Precursor synthesis and radiolabelling of [11C]ADAM:: A potential radioligand for the serotonin transporter exploration by PET

The serotoninergic system is involved in a variety of neurological and psychiatric disorders. Exploration of the serotonin transporters (5-HTT) in living human brain by PET would be of great value for better understanding, diagnosis and therapeutic follow up of these diseases. In order to obtain a selective radioligand to explore the 5-HTT by PET we report the synthesis of [C-11]N,N-dimethyl-2-(2-amino-4-iodophenylthio)-benzylamine ([C-11]ADAM). The precursor for labelling N-demethyl ADAM, was obtained in five steps using 2,5-dibromonitrobenzene and 2-thio-N-methylbenzamide as starting material. [C-11]ADAM was synthesised by N-alkylation of the precursor using [C-11]methyl iodide in DMF. The incorporation yield of [C-11]methyl iodide was in the range of 50 to 70%. Finally [C-11]ADAM was obtained in 30 minutes synthesis time including HPLC and with a radiochemical purity better than 99%.