Mechanism and stereochemistry of nucleophilic substitutions in alkoxysulphonium salts. Part II. Competitive attack at sulphur and carbon in the reaction of alkoxydiarylsulphonium salts with halide ions

Abstract

The stereochemical course of the reaction of optically active diarylethoxysulphonium salts with halide ions to give sulphoxides depends on the nature of the halide. For chloride, bromide, and iodide ions the reaction proceeds with retention of configuration at sulphur, whereas for fluoride ions net inversion is observed; this is tentatively explained on the basis of nucleophilic substitution involving apical attack by fluoride ion and equatorial departure of the leaving group, or of Berry pseudorotation.