An improved synthesis of bis(1,3-di-N-tert-butylimidazol-2-ylidene)palladium(0) and its use in C–C and C–N coupling reactions

Caddick, Stephen; Cloke, F. Geoffrey N.; Clentsmith, Guy K. B.; Hitchcock, Peter B.; McKerrecher, Darren; Titcomb, Lisa; Williams, Meredith

doi:10.1016/s0022-328x(00)00724-5

Cited by 93 publications

(41 citation statements)

References 26 publications

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“…The aim of this section is [95][96][97][98] The strength of the PdÀNHC bonds renders ligand exchange (Schemes 20-25) an excellent general route to Pd-NHC complexes starting from the preformed carbene and Pd II or Pd 0 complexes with alkenes, [99] phosphanes, [91] nitrogen ligands, [45] or bridging chloride [37,100] or acetate ligands. [101] Pure [102] Another approach is to use an azolium salt precursor in the presence of a base to form in situ the NHC, which is captured by Pd (Schemes 16 and 27-29). Even though strong bases such as KHMDS [43] and KOtBu [103] are effective, more often, weak bases such as Cs 2 CO 3 [87] or even NaOAc [44] are used.…”

Section: General Synthetic Methods For Pd-nhc Complexesmentioning

confidence: 99%

“…Caddick, Cloke, and coworkers showed that homoleptic [(NHC) 2 Pd] complexes (161 and 162, Scheme 46) are excellent candidates for the Buchwald-Hartwig amination of aryl chlorides. At 100 8C, a number of N-mono and N,N-disubstituted anilines were obtained in excellent yields within 1 h. [102,138,139] The singly ligated [{(NHC)Pd(NQ)} 2 ] or [(NHC)Pd(dvds)] complexes were generally found to give unsatisfactory yields. However, excellent yields were obtained by the in situ formed catalysts under the same conditions.…”

Section: G Organ Et Almentioning

confidence: 99%

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Palladium Complexes of N‐Heterocyclic Carbenes as Catalysts for Cross‐Coupling Reactions—A Synthetic Chemist's Perspective

2007

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Palladium-catalyzed C-C and C-N bond-forming reactions are among the most versatile and powerful synthetic methods. For the last 15 years, N-heterocyclic carbenes (NHCs) have enjoyed increasing popularity as ligands in Pd-mediated cross-coupling and related transformations because of their superior performance compared to the more traditional tertiary phosphanes. The strong sigma-electron-donating ability of NHCs renders oxidative insertion even in challenging substrates facile, while their steric bulk and particular topology is responsible for fast reductive elimination. The strong Pd-NHC bonds contribute to the high stability of the active species, even at low ligand/Pd ratios and high temperatures. With a number of commercially available, stable, user-friendly, and powerful NHC-Pd precatalysts, the goal of a universal cross-coupling catalyst is within reach. This Review discusses the basics of Pd-NHC chemistry to understand the peculiarities of these catalysts and then gives a critical discussion on their application in C-C and C-N cross-coupling as well as carbopalladation reactions.

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Section: General Synthetic Methods For Pd-nhc Complexesmentioning

confidence: 99%

Section: G Organ Et Almentioning

confidence: 99%

Palladium Complexes of N‐Heterocyclic Carbenes as Catalysts for Cross‐Coupling Reactions—A Synthetic Chemist's Perspective

2007

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“…Bei 100 8C wurden N-mono-und N,N-disubstituierte Aniline binnen 1 h in ausgezeichneten Ausbeuten erhalten. [102,138,139] 2 hergestellten Katalysators verwendete; [223] auch schwache Basen wie Cs 2 CO 3 und K 3 PO 4 waren geeignet. Die Reaktion wurde auch als Tandemreaktion von Sonogashira-Kupplung und Indolcyclisierung in einem Reaktionsgefäß ausgeführt, ergab dann aber geringere Ausbeuten.…”

Section: G Organ Et Alunclassified

Aus der Sicht des Synthetikers: Palladiumkomplexe N‐heterocyclischer Carbene als Katalysatoren für Kreuzkupplungen

2007

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Palladiumkatalysierte C‐C‐ und C‐N‐Kupplungen zählen zu den vielseitigsten und leistungsfähigsten Syntheseverfahren. Seit 15 Jahren erfreuen sich die N‐heterocyclischen Carbene (NHCs) wachsender Beliebtheit als Liganden für palladiumvermittelte Kreuzkupplungen und ähnliche Methoden. Sie sind in vielerlei Hinsicht den üblichen tertiären Phosphanen überlegen. Weil NHCs stark σ‐elektronenschiebend sind, können sie auch anspruchsvolle Substrate zu oxidativen Insertionen bewegen. Andererseits führen ihre Sperrigkeit und ihre besondere Topologie zu einer raschen reduktiven Eliminierung. Schließlich tragen die starken Pd‐NHC‐Bindungen zur hohen Stabilität der aktiven Spezies bei – auch bei niedrigen Ligand/Pd‐Verhältnissen und hohen Temperaturen. Wenn erst stabile, anwenderfreundliche und leistungsstarke NHC‐Pd‐Präkatalysatoren kommerziell verfügbar sind, liegt das Ziel eines universellen Kreuzkupplungskatalysators in greifbarer Nähe. Dieser Aufsatz beschreibt zunächst die chemischen Grundlagen zu den NHC‐Pd‐Komplexen, um ihre Besonderheiten kennenzulernen. Anschließend folgt eine umfassende Diskussion zur Anwendung dieser Katalysatoren in C‐C‐ und C‐N‐Kreuzkupplungen sowie in der Carbopalladierung.

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“…Compound 3 b also resulted from the in situ reduction of [{(h 3 -C 3 H 5 )PdCl} 2 ] in the presence of 2 at 90 8C (55 % yield). [10] This alternative procedure circumvents the use of the expensive starting material 1 b. [11] Scheme 1.…”

mentioning

confidence: 99%

A Defined N-Heterocyclic Carbene Complex for the Palladium-Catalyzed Suzuki Cross-Coupling of Aryl Chlorides at Ambient Temperatures

Gstöttmayr

Böhm

Herdtweck

et al. 2002

Angewandte Chemie International Edition

378

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An improved synthesis of bis(1,3-di-N-tert-butylimidazol-2-ylidene)palladium(0) and its use in C–C and C–N coupling reactions

Cited by 93 publications

References 26 publications

Palladium Complexes of N‐Heterocyclic Carbenes as Catalysts for Cross‐Coupling Reactions—A Synthetic Chemist's Perspective

Palladium Complexes of N‐Heterocyclic Carbenes as Catalysts for Cross‐Coupling Reactions—A Synthetic Chemist's Perspective

Aus der Sicht des Synthetikers: Palladiumkomplexe N‐heterocyclischer Carbene als Katalysatoren für Kreuzkupplungen

A Defined N-Heterocyclic Carbene Complex for the Palladium-Catalyzed Suzuki Cross-Coupling of Aryl Chlorides at Ambient Temperatures

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