RaabPhos, an Air-Stable, Highly Active Ferrocenyl Phosphasilinane Ligand, for Palladium-Catalyzed C–C and C–N Bond-Forming Cross-Coupling Reactions

The air-stable, highly active ferrocenyl phosphasilinane ligand RaabPhos has been synthesized in four steps from readily available starting materials. Although the ligand is not sterically overloaded, it is highly electron-rich and therefore the corresponding Pd catalyst of high activity. Furthermore, RaabPhos is air-stable as a solid as well as in solution. With the application of this novel ligand in various Pd-catalyzed C-C and C-N bond-forming cross-coupling reactions, its reactivity toward unreactive (hetero)aryl chlorides has been explored. We observed, in general, high yields in these transformations under mild conditions.