Sulfoxidation predicting absolute configuration

According to this correlation model, in which the principles of steric control of asymmetric induction at carbon (40) are applied, the stereoselectivity of oxidation should depend on the balance between one transition state [Scheme 1(a)] and a more hindered transition state [Scheme 1(6)] in which the groups and R at sulfur face the moderately and least hindered regions of the peroxy acid, respectively. Based on this model and on the known absolute configuration of (+)-percamphoric acid and (+)-l-phenylperpropionic acid, the correct chirality at sulfur (+)-/ and (-)-5 was predicted for alkyl aryl sulfoxides, provided asymmetric oxidation is performed in chloroform or carbon tetrachloride solution. Although the correlation model for asymmetric oxidation of sulfides to sulfoxides is oversimplified and has been questioned by Mislow (41), it may be used in a tentative way for predicting the chirality at sulfur in simple sulfoxides. 

The oxidation of prostereogcnic sulfides to yield chiral nonracemic sulfoxides, which was reported to proceed with good predictive power in the sense indicated (p401)14. As an application of this rule see the assignment of the absolute configuration 2-ethy]-2-(l-oxo-propyl)-l,3-dithiane 1-oxides (11 and 12, p409)103. 

The absolute configurations of the sulfoxides resulting from the asymmetric oxidation of sulfides are safely predicted by the method shown in Scheme 1.7. In aryl methyl sulfides, one takes aryl as the large (L) group. For methyl alkyl sulfides, it is the methyl group which is the smaller. 7t-Systems play a special role, as often encountered in asymmetric synthesis thus in the oxidation of Me— C=C—Bu", the triple bond has to be taken as the (L) group [54,55]. 

Scheme 1.7 Rule for the prediction of absolute configuration in asymmetric sulfoxidation by the Kagan reagent [54,55]...

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