Convenient direct NCA electrophilic radioiodination of arenes using Iodo-gen™

We have evaluated Iodo-gen™ (1,3,4,6-tetrachloro-3α-6α-diphenylglycoluril) as an oxidant for the radioiodination of various arenes with hydroxy or methoxy substituents. Radioiodination of selected phenols, namely 4-hydroxyephedrine and N-succinimidyl-3-(4-hydroxyphenyl)propionate (Bolton-Hunter reagent) in aqueous solution at both pH 4 and pH 8 give rise to radiochemical yields of equal-or-greater, slanted80%. Radioiodination of less activated anisole derivatives has been achieved using a homogeneous trifluoroacetic acid-water system. Radiochemical yields between 50 and 80% were obtained. The method is not applicable to anisoles containing strong electron-withdrawing substituents.