Synthesis and Stereochemistry of Optically Active Selenonium Imides
Diastereomeric mixtures of 4-phenyl(methyl)selenonium-N-toluene-4'-sulfonimides (dia.-1) amd 4-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.
Synthesis and Stereochemistry of an Optically Selenonium Ylide. X-Ray Molecular Structure of (+)Se-phenyl>(methyl)selenonium 4,4-Dimethyl-2,6-dioxocyclohexylide
Fractional recrystallization of diastereoisomeric phenyl>(methyl)selenonium 4,4-dimethyl-2,6-dioxocyclohexylide from hexane-diethyl ether gave the optically pure (+)-selenonium ylide as stable crystals.The absoute configuration around the selenium atom was determined to be R by X-ray crystallographic analysis.The epimerization of the optically active selenonium ylide by pyramidal inversion was studied.
Fractional recrystallization of diastereomeric methylselenonium 4,4-dimethyl-2,6-dioxocyclohexylide from hexane-ether gave optically pure (+)-selenonium ylide as a stable crystal.