Self-disproportionation of enantiomers of α-trifluoromethyl lactic acid amides via sublimation

The self-disproportionation of enantiomers (SDE): a menace or an opportunity?

“…Very similar cases of an accidental discovery of SDE via sublimation were reported for compounds 3–6 36 when the crude products of enantioselective reactions were subjected to routine drying in vacuum or even during workup procedure using rotary-evaporation. 37 Of particular interest are derivatives of trifluorolactic acid 7 and 8 which readily sublime at slightly elevated temperatures 38 and can be used as model compounds to study various aspects of the SDE via sublimation. 39 In this regard, one may agree that the usually low volatility of organic compounds would limit the general application of SDE via sublimation as an unconventional enantiomeric purification method.…”

The self‐disproportionation of enantiomers (SDE): The effect of scaling down, potential problems versus prospective applications, possible new occurrences, and unrealized opportunities?

“…While recrystallization is a process that is well familiar to all practitioners as a means to obtain an enantiopure fraction from a nonracemic sample, by contrast, for many other physicochemical processes the SDE phenomenon is not widely appreciated, even for sublimation for which there are mounting examples . In addition to the aforementioned processes, other processes for which the SDE has been observed include force field and even distillation and moreover, the phenomenon has been observed to occur for a vast array of compounds.…”

Optical Purifications via Self‐Disproportionation of Enantiomers by Achiral Chromatography: Case Study of a Series of α‐CF3‐containing Secondary Alcohols

“…1 Furthermore, it is generally accepted practice that the analytical data reported in the literature for chiral compounds are measured on samples as they are obtained by asymmetric reactions without further purification to enantiomerically pure state. In this context, one of the promising areas is the self-disproportionation of enantiomers (SDE) [3][4][5][6] demonstrating that optical purification of enantiomerically enriched compounds via separation of racemate from the excess enantiomer †7 can be achieved under achiral conditions of any type of phase-transition [8][9][10][11][12][13][14][15][16][17][18][19][20] or achiral chromatography. 2 Apparently, the major reason for reporting chiral compounds of various enantiomeric purities, is the painstaking, expensive and time-consuming efforts usually associated with the purification of enantiomerically enriched samples to optically pure form.…”

“…Consequently, the development of new, inexpensive and simple enantiomeric purification methods is of critical importance and will undoubtedly find overwhelming support from all chemistry practitioners. In this context, one of the promising areas is the self-disproportionation of enantiomers (SDE) [3][4][5][6] demonstrating that optical purification of enantiomerically enriched compounds via separation of racemate from the excess enantiomer †7 can be achieved under achiral conditions of any type of phase-transition [8][9][10][11][12][13][14][15][16][17][18][19][20] or achiral chromatography. [21][22][23][24][25] In particular, the latter approach might be a method of very general application as it can be applied for crystalline as well as liquid compounds.…”