Sulphur–oxygen cleavage in the reaction of four- and five-membered sultones with hydroxide: evidence for a stereoelectronic effect in sulphonyl reactions

Hydroxide ion cleaves the simple 4- and 5-ring sultones (1a) and (1b) chiefly by S–O rather than the C–O bond breakage normally found with unhindered sulphonic esters; we infer that electron donation to the sulphonyl group by an attached donor atom X is a function of the C–S–X–C dihedral angle such that the electron delocalization is least with the smallest dihedral angle.