ISOLATION AND STEREOCHEMISTRY OF OPTICALLY-ACTIVE TRICOORDINATED SELENIUM AND TELLURIUM COMPOUNDS

The synthesis and stereochemistry of optically active tricoordinated s elenium and tellurium compounds are described. Selenonium ylide, selen onium imide, selenonium salt, telluronium ylide, telluronium salt, and telluroxide were prepared and optically resolved by chromatography us ing an optically active column or by fractional recrystallization of t he epimeric mixtures. Their absolute configurations were determined or estimated based on X-ray crystallographic analysis, specific rotation s, or circular dichroism spectra. Their stability toward racemization was also studied experimentally and theoretically.