LETTER 2191 Sulfur Ylide Mediated Three-Component Aziridination and Epoxidation Reactions Using Vinyl Sulfonium Salts

Abstract: Coupling of diphenylvinyl sulfonium triflate with nu-cleophiles and either aldehydes or imines gives epoxides and aziri-dines, respectively, in a three-component reaction. cis-Aziridines could be formed in good diastereomeric ratio, and the selectivity was correlated to the reactivity of the imine. This represents the first study of cis/trans selectivity in the reactions of imines with non-stabilized sulfur ylides. Key words: sulfur ylides, epoxidations, aziridinations, multicom-ponent reactions, vinyl sulfonium salts Three-component coupling reactions have not only been employed to enhance efficiency in organic synthesis but have also played a central role in diversity-oriented syn-thesis.1 The key to success in the development of such re-actions is controlled reactivity. Nucleophile A (e.g., a cuprate) should react selectively with electrophile B (e.g., an enone) generating an intermediate nucleophile AB which should then react selectively with electrophile C (e.g., an aldehyde), all other permutations (e.g. A+C or AB+C) should be slow or unproductive (Scheme 1). Our interest in vinyl sulfonium salts2 led us to consider their potential use in these types of processes. In particular, the trapping of an intermediate ylide 3 with an aldehyde 4 or imine 5 would furnish an epoxide 6 or aziridine 7, which are very useful products for further elaboratio