Radical-Mediated Carboxylation of Alkyl iodides with [11C]Carbon Monoxide in Solvent Mixtures
2005 (English)In: J. Org. Chem, no 70, 2244-2249 p.Article in journal (Refereed) Published
[carboxyl-11C]Carboxylic acids were prepared from alkyl iodides via photoinitiated radical reactions using 10-8 mol of [11C]carbon monoxide in binary and ternary homogeneous solvent mixtures. Short-(isobutyric), medium-, and long-chain saturated fatty acids (heptadecanoic) were labeled with isolated decay-corrected radiochemical yields ranging from 55% to 70% in 5-7 min reactions. The conversion of [11C]carbon monoxide to products reached 80-90%. To obtain good yields in the reactions performed in water- acetonitrile and water-THF mixtures, the addition of tetrabut-ylammonium hydroxide or potassium hydroxide was essential. The carboxylation was efficient for primary and secondary alkyl iodides. The carboxylation of tertiary iodides was feasible for 1-iodoadamantane but not for tert-butyl iodide. The dependence of the radiochemical yields on reaction time, photoirradiation conditions, and organic and inorganic additives was studied. The method provides a one-step route to [carboxyl-11C]carboxylic acids; traditional methods, in contrast, would require several steps. For example, using the devised reaction, conditions, 3.19 GBq of purified [1-11C]1,10-decanedicarboxylic acid (specific radioactivity 188 GBq/umol) was obtained within 35 min of the end of 10 uAh bombardment. (1-13C)4-Phenylbutyric acid was synthesized using (13C)-carbon monoxide for identifying the labelling position with 1H and 13C NMR.
Place, publisher, year, edition, pages
2005. no 70, 2244-2249 p.
IdentifiersURN: urn:nbn:se:uu:diva-69985DOI: doi:10.1021/jo047806s CCCOAI: oai:DiVA.org:uu-69985DiVA: diva2:97896