Classical organometallic reactions and organometallic-type reactions without using stoichiometric metals

The use of stoichiometric organometallic reagents and stoichiometric metals formed the basis of vast majority of classical reactions for constructing carbon–carbon bonds. The indispensable requirement of stoichiometric metals for such reactions constitutes significant challenges in terms of resource sustainability, operational safety, and chemical-waste management. The recent developments in C–H functionalizations, hydrogenative alkene/alkyne addition to electrophiles, the hydrazone umpolung chemistry, and other emerging fields such as the electrosynthesis and photoredox chemistry provide potential solutions to overcome these inherent challenges.