Synthesis of a dopamine uptake inhibitor for PET studies : 1-[1-(2-benzo(b)thiophenyl)cyclohexyl]-4-(2-[18F]fluoroethyl) piperazine

The BTCP derivative 1-11-(2-benzo[b]thiophenyl) cyclohexyl]-4-(2-hydroxyethyl) piperazine 2 showed, in vitro, high affinity and selectivity for the Dopamine transporter. In order to evaluate the potential of such a compound as an imaging tool for studying the dopaminergic system by Positron Emission Tomography (PET) the cold fluoroethyl BTCP piperazine 6 was synthesized. After checking the biological activity of the cold compound 6, the [ 18 F] analogue 7 was synthesized. The radiosynthesis was carried out by the nucleophilic substitution of 1-[1-(2-benzo[b]thiophenyl) cyclohexyl]-4-(2-chloroethyl) piperazine 5 with cyclotron-produced n.c.a. 18 F - , obtained by the (p,n) reaction on 18 O enriched water.