Ligand-Free Silver Fluoride-Promoted (3 + 2) Annulation of Oxaziridines and α-Isocyanoacetates: A Diastereoselective Route to <i>cis-</i>Imidazolines

A ligand-free silver fluoride-promoted diastereoselective (3 + 2) annulation reaction between oxaziridines and isocyanoacetates was developed, enabling the efficient synthesis of <i>cis</i>-2-imidazolines under mild conditions (room temperature within 10 min) with up to 90% yield. The resulting <i>cis</i>-imidazolines are readily hydrolyzed to <i>anti</i>-α,β-diamino acid derivatives while maintaining the stereochemical integrity. Additionally, the <i>cis-</i>imidazolines can be efficiently converted to their <i>trans</i> epimers in high yields, providing stereodivergent access to the <i>syn</i>-α,β-diamino acid derivatives.