Aromatic N-oxides occupy a central place in the synthesis of azine and azole
derivatives. Unique reactivity of N-oxides makes them versatile substrates for
introduction of various functional groups into the heterocyclic ring. The area of direct
functionalization of C(sp2)–H bonds of aromatic N-oxides with various carbon and
heteroatom substituents has seen renewed interest in recent years, resulting in
introduction of several modern, versatile synthetic protocols into the arsenal of
methods available within the chemistry of nitrogen heteroaromatic compounds. The
aim of this review article is to provide an overview of these recent developments,
together with an appropriate background in more classical N-oxide chemistry. It
focuses on the most important reaction types characteristic for aromatic N-oxides,
rather than the type of heterocyclic ring involved.
Keywords: Aromatic compounds, Azines, Azoles, Cine Substitution, C–HActivation,
Cross-Coupling, Cross-Dehydrogenative Coupling, Deoxygenation,
Dipolar Cycloaddition, Imidazoles, Isoquinolines, Metalation, N-Oxides, Nitrogen
Heterocycles, Nucleophilic Substitution, Oxazoles, Pyridines, Quinolines, Radical
Substitution, Reaction Mechanisms, Thiazoles.
