11C‐Labeled ketanserin: A selective serotonin S2 antagonist

Abstract

AbstractA selective serotonin S2 receptor antagonist, ketanserin, was prepared labeled with carbon‐11 by a rapid synthesis which uses no‐carrier‐added phosgene as the labeled precursor. The ring‐closure reaction in toluene of phosgene with the substituted 2‐aminobenzamide precursor gives a nearly quantitative yield of ketanserin. The 30 min procedure yields 150 mCi of HPLC purified ketanserin at a specific activity of 250 mCi/μ mol. The product's tissue distribution in mice shows a brain uptake and cerebrum to cerebellum ratio that encourages further in vivo receptor binding studies.