2142-66-7Relevant articles and documents
Polyoxometalate-based N-Heterocyclic Carbene (NHC) complexes for palladium-mediated C-C coupling and chloroaryl dehalogenation catalysis
Berardi, Serena,Carraro, Mauro,Iglesias, Manuel,Sartorel, Andrea,Scorrano, Gianfranco,Albrecht, Martin,Bonchio, Marcella
supporting information; experimental part, p. 10662 - 10666 (2010/12/18)
Better together: A novel hybrid N-heterocyclic carbene (NHC) palladium complex, integrating a totally inorganic and polyanionic decatungstate unit, has been synthesized following a convergent strategy. The interplay of the Pd binding domains with the inorganic scaffold is instrumental in accessing multi-turnover catalysis in C-C crosscoupling and aromatic dehalogenation reactions under MW-assisted protocols (see scheme). (Figure Presented).
Pd(PPh3)4-PEG 400 catalyzed protocol for the atom-efficient stille cross-coupling reaction of organotin with aryl bromides
Zhou, Wen-Jun,Wang, Ke-Hu,Wang, Jin-Xian
supporting information; experimental part, p. 5599 - 5602 (2009/12/03)
(Chemical Equation Presented) Aryl bromides (4 equiv) were coupled efficiently with organotin (1 equiv) in an atom-efficient way using the tetra(triphenylphosphine)palladium/polyethylene glycol 400 (Pd(PPh 3)4/PEG 400) catalytic syst
Bis(tetrazolyl)benzenes as ligands in the Suzuki reaction: Promoters or inhibitors?
Burukin,Vasil'ev,Merkulova,Struchkova,Zlotin
, p. 118 - 122 (2007/10/03)
The Suzuki cross-coupling with phenylboronic acid in the presence of the Pd(OAc)2/K3PO4/DMF catalytic system was successful for aryl bromides and somewhat poorer for aryl chlorides. Addition of 1,3-bis(tetrazol-1-yl)benzene or its analogs lowered the yields of biaryls.
A catalytic and mechanistic investigation of a PCP pincer palladium complex in the Stille reaction
Olsson, Daniel,Nilsson, Patrik,El Masnaouy, Mostafa,Wendt, Ola F.
, p. 1924 - 1929 (2007/10/03)
In an improved procedure, the complex {2,6-bis[(diphenylphosphino)methyl] benzene}chloropalladium(II) (1) was synthesised as its THF adduct and the structure was determined by X-ray crystallography. The catalytic properties of the derivative {2,6-bis[(diphenylphosphino)methyl]benzene}(trmuoroacetato) palladium(II) (2) was investigated in the Stille reaction. Complex 2 proves to be an excellent catalyst for the C-C cross-coupling between trimethyl phenyl stannane and aryl bromides using a very low catalyst loading (0.1-0.0001%), giving high turnover numbers (TONs) up to 6.9 × 105. A kinetic investigation of the catalytic reaction suggests a heterogeneous colloidal palladium catalyst formed from the PCP Pd(II) pre-catalyst. The Royal Society of Chemistry 2005.
A Mild and Versatile Method for Palladium-Catalyzed Cross-Coupling of Aryl Halides in Water and Surfactants
Arcadi, Antonio,Cerichelli, Giorgio,Chiarini, Marco,Correa, Mariano,Zorzan, Daniel
, p. 4080 - 4086 (2007/10/03)
Various aqueous surfactants proved to be excellent media for carrying out palladium-catalyzed Suzuki-Miyaura cross-coupling reactions under mild conditions. The dehalogenation side reaction, which is usually a drawback with the aqueous protocol, was not observed. The concentration of the surfactant in water played a pivotal role for the reaction outcome. Smooth cross-coupling of iodoanisole and a variety of aryl bromides, including electron-rich derivatives, with aryl boronic acids occurred at room temperature in high yields either with [Pd(PPh3)4] or Pd/C as catalyst. The water-surfactant Pd/C system combines high activity under ambient conditions (air), easy separation and recyclability. Palladium acetate was found to be effective in cross-coupling of the less reactive aryl chlorides at 100 °C. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
Ligands for metals and improved metal-catalyzed processes based thereon
-
, (2008/06/13)
One aspect of the present invention relates to novel ligands for transition metals. A second aspect of the present invention relates to the use of catalysts comprising these ligands in transition metal-catalyzed carbon-heteroatom and carbon-carbon bond-forming reactions. The subject methods provide improvements in many features of the transition metal-catalyzed reactions, including the range of suitable substrates, reaction conditions, and efficiency.
Intramolecular reactivity of arylcarbenes: Biphenyl-2-ylcarbenes
Dorra, Michael,Gomann, Klaus,Guth, Michael,Kirmse, Wolfgang
, p. 598 - 610 (2007/10/03)
Biphenyl-2-ylcarbenes, 2-ArC6H4CR, were generated photolytically and thermally from diazo precursors. Cyclization, leading to fluorenes, competes with capture of the carbenes by methanol but proceeds faster than intramolecular hydrogen shifts (with R = Me) and intermodular C - H insertion reactions (with R = H in cyclohexane). By comparison of product ratios with kinetic data for related carbenes from the literature, the cyclization rate is estimated as ca 1011 s-1. The intramolecular reactivity of biphenyl-2-ylcarbenes is not significantly attenuated by variation of R (R = H, Me, Ph). Very minor effects of triplet sensitization and methanol quenching indicate that fluorenes arise from spin-equilibrated biphenyl-2-ylcarbenes, presumably from the singlet state. When Ar = mesityl, the carbene predominantly inserts into C - H bonds of the 2′-methyl groups, giving rise to a dihydrophenanthrene. Formation of a fluorene derivative, by formal insertion into C - C bonds, occurs as a minor process. This unprecedented reaction points to intervention of an o-xylylene in which the methyl group migrates. Laser flash photolysis (LFP) of 2-PhC6H4CN2Ph generates a transient absorption which is due to the T0→Tn transition of 9-phenylfluorene rather than to the presumed o-xylylene. On LFP of 2-ArC6H4CN2Ph in trifluoroethanol-acetonitrile, protonation of the carbenes gives rise to carbocations, 2-ArC6H4CH+Ph. The transient absorption spectra of these cations are strongly influenced by twisting about the Ar - Ar bond (Ar = Ph 4.
