Various new chiral building blocks could easily be prepared from optically pure cis and trans ethyl 3-(1′,3′- dioxolan-4′-yl)aziridine-2-carboxylates. A stereochemically pure 1,3-dioxolan in the allyl position of an α-bromoacrylate induced a high (3R*,4′S*) selectivity in the Michael addition with an amine. After oxygen at the inducing centre was exchanged with nitrogen bearing a bulky substituent, the directing influence of this new group was examined. Solvent effects influencing the cis/trans ratio of aziridine formation are discussed.