title: Structure-affinity-relationship study of bicyclic sigma receptor ligands.
abstract: It was postulated that N(6)-allyl bicyclic derivatives 1 bind with N-8 at the proton donor site of the sigma(1) receptor and that a substituent in 2-position of the bicyclic framework 1 results in unfavorable steric interactions with the sigma(1) receptor protein. In order to support this hypothesis both enantiomers of 6-allyl-8-(4-methoxybenzyl)-6,8-diazabi-cyclo[3.2.2]non-2-ene (2/ent-2) and 6-benzyl-8-(4-methoxybenzyl)-6,8-diazabicyclo[3.2.2]nonane 3/ent-3 were synthesized stereoselectively. The (S,S)-configured enantiomers 2 and 3 are the eutomers with eudismic ratios of 31 and 4.8, respectively. Therefore, these enantiomers are used in the sigma(1) pharmacophore model. The N(6)-allyl derivative 2 with a double bond in the three carbon bridge adopts the orientation 2c with N-8 interacting with the sigma(1) receptor proton donor site (Fig. 2) resulting in slightly reduced steric interactions of the small double bond in 2/3-position. The almost C(2)-symmetric benzyl derivative 3 can adopt both orientations 2c and 2d at the sigma (1) receptor (N-8 or N-6 interacts with the sigma (1) receptor proton donor site) resulting in subnanomolar sigma(1) receptor affinity (K(i) = 0.91 nM).
authors.affiliation: Institut für Pharmazeutische und Medizinische Chemie der Universität Münster, Hittorfstrasse 58-62, D-48149 Münster, Germany.
authors.forename: Ralph
authors.initials: R
authors.lastname: Holl
authors.forename: Christian
authors.initials: C
authors.lastname: Geiger
authors.forename: Masakazu
authors.initials: M
authors.lastname: Nambo
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Itami
authors.forename: Dirk
authors.initials: D
authors.lastname: Schepmann
authors.forename: Bernhard
authors.initials: B
authors.lastname: Wünsch
mesh_terms: D000818:Animals; D001643:Bridged Bicyclo Compounds / Q000138:chemical synthesis / Q000378:metabolism / Q000494:pharmacology*; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D008024:Ligands; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D011869:Radioligand Assay; D051381:Rats; D017480:Receptors, sigma / Q000187:drug effects* / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D000097605:Sigma-1 Receptor
chemical_list: D001643:Bridged Bicyclo Compounds; D007202:Indicators and Reagents; D008024:Ligands; D017480:Receptors, sigma; D000097605:Sigma-1 Receptor; C106107:sigma-2 receptor