103-26-4Relevant articles and documents
Palladium nanoparticles on β-cyclodextrin functionalised graphene nanosheets: A supramolecular based heterogeneous catalyst for C-C coupling reactions under green reaction conditions
Putta, Chandrababu,Sharavath, Vittal,Sarkar, Suprabhat,Ghosh, Sutapa
, p. 6652 - 6660 (2015)
The use of functional properties of native cyclodextrins in palladium nanoparticle-β-cyclodextrin-graphene nanosheet (Pd@CD-GNS) catalyzed carbon-carbon (C-C) coupling reactions have been investigated under green reaction conditions. The supramolecular catalyst was prepared by deposition of Pd nanoparticles (Pd NPs) on CD-GNS using ethanol as the greener solvent and in situ reducing agent. The catalyst was characterised by FTIR, XRD, RAMAN, UV-Vis spectroscopy, TEM, SAED, XPS and ICP-AES. The catalytic activity of these catalysts is investigated in C-C coupling reactions such as Suzuki-Miyaura and Heck-Mizoroki reactions of aryl bromides and aryl chlorides containing functional groups under green reaction conditions i.e. in water, under phosphine free and aerobic conditions. This catalyst afforded excellent selectivities for the products in good to excellent yields under low Pd loadings (0.2-0.05 mol%), while ensuring the recovery and reusability of the catalysts. The reused catalyst was characterized by FTIR, TEM, XPS and ICP-AES. The CD supramolecular mediators loaded on GNS act as stabilising agents for the Pd NPs. The excellent catalytic activity of this system was attributed to the presence of CDs, excellent dispersibility in water, hydrophobic nature of the GNS support for the accumulation of organic substrates in water, "Breslow effect", the presence of PTC to overcome the mass transfer limitation onto the surface of GNS and formation of ternary CD/substrate/additive complexes on the Pd-GNS surface.
2-Pyridyl substituents enhance the activity of palladium-phospha-adamantane catalysts for the methoxycarbonylation of phenylacetylene
Shuttleworth, Timothy A.,Miles-Hobbs, Alexandra M.,Pringle, Paul G.,Sparkes, Hazel A.
, p. 125 - 137 (2017)
The synthesis of a series of CgPAr ligands is reported, where CgP is the 6-phospha-2,4,8-trioxa-1,3,5,7-tetramethyladamant-6-yl moiety and Ar = 2-pyridyl (L2), 3-pyridyl (L3), 2-pyrimidyl (L4), 4-R-2-pyridyl [R = Me (L5a), CF3 (L6a), SiMe3 (L7a)] or 6-R-2-pyridyl [R = Me (L5b), CF3 (L6b), SiMe3 (L7b). Testing of these ligands in the Pd-catalysed methoxycarbonylation of phenylacetylene reveals that the activity and branched selectivity of the catalysts derived from these ligands varies as a function of the N-heterocycle, with the catalyst derived from L5b being the most active of those tested. This, together with the poor performance of catalysts derived from L3 supports the hypothesis that the catalysis proceeds by a “proton shuttling” mechanism, an idea that previously had only been applied to arylphosphines. Reaction of [PtCl2(cod)] with L where L = L2 or L4-7 yields a rac/meso mixture of the trans-[PtCl2(L)2] (1a-h) complexes, three of which are structurally characterised. 31P NMR spectroscopy shows that reaction of L3 with [PtCl2(cod)] gives a mixture of mononuclear and binuclear metal complexes in solution. The complex trans-[PdCl2(L2)2] (4) reacts with AgBF4 to give the [PdCl(κ1-L2)(κ2-L2)]BF4 (5) with spectroscopic and structural characterisation confirming the presence of a P,N-chelate. 1H and 31P NMR evidence supports the assignment of a pyridyl-protonated species being formed upon treatment of 4 with TsOH·H2O in CD2Cl2; both the protonated species and chelate 5 are observed when the reaction is carried out in MeOH.
Chalcone and cinnamate synthesis via one-pot enol silane formation-Mukaiyama aldol reactions of ketones and acetate esters
Downey, C. Wade,Glist, Hadleigh M.,Takashima, Anna,Bottum, Samuel R.,Dixon, Grant J.
, p. 3080 - 3083 (2018)
Aryl alkyl ketones, acetate esters, and acetamides undergo facile one-pot enol silane formation, Mukaiyama aldol addition, and dehydrosilyloxylation in the presence of an amine base and excess trimethylsilyl trifluoromethanesulfonate. The chalcone and cinnamate products are generally recovered in high yield. The relative stoichiometry of the trimethylsilyl trifluoromethanesulfonate and amine base reagents determines whether the reaction yields the β-silyloxy carbonyl product or the α,β-unsaturated carbonyl.
Highly reactive heterogeneous Heck and hydrogenation catalysts constructed through 'bottom-up' nanoparticle self-assembly
Galow, Trent H.,Drechsler, Ulf,Hanson, Jarrod A.,Rotello, Vincent M.
, p. 1076 - 1077 (2002)
Polymer-mediated self-assembly of functionalized Pd and SiO2 nanoparticles provides highly active hydrogenation and Heck coupling catalysts.
Simultaneous immobilization of a matrix containing palladium and phase transfer catalyst on silica nanoparticles: Application as a recoverable catalyst for the Heck reaction in neat water
Hajipour, Abdol R.,Azizi, Ghobad
, p. 20704 - 20708 (2014)
Simultaneous covalent anchoring of a phosphonium-palladium complex/phase transfer catalyst matrix on the surface of silica nanoparticles and the application of the resulting catalyst in the Heck reaction of a variety of different haloarenes in neat aqueous media is described. This journal is the Partner Organisations 2014.
Palladium(II)-catalyzed phenylation of unsaturated compounds using phenylantimony chlorides under air
Matoba, Kazutaka,Motofusa, Shin-Ichi,Sik Cho, Chan,Ohe, Kouichi,Uemura, Sakae
, p. 3 - 10 (1999)
Diphenylantimony chloride and phenylantimony dichloride, mainly the former, react smoothly with alkenes in acetonitrile at r.t. in the presence of a catalytic amount of Pd(OAc)2 under air to afford the corresponding phenylated alkenes (Heck-type reaction). The addition of AgOAc as reoxidant is not necessary for this reaction in sharp contrast to similar reactions using triarylstibines. The oxygen absorption is confirmed in this catalytic reaction and the reaction does not proceed catalytically in palladium(II) under inert gases, such as nitrogen or argon. Even under air the addition of a radical scavenger stopped the reaction. The regeneration of PhPdOAc species from Ph2SbCl, HPdOAc species and oxygen is proposed as a key step in the catalytic cycle where oxygen-containing radical species might be present as intermediates.
Highly active Pd(II) cyclometallated imine catalysts for the Heck reaction
Ohff, Manuela,Ohff, Andreas,Milstein, David
, p. 357 - 358 (1999)
The new cyclopalladated, phosphine-free imine complexes 1-3 are exceptional catalysts for the Heck arylation, leading to more than a million turnovers in some cases; the catalysts are very thermally and air stable and are recovered unchanged after the catalysis.
Silica hybrid material containing Pd-NHC complex as heterogeneous catalyst for Mizoroki-Heck reactions
Polshettiwar, Vivek,Hesemann, Peter,Moreau, Jo?l J.E.
, p. 5363 - 5366 (2007)
A silica hybrid material containing palladium-N-heterocyclic carbene complexes was prepared by the sol-gel transformation of a molecular triethoxysilylated Pd-NHC complex. The material showed high activity as heterogeneous catalyst in Mizoroki-Heck reaction of aryl bromides and -iodides with styrene and methyl acrylate and could be re-used in at least five reaction cycles with unchanged catalytic properties.
Magnetic dendritic polymer nanocomposites as supports for palladium: A highly efficient and reusable catalyst for Mizoroki-Heck and Suzuki-Miyaura coupling reactions
Ma, Rong,Yang, Pengbo,Bian, Fengling
, p. 4748 - 4756 (2018)
A novel catalyst Fe3O4@SiO2-Dendrimer-Pd based on palladium immobilized on magnetic dendritic polymer nanocomposites was successfully synthesized and characterized by FT-IR, EA, XRD, TEM, EDX, VSM and XPS. This nanocatalyst showed excellent catalytic activity for solvent-free Mizoroki-Heck reaction and Suzuki-Miyaura reaction in EtOH/H2O at a palladium loading of only 0.009 mol%. Moreover, the Fe3O4@SiO2-Dendrimer-Pd catalyst could be conveniently recovered by an external magnet and used consecutively five times with excellent yields. The remarkable catalytic performances and convenient magnetic separability of the Fe3O4@SiO2-Dendrimer-Pd catalyst make it promising for practical application.
Synthesis of novel palladacycles and their application in heck and Suzuki reactions under aerobic conditions
Xiong, Zhengchang,Wang, Nengdong,Dai, Mingji,Li, Ang,Chen, Jiahua,Yang, Zhen
, p. 3337 - 3340 (2004)
(Chemical Equation Presented) Design and synthesis of a novel family of furancarbothioamide-based palladacycles are reported herein. These palladacycles are thermally stable, not sensitive to air or moisture, and are applied effectively in the Heck reaction of aryl halides with terminal olefins and in the Suzuki reaction of aryl halides with arylboronic acids. These reactions were performed under aerobic conditions, leading to turnover numbers (TONs) up to 1 × 105.
