The Intriguing Effects of Substituents in the -Phenethyl Moiety of Norhydromorphone: A Bifunctional Opioid from a Set of "Tail Wags Dog" Experiments.

(-)--Phenethyl analogs of optically pure -norhydromorphone were synthesized and pharmacologically evaluated in several in vitro assays (opioid receptor binding, stimulation of [S]GTPγS binding, forskolin-induced cAMP accumulation assay, and MOR-mediated β-arrestin recruitment assays). "Body" and "tail" interactions with opioid receptors (a subset of Portoghese's message-address theory) were used for molecular modeling and simulations, where the "address" can be considered the "body" of the hydromorphone molecule and the "message" delivered by the substituent (tail) on the aromatic ring of the -phenethyl moiety. One compound, N-p-chloro-phenethynorhydromorphone ((7aR,12bS)-3-(4-chlorophenethyl)-9-hydroxy-2,3,4,4a,5,6-hexahydro-1H-4,12-methanobenzofuro[3,2-e]isoquinolin-7(7aH)-one, ), was found to have nanomolar binding affinity at MOR and DOR.