Transition Metal Complexes of an (<i>S,S</i>)-1,2-Diphenylethylamine-Functionalized N-Heterocyclic Carbene: A New Member of the Asymmetric NHC Ligand Family

Wan, Kai Y.; Lough, Alan J.; Morris, Robert H.

doi:10.1021/acs.organomet.6b00031

Cited by 25 publications

(33 citation statements)

References 54 publications

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“…For example in 2016, the Morris group have reported the use of chiral NHCs containing a primary amine as a chelator. [38][39][40] The use of such ligands was examined with several metal centers, such as Ru, [38][39][40] Ir, [38][39][40] Ag, 38,39 and Cu, 38,39 as well as on a number of catalytic reactions like the hydrogenation of acetophenone 38 and N-phenylbenzylimine 40 and ketones in general. 39 These catalysts were often able to achieve high yields and showed promising ability towards asymmetric catalysis.…”

Section: Figurementioning

confidence: 99%

Electronic Effects on Chiral NHC–Transition-Metal Catalysis

Yong

Thurston

2019

Synthesis

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Though the properties of N-heterocyclic carbenes (NHCs) are generally dominated by the very strong σ donating character, electronic activation has emerged as an effective method to cooperate with typical carbon-framework steric optimization for highly enantioselective chiral NHC–transition-metal catalysis in recent years. NHC electronic changes associated with structural variations are now better understood by quantitative analysis using various methods. Here we highlighted and correlated some interesting chiral induction improvement methods, which were brought by electronic and steric cooperation on chiral NHC–transition-metal catalysis.1 Introduction2 Hemilabile Sidechains on NHC Ligands3 Electronic and Bond Angle Changes Brought by NHC Core Size Variations4 Electronic Activators on the NHC Core5 Conjugated Systems and Fused Ring Structures6 Remote Electronic Activators on the N-Aryl Ring7 Summary and Outlook

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Section: Figurementioning

confidence: 99%

Electronic Effects on Chiral NHC–Transition-Metal Catalysis

Yong

Thurston

2019

Synthesis

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“…The Ag-Ccarbene bond lengths are relatively long (2.117(6) Å and 2.087(5) Å;), though within the normal range for complexes with T-shaped geometry. 27 It is unusual for a Ag-bis(NHC) complex to result from an imidazolium salt with a coordinating anion, with 2Ag(NHC)X [Ag(NHC)2][AgX2] (X = coordinating anion) being more common. 28 Elemental analysis confirms the Ag(NHC)2Br stoichiometry in the bulk of C2, which was isolated in 68% yield.…”

Section: Takedownmentioning

confidence: 99%

Tethered N-Heterocyclic Carbene-Carboranyl Silver Complexes for Cancer Therapy

et al. 2019

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Silver complexes of tethered N-heterocyclic carbene-carboranyl ligands have been prepared and fully characterized. The first example of silver bonded directly to the cage of o-carborane has been identified in the solid state. The presence of a carboranyl N substituent on the N-heterocyclic carbene significantly enhances the in vitro cytotoxicity of the silver complex against HCT116 p53+/+ and HCT116 p53–/– colon cancer cells in comparison to a phenyl derivative. Conversely, the presence of a carboranyl on the backbone of a xanthine-derived N-heterocyclic carbene decreases the in vitro cytotoxicity of the silver complex in comparison to its phenyl derivative. Stability studies on the xanthine-derived ligands and complexes show that decomposition via deboronation occurs in hydrous dimethyl sulfoxide, which may attribute to the contrasting in vitro behaviors of the carborane-containing complexes.

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“…Furthermore, these complexes were employed as NHC transfer candidates to prepare the corresponding targeted sterically hindered Au complexes that can efficiently catalyze the intermolecular [2+2] cycloaddition of alkynes with olefins affording 57–71% yields with enantiomer ratios of 65:35 and 58:42. Similarly, Morris and co‐workers reported the structural diversity in Ag complexes 139 – 141 (Figure ) possessing a bichiral NHC ligand . A chiral 1‐methylimidazolium salt was prepared by a simple S N 2 reaction of a Boc‐protected bichiral sulfamidate with 1‐methylimidazole in toluene for 1.5 h under reflux conditions.…”

Section: Ag(i)‐carbene Complexes Of Chiral Nhc Ligandsmentioning

confidence: 88%

Coinage Metal Complexes of Chiral N‐Heterocyclic Carbene Ligands: Syntheses and Applications in Asymmetric Catalysis

et al. 2020

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Chiral N‐heterocyclic carbenes (NHCs) have become ligands of choice due to their remarkable catalytic activity in organic transformation reactions. Combining the chiral NHC ligand family and coinage metals became a productive area of research. The organometallic chemistry of coinage metals with the chiral N‐heterocyclic carbene (NHC) ligands is reviewed, with a special emphasis on the synthesis, characterization and possible applications obtained. Significant sections are devoted to the various recently developed coinage metal‐chiral NHC complexes and a detailed comparison of their activities which aims to rationalize the structure–activity relationships. Various methods of preparations of coinage metal‐chiral NHC complexes along with some typical examples of reactivity and mechanisms are covered. Cu‐chiral NHC complexes involved in conjugated additions, allylic substitutions, boration of alkenes, hydrosilylation of ketones and formation of alkenes are covered, along with some remarkable examples and reactivity of Ag‐chiral NHC complexes. Finally, applications of Au‐chiral NHC complexes in the asymmetric cyclization of ester‐functionalized 1,6‐enynes, 1,6‐enyneamines and substituted propargyloxymethanes are also reviewed.

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Transition Metal Complexes of an (S,S)-1,2-Diphenylethylamine-Functionalized N-Heterocyclic Carbene: A New Member of the Asymmetric NHC Ligand Family

Cited by 25 publications

References 54 publications

Electronic Effects on Chiral NHC–Transition-Metal Catalysis

Electronic Effects on Chiral NHC–Transition-Metal Catalysis

Tethered N-Heterocyclic Carbene-Carboranyl Silver Complexes for Cancer Therapy

Coinage Metal Complexes of Chiral N‐Heterocyclic Carbene Ligands: Syntheses and Applications in Asymmetric Catalysis

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