TY - JOUR ID - 2325 TI - Conformational and configurational behaviour of κ-agonistic 3,7-diazabicyclo[3.3.1]nonan-9-ones—synthesis, nuclear magnetic resonance studies and semiempirical PM3 calculations JO - J. Chem. Soc., Perkin Trans. 2 PY - 1999 SP - 1827-1834 AU - Siener, T. AU - Holzgrabe, U. AU - Drosihn, S. AU - Brandt, W. AU - VL - 1999 UR - DO - 10.1039/A806641H AB - 2,4-Diaryl substituted 3,7-diazabicyclo[3.3.1]nonan-9-one 1,5-diesters were found to have a high affinity for κ-opioid receptors. To develop highly potent analgesics, the purpose of this study was the synthesis and the structural characterisation of the novel 2,4-bis(4-nitrophenyl), 2,4-bis(3-nitrophenyl), 2,4-bis(4-quinolyl), 2,4-bis(2-quinolyl), 2,4-bis(1-naphthyl) and 2,4-bis(2-naphthyl) substituted 3,7-diazabicyclo[3.3.1]nonan-9-one 1,5-diesters by means of NMR spectroscopy and molecular modelling. It could be proved that several derivatives undergo trans–cis-isomerisation of the aromatic rings linked to the rigid skeleton whereas others show rotational isomerisation. Semiempirical quantum-chemical PM3 calculations were performed to analyse the thermodynamic stability of the isomers as well as the mechanism of the trans–cis- or cis–trans-conversion. A2 - C1 - Bioorganic Chemistry ER -