6‐[123I]Iodo‐2‐[[4‐(2‐methoxyphenyl) piperazin‐1‐yl]methyl]imidazo[1,2‐a]pyridine as potential SPECT agent for imaging dopamine D4 receptor: synthesis and in vivo evaluation in a nonhuman primate

The dopamine D₄ receptor subtype has drawn considerable attention due to its potential implication in schizophrenia and erectile dysfunction. 6‐[¹²³I]Iodo‐2‐[[4‐(2‐methoxyphenyl)piperazin‐1‐yl]methyl]imidazo[1,2‐a]pyridine [¹²³I]‐1, a potent and selective new dopamine D₄ agonist, was synthesized by classical iododestannylation using sodium [¹²³I]iodide and chloramine‐T. Radiolabeling yield varied from 34 to 38% with a radiochemical purity exceeding 99%. Despite a good in vitro profile, in vivo evaluation of this radioligand in baboon showed no brain uptake after i.v. injection. Copyright © 2008 John Wiley & Sons, Ltd.