(2‐Bromoethyl)sulfonium Trifluoromethanesulfonates in Stereoselective Annulation Reactions for the Formation of Fused Bicyclic Epoxides and Aziridines

A versatile and simple method is reported for the synthesis of bicyclic epoxide and aziridinefused heterocycles (up to 98% yield, up to 96 : 4 er or up to 15 : 1 dr), using a tandem Michael addition/ JohnsonCoreyChaykovsky annulation approach. A new chiral (2‐bromoethyl)sulfonium reagent is described, based on an easily available chiral sulfide; it promotes or enhances stereoselectivity in the reaction.