SYNTHESIS OF HIGH SPECIFIC ACTIVITY (3,4-[H-3]CYCLOHEXYL)-N-[1(2-BENZO[B]THIENYL)CYCLOHEXYL]PIPERIDINE ([H-3]BTCP) - A SELECTIVE PROBE FOR THE DOPAMINE-REUPTAKE COMPLEX

High specific activity [H-3]BTCP, a radioligand for the dopamine-reuptake complex was synthesized in 7-steps starting with the readily available starting materials, cyclohexane-1,4-dione monoethylene ketal and benzo[b]thiophene; the tritium label was introduced in the final step on the 3- and 4- positions of the cyclohexyl ring by catalytic tritiation of N-[4-(2-benzo[b]thienyl)cyclohexenyl]piperidine to give [H-3]BTCP in 7.3% yield with a specific activity of 29.8 Ci/mmol (51.4% isotopic incorporation).