Synthesis and evaluation of a broad range of new chiral phosphine–carbene ligands for asymmetric hydrogenation

Passays, Johan; Ayad, Tahar; Ratovelomanana‐Vidal, Virginie; Gaumont, Annie‐Claude; Jubault, Philippe; Leclerc, E.

doi:10.1016/j.tetasy.2011.02.017

Cited by 13 publications

(3 citation statements)

References 60 publications

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“…In 2006, the application of phosphine/phosphinite carbene ligands 54 and 55 (Figure ; R = Me, i Pr, Mes) in the Ir-catalyzed hydrogenation of both E - and Z -aryl/alkyl trisubstituted olefins was reported to give low activities and enantioselectivities (ee’s up to 63%) . Later, phosphine-carbene ligands 56 (Figure ; R 1 = Me, Et, i Pr; R 2 = 2,4,6-Me 3 -Ph, 2,6- i Pr 2 -Ph) that formed a larger chelate ring-size upon coordination to Ir, provided higher activities, but enantioselectivities were still moderate …”

Section: Aryl- and Alkyl-substituted Alkenesmentioning

confidence: 99%

Asymmetric Hydrogenation of Olefins Using Chiral Crabtree-type Catalysts: Scope and Limitations

et al. 2013

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Section: Aryl- and Alkyl-substituted Alkenesmentioning

confidence: 99%

Asymmetric Hydrogenation of Olefins Using Chiral Crabtree-type Catalysts: Scope and Limitations

et al. 2013

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“…There are several review articles reported in the past decade, which are dedicated to NHC ligands bearing one additional donor group [ 7 , 8 , 9 , 10 ]. Included in these review articles are bidentate NHC ligands with phosphorous tether [ 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ], nitrogen [ 20 , 21 , 22 , 23 , 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ], and oxygen tethers [ 38 , 39 , 40 , 41 , 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 , 54 , 55 , 56 , 57 , 58 , 59 ,…”

Section: Introductionmentioning

confidence: 99%

Recent Advances in Catalysis Involving Bidentate N-Heterocyclic Carbene Ligands

2021

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Since the discovery of persistent carbenes by the isolation of 1,3-di-l-adamantylimidazol-2-ylidene by Arduengo and coworkers, we witnessed a fast growth in the design and applications of this class of ligands and their metal complexes. Modular synthesis and ease of electronic and steric adjustability made this class of sigma donors highly popular among chemists. While the nature of the metal-carbon bond in transition metal complexes bearing N-heterocyclic carbenes (NHCs) is predominantly considered to be neutral sigma or dative bonds, the strength of the bond is highly dependent on the energy match between the highest occupied molecular orbital (HOMO) of the NHC ligand and that of the metal ion. Because of their versatility, the coordination chemistry of NHC ligands with was explored with almost all transition metal ions. Other than the transition metals, NHCs are also capable of establishing a chemical bond with the main group elements. The advances in the catalytic applications of the NHC ligands linked with a second tether are discussed. For clarity, more frequently targeted catalytic reactions are considered first. Carbon–carbon coupling reactions, transfer hydrogenation of alkenes and carbonyl compounds, ketone hydrosilylation, and chiral catalysis are among highly popular reactions. Areas where the efficacy of the NHC based catalytic systems were explored to a lesser extent include CO2 reduction, C-H borylation, alkyl amination, and hydroamination reactions. Furthermore, the synthesis and applications of transition metal complexes are covered.

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“…Although the first P-NHC iridium complex was developed for asymmetric hydrogenation by Bolm in 2004, iridium complexes with hybrid P-NHC ligands remain rare. Except for Bolm′s complex (Chart ), they all contain an alkyl chain as spacer between the P and NHC donor groups of the chelating P-NHC ligand. ,,,,,− We will describe below the first example, to the best of our knowledge, of a dinuclear Ir complex with a hybrid P-NHC ligand, which extends the range of known P-NHC Ir complexes to a new class of dimetallacyclic complexes.…”

Section: Introductionmentioning

confidence: 99%

Complexes with Hybrid Phosphorus-NHC Ligands: Pincer-Type Ir Hydrides, Dinuclear Ag and Ir and Tetranuclear Cu and Ag Complexes

Liu

Braunstein

2013

Inorg. Chem.

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Three types of hybrid phosphorus-imidazolium salts, 1-methyl-3-(3-((diphenylphosphino)methyl)benzyl)-1H-imidazol-3-ium hexafluorophosphate (2·PF6), 1-methyl-3-(3-(di-tert-butylphosphinooxy)phenyl)imidazolium iodide (8a), and 3-(3-((diphenylphosphoryl)methyl)phenyl)-1-methyl-1H-imidazol-3-ium iodide (11) have been prepared and used as precursors to phosphine-NHC, phosphinite-NHC, and phosphoryl-NHC metal complexes, respectively. The structure of 11 has been determined by X-ray diffraction. The Ag(I) and Ir(I) complexes of the phosphine-NHC ligand, [Ag(μ-P-NHC,κC,κP)]2(PF6)2 (3) and [Ir(cod)(μ-P-NHC,κC,κP)]2(PF6)2 (4), were obtained and characterized by NMR, ESI-MS, elemental analysis, and X-ray diffraction. Both complexes are dinuclear and dicationic, with two P-NHC ligands bridging the two metal centers. The presence of the P donor led for 3 to an unprecedented structure compared to that of related Ag(I) complexes with trans spanning bis-NHC ligands. Complex 4 is the first example of a dinuclear iridium complex with a hybrid P-NHC ligand. The new hydrido, Ir(III) pincer-type complex [IrH(CNHCCCNHC)(MeCN)]PF6 (7) is suggested to have a square-pyramidal structure. The tetranuclear Ag(I) complex with the phosphinite-NHC ligand, [Ag2(μ3-I)(μ-PO-NHC,κP,κCNHC)]2 (9a) has a cubane-type structure, with alternating silver and iodine apexes and two PO-NHC ligands bridging opposite edges of the Ag4 tetrahedron. The Ir(III) pincer complexes [IrH(I)(PO-NHC,κP,κC,κCNHC)(Me)] (10a) and [IrH(I)(PO-NHC,κP,κC,κCNHC)(n-Bu)] (10b), with Me or n-Bu substituents on the nitrogen atom, respectively, have been prepared and characterized. Ag(I) and Cu(I) complexes with the phosphoryl-NHC ligand are reported and the centrosymmetric structure of the latter, [Cu(OP-NHC,κCNHC)2(μ-I){Cu(μ-I)}]2 (13), was established by X-ray diffraction and consists of a central Cu2(μ-I)2 rhombus connected by single iodide bridges to two Cu(OP-NHC,κCNHC)2 moieties. The Ir(III) hydride pincer complexes 10a,b were tested as catalyst precursors for the C-H bond activation of alkanes. Although their efficiency was significantly lower for transfer dehydrogenation from cyclooctane (coa) to t-butylethylene (tbe) than that of known PCP-Ir systems, these results represent the first attempts to study the catalytic properties of hybrid P-NHC iridium pincer complexes.

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Synthesis and evaluation of a broad range of new chiral phosphine–carbene ligands for asymmetric hydrogenation

Cited by 13 publications

References 60 publications

Asymmetric Hydrogenation of Olefins Using Chiral Crabtree-type Catalysts: Scope and Limitations

Asymmetric Hydrogenation of Olefins Using Chiral Crabtree-type Catalysts: Scope and Limitations

Recent Advances in Catalysis Involving Bidentate N-Heterocyclic Carbene Ligands

Complexes with Hybrid Phosphorus-NHC Ligands: Pincer-Type Ir Hydrides, Dinuclear Ag and Ir and Tetranuclear Cu and Ag Complexes

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