Preparation of tritium labelled benzamide dopamine‐D₂ lignads at high specific activity

A method for the preparation of tritium labelled potential neuroleptics of the benzamide class possessing highly potent dopamine‐ D 2 binding properties, is described. The pyrrolidine moiety of the molecule is labelled with tritium by hydrogenation, to a specific activity of up to 58 Ci/mmol and subsequently reacted with an acid chloride. The specificity of the label is confirmed by 3 H‐NMR.