Development of an N-heterocyclic carbene ligand based on concept of chiral mimetic

Arao, Takafumi; Kondo, Kazuhiro; Aoyama, Toyohiko

doi:10.1016/j.tetlet.2005.12.098

Cited by 68 publications

(20 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…[211] Independently of our research group, Togni and co-workers prepared (NHC)PdI 2 -pyridine complexes with chiral, N-ferrocenyl-substituted NHCs. [212] Even though good yields of 309 were obtained (70 %), the ee value was only 9 %.…”

Section: Methodsmentioning

confidence: 99%

“…An array of functionalized alkanes (200)(201)(202)(203)(204), including the chiral terpene-derived ketone 204, as well as sterically hindered biaryls (206)(207)(208) or heteroaromatic molecules (209)(210)(211) were obtained in high yields. Increasing the proportion of the polar solvent (THF/NMP or DMI to 1:2 or 1:3) and/or the temperature to 60 8C was necessary for high yields when challenging substrate combinations were used.…”

Section: Reviewsmentioning

confidence: 99%

See 1 more Smart Citation

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

2007

View full text Add to dashboard Cite

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.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Reviewsmentioning

confidence: 99%

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

2007

View full text Add to dashboard Cite

show abstract

“…Mit der milderen Base LiOtBu anstelle von NaOtBu war die Ausbeute beträchtlich höher, ohne dass der ee-Wert signifikant abnahm. [211] Unabhängig von uns stellten Togni und Mitarbeiter (NHC)PdI 2 -Pyridinkomplexe mit chiralen NFerrocenyl-NHCs her. [212] Das Produkt 309 wurde mit diesen Katalysatoren in guter Ausbeute erhalten (70 %), der ee-Wert betrug jedoch nur 9 %.…”

Section: Arylierung Von Enolatenunclassified

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

2007

View full text Add to dashboard Cite

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.

show abstract

“…[1][2][3][4][5][6] We have been quite recently developing a novel N-heterocyclic carbene ligand 7,8) 1 based on the concept of chiral mimetic. [7][8][9][10][11][12][13] The N-heterocyclic carbene ligand 1 has been found to construct quaternary carbon streocenters with up to 65% enantioselectivity in Pd-catalyzed enantioselective intramolecular a-arylation of N-(2-bromophenyl)-N-methyl-2-arylpropanamide 2 (Chart 1). The enantioselectivity obtained is, to the best of our knowledge, the high level in the reported literature, 14,15) although the chemical yield is moderate.…”

mentioning

confidence: 99%

Asymmetric Construction of Quaternary Carbon Stereocenter by Pd-Catalyzed Intramolecular .ALPHA.-Arylation

Arao

Kondo

Aoyama

2006

CHEMICAL & PHARMACEUTICAL BULLETIN

Self Cite

View full text Add to dashboard Cite

show abstract

Development of an N-heterocyclic carbene ligand based on concept of chiral mimetic

Cited by 68 publications

References 25 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

Asymmetric Construction of Quaternary Carbon Stereocenter by Pd-Catalyzed Intramolecular .ALPHA.-Arylation

Contact Info

Product

Resources

About