Discovery of an Opioid κ Receptor Selective Pure Antagonist from a Library of N-Substituted 4β-Methyl-5-(3-hydroxyphenyl)morphans

A library of compounds biased toward opioid receptor antagonist activity was prepared by incorporating N-phenylpropyl-4beta-methyl-5-(3-hydroxyphenyl)morphans as the core scaffold using simultaneous solution phase synthetic methodology. From this library, N-phenylpropyl-4beta-methyl-5-(3-hydroxyphenyl)-7alpha-[3-(1-piperidinyl)propanamido]morphan [(-)-3b] was identified as the first potent and selective kappa opioid receptor antagonist from the 5-phenylmorphan class of opioids.