In summary, an operationally simple synthesis of rare αheterocyclic aziridines has been developed via the Brønsted acidcatalyzed Michael addition of anilines to chloroalkenes. Degradation of the syn-diastereomer of the chloroamine products by trace acid allows the isolation of a single anti-diastereomer, which has been rationalized by computational modelling. The anti-chloroamine products can then be readily converted to the corresponding cis-aziridines with complete stereochemical fidelity. The scope of this transformation has been demonstrated, and despite some limitations, this approach offers a solution to a considerable gap in this area of chemical space that cannot currently be accessed by alternative synthetic methodologies.