Nitrene-transfer reactions have been a powerful synthetic method for direct incorporation of nitrogen atoms into organic molecules. Discovery of novel nitrene-transfer reactions has been dominantly supported by not only the improvement in transition-metal catalysts but also by the employment of novel precursors of nitrenoids. Since the pioneering works utilizing organic azides or iminoiodinanes as practical synthetic tools for nitrogen-containing compounds were reported, a new approach using various N-heterocycles containing strain energy or a weak bond has emerged. In this review, we briefly summarize the history of nitrene-transfer chemistry from the viewpoint of its precursors. In particular, the use of N-heterocycles such as 2H-azirines, 1,4,2-dioxazol-5-ones, 1,2,4-oxadiazol-5-ones, isoxazol-5(4H)-ones, and isoxazoles are comprehensively described, showing the recent remarkable progress in this chemistry.

A ruthenium-catalyzed reaction of alkene-tethered isoxazol-5(4H)-ones affording pyridines has been developed. Di-, tri-, and tetrasubstituted pyridines were obtained from various isoxazolones in good yields.

anti-Selective iodocyanation and dicyanation of various internal alkynes has been developed by means of a simple copper catalyst system. The selectivity of the products was switched by tuning the reaction conditions. Mechanistic studies have revealed all of the stepwise pathways including diiodide formation, selective monocyanation, and second cyanation processes.

Polysubstituted cyclohexenes bearing 1,3 (meta) substitution patterns are challenging to access using the Diels–Alder reaction (the ortho–para rule). Here, we report a cobalt-catalyzed reductive [5 + 1]-cycloaddition between a vinylcyclopropane and a vinylidene to provide methylenecyclohexenes bearing all-meta relationships. Vinylidene equivalents are generated from 1,1-dichloroalkenes using Zn as a stoichiometric reductant. Experimental observations are consistent with a mechanism involving a cobaltacyclobutane formed from a [2 + 2]-cycloaddition between a cobalt vinylidene and a vinylcyclopropane.

A dinuclear iridium­(II) complex with 1,3-butadiene-1,4-diyl backbone and iridium–iridium bonding interaction has been found from the complexation of an iridium­(I) precursor and an alkyne-containing bisphosphine ligand. This complex shows binding ability toward a variety of cations such as Ag+, I+, H+ to afford merged cationic diiridium complexes. Structural differences and electronic features of iridium–iridium bonding are discussed using X-ray crystallographic analyses as well as in silico studies with density functional theory.