Chiral aziridination of cyclic alpha-bromoenones is achieved by the use of the lithium salt of (Ss)-(+)-p-toluenesulfinamide, which leads to products with diastereomeric excesses in the range of 30-65% using a simple protocol. A key factor associated with chiral induction is the incorporation of the reacting olefin in a cycle, indicating the importance of conformational restriction in the reacting double bond.