Increasing Catalyst Efficiency in C-H Activation Catalysis.

C-H activation reactions with high catalyst turnover numbers are still very rare in the literature and 10 mol % is a common catalyst loading in this field. We offer a representative overview of efficient C-H activation catalysis to highlight this neglected aspect of catalysis development and inspire future effort towards more efficient C-H activation. Examples ranging from palladium catalysis, Cp*RhIII - and Cp*CoIII -catalysis, the C-H borylation and silylation to methane C-H activation are presented. In these reactions, up to tens of thousands of catalyst turnovers have been observed.