We Already Know Everything about Oxidative Addition to Pd(0): Do We?

The oxidative addition (OA) of organic electrophiles to Pd(0) is a fundamental step in organopalladium chemistry and plays a key role in palladium-catalyzed cross-coupling reactions. This perspective summarizes selected mechanistic studies of the Pd(0)-to-Pd(II) OA process involving organic halides and pseudohalides with a focus on systems relevant to catalytic reactions. The results are organized according to the nature of supporting ligands, extracting general trends, and describing the most relevant examples. The formation of active species from precatalysts is surveyed, as well as the influence of different species that could be present under catalytic conditions and influence the OA process, providing guidelines to facilitate the understanding and the improvement of catalytic reactions.