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Aliphatic 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 time. 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/umol within approcimately 25 min of the production of [11C]carbon monoxide. Two (13C]substituted esters were synthesised using this method to verify the labelling position.