Protonenresonanz-Untersuchugen zur Inversion am dreibindigen Stickstoffatom 6. Preparative Separations of Enantiomeric Diaziridines by Liquid Chromatography on Triacetylcellulose. Racemizations Monitored by Polarimetry and by ¹H NMR

Abstract

Enantiomeric diaziridines have been partially separated by chromatography on triacetlycellulose. (−)-2, (+)-4, and (−)-4 were obtained almost pure, enantiomeric purities (Table 1) being measured by 1H NMR in the presence of optically active additives. The same procedure was tested for monitoring racemizations (Table 2) which were also studied, with higher accuracy, by polarimetry. The barriers to nitrogen inversion, converting the trans-diaziridines 2and4into cis-intermediates, are compared with known ΔG≠ values.