ABSTRACT
Stereochemistry of the sulfur atom itself is of major importance in the chiral three-coordinate sulfur species, sulfoxides, sulfilimines, and sulfonium salts. The stereochemistry depends on the substituent on the sulfinyl function; the diastereomeric ratio remains the same regardless of the electrophile used for each sulfoxide. This chapter discusses the compounds and several of a higher coordination number. Most other compounds such as sulfoxides, sulfilimines, and sulfonium salts have trigonal pyramidal structures of an intrinsically chiral nature. The stability of chirality, expressed in terms of the rate of pyramidal inversion, depends mainly on the bond angles around the central sulfur atom, the bond lengths, and the electronegativity of the atom attached to the central sulfur atom. The rate of pyramidal inversion has been measured only for a few kinds of tricoordinate sulfur compounds, such as sulfoxides, sulfilimines, sulfonium salts, and sulfonium ylides.
