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. Dichlorobis[1-(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 degrees 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.
Bolliger
Jeanne L
JL
Department of Inorganic Chemistry, University of Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
Frech
Christian M
CM
D002384:Catalysis; D003432:Cross-Linking Reagents / Q000737:chemistry; D018360:Crystallography, X-Ray; D008024:Ligands; D008958:Models, Molecular; D053758:Nanoparticles / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010165:Palladium / Q000737:chemistry*; D010720:Phosphines / Q000737:chemistry*; D013237:Stereoisomerism
D003432:Cross-Linking Reagents; D008024:Ligands; D009942:Organometallic Compounds; D010720:Phosphines; C550431:dichlorobis(1-(dicyclohexylphosphanyl)piperidine)palladium; D010165:Palladium