A Reassessment of the Transition-Metal Free Suzuki-Type Coupling Methodology

Arvela, Riina K.; Leadbeater, Nicholas E.; Sangi, Michael S.; Williams, Victoria; Granados, Patricia; Singer, Robert D.

doi:10.1021/jo048531j

Cited by 380 publications

(210 citation statements)

References 30 publications

(33 reference statements)

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“…Suzuki-type aryl cross-coupling reactions have been tested with a variety of catalysts (see Scheme 84). Given the fact that very low catalyst loadings are usually sufficient to catalyze this reaction, 163 good catalytic activities are not very surprising. Notably, the kinetic reaction profile of some catalytic runs (e.g., 111b, cf.…”

Section: Carbon-carbon Cross-coupling Reactionsmentioning

confidence: 99%

Beyond ConventionalN-Heterocyclic Carbenes: Abnormal, Remote, and Other Classes of NHC Ligands with Reduced Heteroatom Stabilization

et al. 2009

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theme are found via the replacement or displacement of one N atom, thus providing carbenes derived from pyrazolium, isothiazolium, and even quinolinium salts that contain a stabilizing heteroatom in a remote position (G-J in Figure 1). Recently, carbenes such as K, which are comprised of only one heteroatom and lack delocalization through the heterocycle, have been discovered as versatile ligands, thus constituting another important class of carbenes with low heteroatom stabilization. Both the synthesis of the organometallic complexes of these ligands as well as the (catalytic) properties of the coordinated metal centers generally show distinct differences, compared to the more classical NHC complexes, such as C2-metallated imidazolylidenes. This review intends to describe such differences and highlights the chemical peculiarities of these types of N-heterocyclic carbene complexes. It introduces, in a qualitative manner, the synthetic routes that have been established for the preparation of such complexes, covering the literature from the very beginning of activities in this area up to 2008. While specialized reviews on some aspects of the present topic have recently appeared, 7 a comprehensive overview of the subject has not been available thus far. Rather than just being descriptive, the present account is mainly directed toward the impact of these still unusual metal-carbene bonding modes on the electronic properties and on the new catalytic applications that have been realized by employing such new carbene complexes. As a consequence of our focus on complexes with less-stabilized heterocyclic ligands, systems comprising acyclic carbenes have not been included, and the interested reader is, instead, referred to the pioneering and

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Section: Carbon-carbon Cross-coupling Reactionsmentioning

confidence: 99%

Beyond ConventionalN-Heterocyclic Carbenes: Abnormal, Remote, and Other Classes of NHC Ligands with Reduced Heteroatom Stabilization

et al. 2009

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“…[14] Even so, the involvement of soluble, catalytically active Pd species cannot be ruled out entirely, [15,16] as it is known that Suzuki-Miyaura reactions can be catalysed by ppb-levels of Pd. [17] In this work, the catalyst activity and leaching profile of these catalysts were validated and compared by filtration test and reaction progress, using the cross-coupling between 2-bromoanisole (1) and 4-fluorophenylboronic acid (2) initially as the model substrates, in an alcoholic solvent in the presence of K 3 PO 4 ( Figure 6). Using pristine catalysts, reactions were complete within 3 h at 75 °C.…”

Section: Choice Of Catalyst and Leaching Studymentioning

confidence: 99%

Catalysis in flow: Operando study of Pd catalyst speciation and leaching

et al. 2014

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Highlights: A custom-made plug-flow reactor (PFR) was constructed for examining Pd catalysis  Leaching/reaction profiles of two Pd catalysts for the Suzuki-Miyaura reaction were established by filtration studies.  The PFR was used to examine catalyst activation and deactivation processes  Ethanol was found to affect the catalysts differently  Leaching and speciation of Pd along the catalyst bed has been observed for the very first time. Catal Today (Highlights

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“…Research groups around the world are investigating modifications of the reaction that work in aqueous media or with trace amounts of catalysts. For example, Leadbeater and his team carry out the Suzuki coupling using ultra-low (ppb) palladium concentration in water, 46 while Kabalka and colleagues have combined a solvent-free, solid-state approach with the application of microwave radiation to achieve coupling in just a few minutes. 47 Ionic liquids, which are excellent solvents for transition-metal catalysts, are also being investigated.…”

Section: ç the Futurementioning

confidence: 99%

Cross-coupling Reactions of Organoboranes: An Easy Method for C–C Bonding

Suzuki¹,

Yamamoto²

2011

Chemistry Letters

151

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The palladium-catalyzed cross-coupling reaction between different types of organoboron compounds and various organic halides or triflates in the presence of base provides a powerful and general methodology for the formation of carboncarbon bonds. The Csp 2 B compounds (such as aryl-and 1-alkenylboron derivatives) and Csp 3 B compounds (alkylboron compounds) readily cross-couple with organic electrophiles to give coupled products selectively in high yields. Recently, the CspB compounds (1-alkynylboron derivatives) have been also observed to react with organic electrophiles to produce expected cross-coupled products. The overview of some of such coupling reactions is discussed here in this article. Ç IntroductionCarboncarbon bond formation reactions are important processes in chemistry, because they provide key steps in building complex, bioactive molecules developed as pharmaceuticals and agrochemicals. They are also vital in developing a new generation of ingeniously designed organic materials with novel electronic, optical, or mechanical properties, likely to play a significant role in the burgeoning area of nanotechnology.During the past 40 years, most important carboncarbon bond-forming methodologies have involved using transition metals to mediate the reactions in a controlled and selective manner. The palladium-catalyzed cross-coupling reaction between different types of organoboron compounds and various organic electrophiles including halides or triflates in the presence of base provides a powerful and general methodology for the formation of carboncarbon bonds. Here, some representatives of such reactions are shown in Scheme 1. Numbers in parentheses indicate the years first reported by our group.As one defect of the reaction, one would point out the use of bases. However, the difficulty could be overcome by using suitable solvent systems and adequate bases. Consequently, these coupling reactions have been actively utilized not only in academic laboratories but also in industrial processes. In this paper, three topics, routes to conjugated alkadienes, application to biaryls, and B-alkyl-borane coupling will be discussed. In addition, recent topics will be introduced.Such coupling reactions offer several advantages: (1) Ready availability of reactants. Cross-coupling reactions between vinylic boranes and vinylic halides were not reported to proceed smoothly in the presence of only palladium catalysts. During the initial stage of our exploration, we postulated that a drawback of the coupling is caused by the following aspects of the mechanism. The common mechanism of transition-metal-catalyzed coupling reactions of organometallic compounds with organic halides involves sequential (a) oxidative addition, (b) transmetalation, and (c) reductive elimination.1 It appeared that one of the major reasons that 1-alkenylboranes cannot react with 1-alkenyl halides is step (b). The transmetalation process between RMX (M = transition metal, X = halogen) and organoboranes does not occur readily because of the wea...

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A Reassessment of the Transition-Metal Free Suzuki-Type Coupling Methodology

Cited by 380 publications

References 30 publications

Beyond ConventionalN-Heterocyclic Carbenes: Abnormal, Remote, and Other Classes of NHC Ligands with Reduced Heteroatom Stabilization

Beyond ConventionalN-Heterocyclic Carbenes: Abnormal, Remote, and Other Classes of NHC Ligands with Reduced Heteroatom Stabilization

Catalysis in flow: Operando study of Pd catalyst speciation and leaching

Cross-coupling Reactions of Organoboranes: An Easy Method for C–C Bonding

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