Design of highly active heterogeneous palladium catalysts for the activation of aryl chlorides in Heck reactions

Pröckl, Sandra S.; Kleist, Wolfgang; Köhler, Klaus

doi:10.1016/j.tet.2005.06.111

Cited by 86 publications

(61 citation statements)

References 30 publications

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“…[42] This result contrasts with that obtained from ICP-AES analyses of the clear supernatant solutions while evaluating the recycling, attesting clearly that dissolution-redeposition equilibrium occurs during such coupling reactions, as has often been suggested in the literature. [73,[83][84][85] This equilibrium is therefore clearly dependent on the reaction temperature, and is strongly displaced toward the redeposition at low (ambient) temperatures.…”

Section: Resultsmentioning

confidence: 99%

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Efficient Heterogeneously Palladium‐Catalysed Heck Arylation of Acrolein Diethyl Acetal. Selective Synthesis of Cinnamaldehydes or 3‐Arylpropionic Esters

et al. 2007

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) 4 ]/NaY} catalyst was applied successfully to the Heck arylation of acrolein diethyl acetal using a large variety of aryl and heteroaryl bromides. Depending on the reaction conditions (Heck versus Cacchi) good to high selectivities toward the 3-arylpropionic esters or to the cinnamaldehydes were achieved, respectively. Under classical Heck conditions, while the catalyst was found to be stable over the two first runs, it showed significant loss of activity from the third cycle. Under Cacchi conditions, the catalyst could not be reused as it led to high dehalogenation rates. All results indicate that the reactions proceed through dissolved palladium species in the bulk solution (leaching). As observed by transmission electronic microscopic (TEM) analyses, while these species can be trapped and stabilised by the zeolite framework under the Heck conditions, they tend to form large palladium(0) aggregates under the Cacchi conditions leading to dehalogenation rather than to the expected Heck coupling.

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Section: Resultsmentioning

confidence: 99%

“…[75][76][77][78][79] Among them the zeolites showed exceptional activity and stability. [62,69,70,73] Most of the work reported in this area concerned mainly model reactions, reacting aryl iodides and bromides with styrene or acrylates. Few reports concern the reaction of aryl chlorides with styrene.…”

Section: Introductionmentioning

confidence: 99%

Efficient Heterogeneously Palladium‐Catalysed Heck Arylation of Acrolein Diethyl Acetal. Selective Synthesis of Cinnamaldehydes or 3‐Arylpropionic Esters

et al. 2007

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“…5). The peaks at −66.5, −100.5 and −109.6 ppm can be attributed to the SiC(OSi) 3 (T 3 ), Si(OH)(OSi) 3 (Q 3 ) and Si(OSi) 4 (Q 4 ) silicon species, 30,45 respectively. The existence of T 3 confirms that MCM-41 has been modified by organic moieties.…”

Section: 41mentioning

confidence: 99%

Palladium chloride anchored on organic functionalized MCM‐41 as a catalyst for the Heck reaction

Fan

Cheng

Zhu

et al. 2007

Applied Organom Chemis

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Palladium chloride was grafted to amino-functionalized MCM-41 to prepare heterogeneous catalysts. XRD, N 2 adsorption-desorption isotherms, IR, 13 C and 29 Si cross-polarization magic-angle spinning NMR spectroscopy and XPS techniques were employed to characterize the catalytic materials. The heterogeneous palladium catalyst exhibited excellent catalytic activity for the Heck vinylation of iodobenzene with methyl acrylate, giving 92% yield of methyl cinnamate in the presence of Nmethylpyrrolidone (NMP) and triethylamine (Et 3 N). The stability of the heterogeneous catalyst was also studied in detail. The catalytic tests showed that the palladium leaching correlated to solvent, base and palladium loading. The heterogeneous catalyst exhibited excellent stability towards loss of activity and palladium leaching was not observed during six recycles in the presence of toluene and Na 2 CO 3 .

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“…[10] Corresponding reports do not exist for Suzuki couplings until now. Moreover, palladium on carbon has been most extensively researched for Suzuki reactions so far.…”

Section: Introductionmentioning

confidence: 99%

Supported Palladium Catalysts for Suzuki Reactions: Structure‐Property Relationships, Optimized Reaction Protocol and Control of Palladium Leaching

et al. 2008

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Palladium on metal oxides and on activated carbon with particular properties (high palladium dispersion, low degree of reduction, water content) are shown to be highly active (tunrover number, TON = 20,000; turnover frequency, TOF = 16,600), selective and robust catalysts for Suzuki cross-couplings of aryl bromides and activated aryl chlorides. Catalysts and reaction protocol offer combined advantages of high catalytic efficiency under ambient conditions (air and moisture), easy separation and reuse and quantitative recovery of palladium. The palladium concentration in solution during the reaction correlates clearly with the progress of the reaction and indicates that dissolved molecular palladium is in fact the catalytically active species. Dissolved palladium is redeposited onto the support at the end of the reaction. Additional minimization of the palladium content in solution (down to 0.1 ppm) could be achieved by simple procedures which meet the requirements of pharmaceutical industry.

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Design of highly active heterogeneous palladium catalysts for the activation of aryl chlorides in Heck reactions

Cited by 86 publications

References 30 publications

Efficient Heterogeneously Palladium‐Catalysed Heck Arylation of Acrolein Diethyl Acetal. Selective Synthesis of Cinnamaldehydes or 3‐Arylpropionic Esters

Efficient Heterogeneously Palladium‐Catalysed Heck Arylation of Acrolein Diethyl Acetal. Selective Synthesis of Cinnamaldehydes or 3‐Arylpropionic Esters

Palladium chloride anchored on organic functionalized MCM‐41 as a catalyst for the Heck reaction

Supported Palladium Catalysts for Suzuki Reactions: Structure‐Property Relationships, Optimized Reaction Protocol and Control of Palladium Leaching

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