Palladacycles as Efficient Precatalysts for Negishi and Buchwald-Hartwig Amination Reactions

Resumen

In this chapter we discuss the contribution of palladacycles to the development of two specific cross-coupling reactions named after their discoverers: Negishi coupling and Buchwald-Hartwig amination. Since the main impact of palladacycles in Negishi coupling corresponds to the four generations (palladacycles G1–G4) developed by Buchwald and coworkers, we will first introduce these palladacycles in the frame of Buchwald-Hartwig amination. Thus the chapter starts by addressing this reaction, including an overview of its general features, such as the role of palladium source and the ancillary ligands. The subsequent discussion is organized in the following three groups of palladacycles: (i) Herrmann-Beller palladacycle and related that incorporate an ortho-metallated phosphine/P-donor atom, (ii) several CˆN Buchwald generations of catalysts and all those other incorporating a CˆN backbone, (iii) Nolan palladacycles and related that incorporate NHC ligands instead of phosphines. To end, we present the reports on palladacycles used as precatalysts in the Negishi coupling.