The enantiomers of N-aryl-2-thioxo-4-oxazolidinones and N-arylrhodanines. Investigation by liquid chromatography, circular dichroism and thermal racemization

Abstract

The enantiomers of the sterically hindered title heterobiaryls 1 and 2 have been investigated for the first time analytically and enriched semi-preparatively by liquid chromatography on triacetyl- and tribenzoylcellulose. The circular dichroism spectra of the enriched enantiomers provide relative configurations which are discussed with respect to the order of chromatographic elution. Barriers to rotation about the C–N bond have been determined (104–121 kJ mol–1) and are rationalized qualitatively by repulsive interactions in a planar transition state traversed upon partial rotation.