Dramatic Increase of Turnover Numbers in Palladium-Catalyzed Coupling Reactions Using High-Pressure Conditions

Hillers, Stephan; Sartori, Sabrina; Reiser, Oliver

doi:10.1021/ja952654r

Cited by 71 publications

(31 citation statements)

References 19 publications

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“…For standard Heck reactions and Suzuki couplings, TONs of > 10 4 and > 10 5 were observed, respectively, but this approach is made unattractive by the extremely large L:Pd ratio that had to be used. [219,220] Interestingly, pressure can dramatically increase maximum TON, as demonstrated by Reiser et al [221] This interesting observation has not been followed up with more studies of TON vs. pressure, but it is intriguing enough to warrant extension to other catalytic systems (Scheme 21).…”

Section: Traditional Catalytic Systemsmentioning

confidence: 91%

High‐Turnover Palladium Catalysts in Cross‐Coupling and Heck Chemistry: A Critical Overview

2004

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This review discusses the problems associated with developing high-turnover catalysts for the cross-coupling and Heck reactions. New developments in the area, principally constituted by palladacycles and coordinatively unsaturated Pd catalysts featuring bulky phosphanes of high donicity, are reviewed from a mechanistic and synthetic standpoint, and compared with more traditional catalysts obtained from conventional mono-and polydentate Nand P-based ligands, as well as Pd catalysts without strong ligands, such as Pd colloids or heterogeneous catalysts. Carbene ligands are also briefly presented. Whereas a single, most promising approach to highturnover Pd catalysis cannot presently be defined, it is clear that the new "PdL 1 " catalysts (where L 1 is a monodentate bulky P ligand of high donicity) represent the latest, most important development in Pd research, certainly from the standpoint of scope and probably also from the standpoint of efficiency. High turnovers with these catalysts have been described and their use will certainly increase in the next few years. The review ends with a brief discussion containing practical considerations on how to choose a high TON catalyst for a given Heck or cross-coupling reaction of interest.

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Section: Traditional Catalytic Systemsmentioning

confidence: 91%

High‐Turnover Palladium Catalysts in Cross‐Coupling and Heck Chemistry: A Critical Overview

2004

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“…[29] Moreover, for the palladium catalyzed cross-coupling of iodobenzene with 2,3-dihydrofuran, very high pressures amounting to 8 kbar has been reported to increase the turnover number in organic solvent systems, owing to an improved lifetime of the catalysts. [30,31] Unlike the Heck reaction in normal organic solutions, small pressure changes can make substantial variations in the rate constant in supercritical fluids because the absolute value of activation volume is in the orders of liters per mol. [16] As a result, for the Heck coupling reaction in scH 2 O, increasing the pressure from 20.3 to 32.1 MPa would elicit 40 % augmentation in the conversion.…”

Section: à3mentioning

confidence: 99%

Heck Coupling Reaction of Iodobenzene and Styrene Using Supercritical Water in the Absence of a Catalyst

Zhang

Sato

Zhao

et al. 2004

Chemistry A European J

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Heck coupling reaction of iodobenzene and styrene proceeds rapidly and selectively in supercritical water even without any catalyst in the presence of base. Both the choice of base and the reaction conditions had a significant effect on the conversion and the selectivity of the coupling products. The addition of a relatively mild base such as potassium acetate facilitated the cross-coupling reaction, while the hydrolysis of phenyl halide was favored in the presence of a strong base. The conversion and the yields of coupling products increased with increasing temperature, reaching a maximum at 650 K near the critical temperature of water, and then decreased as the temperature was further increased. Water density had a significant influence on the reaction rate, showing nearly 30% augmentation with a slight increase in density from 0.45 to 0.56 g cm(-3), but had less effect on the product selectivity. Two possibilities of the role of water responsible for the noncatalytic Heck coupling reaction in supercritical water, that is, ion and water-catalyzed mechanisms have been considered.

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“…Alkenyl mesylates appear to be less suitable for Heck reactions [244]. The coupling reaction can be accelerated by applying high pressure [11,162,215,[280][281][282]. Starting with the 2-chlorocyclohexenylnonaflate 37 prepared in a single step from chlorocyclohexanone [240], the first Heck coupling with methyl acrylate is achieved in 96% yield at 60 • C and ambient pressure.…”

Section: The Leaving Groupsmentioning

confidence: 99%

“…The absolute values of the activation volumes, which were ascertained from the pressure-dependent rate coefficients, increase as follows: 1-iodocyclohexene/Pd(OAc) 2 < Ph-I/Pd(OAc) 2 ≈ Ph-I/1a < Ph-Br/1a. Under high pressure, the lifetime of the active palladium catalyst and thereby the turnover numbers are greatly enhanced [162].…”

mentioning

confidence: 99%

Cross‐Coupling of Organyl Halides with Alkenes – The Heck Reaction

Bräse¹,

Meijere²

2013

Metal‐Catalyzed Cross‐Coupling Reactions and More

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The carbopalladation of an alkene by an organylpalladium halide is the essential step in one of the major contemporary metal-catalyzed C-C coupling reactions. About 45 years ago, a Japanese and an American group almost simultaneously designed and executed palladium-mediated coupling reactions of aryl and alkenyl halides with alkenes [1]. In subsequent investigations, Richard Heck and his group developed this reaction into a catalytic transformation and started to demonstrate its usefulness as well as its rather broad scope. The real push to utilize this powerful C-C-bondforming process, however, started only around the mid-1980s, and by now, an impressive number of publications have established the meanwhile so-called Heck reaction [2] 1) as an indispensable method in Organic Synthesis [3][4][5][6][7]. The universal recognition of the importance of the Heck reaction and the Negishi as well as the Suzuki coupling eventually won the Nobel Prize for Richard Heck along with Ei-ichi Negishi and Akira Suzuki in 2010. The applications of the Heck reaction range from the preparation of -functionalized and unfunctionalized -hydrocarbons, novel polymers, and dyes to new advanced enantioselective syntheses of natural products and biologically active nonnatural compounds. The more or less simultaneous developments of mechanistically related variants, namely, the Kumada, Suzuki, Stille, Hiyama, and Negishi coupling reactions (Chapters 12, 2, 3, 4, and 15, respectively) of metallated alkenes and arenes with aryl and alkenyl halides or the metal-catalyzed formation and cycloisomerization of enynes have drawn profit from the improvement of and mechanistic insights into the Heck reaction. This, of course, applies vice versa as well. Using only a catalytic amount of a palladium(0) complex or a precursor to a palladium species, the Heck reaction can bring about unprecedented structural changes, particularly when conducted intramolecularly. The full potential of this palladium-catalyzed process is still being further explored as demonstrated by a total of over 7000 publications in the past 40 years by 1) The alkynylation of aryl and alkenyl halides, frequently also considered as Heck reactions, is described in Chapter 6.

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Dramatic Increase of Turnover Numbers in Palladium-Catalyzed Coupling Reactions Using High-Pressure Conditions

Cited by 71 publications

References 19 publications

High‐Turnover Palladium Catalysts in Cross‐Coupling and Heck Chemistry: A Critical Overview

High‐Turnover Palladium Catalysts in Cross‐Coupling and Heck Chemistry: A Critical Overview

Heck Coupling Reaction of Iodobenzene and Styrene Using Supercritical Water in the Absence of a Catalyst

Cross‐Coupling of Organyl Halides with Alkenes – The Heck Reaction

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