Dual reaction pathways in the magnesium-mediated synthesis of aziridines from benzal halides and imines

Reaction between benzal dihalides, benzaldehyde imines, and magnesium in ether affords aziridines in modest yields. Two mechanistic pathways for aziridine formation are discerned. One path involves nucleophilic attack by an alpha-halo Grignard species on the imine; the other involves electrophilic attack on imine by phenylcarbene to afford an azomethine ylide.