SYNTHESIS OF [H-3] DIPPA - A POTENT IRREVERSIBLE ANTAGONIST SELECTIVEFOR THE KAPPA-OPIOID RECEPTOR

iocyanatophenyl)-2-(1-pyrrolidinyl)ethyl]acetamide (1, DIPPA) has been previously reported to be an opioid receptor affinity label that prod uces selective and long-lasting kappa opioid receptor antagonism in mi ce. High specific activity [H-3]DIPPA (39.7 Ci/mmol) was prepared by b romination and catalytic tritiation of the amino precursor of DIPPA fo llowed by conversion to the isothiocyanate with thiophosgene.