Substituent Effect on the Enantioface-Differentiating Reaction of (R)-[Lithiomethyl p-Tolyl Sulfoxide] with m- or p-Substituted Acetophenones

When lithiomethyl p-tolyl sulfoxide derived from (R)-(+)-[methyl p-tolyl sulfoxide] was allowed to react with acetophenones which have a variety of m- or p-substituents, the corresponding diastereometic mixture of β-hydroxy sulfoxides (RsSc and RsRc) was produced. The degree of enantioselectivity was affected by the nature of the substituent on benzene ring. The logarithms of the RsSc/RsRc values thus obtained gave a good correlation with Hammett’s σ values, affording a negative straight line. The results have been discussed in view of the stereochemical cource of the reaction.