Recent Progress on Pyridine N-Oxide in Organic Transformations: A Review

Abstract

Pyridine derivatives are one of the most important moieties in the synthesis of various biologically active compounds containing heterocyclic ring. But, due to the low reactivity of pyridine, pyridine N-oxides were used as a reactant to develop some bio-active pyridine derivatives in good amount of yields with high regioselectivity. For that reason, synthesis of various substituted pyridine N-oxides grabbed the attention of many chemists due to their importance in the formation of various bioactive moieties and their application in various fields like it can be used as a catalyst, oxidant etc. This review is focused on various C−H activation reactions like arylation, acylation, alkylation, alkenylation, cross-coupling reactions and halogenation reactions in both metal-catalysed and metal-free pathway along with their probable mechanism and reaction scopes. The main focus of this review is to discuss about versatile synthetic pathways of pyridine and pyridine N-oxide derivatives using pyridine N-oxides as a substrate as well as their mechanistic studies and the scope of the reactions. Besides all of that, this review also discussed about the application (e. g., catalyst) of pyridine N-oxides in various organic transformation.