Structural features of diastereomeric oxazolidin-2-ones

Model diastereomeric oxazolidinones containing various substituents at positions 3 and 5 were synthesized. Several individual diastereomers bearing methyl groups at positions 4 and 5 in cis-and trans orientations were isolated. The TLC and ¹H NMR spectroscopic data suggest that diastereomers, particularly those containing the aryl substituent at position 5, are substantially different in the physical and spectral properties. The configurations of some diastereomers were established by X-ray diffraction and NOESY spectroscopy. For these compounds, the reliable assignment of the characteristic ¹H NMR signals of individual groups was made, which provided evidence for the cis or trans orientation of the methyl groups at positions 4 and 5. The scope of the method as applied to the determination of the cis and trans isomers from their ¹H NMR spectra is discussed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 133–139, January, 2007.