Tritium labelled (±)‐7‐chloro‐8‐hydroxy‐3‐methyl‐1‐phenyl‐2,3,4,5‐tetrahydro‐1H‐3‐benzazepine (SCH23390)

The antipsychotic drug, SCH23390, once thought to be the first selective D₁ dopamine antagonist, is now believed to possibly produce its profound antidopaminergic and antipsychotic effects via molecular sites that involve recognition characteristics similar to, or are a subpopulation of the D₁ dopamine receptors. Tritium labelled SCH23390 has been prepared in our laboratory by palladium catalyezed reductive aryl debromination of a brominated precursor with carrier free tritium gas in THF. The product is labelled in the 9‐position of the benzazepine ring and a specific activity of 5.6 Ci/mmole was obtained.