Nucleophilic Substitution of Tricoordinate Sulfur Atom of Sulfonium Salt with Retention of Configuration. Different Stereochemistry of Substitution by Amidate Anions

Abstract

Abstract Optically active N-substituted S-(o-methoxyphenyl)-S-phenylsulfilimines were obtained in moderate yields upon simple treatment of a mixture of o-methoxyphenyl phenyl sulfide and t-butyl hypochlorite in the presence of l-menthol and followed by amidate anions. Although some sulfilimines (N-tosyl-, N-benzoyl-, and N-(chloroacetyl)sulfilimines) were found to be rich in S-configuration around the sulfur atom, the others (N-(dichloroacetyl)-, N-(trichloroacetyl)-, and N-(trifluoroacetyl)sulfilimines) were found to be rich in R-configuration around the sulfur atom. In the displacement of l-menthyloxy group on the sulfur atom of the incipiently formed l-menthyloxysulfonium salt with p-toluenesulfonamidate, benzamidate, and chloroacetamidate anions, the respective N-acylsulfilimines of S-configuration were obtained by substitution with inversion of configuration, while N-acylsulfilimines having R-configuration were obtained by substitution of the same l-menthyloxysulfonium salt by polyhaloacetamidate anions such as dichloroacetamidate, trichloroacetamidate, and trifluoroacetamidate anions, with retention of configuration.