Opioid binding and in vitro profiles of a series of 4-hdroxy-3-methoxyindolomorphinans. Transformation of a delta-selective ligand into a high affinity kappa-selective ligand by introduction of a 5,14-substituted bridge.

ABSTRACT

In investigation of the effects of 14-substitution in the indolomorphinan series of delta-selective opioid ligands, 5,14-bridged indolomorphinans (4) were prepared from the equivalent dihydrothebainone acid-catalyzed rearrangement products of the dihydrothevinols. Though the new ligands generally had low affinity for opioid receptors and no delta-selectivity, 4b had high kappa-affinity and substantial selectivity which was also seen in the precursor morphinanone (3b). This indicates that the methylbenzylidene-substituted bridge in these compounds is a dominant kappa-opioid receptor binding motif.