This feature article highlights the potentiality of organic azides (RN₃) for the intermolecular amination of sp³ and sp² C–H bonds. A compendium of employed catalytic systems, together with a discussion of involved mechanisms, is provided.

Nitrene transfer reactions represent a useful methodology to synthesize in a few steps high added-value compounds used as organic intermediates. Herein, we describe the catalytic activity of metal porphyrin complexes in a wide range of reactions such as C–H hydrocarbon amination and olefin aziridination to synthesize nitrogen containing molecules. All the most important nitrene sources have been reviewed stressing the potentiality and limits of each one in the particular class of chemical transformation.

The complex Ru(TPP)(NAr)₂ inserts a nitrene group into allylic and benzylic C–H bonds and is the key intermediate in the ruthenium porphyrin-catalyzed amination of hydrocarbons by aryl azides.

Two original macrocyclic silver(I)(pyridine-containing ligand) complexes [Ag(I)(Pc-L)] were synthesized and characterized. Their ability to catalyze the coupling among aldehydes, terminal alkynes and amines (A³-coupling) was demonstrated. The reaction could be performed under conventional as well as dielectric heating. The catalysts were effective in both cases, but dielectric heating allowed a lower catalyst loading and reduced ratio among reaction partners in shorter reaction times. The reaction scope was broad, including aryl/alkyl aldehydes, aryl/alkyl acetylenes and secondary aliphatic amines. Some unprecedented propargylamines have been prepared. The new catalytic system was also tested with more challenging coupling partners such as aniline and ketones.

The synthesis of 3-substituted-1-alkoxyisochromenes starting from 2-alkynylbenzaldehydes and different alcohols is reported. The reaction is catalyzed by a silver(I) complex with an original macrocyclic pyridine-containing ligand. The approach is characterized by absolute regioselectivity, mild reaction conditions, good to excellent reaction yields, cleanness of the reaction, and reduced purification steps. The reaction mechanism was investigated by in-depth ¹H NMR experiments and an aimed “trapping” experiment.