Synthesis and Stereochemistry of Optically Active Selenonium Imides.

Diastereoisomeric mixtures of 4-[(–)-menthyloxycarbonyl]phenyl(methyl)selenonium-N-toluene-4′sulfonimides (dia.-1) and 4-[(–)-menthyloxycarbonyl]phenyl(2′, 4′, 6′-triisopropylphenyl)selenonium N-toluene-4″-sulfonimides (dia.-7) were synthesized. Optical resolution by the fractional recrystallization of dia.-7 from methanol gave the optically pure (–)-selenonium imide as stable crystals. The absolute configuration around the selenium atom was determined to be S based on the CD spectra. The kinetics for the epimerization by pyramidal inversion of the optically active selenonium imide were studied.