Five-Membered Hetarene N-Oxides: Recent Advances in Synthesis and Reactivity
Five-membered heterocyclic N-oxides attract special attention due to their significant potential applications in medicinal chemistry and advanced materials science. In this regard, novel methods for their synthesis and functionalization are in constant demand. In this short review, recent state-of-the-art achievements in the chemistry of isoxazoline N-oxides, 1,2,3-triazole 1-oxides and 1,2,5-oxadiazole 2-oxides are summarized. The main routes involving transition-metal-catalyzed and metal-free functionalization protocols along with mechanistic considerations are outlined. The transformations of these hetarene N-oxide rings as precursors to other nitrogen heterocyclic systems are also presented.