 However, applying the same strategy to "meta"- or "para"- C-H functionalization does not work because the corresponding cyclophane-like cyclic pre-transition state is highly strained.Thus, while "ortho"-selectivity has been achieved by numerous catalytic systems, "meta"- and "para"-selectivity remains a challenge.In recent years, new strategies that override the electronic and steric bias have been developed to address "meta"-C–H functionalization.