Synthesis of Aliphatic [carbonyl‐11C]Esters Using [11C]Carbon Monoxide

Abstract

AbstractAliphatic esters were labelled with a short‐lived radionuclide, 11C with t½ = 20.3 min, at the carbonyl position using [11C]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 tert‐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/μmol within approximately 25 min of the production of [11C]carbon monoxide. Two (13C)substituted esters were synthesised using this method to verify the labelling position. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)