Self-disproportionation of enantiomers of 3,3,3-trifluorolactic acid amides via sublimation

Preparation of racemic and enantiomerically enriched N-phenyl- and N-benzyl-3,3,3-trifluorolactic acid amides has been developed. These compounds were found to have substantial magnitude of the self-disproportionation of enantiomers (SDE) via sublimation. For example, when N-phenyl-3,3,3-trifluorolactic acid amide of 87% ee was sublimed (12 h) from a Petri dish at 80 °C open to the atmosphere, the enantiomeric excess of the remainder increased to 96% ee. On the other hand, when a sample of the same compound of 67% ee was subjected to SDE via sublimation under the same conditions, the enantiomeric excess has decreased to 18% ee. These preliminary results as well as excellent chemical and physico-chemical characteristics of these amide derivatives render them as readily available and very promising substrates for systematic study of SDE via sublimation.

Graphical abstractN-Phenyl- and N-benzyl-3,3,3-trifluorolactic acid amides were found to strongly exhibit the phenomenon of self-disproportionation of enantiomers (SDE) via sublimation. The results described in this paper support the hypothesis that compounds containing –CF3 group directly bonded to a stereogenic carbon center can induce an SDE effect.Figure optionsDownload full-size imageDownload as PowerPoint slide