title: Absolute stereochemistry and dopaminergic activity of enantiomers of 2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine.
abstract: Resolution of the unique dopamine receptor agonist 2,3,4,5-tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine (1) was achieved by a stereospecific multistep conversion of the readily separated enantiomers of its O,O,N-trimethylated precursor 2. The absolute stereochemistry of the antipodes of 2-MeI was determined by single-crystal X-ray diffractometric analysis, thus permitting assignment of the configuration of stereospecifically related 1, as well as that of the synthetic intermediates. High-performance liquid chromatography of diastereoisomeric derivatives was utilized to determine the enantiomeric excess of the R (greater than 97%) and S (greater than 89%) isomers of 1. Examination of the isomers in several in vitro and in vivo tests for both central and peripheral dopaminergic activity revealed that activity resided almost exclusively in the R isomer. The results suggest that the properly oriented 1-phenyl substituent of 1 is important for dopamine-like activity; it may contribute to receptor binding by interaction with a chirally defined accessory site. Configurational and conformational requirements for receptor binding of 1 are considered in relationship to previously described dopaminergic agents. These studies, in accord with previous suggestions, indicate that (R)-1 interacts with dopamine receptors in a conformation in which the catecholic hydroxyls and basic nitrogen are at least nearly maximally separated.
mesh_terms: D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D001552:Benzazepines / Q000138:chemical synthesis* / Q000494:pharmacology; D001667:Binding, Competitive; D055598:Chemical Phenomena; D002621:Chemistry; D004285:Dogs; D066298:In Vitro Techniques; D008297:Male; D008968:Molecular Conformation; D051381:Rats; D011954:Receptors, Dopamine / Q000187:drug effects*; D012079:Renal Circulation / Q000187:drug effects; D013134:Spiperone / Q000378:metabolism; D013237:Stereoisomerism; D013378:Substantia Nigra / Q000502:physiology; D014665:Vasodilator Agents
chemical_list: D001552:Benzazepines; D011954:Receptors, Dopamine; D014665:Vasodilator Agents; D013134:Spiperone; D015647:2,3,4,5-Tetrahydro-7,8-dihydroxy-1-phenyl-1H-3-benzazepine; D000262:Adenylyl Cyclases