using [<sup>11</sup>C]carbon monoxide. The carbonylation products, labelled carboxylic acids, esters and aldehydes, were reduced to their corresponding alcohols and converted to alkyl iodides. [1-<sup>11</sup>C]Ethyl iodide was obtained via palladium-mediated carbonylation of methyl iodide with a decay-corrected radiochemical yield of 55 ± 5%. [1-<sup>11</sup>C]Propyl iodide and [1-<sup>11</sup>C]butyl iodide were synthesized via the hydroformylation of ethene and propene with decay-corrected radiochemical yields of 58 ± 4% and 34 ± 2%, respectively. [1-<sup>11</sup>C]Ethyl iodide was obtained with a specific radioactivity of 84 GBq/mmol from 10 GBq of [<sup>11</sup>C]carbon monoxide. [1-<sup>11</sup>C]Propyl iodide was synthesized with a specific radioactivity of 270 GBq/mmol from 12 GBq and [1-<sup>11</sup>C]butyl iodide with 146 GBq/mmol from 8 GBq. </p><p>Palladium-mediated hydroxycarbonylation of acetylene was used in the synthesis of [1-<sup>11</sup>C]acrylic acid. The labelled carboxylic acid was converted to its acid chloride and subsequently treated with amine to yield <i>N-</i>[<i>carbonyl</i>-<sup>11</sup>C]benzylacrylamide. In an alternative method, [<i>carbonyl</i>-<sup>11</sup>C]acrylamides were synthesized in decay-corrected radiochemical yields up to 81% via palladium-mediated carbonylative cross-coupling of vinyl halides and amines. Starting from 10 ± 0.5 GBq of [<sup>11</sup>C]carbon monoxide, <i>N-</i>[<i>carbonyl</i>-<sup>11</sup>C]benzylacrylamide was obtained in 4 min with a specific radioactivity of 330 ± 4 GBq/µmol. </p>

Identiferoai:union.ndltd.org:UPSALLA/oai:DiVA.org:uu-7171
Date January 2006
CreatorsEriksson, Jonas
PublisherUppsala University, Organic Chemistry, Uppsala : Acta Universitatis Upsaliensis
Source SetsDiVA Archive at Upsalla University
LanguageEnglish
Detected LanguageEnglish
TypeDoctoral thesis, comprehensive summary, text
RelationDigital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, 1651-6214 ; 227

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