Nickel-Catalyzed Aryl Borylations: Opportunities and Challenges for Innovation

The utility of aryl boronic acids, esters, and their congeners has led to the development of methods spanning from early synthesis strategies via deprotonations and metal/halogen exchange protocols to sophisticated and well-studied Pd-catalyzed Miyaura borylations and Ir-catalyzed C-H activations. Ni catalysis has also emerged as an approach that is not only more economical and environmentally sustainable than precious metal catalysis but also enables access to mechanistic pathways and substrates that are typically inaccessible with Pd catalysis. While Ni-catalyzed aryl borylations have been successfully demonstrated in the academic and industrial literature for decades, the lack of general conditions and Ni-specific reaction design studies prevents broader application of these methods. In this Perspective, we discuss the current state of the literature regarding Ni-catalyzed aryl borylation and suggest areas of focus for continued study. Advances in mechanistic insight, rational ligand design, high-throughput platforms, and machine-learning models will be instrumental in establishing dependable starting conditions that may largely eliminate the need for cumbersome substrate-tailored optimization. Ni-catalyzed aryl borylations have shown enough promise to become a prominent topic in the current literature, and developing a well-understood suite of general reaction conditions will allow this mode of reactivity to become a competitive borylative strategy.