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

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