Asymmetric induction and configurational correlations in oxidations at sulphur. Part III. Oxidations of aryl alkyl sulphides to sulphoxides by optically active peroxy-acids

Abstract

Oxidation of aryl alkyl sulphides by optically active peroxy-acids (R¹R²R³C·CO₃H; R¹, R², and R³ aliphatic or aromatic) in chloroform solution yields optically active sulphoxides. The chirality of the sulphoxides depends on that of the peroxy-acids; it also depends on the nature of the alkyl group of the sulphide, since the same peroxy-acid gives products of different chirality from phenyl methyl and from phenyl t-butyl sulphide. The optical yield is two to four times greater when the oxidation temperature is reduced from 0 to –50°. The factors governing asymmetric induction in the oxidations at sulphur are interpreted in terms of eclipsing effects of small, medium, and large groups. As in asymmetric inductions at carbon the proposed model is no longer valid when solvation effects and electrostatic interactions cannot be discounted in favour of steric factors.