Dopamine/serotonin receptor ligands. 12(1): SAR studies on hexahydro-dibenz[d,g]azecines lead to 4-chloro-7-methyl-5,6,7,8,9,14-hexahydrodibenz[d,g]azecin-3-ol, the first picomolar D5-selective dopamine-receptor antagonist

J Med Chem. 2006 Mar 23;49(6):2110-6. doi: 10.1021/jm051237e.

Abstract

Hydroxylated, methoxylated, and/or chlorinated 7-methyl-5,6,7,8,9,14-hexahydrodibenz[d,g]azecines were generally synthesized out of substituted 2-phenylethylamines and isochromanones by Bischler-Napieralski cyclization of the resulting benzamides to dibenzoquinolizines and the quaternization and cleavage of the central C-N bond under Birch conditions. Chlorination of 2-phenylethylamines was useful for the site direction of cyclization, but chlorine atoms were removed under Birch conditions so that chlorination had to be repeated to get the respective chlorinated dibenz[d,g]azecines. The target compounds were tested for their affinity at the different human-cloned dopamine-receptor subtypes (D1 family, D2 family). Generally, hydroxylation and chlorination of the dibenz-azecines increased affinities significantly. 1-Chloro-2-hydroxy-hexahydro-dibenz[d,g]azecine was a subnanomolar antagonist at both subtype families. 4-Chloro-3-hydroxy-7-methyl-5,6,7,8,9,14-hexahydro-dibenz[d,g]azecine was identified as the most potent and selective dopamine D5 receptor ligand described to date with Ki(D1)=0.83, Ki(D2L)=4.0, Ki(D3)=24.6, Ki(D4)=5.2 nM, and Ki(D5)=57 pM (radioligand binding experiments), respectively.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Calcium / metabolism
  • Cell Line
  • Cricetinae
  • Cricetulus
  • Heterocyclic Compounds, 3-Ring / chemical synthesis*
  • Heterocyclic Compounds, 3-Ring / chemistry
  • Heterocyclic Compounds, 3-Ring / pharmacology
  • Humans
  • Ligands
  • Radioligand Assay
  • Receptors, Dopamine D5 / antagonists & inhibitors*
  • Structure-Activity Relationship

Substances

  • 4-chloro-7-methyl-5,6,7,8,9,14-hexahydrodibenz(d,g)azecin-3-ol
  • Heterocyclic Compounds, 3-Ring
  • Ligands
  • Receptors, Dopamine D5
  • Calcium