Dichloro‐Bis(aminophosphine) Complexes of Palladium: Highly Convenient,Reliable and Extremely Active Suzuki–Miyaura Catalysts with Excellent Functional Group Tolerance

Dichloro‐bis(aminophosphine) complexes are stable depot forms of palladium nanoparticles and have proved to be excellent Suzuki–Miyaura catalysts. Simple modifications of the ligand (and/or the addition of water to the reaction mixture) have allowed their formation to be controlled. Dichlorobis1‐(dicyclohexylphosphanyl)piperidine]palladium ( 3 ), the most active catalyst of the investigated systems, is a highly convenient, reliable, and extremely active Suzuki catalyst with excellent functional group tolerance that enables the quantitative coupling of a wide variety of activated, nonactivated, and deactivated and/or sterically hindered functionalized and heterocyclic aryl and benzyl bromides with only a slight excess (1.1–1.2 equiv) of arylboronic acid at 80 °C in the presence of 0.2 mol % of the catalyst in technical grade toluene in flasks open to the air. Conversions of >95 % were generally achieved within only a few minutes. The reaction protocol presented herein is universally applicable. Side‐products have only rarely been detected. The catalytic activities of the aminophosphine‐based systems were found to be dramatically improved compared with their phosphine analogue as a result of significantly faster palladium nanoparticle formation. The decomposition products of the catalysts are dicyclohexylphosphinate, cyclohexylphosphonate, and phosphate, which can easily be separated from the coupling products, a great advantage when compared with non‐water‐soluble phosphine‐based systems.