Recent Advances in Copper-Catalyzed Functionalization of Unactivated C(sp3)-H Bonds

C(sp(3))-H functionalization is a core part of organic chemistry because of the presence of C(sp(3))-H bonds in various organic molecules. However, since most C(sp(3))-H bonds are non-reactive, their functionalization is an uphill task. Standard methods of functionalization employ pre-functionalized reactants, expensive organometallic reagents, strong acids or bases and similar other harsh reaction conditions. These methods eventually affect the reaction and prevent it from yielding optimum results. Transition metal-based catalysts like Pd, Rh and Ru provide a direct functionalization route without unwanted pre-functionalization steps. These catalysts furnish superior results under mild reaction conditions. But, their expense, toxicity and low natural abundance prevent them from achieving ideality. Therefore, 3d transition metal catalysts like Mn, Fe, Co, Ni and Cu catalysts have gained significance as an alternative for conventional transition metal catalysts due to their high natural abundance, low toxicity and affordability. Copper-based catalysts are particularly important owing to the wide range of oxidation states of copper and the facile tunability of their catalytic properties. Hence, an immense amount of research is being conducted on the catalytic activity of copper for C(sp(3))-H functionalization. This review aims to provide a detailed overview of some recent reports on C(sp(3))-H functionalization using catalytic systems based on copper.