Chapter 3 Three-membered ring systems

Abstract

Three-membered ring systems, epoxides and aziridines in particular, are excellent synthetic intermediates. This is largely because of their ability to be converted into other functional groups, such as diols, diamines, and amino alcohols to name a few. While the synthesis of aziridines and epoxides can be quite challenging, the rewards for a selective and high-yielding synthesis can be substantial. Epoxides are possibly the most studied of the three-membered heterocycles. While host methods for the synthesis of epoxides have been developed, work continues, especially in the development of more chemo-, regio-, and stereoselective methods. The development of new metal-based epoxidation catalysts continues to garner significant levels of activity. The use of a Mn-based catalyst with a water-soluble ligand provides excellent yields of the corresponding epoxides. In earlier studies, the use of a hydrazinium salt as a nitrogen transfer agent in combination with base proved to be a synthetically useful method for the synthesis of aziridine. Hydrazinium salt can be readily prepared as either the iodide or nitrate salt, although the iodide synthesis is more convenient.