Synthesis of Monocarbenepalladium(0) Complexes and Their Catalytic Behavior in Cross-Coupling Reactions of Aryldiazonium Salts

Selvakumar, Kumaravel; Zapf, Alexander; Spannenberg, Anke; Beller, Matthias

doi:10.1002/1521-3765(20020902)8:17<3901::aid-chem3901>3.0.co;2-e

Cited by 150 publications

(70 citation statements)

References 9 publications

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“…The dimeric compound [Pd 0 (NHC)(quinone)] 2 consists of two monomeric Pd(0) complex fragments which contain a carbene ligand and two quinones [6]. They provide the bridges for the dimeric structure.…”

Section: Discussionmentioning

confidence: 99%

“…While this is not unexpected such studies are necessary to understand the reactivity of NHC complexes in general. Our present investigation of [Pd 0 (NHC)(quinone)] 2 [6] with NHC = 1,3-bis(2,4,6-trimethylphenyl)-imidazol-2-ylidene and quinone = 1,4-naphthoquinone is facilitated by the reasonable thermal stability of this compound under ambient conditions. and 1,4-dihydroxynaphthalene (Acros Organics) were commercially available and used without further purification.…”

Section: Introductionmentioning

confidence: 99%

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Excited state properties of [Pd0(NHC)(quinone)]2 with NHC=1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene and quinone=1,4-naphthoquinone

Kunkely

Vogler

2005

Journal of Organometallic Chemistry

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Excited state properties of [Pd0(NHC)(quinone)]2 with NHC=1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene and quinone=1,4-naphthoquinone

Kunkely

Vogler

2005

Journal of Organometallic Chemistry

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“…14 The comparison of the catalytic activity between 26 complexes did not allow to conclude any universal trend, but complex 4 exhibited higher activity than complex 5 what may be attributed to ·-and ³-contributions of the substituents in the corresponding NHCligand. Interestingly, the palladium(0) complex 25, which has been prepared by Beller's research group and employed in the MatsudaHeck reaction (vide infra), 15 catalyzed also the reaction between aryl iodides and enones yielding the MizorokiHeck product or the conjugate addition depending on the base employed. 13 The synthesis of complex 26, which bears NHC ligands in "normal" and "abnormal" binding motifs, has been described by direct metalation of the corresponding imidazolium salt with palladium(II) acetate.…”

Section: ç Mizoroki-heck Reactionmentioning

confidence: 99%

“…Beller and co-workers have obtained similar good results employing a monocarbene palladium(0) complex, such as 25, performing the reaction in MeOH at 5065°C. 15 The catalytic system formed in situ from palladium(II) acetate and the hydroxy-functionalized imidazolium salt 217 (in a 1:2 ratio) has been employed in the MatsudaHeck reaction of Chart 24. different olefins (i.e., methyl and t-butyl acrylates, styrene, acrylamide, and cyclohexene) and arenediazonium tetrafluoroborates. 74 The reactions were performed with low catalyst loadings (0.5 mol % of Pd) in EtOH at 36°C (Table 5).…”

Section: ç Matsuda-heck Reactionmentioning

confidence: 99%

Heterocyclic Carbene–Metal-catalyzed Csp2–Csp2 and Csp–Csp2 Couplings Using Nonmetallic Substrates

Yus¹,

Pastor²

2013

Chemistry Letters

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The use of carbene ligands for transition-metal complexes has been developed in the last decades, being of special interest those carbenes derived from a nitrogen-containing heterocyclic system. An interesting variety of carbenemetal complexes has been tested in the MizorokiHeck reaction. In comparison, few examples can be found for the MatsudaHeck version of this coupling reaction. Additionally, the Sonogashira coupling has been also catalyzed with different carbenemetal catalysts. Ç IntroductionN-Heterocyclic carbenes (NHCs) have emerged in the last years as a new family of ligands with interesting electronic and structural properties.1 The combination of their strong ·-donor and poor ³-acceptor abilities results in good coordination stability and versatility. Consequently, the use of NHC ligands based on imidazolium ions and related heterocycles has appeared as an alternative to phosphanes in the design of new organometallic catalysts.2 One of the main advantages of employing NHC-based catalysts compared with phosphanebased ones is that they are far less prone to oxidation, allowing their prolonged use, and reuse. Although NHCs were presented as simple tertiary phophane mimics, they have been recognized as much more over the past decade. Therefore, NHC ligands have become an interesting alternative to other types of ligands in different cross-coupling catalytic reactions mediated by transition metals.3 Moreover, the easy introduction of chiral elements in the corresponding precursors have made chiral NHCs promising chiral ligands in metal-based asymmetric catalysis. 4 The comparison between phosphane and NHC ligands, from a mechanistic point of view, has been studied, clear differences being found.5 First, the possibility of carbene ligand dissociation is greatly reduced due to its stronger donor ability; and second, the reactivity of the NHCmetal complex is higher probably caused by the lack of back-donation from the metal to the carbene ligand. Jutand and co-workers studied the reactivity of monocarbene and bis(carbene) Pd(0) complexes toward the oxidative addition of aryl halides, concluding that the electronic and steric properties of the carbene ligand are important factors in this step of the catalytic process. 6 Among the carboncarbon coupling reactions, the activation of a CH from an alkene (MizorokiHeck reaction) or an alkyne (Sonogashira reaction) are of special interest. This highlight review describes the progress on the topic of NHC ligands for transition-metal-catalyzed coupling reactions, employing nonmetallic reagents. Thus, both different NHC precursors and NHCmetal complexes with catalytic activity in the Mizoroki Heck, MatsudaHeck, and Sonogashira reactions are compiled. Ç Mizoroki-Heck ReactionIn 1995, Herrmann and co-workers introduced the use of bis(NHC)Pd complexes as catalysts with long-term stability in the MizorokiHeck reaction.7 Indeed, the carbenes derived from imidazole stabilized the palladium complexes due to their pronounced donor properties, being more stable toward...

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“…The interesting use of diazonium salts instead of halides or triflates has been preferred in the last decade [14][15][16][17][18][19] owing to the higher reactivity of diazoniums which produce a better leaving group (nitrogen) than halides or triflates [20,21]. Moreover, the use of the more readily available aniline derivatives as the arenediazonium salt precursors has more economic benefits in comparison with their halide or triflate alternatives [22][23][24][25][26]. Also, these reactions can usually be carried out under milder conditions, shorter reaction times, and with higher yields than conventional Heck reactions without using a base and additional ligands [27,28].…”

Section: Introductionmentioning

confidence: 99%

Heck-type reaction of aryldiazonium silica sulfates

et al. 2011

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Aryldiazonium silica sulfates were employed as new and efficient reagents for Heck-type arylation reactions with styrene and methyl acrylate. The reactions were carried out in an organic solvent, in the presence of Pd(OAc) 2 as precatalyst without use of base and free ligand. The trans isomers of desired products, methyl cinnamates and stilbenes, were obtained with full conversion. Use of a catalytic amount of Pd(OAc) 2 produced the corresponding products in short reaction times and excellent yields.

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Synthesis of Monocarbenepalladium(0) Complexes and Their Catalytic Behavior in Cross-Coupling Reactions of Aryldiazonium Salts

Cited by 150 publications

References 9 publications

Excited state properties of [Pd0(NHC)(quinone)]2 with NHC=1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene and quinone=1,4-naphthoquinone

Excited state properties of [Pd0(NHC)(quinone)]2 with NHC=1,3-bis(2,4,6-trimethylphenyl)imidazol-2-ylidene and quinone=1,4-naphthoquinone

Heterocyclic Carbene–Metal-catalyzed Csp2–Csp2 and Csp–Csp2 Couplings Using Nonmetallic Substrates

Heck-type reaction of aryldiazonium silica sulfates

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