Magnetic Nanoparticles‐Supported Palladium: A Highly Efficient and Reusable Catalyst for the Suzuki,Sonogashira, and Heck Reactions

A highly efficient, air‐ and moisture‐stable and easily recoverable magnetic nanoparticle‐supported palladium catalyst has been developed for the Suzuki, Sonogashira and Heck reactions. A wide range of substrates was coupled successfully under aerobic conditions. In particular, the performance of the magnetic separation of the catalyst was very efficient, and it is possible to recover and reuse it at least eight times without significant loss of its catalytic activity.     

Fluorapatite‐Supported Palladium Catalyst for Suzuki and Heck Coupling Reactions of Haloarenes

A fluorapatite‐supported palladium catalyst (PdFAP) was synthesized by treatment of fluorapatite (prepared by incorporating the basic species fluoride ion into apatite in situ by co‐precipitation) with bis(benzonitrile)palladium(II ) chloride in acetone. The catalyst displayed high catalytic activity for Suzuki coupling of aryl iodides and bromides with boronic acids at room temperature and chloroarenes at 130 °C in the presence of tetrabutylammonium bromide to give biaryls in excellent yields. Heck olefination of chloroarenes was also successfully carried out by this catalyst. PdFAP was recovered quantitatively by simple filtration and reused with consistent activity. PdFAP was well characterized by XRD, FTIR, XPS, ICP‐AES, CO₂ TPD and CHN elemental analysis.     

Anchoring of Copper(II) Schiff Base Complex into Aminopropyl-Functionalised MCM-41: A Novel,Efficient and Reusable Catalyst for Selective Oxidation of Alcohols

A copper(II) complex containing tetradentate N₂O₂ Schiff base ligand immobilized into aminopropyl-functionalised MCM-41 (mobile crystalline material number 41), was prepared and characterized by Fourier-transform infrared, X-ray diffraction, scanning electron microscopy, thermogravimetric analysis, N₂ adsorption–desorption and inductively coupled plasma analysis techniques. The novel heterogeneous catalyst, MCM-41-pr-NH₂-CuL, can be successfully applied for efficient and selective oxidation of different primary and secondary alcohols to the corresponding carbonyl compounds using hydrogen peroxide as an oxidant in acetonitrile at 60 °C. The effect of reaction parameters such as solvent, amount of catalyst, temperature and kind of oxidant on the oxidation of benzyl alcohol was also studied. The prepared catalyst could be recovered and reused four times without important loss of its catalytic performance. The heterogeneous MCM-41-pr-NH₂-CuL catalyst was found to be catalytically more active in the oxidation of alcohols compared to the similar type of copper(II) Schiff base complex in homogeneous media under the same reaction conditions.     

A Practical Recycle of a Ligand‐Free Palladium Catalyst for Heck Reactions

Ligand‐free palladium can be recovered almost quantitatively from Heck reaction mixtures by filtration after its deposition on a carrier such as silica or celite. Subsequently, it is re‐activated to its original activity by adding a small amount of iodine or bromine prior to the next reaction cycle. The catalyst results in excellent yields and selectivities, even for the less reactive aryl bromides. A catalytic cycle based on anionic palladium intermediates is proposed.     

Oxidation and Oxidative Bromination Reactions Catalyzed By a Reusable Polymer-Anchored Iron(III) Complex in Water at Room Temperature

A polymer-anchored iron(III) catalyst was synthesized and characterized. Its catalytic activity was evaluated for the oxidation of various alkenes, sulfides, aromatic alcohols and ethylbenzene with 30 % H₂O₂ as the oxidizing agent. The catalyst was also effective for the oxidative bromination reaction with 80–100 % selectivity of monobrominated products with H₂O₂/KBr at room temperature. The above reactions require a minimum amount of H₂O₂ and short reaction time. Most importantly, all the above reactions occur in aqueous medium. The catalyst can be facilely recovered and reused six-atimes without significant decrease in its activity and selectivity.     

Pd[tBuNH(S)NHP(O)(OiPr)2-S]2Cl2 Complex as Air- and Moisture-Stable Catalyst for Palladium Catalyzed Suzuki Cross-Coupling Reaction

A highly efficient Suzuki cross-coupling reaction between phenyl bromide and phenylboronic acid catalyzed by the palladium complex Pd[tBuNH(S)NHP(O)(OiPr)₂-S]₂Cl₂ in acetonitrile, toluene, THF or DMF has been investigated. The bases we have employed for this reaction were Na₂CO₃, K₂CO₃ or Cs₂CO₃. It was established that using DMF and K₂CO₃ at 100 °C shows excellent yields of the product at the catalyst amount of 0.1 mmol. The cross-coupling reactions of iodo- and chloro-benzene with phenylboronic acid were also investigated. The influence of the halide nature was as expected.     

Mercapto-Functionalized MCM-41 Anchored Palladium(0) Complex as an Efficient Catalyst for the Heterogeneous Suzuki Reaction

Mercapto-functionalized MCM-41 anchored palladium(0) complex is an efficient catalyst for the heterogeneous Suzuki reaction of arylboronic acids with aryl halides. Our system not only solves the basic problems of catalyst separation and recovery but also avoids the use of phosphine ligands.     

Water‐Soluble Chiral Ruthenium(II) Phenyloxazoline Complex: Reusable and Highly Enantioselective Catalyst for Intramolecular Cyclopropanation Reactions

The intramolecular cyclopropanation of various trans‐allylic diazoacetates and alkenyl diazoketones has been achieved with excellent enantioselectivities of up to 98% ee and in quantitative yields by using a water‐soluble ruthenium(II)/hydroxymethyl(phenyl)oxazoline catalyst in a water/ether biphasic medium. The catalyst could be reused at least five times.     

Suzuki Cross-Coupling Reaction Catalyzed by the Palladium Complex Pd[N-MorphC(S)NP(O)(OiPr)2-O,S]2

Suzuki cross-coupling reaction between phenyl bromide and phenylboronic acid, catalyzed by the palladium complex Pd[N-MorphC(S)NP(O)(OiPr)₂-1,5-O,S)]₂ in acetonitrile, toluene, THF or DMF has been investigated. Bases employed for the reaction were Na₂CO₃, K₂CO₃ or Cs₂CO₃. Varying largely the experimental conditions we found that excellent yields of the product were obtained using toluene and K₂CO₃ at 100 °C at the catalyst amount of 0.02 mmol.     

Thiosemicarbazone Salicylaldiminato‐Palladium(II)‐Catalyzed Mizoroki–Heck Reactions

Four tridentate thiosemicarbazone salicylaldiminato‐palladium(II) complexes of the general formula [Pd(saltsc‐R)PPh₃] [saltsc=salicylaldehyde thiosemicarbazone; R=H ( 1 ), 3‐tert‐butyl ( 2 ), 3‐methoxy ( 3 ), 5‐chloro ( 4 )], have been evaluated as catalyst precursors for the Mizoroki–Heck coupling reaction between a variety of electron‐rich and electron‐poor aryl halides and olefins. The palladium complexes (0.1–1 mol% loading) were found to effectively catalyze these reactions with high yields being obtained when aryl iodides and aryl bromides were utilized. The effects of base, catalyst loading, reaction temperature and reaction time on the catalytic activity of the most active complex were also investigated.     

Recyclable Heterogeneous Palladium Catalysts in Pure Water: Sustainable Developments in Suzuki,Heck, Sonogashira and Tsuji–Trost Reactions

This review summarizes the progress made essentially these last ten years on heterogeneous palladium catalysis in pure water. The work covers four important palladium‐catalyzed transformations for carbon‐carbon bond formation: Suzuki, Heck, Sonogashira and Tsuji–Trost reactions. The discussion focuses on the efficiency and reusability of the heterogeneous catalysts as well as on the experimental conditions from a sustainable chemistry point of view. The review is introduced by a discussion on mechanistic aspects inherent to heterogeneous catalysis.