A One‐Pot Approach to Multisubstituted Fused Aziridines: Formal Intermolecular [2+1] Cycloaddition Reaction between Saccharin‐Derived Cyclic Ketimines and Sulfur Ylides

Herein a concise and efficient method for synthesis of aziridines has been developed via a formal intermolecular [2+1] cycloaddition reaction of saccharin-derived cyclic ketimines with sulfur ylides in high yields under mild conditions. This methodology features high atom-economy, broad substrate scope and an operationally simple procedure, affording the aziridines with excellent yields and diastereoselectivity (>20:1 dr). In the present of base, the aziridine products could be readily converted to benzothiazines by an unusual rearrangement reaction.