Synthesis of 122 I‐ and 125 I‐labelled meta ‐dimethoxy‐N,N‐dimethyliodophenylisopropylamines

The syntheses of 122 I‐ and 125 I‐labelled 2,4‐dimethoxy‐N,N‐dimethyl‐5‐iodophenylisopropylamine, 3,5‐dimethoxy‐N,N‐dimethyl‐2‐iodophenylisopropylamine and 2,6‐dimethoxy‐N,N‐dimethyl‐3‐iodophenylisopropylamine are described. The speed (3 min, including purification) and yield (45‐85%) obtained in direct iodination procedures utilizing chloramine‐T have allowed the use of the short‐lived positron emitter 122 I (t 1/2 = 3.6 min) in brain blood flow imaging studies. The three appropriate precursors (the meta ‐dimethoxy‐N,N‐dimethylphenylisopropylamines) were prepared from the corresponding phenyl acetone analogues by reductive amination employing dimethylamine and NaCNBH 3 . The ketones were obtained from the appropriate nitrostyrenes through reduction with elemental Fe.