title: Synthesis, X-ray crystallographic determination, and opioid activity of erythro-5-methylmethadone enantiomers. Evidence which suggests that mu and delta opioid receptors possess different stereochemical requirements.
abstract: Enantiomers of erythro-5-methylmethadone (3) were synthesized from optical antipodes of erythro-3-(dimethyl-amino)-2-butanol. X-ray crystallographic analysis of (-)-3 perchlorate revealed that it possesses the 5S,6S absolute configuration. It was found that (-)-3 is substantially more potent than its enantiomer (+)-3 as an opioid agonist in vivo and in vitro. In vitro tests (guinea pig ileal longitudinal muscle and mouse vas deferens preparations) suggest that (-)-3 mediates its effect chiefly through mu opioid receptors. On the other hand, (+)-3 and the more potent enantiomers of methadone, (-)-1, and isomethadone, (-)-2, appear to have less mu-receptor selectivity and interact with a greater fraction of delta receptors than does (-)-3. The fact that the solid-state conformation of (-)-3 differs from that of (-)-1 and (-)-2, which show great similarity in conformational features, suggests that mu and delta receptors have different conformational requirements. The possibility of different modes of interaction with a single opioid receptor population also is discussed.
mesh_terms: D000818:Animals; D055598:Chemical Phenomena; D002621:Chemistry; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D008691:Methadone / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000494:pharmacology; D051379:Mice; D008958:Models, Molecular; D008968:Molecular Conformation; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects; D009294:Narcotics / Q000138:chemical synthesis*; D011957:Receptors, Opioid / Q000187:drug effects*; D017450:Receptors, Opioid, mu; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D014961:X-Ray Diffraction
chemical_list: D009294:Narcotics; D011957:Receptors, Opioid; D017450:Receptors, Opioid, mu; C034073:5-methylmethadone; D008691:Methadone