Thermomorphic fluorous imine and thioether palladacycles as precursors for highly active Heck and Suzuki catalysts; evidence for palladium nanoparticle pathways

Rocaboy, Christian; Gladysz, J. A.

doi:10.1039/b208545n

Cited by 177 publications

(146 citation statements)

References 76 publications

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“…[87] Attempts at creating a highly recyclable imine-palladacycle by attaching fluorous tails to these imine precatalysts (e.g., 9d) have been unsuccessful, mainly due to the formation of Pd(0) nanoparticles as the active species, as demonstrated by TEM. [88,89] These experiments confirm that imine-palladacycles are catalytically inactive and are a slow source of active Pd(0) nanoparticles. [39,90] Oxime-palladacycles 4a -f are even more impressive than imine-palladacycles, and reach TONs of 10 10 in classical Heck reactions with iodobenzene.…”

Section: Vittorio Farina ð3þsupporting

confidence: 65%

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: Vittorio Farina ð3þsupporting

confidence: 65%

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

2004

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“…Many palladacycles have also been described as useful catalysts of cross-coupling and related reactions [114][115][116][117][118][119][120][121][122]. However, strong evidence has been accumulated that indicates that the palladacycles merely act as a reservoir of Pd(II), that requires reduction to Pd(0) to enter into the catalytic cycle [119,120,123].…”

Section: Palladacycles As Catalystsmentioning

confidence: 99%

Mechanistic Aspects of Metal‐Catalyzed C—C and C—X Bond‐Forming Reactions

Echavarren

Cárdenas

2005

ChemInform

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Cross-coupling reactions, such as the Stille reaction of organostannanes [1][2][3] and the Suzuki (or Suzuki-Miyaura) cross-coupling of organoboron compounds [4] have settled amongst the more general and selective palladium-catalyzed cross-coupling reactions [5] (Scheme 1-1). These reactions are closely related to other cross-couplings based on transmetallations of a variety of hard or soft organometallic nucleophiles [6] such as the Hiyama [7,8], Sonogashira [9], Kumada (or Kumada-Corriu), and other related couplings [10][11][12].Coupling reactions are somewhat related to the Heck alkenylation of organic electrophiles [13, 14], which is often referred to in the literature as a coupling process. However, although the first steps in both processes are identical, in the Heck reaction there is no transmetallation step. In the alkenylation reaction, the C-C bond is formed by an insertion process, which is followed by a b-hydride elimination to form the substituted alkene product. Cross-coupling (transmetallationbased) processes are a family of closely related catalytic processes that share most mechanistic aspects, although some differences exist on the activation of the organometallic nucleophile. So far, most of the detailed mechanistic studies have cen-

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“…(Cassol et al, 2005;Migowski & Dupont, 2007) This indicates, at least for ligand-free Pd sources, that soluble Pd-NPs are involved as a reservoir of active species. (Reetz & Westermann, 2000;Rocaboy & Gladysz, 2003;Tromp et al, 2003) The first article of a zero-valent Pd complex suitable for the formation of Pd-NPs, by Takahashi and co-workers was published in 1970, used Pd(dba) 2 (dba = dibenzylideneacetone) under thermal decomposition conditions forming metallic palladium and dba in solution. (Takahashi et al, 1970) More studies of Pd-NP synthesis and its applications followed in the 1980s and 1990s by, for example Bönnemann, Reetz and their respective co-workers.…”

Section: Introductionmentioning

confidence: 99%

Palladium Nanoscale Catalysts in Ionic Liquids: Coupling and Hydrogenation Reactions

Prechtl¹,

Scholten²,

Dupont³

2011

Ionic Liquids: Applications and Perspectives

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Thermomorphic fluorous imine and thioether palladacycles as precursors for highly active Heck and Suzuki catalysts; evidence for palladium nanoparticle pathways

Cited by 177 publications

References 76 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

Mechanistic Aspects of Metal‐Catalyzed C—C and C—X Bond‐Forming Reactions

Palladium Nanoscale Catalysts in Ionic Liquids: Coupling and Hydrogenation Reactions

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