A new class of PN3-pincer ligands for metal–ligand cooperative catalysis

Li, Huaifeng; Zheng, Bin; Huang, Kuo‐Wei

doi:10.1016/j.ccr.2014.11.010

Cited by 180 publications

(99 citation statements)

References 105 publications

(118 reference statements)

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“…11 Haupt and coworker introduced such PN3P ligands 12 and Kirchner and coworker have demonstrated the broad applicability of the ligand class. 13 Reports on cobalt complexes stabilized by such ligands are rare. 13e,14,15…”

Section: Scheme 1 Known Homogenous Cobalt Catalysts For C=o Bond Hydmentioning

confidence: 99%

A Highly Active and Easily Accessible Cobalt Catalyst for Selective Hydrogenation of C═O Bonds

2015

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The substitution of high-price noble metals such as Ir, Ru, Rh, Pd, and Pt by earth-abundant, inexpensive metals like Co is an attractive goal in (homogeneous) catalysis. Only two examples of Co catalysts, showing efficient C═O bond hydrogenation rates, are described. Here, we report on a novel, easy-to-synthesize Co catalyst family. Catalyst activation takes place via addition of 2 equiv of a metal base to the cobalt dichlorido precatalysts. Aldehydes and ketones of different types (dialkyl, aryl-alkyl, diaryl) are hydrogenated quantitatively under mild conditions partially with catalyst loadings as low as 0.25 mol%. A comparison of the most active Co catalyst with an Ir catalyst stabilized by the same ligand indicates the superiority of Co. Unique selectivity toward C═O bonds in the presence of C═C bonds has been observed. This selectivity is opposite to that of existing Co catalysts and surprising because of the directing influence of a hydroxyl group in C═C bond hydrogenation.

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Section: Scheme 1 Known Homogenous Cobalt Catalysts For C=o Bond Hydmentioning

confidence: 99%

A Highly Active and Easily Accessible Cobalt Catalyst for Selective Hydrogenation of C═O Bonds

2015

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“…A very good functional group tolerance including the quantitative and selective hydrogenation of a ketone in the presence of a non-shielded olefin is observed. Since PN 5 Pligands and the related PN 3 P-ligands, [8] introduced by Haupt and co-workers [9] and intensively used by the Kirchner group in recent years, [10] are simple to vary, ligand or catalyst libraries can be used to identify catalytically active species. This observation emphasizes an advantage and the importance of homogeneous catalysts in 3d-metal catalysis.…”

mentioning

confidence: 99%

“…[1] The key motivation for this shift of interest results from the need of the conservation of our elemental resources as a central issue of a more sustainable future. Since PN 5 Pligands and the related PN 3 P-ligands, [8] introduced by Haupt and co-workers [9] and intensively used by the Kirchner group in recent years, [10] are simple to vary, ligand or catalyst libraries can be used to identify catalytically active species. [2] The application of homogeneous hydrogenation catalysts is especially promising for the reduction of C = O bonds since a bifunctional mechanism involving the ligand can operate for efficient H 2 activation.…”

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confidence: 99%

Highly Active and Selective Manganese C=O Bond Hydrogenation Catalysts: The Importance of the Multidentate Ligand, the Ancillary Ligands, and the Oxidation State

et al. 2016

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The replacement of expensive noble metals by earth-abundant transition metals is a central topic in catalysis. Herein, we introduce a highly active and selective homogeneous manganese-based C=O bond hydrogenation catalyst. Our catalyst has a broad substrate scope, it is able to hydrogenate aryl-alkyl, diaryl, dialkyl, and cycloalkyl ketones as well as aldehydes. A very good functional group tolerance including the quantitative and selective hydrogenation of a ketone in the presence of a non-shielded olefin is observed. In Mn hydrogenation catalysis, the combination of the multidentate ligand, the oxidation state of the metal, and the choice of the right ancillary ligand is crucial for high activity. This observation emphasizes an advantage and the importance of homogeneous catalysts in 3d-metal catalysis. For coordination compounds, fine-tuning of a complex coordination environment is easily accomplished in comparison to enzyme and/or heterogeneous catalysts.

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“…The nitrogen atom may be in the coordination sphere of the transition metal or located in the ligand backbone, having no direct interaction with the metal. 3 C-H activation remains to be a topic of intense research, with a major focus on site-specific and regioselective functionalization. Intramolecular ligand-assisted metal-mediated C-H activation, via a directing group, is frequently utilized 4 but intermolecular C-H activation facilitated by a reactive ligand (Figure 1) that functions as internal base is much less explored.…”

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confidence: 99%

Intermolecular C–H activation with an Ir-METAMORPhos piano-stool complex – multiple reaction steps at a reactive ligand

et al. 2015

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Substrate activation by means of a reactive ligand is a topic of much interest. Herein we describe a stoichiometric anti-Markovnikov C-N bond formation involving ligand reactivity in multiple steps along the reaction coordinate, including ligand assisted substrate (de)protonation and C-N bond formation, as illustrated by a combined experimental, spectroscopic and computational study. This affords a highly unusual four-membered iridacycle bearing an exo-cyclic C=C double bond.

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A new class of PN3-pincer ligands for metal–ligand cooperative catalysis

Cited by 180 publications

References 105 publications

A Highly Active and Easily Accessible Cobalt Catalyst for Selective Hydrogenation of C═O Bonds

A Highly Active and Easily Accessible Cobalt Catalyst for Selective Hydrogenation of C═O Bonds

Highly Active and Selective Manganese C=O Bond Hydrogenation Catalysts: The Importance of the Multidentate Ligand, the Ancillary Ligands, and the Oxidation State

Intermolecular C–H activation with an Ir-METAMORPhos piano-stool complex – multiple reaction steps at a reactive ligand

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