Centrally chiral compounds of sulphur

The most important class of chiral sulphur compounds is the sulphoxides. As a result of the presence of the lone pair, the stereochemistry at sulphur is pyramidal and molecules of the general type (38) and (39) are opposite enantiomers. The sulphoxides are of considerable importance in asymmetric synthesis (see chapter 5) and, as for the phosphines, are generally obtained in enantiomerically pure form by resolution. 

If the lone pair in (38) or (39) is replaced by a double bond to oxygen the resulting sulphone is obviously achiral but if it is instead replaced by a double bond to nitrogen, we get another type of chiral sulphur compound, the sulphoximines (40) which have also been used for asymmetric synthesis (see section 5.1.3). The sulphonium salts (41) are also potentially chiral. A review of the chiral compounds of sulphur is available, 

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