The oxidation of organic sulphides by Mortierellaisabellina. 2. Effects of substituents on the stereochemistry of sulphoxide formation

Abstract

A series of para-substituted alkyl aryl sulphides has been transformed stereoselectively to the sulphoxide by incubation with the fungus Mortierellaisabellina. The enantiomeric purity of the products was dependent on the nature of substitution in the aromatic ring and at sulphur. Comparisons of the enantiomeric purities obtained from sulphides with para substituents of the same steric size but different electronic properties indicate that the stereoselectivity of S oxidation is susceptible to electron withdrawing or donating factors. This conclusion lends credence to a stepwise oxidation mechanism involving an electron deficient sulphur intermediate.