Synthesis of [2‐{(4‐chlorophenyl) (4‐[125I]iodophenyl)} methoxyethyl]‐1‐piperidine‐3‐carboxylic acid, [125I]CIPCA: A potential radiotracer for GABA uptake sites

The synthesis of racemic [2-{(4-Chlorophenyl)(4-iodophenyl)} methoxyethyl]-1-piperidine-3-carboxylic acid, (CIPCA) and its radioiodinated analog [ 125 I]CIPCA is described. CIPCA was synthesized from 4-iodobenzoyl chloride in five steps in 16% overall yield. Ammonium sulfate catalyzed solid-state isotopic exchange of CIPCA with Na 125 I provided [ 125 I]CIPCA in 34% isolated radiochemical yield at a specific activity of 118 Ci/mmol. [ 125 I]CIPCA demonstrated moderate brain extraction and good in vivo radiostability in preliminary biodistribution studies conducted in CD-1 mice. [ 125 I]CIPCA is a potentially useful radiotracer for study of the GABA uptake system