SYNTHESIS OF ODOPHENYL))METHOXYETHYL]-1-PIPERIDINE-3-CARBOXYLIC ACID,[I-125] CIPCA - A POTENTIAL RADIOTRACER FOR GABA UPTAKE SITES

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