Diazo Compounds: Versatile Synthons for the Synthesis of Nitrogen Heterocycles via Transition Metal-Catalyzed Cascade C-H Activation/Carbene Insertion/Annulation Reactions

This review covers some unique diazo compounds, the coupling partners to access various versatile functionalized nitrogen heterocycles, such as indoles, indolines, isoquinolines, isoquinolones, and so on. Different transition metals (such as Rh, Pd, Ru, Ir, Cu, and Co) are involved in these transformations, which involve consecutive processes: transition metal-catalyzed cascade C-H activation/carbene insertion/intramolecular annulation.