Synthesis of aliphatic [carbonyl-11C]esters using [11C]carbon monoxide

Aliphatic esters were labelled with a short-lived radionuclide, C-11 with t(1/2) = 20.3 min, at the carbonyl position using [C-11]carbon monoxide via rapid (6 min) photoinduced radical-mediated carbonylation reactions. The esters were prepared from primary, secondary, and tertiary alkyl iodides, and various alcohols, including tent-butyl alcohol and phenol. The use of strong bases was necessary to achieve good radiochemical yields in short reaction times. Isolated decay-corrected radiochemical yields were in the range of 40-68%. For example, methyl hydrogen dodecanoate was labelled at the ester carbonyl in 61% isolated decay-corrected radiochemical yield with a specific radioactivity of 158 GBq/mu mol within approximately 25 min of the production of [C-11]carbon monoxide. Two (C-13) substituted esters were synthesised using this method to verify the labelling position. ((c) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005).