The Diversity of Heterocyclic N-oxide Molecules: Highlights on their Potential in Organic Synthesis, Catalysis and Drug Applications

The synthesis and chemistry of heterocyclic N-oxide derivatives such as those from pyridine and indazole are very well-known due to their usefulness as versatile synthetic intermediates and their biological importance. These classes of organic compounds have been demonstrated in many interesting and amazing functionalities, particularly vital in the areas including metal complexes formation, catalysts design, asymmetric catalysis and synthesis, and medicinal applications (some potent N-oxide compounds with anticancer, antibacterial, anti-inflammatory activity, etc.). Therefore, the heterocyclic N-oxide motif has been successfully employed in a number of recent advanced chemistry and drug development investigations. In the present review, our primary aim was to provide a relevant summary focusing on the topics of organic synthesis and medical application potential of the compounds cited, which could be attractive and give some insights to researchers in the field. Therefore, we mainly highlight the importance of heterocyclic N-oxide derivatives including those synthesized from imidazole, indazole, indole, pyridazine, pyrazine, pyridine, and pyrimidine in organic syntheses and catalysis, and drug applications. Over the past years, a number of reviews have been published on the organic synthesis and catalysis of N-oxides. We thus concentrated on highlighting those rarely mentioned or recently reported systems.