Synthesis of Chiral Ferrocenyl Imidazolium Salts and Their Rhodium(I) and Iridium(I) Complexes

Seo, Hwimin; Kim, Bo Yun; Lee, Jae Hoon; Park, Hee Jung; Son, Seung Uk; Chung, Young Keun

doi:10.1021/om0303193

Cited by 109 publications

(29 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…They were the first chiral NHC ligands. [197] Additional imidazolium salts with chiral N,N'-substituents, such as 109, [198] 110 [199] and 111, [200] were subsequently synthesized. The triazolium salts 112, [201] 113, [202] and 114 [203] containing chiral N-substituents have also been described.…”

Section: Methodsmentioning

confidence: 99%

Heterocyclic Carbenes: Synthesis and Coordination Chemistry

2008

View full text Add to dashboard Cite

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.

show abstract

Section: Methodsmentioning

confidence: 99%

Heterocyclic Carbenes: Synthesis and Coordination Chemistry

2008

View full text Add to dashboard Cite

show abstract

“…The concept of steric tuning was further refined by Glorius and co-workers, who prepared a range of pentacyclic NHC precursors (46)(47)(48)(49)(50)(51) bearing conformationally flexible cyclic rings in proximity to the Pd center (Scheme 15). [83,84] These NHCs proved to be slightly less s donating than the monocyclic imidazolium derivatives as a result of the electron-withdrawing effect of the oxygen atoms at the distal carbon atoms of the imidazolium ring.…”

Section: Improving the Catalytic Activity Of Nhc Ligandsmentioning

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

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

“…This complex is characterized by ferrocenyl Cp rings that are virtually eclipsed. Despite the rigida nnulated structure of the C 1 -symmetric NHC ligand, the torsion angle defined by N-2a À C-1a À Ir-1a À C-l1a [98.6(3) 8 8]i sc loser to that observed in related Ir(COD)Cl complexes bearing non-annulated [18] [13a]…”

Section: Resultsmentioning

confidence: 99%

Low Pressure Asymmetric Hydrogenation of Quinolines using an Annulated Planar Chiral N‐Ferrocenyl NHC‐Iridium Complex

John¹,

Wilson‐Konderka²,

Metallinos³

2015

Adv Synth Catal

View full text Add to dashboard Cite

Annulated planar chiral N-ferrocenylimidazolones,o btainedb ya cid-mediated cyclization of diphenylmethanol derivatives,m ay be reduced with diisobutylaluminium hydide (DIBAL-H) to afford as eries of surprisingly stable and isolable hemiaminal ether aminals. Tw oo ft hese derivatives can be oxidized with triphenylcarbenium tetrafluoroborate to imidazolinium salt precursors of N-heterocyclic carbenes (NHCs). Deprotonation of these salts in the presenceo f( cyclooctadiene)iridium chloride dimer {[Ir(COD)Cl] 2 }p rovides chiral coordination complexes bearing N-ferrocenyl NHCsw ith unique rigid tetracyclic frameworks.C ationic analogues of these complexes catalyze the asymmetric hydrogenation of 2-substituted quinolines under very mild conditions( 1mol% complex, 1mol% PPh 3 ,1 -5 atm H 2 , toluene,2 5 8 8 C) in appreciable enantioselectivity (up to 90:10 er). Thes ensitivityo ft he hydrogenation process to changes in the phosphineadditive suggests that an outer-sphere reactionm echanism may be involved, as proposed for ar elated achiral NHC-Ir complexr eported by Crabtree and co-workers.

show abstract

Synthesis of Chiral Ferrocenyl Imidazolium Salts and Their Rhodium(I) and Iridium(I) Complexes

Cited by 109 publications

References 35 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

Low Pressure Asymmetric Hydrogenation of Quinolines using an Annulated Planar Chiral N‐Ferrocenyl NHC‐Iridium Complex

Contact Info

Product

Resources

About