SYNTHESIS, NMR AND X-RAY STRUCTURAL INVESTIGATION OF 5-METHOXY-9,10-DIHYDRO-4-AZAPHENANTHRENE N-OXIDE AND ITS FREE AMINE

Three-dimensional structures of the title compounds (1 and 2, respecti vely) were investigated by magnetic-resonance spectroscopy and single- crystal X-ray diffraction. Each of the compounds was found to exist in the form of a pair of conformational enantiomers due to the nonplanar arrangement of both aromatic rings, which gave the angles between the ir planes of 41.5(5)degrees and 39.0(5)degrees for molecules A and B o f 1 and 27.4(1)degrees for 2. The enantiomers of 1 revealed significan t stability both in solution (in the NMR time scale) and in solid stat e, while in the case of the free amine 2 temperature dependent H-1 NMR spectra show fast interconversion of the rotamers that is only frozen out in the crystal structure.