Diastereoselective Iron-Catalyzed [4 + 1] Cycloadditions of Imines with Sulfoxonium Ylides Enable Modular Synthesis of Oxazolidin-2-ones: O- versus N-Nucleophilic Attack

Presented herein is a protocol for the iron-catalyzed [4 + 1] cycloadditions of N-Boc-imines with β-ketosulfoxonum ylides through a succession of nucleophilic additions and intramolecular annulation, giving access to functionalized oxazolidine-2-ones in generally good yields. In contrast to the renown Corey-Chaykovsky reaction via N attack to furnish aziridines, this method afforded oxazolidine-2-ones via an O-nucleophilic attack. Features of this strategy include readily accessible starting materials, sustainable catalyst, post-functionalizations of complex molecules, scalability, and exceptional control over diastereoselectivity.