Diastereoselective Synthesis of Cyclopropylamines

Significance

Chiral three-membered rings are important components of biologically active molecules. Although there are efficient protocols to synthesize chiral aziridines like 4, few good methods exist to prepare chiral substituted cyclopro­pylamines 3. The authors reported a simple chemodivergent procedure to access either aziridines 4 or cyclopropylamines 3 from hindered α-chloro­ketone 1. The outcome of the reaction depends solely on the basicity of the Grignard reagent used. Aryl, alkyl, and alkenyl magnesium species gave the aminocyclopropanes; only allyl magnesium bromide led to an aziridine.