A facile and highly diastereoselective aziridination of chiral camphor N-enoylpyrazolidinones with N-aminophthalimide

Reaction of various chiral camphor N-enoylpyrazolidinones 2a-g with N-aminophthalimide in the presence of lead tetraacetate in CH₂Cl₂ proceed smoothly afford the corresponding N-phthalimidoaziridines (3a-e, 4f-g) with excellent material yields (86-95%) at room temperature in 5 min. High levels of diastereoselectivities (up to >95:5 dr) were obtained. The solvent effect was investigated, and the auxiliary can be easily recovered in high yields under mild reaction conditions.