Peptidomimetics containing an aziridine moiety have been reported as potent cysteine protease inhibitors. In this sense, the development of stereoselective and sustainable synthetic strategies to obtain three-membered N-heterocyclic compounds has gained importance in the last decades. In this work, an efficient method was designed to achieve highly functionalized aziridine peptidomimetics via a sequential reaction, which involves the organocatalytic aziridination of α,β-unsaturated aldehydes followed by the Passerini multicomponent reaction in an environmentally friendly solvent mixture (ethanol: water).