Dialkyl sulphoxides chiral

The synthesis of chiral dialkyl sulphoxides of high optical purity from dia-stereoisomeric alkanesulphinates has a serious limitation because the sulphinates are not... 

Pyrolysis (in boiling toluene) of the sulphoxide obtained from a dialkyl (l-phenylth> ioalkyl)phosphonate (339) and 3-chloroperoxybenzoic acid affords an alkenephosphonic diester, and subsequent work showed that the sequence was adaptable to the production of chiral esters of alkenylphosphonic diester with optical purities of not less than 93%. Use of the ( S )p-phosphonic amide 340 afforded a mixture of the (E)-(S)p- and (Z)-(S)p-stereoisomers (341), separable by chromatographic methods. ... 

Earlier, attention was drawn to a novel application of the oxidative desulphurization reaction which occurs between sulphoxides and phosphonothioic acid esters. When 1 mol of the thio acid is allowed to remain in contact with 2 mol of a racemic methyl alkyl sulphoxide for 2 weeks at room temperature, the unreacted sulphoxide is found to be optically active, a result which represents asymmetric deoxygenation of the sulphoxide. The chemical course of the reaction is consistent with Scheme 31. Since the appearance of the initial results, corrections have been made to the configurations of the phosphorus-containing substrates, and hence the stereochemical details and mechanistic arguments require reappraisal neverthless, the fact remains that (-t-)-sulphoxides are obtained by the use of the ( S)-(-)-acids, R (R O)P(S)OH , a feature which can be used to determine the chirality of other like acids. Dialkyl and alkyl aryl sulphoxides are also known to form diastereoisomeric complexes with (5)-(-)-/er butylphenylphosphinothioic acid, distinguishable by their NMR spectra, and through such complexation it is possible to assess the enantiomeric composition of the sulphoxide " ... 

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