The synthetic potential of three-membered ring aza-heterocycles

Functionalized aziridines, especially aziridine-2-carboxylic esters, are hi ghly valuable small-ring heterocycles for the synthesis of a large variety of anomalous amino acids, new types of ligands for catalytic purposes, new synthons, and four- and five-membered ring heterocycles through ring expans ion reactions. This review highlights the aziridine chemistry with the focu s on the utility of aziridine esters. The synthesis and chemistry of the hi ghly strained azirine carboxylic esters is also briefly reviewed.