Lewis Acid Induced Rearrangement of 1-Hetero-2,3-Epoxides. Synthesis, Reactivity and Synthetic Applications of Homochiral Thiiranium and Aziridinium Ion Intermediates

Article abstract of DOI:10.1055/s-1997-3729

2,3-Epoxy sulfides and 2,3-epoxy amines, prepared in an optically active form via the Sharpless asymmetric epoxidation, both undergo a Lewis acid induced rearrangement to give the corresponding thiiranium and aziridinium ions respectively. These reactive intermediates, generated in situ, react efficiently with a variety of nucleophiles such as silylated aromatic heterocycles, amides, and amines, including amino acid derivatives. Imines can be used as synthetic equivalents of primary amine nucleophiles, which effectively allows selective monoalkylation with a reactive thiiranium ion intermediate. Applications of this new methodology, and mechanistic studies are also discussed.