Suzuki Coupling Of Aryl Bromides Research Articles

Carbonylative Suzuki coupling reactions catalyzed by ONO pincer–type Pd(II) complexes using chloroform as a carbon monoxide surrogate

Benzoylhydrazone Schiff base–ligated three new ONO pincer–type palladium(II) complexes, [(PdL1(PPh3)] (1), [(PdL2(PPh3)] (2), and [(PdL3(PPh3)] (3), were synthesized by the reaction of the respective ligand, N‐(2‐hydroxybenzylidene)benzohydrazide (HL1), N‐(2‐hydroxy‐3‐methoxybenzylidene)benzohydrazide (HL2), or N‐(5‐bromo‐2‐hydroxybenzylidene) benzohydrazide (HL3), with Pd(OAc)2 and PPh3 in methanol and isolated as air‐stable reddish‐orange crystalline solids in high yields (78%–83%). All three complexes were fully characterized by elemental analysis, Fourier‐transform infrared spectroscopy, UV–Visible, 1H nuclear magnetic resonance (NMR), 13C{1H} NMR, and 31P{1H} NMR spectroscopic studies. The molecular structure of all three complexes was established unambiguously by single‐crystal X‐ray diffraction studies which revealed a distorted square planar geometry of all three complexes. The ONO pincer–type ligands occupied three coordination sites at the palladium, while the fourth site is occupied by the monodentate triphenylphosphine ligand. The catalytic potential of all three complexes was explored in the carbonylative Suzuki coupling of aryl bromides and iodides with arylboronic acids to yield biaryl ketones, using CHCl3 as the source of carbonyl. The reported protocol is convenient and safe as it obviates the use of carbon monoxide (CO) balloons or pressured CO reactors which are otherwise needed for the carbonylation reactions. The methodology has been successfully applied to the synthesis of two antineoplastic drugs, namely, phenstatin and naphthylphenstatin, in good yields (81% and 85%, respectively). Under the optimized reaction conditions, complex 2 exhibited the best catalytic activity in the carbonylative Suzuki couplings. The reported catalysts have wide reaction scope with good functional group tolerance. All catalysts could be retrieved from the reaction after completion and recycled up to three times with insignificant loss in the catalytic activity.

A fluorescence active catalyst support comprising carbon quantum dots and magnesium oxide doping for stabilization of palladium nanoparticles: Application as a recoverable catalyst for Suzuki reaction in water

Novel magnesium oxide-carbon quantum dots are synthesized and used for the formation and stabilization of palladium nanoparticles. This highly water dispersible material, Pd@MgO-CQD, has been used as an active catalyst for Suzuki coupling of aryl bromides at room temperature and aryl chlorides at 80°C in water. Using fluorescence emission of the material, a new protocol for determining Pd loading and leaching in catalyst preparation and recycling process is developed.

Palladium nanoparticle anchored polyphosphazene nanotubes: preparation and catalytic activity on aryl coupling reactions

Highly accessible-supported palladium (Pd) nanoparticles anchored polyphosphazene (PPZ) nanotubes (NTs) having average diameter of 120 nm were synthesized rapidly at room temperature and homogeneously decorated with Pd nanoparticles. The resultant PPZ–Pd nanocomposites were morphologically and structurally characterized by means of transmission electron microscope equipped with energy-dispersive X-ray spectroscopy and X-ray diffraction analysis. Characterization results showed that the Pd nanoparticles with good dispersibility could be well anchored onto the surfaces of the PPZ NTs. The PPZ–Pd NTs show enhanced catalytic activity for the Suzuki coupling of aryl bromides with arylboronic acid. In addition, these PPZ–Pd NTs show excellent behaviour as reusable catalysts of the Suzuki and Heck coupling reactions.

A Simple Hydrophilic Palladium(II) Complex as a Highly Efficient Catalyst for Room Temperature Aerobic Suzuki Coupling Reactions in Aqueous Media

A study on room temperature Suzuki cross-coupling in an aqueous medium was carried out using a simple hydrophilic palladium (II) complex, trans-PdCl2(NH2CH2COOH)2 as catalyst in the presence of K2CO3 in air. This approach with a comparatively inexpensive and hydrophilic catalyst, mild reaction condition and aqueous media exhibits excellent catalytic activity towards the Suzuki coupling of aryl bromides and arylboronic acids, and good yields were obtained in the Suzuki coupling of activated aryl chlorides.

Conjugated polymer stabilized palladium nanoparticles as a versatile catalyst for Suzuki cross-coupling reactions for both aryl and heteroaryl bromide systems

A simple and efficient procedure for Suzuki coupling of aryl bromides with phenylboronic acid, catalyzed by an in situ-generated palladium(0)–polymer composite in the absence of any phosphine ligand, has been reported. The catalyst is remarkably active having a high TOF value for both aryl and heteroaryl systems, and is recyclable up to three runs with minimum loss of efficiency.

Suzuki Coupling in Water with Pd-NHC Immobilized on Fe3O4/Ionic Liquid

An immobilized Pd-NHC catalyst 1 was prepared according to equation 1. Catalyst 1 was found to promote the Suzuki coupling of aryl bromides 2 and aryl boronic acids 3 to give the corresponding biaryl products 4 in up to 100% yield (28 examples).

Tris(2-methoxyphenyl)phosphine as a Highly Active Ligand for the Synthesis of Biaryls by Suzuki Coupling Reaction

A <TEX>$Pd(OAc)_2/(o-MeOPh)_3P$</TEX> system has been developed for the catalytic Suzuki coupling of aryl bromides with arylboronic acids. Our catalyst system covers a broad spectrum of commonly available arylboronic acids and aryl bromides to provide biaryls in very good yields. The catalyst system works very well in the synthesis of sterically hindered biaryls.

Sterically Demanding, Zwitterionic Trialkylphosphonium Sulfonates as Air-Stable Ligand Precursors for Efficient Palladium-Catalyzed Cross-Couplings of Aryl Bromides and Chlorides

3-(Di-tert-butylphosphonium)propane sulfonate (DTBPPS) and 3-(diadamantylphosphonium)propane sulfonate (DAPPS) are air-stable pre-ligands for aqueous-phase palladium-catalyzed cross-coupling reactions. Both DTBPPS and DAPPS were found to give active catalysts for the Sonogashira coupling of aryl bromides at room temperature and 4-chloroanisole at 80 °C. These ligands also gave effective catalysts for the aqueous-phase Suzuki coupling of aryl bromides at room temperature.

Water‐soluble 2‐arylnaphthoxazole‐derived palladium (II) complexes as phosphine‐free catalysts for the Suzuki reaction in aqueous solvent

AbstractTwo water‐soluble palladium (II) complexes 2 and 4 have been synthesized from easily available 2‐arylnaphthoxazole derivatives. They were successfully applied to the Suzuki coupling of aryl bromides with phenylboronic acid in water at 100 °C under phosphine‐free conditions. Copyright © 2008 John Wiley &amp; Sons, Ltd.

An Efficient Heterogeneous Pd Catalyst for the Suzuki Coupling: Pd/Al2O3

Abstract PdII-loading alumina catalyst, which is simply prepared through impregnation of γ–alumina with Pd(OAc)2 followed by calcination in the air, shows a high catalytic activity for the Suzuki coupling of aryl bromides with arylboronic acids under phosphine ligand-free conditions. Only 0.25 mol % of palladium is sufficient for the promotion of the couplings in ethanol.

Water‐Soluble Palladacycles as Precursors to Highly Recyclable Catalysts for the Suzuki Coupling of Aryl Bromides in Aqueous Solvents.

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Water-Soluble Palladacycles as Precursors to Highly Recyclable Catalysts for the Suzuki Coupling of Aryl Bromides in Aqueous Solvents

A family of water-soluble palladacycles was prepared from benzylamine or benzaldehyde imine ligands bearing hydrophilic functional groups. The palladacycles derived from N,N-dimethyl-p-hydroxybenzylamine (7) and sodium 4-(N-benzylideneamino)benzenesulfonate (10) gave active catalysts for the Suzuki coupling of aryl bromides and activated aryl chlorides in combination with (2-di-tert-butylphosphinoethyl)trimethylammonium chloride (t-Bu-Amphos). The catalyst derived from 10/t-Bu-Amphos could be used for 12 reaction cycles in the Suzuki coupling of 4-bromotoluene at 80 °C before a significant loss of catalyst activity was observed.

Self-Supported Heterogeneous Star-Shaped Oxime-Palladacycle Catalysts for the Suzuki Coupling Reactions

A novel strategy to synthesize heterogeneous star-shaped oxime-palladacycle catalysts, which exhibited good catalytic activity and recyclability in the Suzuki coupling of aryl bromides and chlorides, was described.

Palladium Complexes with Metallocene-Bridged Bidentate Diphosphine Ligands: Synthesis, Structure, and Catalytic Activity in Amination and Cross-Coupling Reactions

The syntheses and characterization of series of new metallocene-bridged diphosphines and the structures of complexes of some of them with Pd(II) are reported. These complexes were examined as the catalysts in amination reactions of halogenoarenes and in the Suzuki reaction. The complexes based on ruthenocene (2) and osmocene (3) showed lower activities then the palladium complex with dppf in amination reactions and the same activities in the Suzuki reaction. New palladium complexes with the bidentate bulky and electron-rich ligands Fe(η5-C5H4P(o-PriC6H4)2)2 (6) and Fe(η5-C5H4P(o-MeOC6H4)2)2 (5) showed a very high catalytic activity in amination and Suzuki coupling of aryl bromides. A complex with ligand 6 was used in the amination of 4-bromotoluene by primary and secondary amines and showed excellent activity.

A highly active palladium-phosphoramidite catalyst for the Suzuki cross-coupling of aryl bromides

A highly efficient palladium-catalyzed Suzuki coupling of aryl bromides with arylboronic acids using phosphoramidite ligand 2c was developed. The phosphoramidite ligands are cost-effective and easily prepared from inexpensive, commercially available starting materials using a simple, efficient method. It represents an advance toward the discovery of low-cost catalyst systems for eventual availability.

Nickel-promoted ligand-free palladium-catalyzed Suzuki coupling reaction

A Ni-promoted ligand free palladium catalyst system for Suzuki coupling of aryl bromides has been developed in high efficiency under mild reaction conditions. It was obtained in situ by introducing NiCl2 to PdCl2/PVP using a parallel high-throughput screening technique. A wide range of aryl bromides bearing a variety of functional groups was evaluated.

New Pyrazole‐Tethered Schiffs Bases as Ligands for the Suzuki Reaction.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Synthesis of cobalt-containing monodentate phosphine ligand and application toward Suzuki cross-coupling reactions

A bulky, dicobalt complexed, mono-dentate phosphine, [(μ-PPh 2CH 2PPh 2)Co 2(CO) 4](μ,η-PhC CPCy 2) ( 4), was prepared from the reactions of the bis(diphenylphosphino)methylene (dppm)-bridged dicobalt complex Co 2(CO) 6(μ-Ph 2PCH 2PPh 2) ( 2) with PhC CPCy 2 ( 3). Combination of 4 and Pd(OAc) 2 (1:1) gave an active catalyst for the palladium-catalyzed Suzuki coupling of aryl bromides with phenylboronic acid; the catalytic reactions can be performed even under low catalyst loadings (0.1–0.001 mol% 4/Pd(OAc) 2). Compound 4 has been proved to be an authentic and effective mono-dentate phosphine ligand. Crucial factors such as 4/Pd(OAc) 2 ratio, base being used, solvent volume, temperature, and electronic variation of the aryl bromides in reactions were also investigated and results are reported.

Nanoparticulate Palladium Supported by Covalently Modified Silicas: Synthesis, Characterization, and Application as Catalysts for the Suzuki Coupling of Aryl Halides

We present a study of the use of amine-functionalized, mesoporous silicas as supports for nanoparticulate palladium, and the use of the composite materials as heterogeneous catalysts for the Suzuki coupling of aryl bromides. Upon modification of the silica, via attachment of N-functionalized aminopropylsilyl ethers to surface silanol groups, only a small reduction in surface area and average pore diameter is observed. The mesoporosity and high surface area are also maintained after introduction of nanoparticulate palladium, as evidenced by the measurement of BET nitrogen sorption isotherms. Electron microscopy shows that the palladium particles are well-dispersed and of typical diameter 3−6 nm. Catalysis was initially tested using the coupling of phenylboronic acid with 4-bromoanisole in the presence of K2CO3 and with toluene as solvent. This revealed that the choice of organic modification has a crucial role in determining the activity and recyclability of the catalyst: optimum behavior was found for diamine- and triamine-containing systems, while quaternary alkylammonium salts showed poor activities. The optimized catalysts are also active in the coupling of a range of aryl bromides and phenylboronic acids, and after three catalytic runs they show virtually no drop in activity. Upon further cycling, however, and after six catalytic runs, we do observe a drop in activity, and this is accompanied by some leaching of palladium and pore-blocking by reaction products and byproducts.

New pyrazole-tethered Schiffs bases as ligands for the Suzuki reaction

Pyrazole-tethered Schiffs base ligands 2 promote Suzuki coupling of aryl bromides and chlorides with phenylboronic acid efficiently under mild conditions.