First Chelated Chiral <i>N</i>-Heterocyclic <i>Bis-</i>Carbene Complexes

Clyne, Dean S.; Jin, Jian; Genest, Evan; Gallucci, and Judith C.; RajanBabu, T. V.

doi:10.1021/ol005694v

Cited by 186 publications

(100 citation statements)

References 36 publications

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“…Bridging of two carbene donor groups with the 1,1'-binaphthyl moiety leads to ligands with axial chirality. The diimidazolium salt 117 [206] and the analogous benzimidazolium derivative [207] belong to these ligand precursors as well as the hydroxy-substituted imidazolium derivative 118. [208] The fourth group of chiral N-heterocyclic carbenes or imidazolium precursors are the planar-chiral derivatives.…”

Section: Methodsmentioning

confidence: 99%

Heterocyclic Carbenes: Synthesis and Coordination Chemistry

2008

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The chemistry of heterocyclic carbenes has experienced a rapid development over the last years. In addition to the imidazolin-2-ylidenes, a large number of cyclic diaminocarbenes with different ring sizes have been described. Aside from diaminocarbenes, P-heterocyclic carbenes, and derivatives with only one, or even no heteroatom within the carbene ring are known. New methods for the synthesis of complexes with N-heterocyclic carbene ligands such as the oxidative addition or the metal atom template controlled cyclization of beta-functionalized isocyanides have been developed recently. This review summarizes the new developments regarding the synthesis of N-heterocyclic carbenes and their metal complexes.

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Section: Methodsmentioning

confidence: 99%

Heterocyclic Carbenes: Synthesis and Coordination Chemistry

2008

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“…Additional studies are needed to probe the detailed structure-activity relationships of such tethered systems. In addition, the research groups of Shi [186] (431, Scheme 81) and RajanBabu [242] prepared palladium complexes with chelating dicarbenes derived from chiral amines that showed reasonable activity in the HeckMizoroki arylation of acrylate esters. Doubly ligated complexes of carbenes derived from heterocycles other than imidazole have also shown excellent applicability in the Heck-Mizoroki reaction.…”

Section: Carbopalladations Of Alkenes and The Heck-mizoroki Reactionmentioning

confidence: 99%

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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“…Zusätzlich stellten die Gruppen um Shi [186] (431, Schema 81) und RajanBabu [242] Palladiumkomplexe von [243] Interessanterweise waren Komplexe, die ausgehend von verwandten Bis(oxazolium)salzen erhalten wurden, weniger aktiv. Buchmeiser et al untersuchten den analogen Komplex 400 des sechsgliedrigen cyclischen Diaminocarbens.…”

Section: G Organ Et Alunclassified

“…B. 418, 419; Abbildung 10; 431, Schema 81) mit chiralen Pd-NHC-Komplexen [107,186,242] gute Umsätze erzielt werden. In keinem Fall gelang aber der Aufbau eines Stereozentrums, und keiner der Komplexe wurde für asymmetrische Heck-Mizoroki-Reaktionen eingesetzt.…”

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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First Chelated Chiral N-Heterocyclic Bis-Carbene Complexes

Cited by 186 publications

References 36 publications

Heterocyclic Carbenes: Synthesis and Coordination Chemistry

Heterocyclic Carbenes: Synthesis and Coordination Chemistry

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

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