Recent Advances in Cycloaddition Reactions of Heterocyclic N-Oxides

Abstract

1,3-Dipolar cycloaddition ofN-oxides of azines and azoles has become a reliable and versatile synthetic method of preparation of highly functionalized nitrogen heterocycles. Mechanisms of cycloaddition of N-oxides are outlined, including various reaction pathways available for the initial five-membered cycloadducts. Cycloaddition to multiple carbon–carbon, carbon–nitrogen, and carbon–sulfur bonds is discussed, with particular emphasis on modern methods of selective C-2-functionalization of the heteroaromatic ring.