Synthesis of [C-11]Lu 29-066, a 5-HT2 receptor antagonist

Lu 29-066(1-(2-{ 4-[2,5-dimethyl-3 -(4-fluorophenyl)-1H-indol-1 -yl]piperid inl-yl} ethyl)-2-imidazolidinone), a selective antagonist of serotoninergic 5-HT2 receptors; was labelled with carbon-ii. The synthesis of the non-rad ioactive precursor and its reaction with [C-11]phosgene affording [C-11]Lu 29-066 are described. Approximately 1.5 to 2.2 GBq (40-60 mCi) of the radio ligand were obtained with a specific activity ranging from 11 to 18.5 GBq/m u mol (300-500 mCi/mu mol) and analytical HPLC showed a radiochemical purit y over 99%.