313513-80-3Relevant academic research and scientific papers
Conformational studies by dynamic NMR, 77: Stereomutation of the enantiomers of hindered O-substituted oximes
Leardini, Rino,Lunazzi, Lodovico,Mazzanti, Andrea,McNab, Hamish,Nanni, Daniele
, p. 3439 - 3446 (2007/10/03)
As anticipated by Molecular Mechanics calculations, the (E) and (Z) isomers of diaryl ketone oximes containing a bulky substituent (PhS or Ph2N) in the ortho position of the phenyl ring, display different conformational preferences. Whereas the (E) isomers exhibit a plane of symmetry at any accessible temperature, the (Z) isomers exist as a pair of stereolabile enantiomers that were detected by low-temperature NMR spectroscopy in a chiral environment. In a number of O-substituted oximes, the enantiomerisation barriers of the (Z) isomers were determined by monitoring the line shape of the NMR signals of diastereotopic methylene hydrogen atoms as a function of temperature. The four stereoisomers, generated by the combination of the conformational axial chirality with the configurationally stable chirality of a stereogenic centre, have been all detected in a specifically substituted oxime and monitored in an appropriate chiral environment. The NMR results in solution were confirmed by X-ray diffraction measurements in the solid state.
