Stereoisomerization of [beta]-hydroxy-[alpha]-sulfenyl-[gamma]-butyrolactones controlled by two concomitant 1,4-type nonbonded sulfur-oxygen interactions as analyzed by X-ray crystallography

Nine [beta]-hydroxy-[alpha]-sulfenyl[gamma]-butyrolactones having different substituents are prepared and crystal structures of syn-syn lactones are determined. The X-ray and theoretical studies have shown that two concomitant, attractive 1,4-intramolecular interactions of divalent sulfur with both carbonyl and hydroxyl oxygens are the driving force for the stereochemical preference and the nonbonded sulfur-oxygen interactions have controlled the stereoselectivity of the reaction.