Ruthenium-Catalysed Asymmetric Reduction of Ketones

Zanotti‐Gerosa, Antonio; Hems, William P.; Groarke, Michelle; Hancock, Fred

doi:10.1595/147106705x75421

Cited by 52 publications

(16 citation statements)

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“…By considering the previously reported studies and our observations, the following mechanism for the present catalytic TH can be proposed which is sketched in Scheme . According to this plausible mechanism the attack of 2‐propanol on the metal center of the catalyst, in the presence of base, produced intermediate (I).…”

Section: Resultsmentioning

confidence: 69%

Synthesis of a novel magnetic nanocatalyst based on rhodium complex for transfer hydrogenation of ketone

Kooti

Nasiri

2019

Applied Organom Chemis

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Section: Resultsmentioning

confidence: 69%

Synthesis of a novel magnetic nanocatalyst based on rhodium complex for transfer hydrogenation of ketone

Kooti

Nasiri

2019

Applied Organom Chemis

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“…Some of them display high reactivity and selectivity in many catalytic transformations and, in particular, in the hydrogenation of different unsaturated compounds, such as α,β-unsaturated ketones and imines, using molecular H 2 and transfer hydrogenation (TH) protocols as reducing agents [6][7][8][9]. The employment of these last methodologies offers attractive advantages including the use of inexpensive and easy to handle hydrogen donors instead of explosive hydrogen gas, mild reaction conditions, and the possibility of using environmentally friendly solvents such as water [10][11][12].…”

Section: Introductionmentioning

confidence: 99%

“…For example, cyclopentadienyl (Cp) and pentamethylcyclopentadienyl (Cp*) Ru(II) complexes such as [RuCpCl(PTA) 2 ], [RuCp(MeCN)(PTA) 2 ](PF 6 ), [RuCp*Cl(PTA) 2 ], active catalysts for the hydrogenation of benzylidene acetone (BZA) under H2 pressure in a biphasic water/octane solvent mixture showing a high chemoselectivity to C=C double bond reduction [18,19].…”

Section: Introductionmentioning

confidence: 99%

Ruthenium(II)-Arene Complexes of the Water-Soluble Ligand CAP as Catalysts for Homogeneous Transfer Hydrogenations in Aqueous Phase

2018

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Abstract:The neutral Ru(II) complex κP-[RuCl 2 (η 6 -p-cymene)(CAP)] (1), and the two ionic complexes κP-[RuCl(η 6 -p-cymene)(MeCN)(CAP)]PF 6 (2) and κP-[RuCl(η 6 -p-cymene)(CAP) 2 ]PF 6 (3), containing the water-soluble phosphine 1,4,7-triaza-9-phosphatricyclo[5.3.2.1]tridecane (CAP), were tested as catalysts for homogeneous hydrogenation of benzylidene acetone, selectively producing the saturated ketone as product. The catalytic tests were carried out in aqueous phase under transfer hydrogenation conditions, at mild temperatures using sodium formate as hydrogen source. Complex 3, which showed the highest stability under the reaction conditions applied, was also tested for C=N bond reduction from selected cyclic imines. Preliminary NMR studies run under pseudo-catalytic conditions starting from 3 showed the formation of κP-[RuH(η 6 -p-cymene)(CAP) 2 ]PF 6 (4) as the pivotal species in catalysis.

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“…1 Hydrogenation reactions are mostly applied in industry for the synthesis of fine chemicals, in the pharmaceutical industry for the synthesis of certain alcohol compounds, in the synthesis of agrochemicals, as well as the production of fragrances and flavours. 1 Hydrogenation reactions are mostly applied in industry for the synthesis of fine chemicals, in the pharmaceutical industry for the synthesis of certain alcohol compounds, in the synthesis of agrochemicals, as well as the production of fragrances and flavours.…”

Section: Introductionmentioning

confidence: 99%

Structural, kinetic, and DFT studies of the transfer hydrogenation of ketones mediated by (pyrazole)pyridine iron(ii) and nickel(ii) complexes

et al. 2016

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A series of iron(II) and nickel(II) complexes chelated by 2-pyrazolyl(methyl)pyridine (L1), 2,6-bis(pyrazolylmethyl)pyridine (L2), and 2,6-bis(pyrazolyl)pyridine (L3) ligands have been investigated as transfer hydrogenation (TH) catalysts for a range of ketones. Nine chelates in total were studied: (8), and [Fe(L3)Cl2] (9). Attempted crystallization of complexes 4 and 6 afforded stable six-coordinate cationic species 4a and 6a with a 2:1 ligand:metal (L:M) stoichiometry, as opposed to the monochelates that function as precursors to catalytic species for TH reactions. Crystallization of 7⋅ ⋅ ⋅ ⋅4H2O and 8⋅ ⋅ ⋅ ⋅2H2O, in contrast, afforded tri-and bis(aqua) salts of L3 chelated to Ni(II) in a 1:1 L:M stoichiometry, respectively. Complexes 1-9 formed active catalysts for TH of a range of ketones in 2-propanol at 82 °C. Both the nature of the metal ion and ligand moiety had a discernible impact on the catalytic activities of the complexes, with nickel(II) chelate 5 affording the most active catalyst (kobs, 4.3 × 10 -5 s -1 ) when the inductive phase lag was appropriately modelled in the kinetics. Iron(II) complex 3 formed the most active TH catalyst without a significant inductive phase lag in the kinetics. DFT and solid angle calculations were used to rationalize the kinetic data: both steric shielding of the metal ion and electronic effects correlating with the metal-ligand distances appear to be significant factors underpinning the reactivity of 1-9. Catalysts derived from 1 and 9 exhibit a distinct preference for aryl ketone substrates, suggesting the possible involvement of π-type catalyst⋅⋅⋅substrate adducts in their catalytic cycles. A catalytic cycle involving only 4 steps (after induction) with stable DFT-simulated structures is proposed which accounts for the experimental data for the system. Please do not adjust marginsPlease do not adjust margins catalysis in the ATH of a series of aromatic ketones using 2propanol as the hydrogen source. 19 Collectively, however,there are comparatively few reports on transfer hydrogenations of ketones in alcohols in the presence of nickel catalysts. As part of our continued investigation of late transition metal-catalysed TH reactions of ketones, 20 we herein report the use of iron(II) and nickel(II) complexes of three (pyrazolyl)pyridine-based ligands as TH catalysts for a range of ketone substrates (compounds 1-9, Scheme 2). Since TH catalysts for ketones typically operate via an induction phase (activation of a precatalyst to an active catalytic species), they are intrinsically difficult to delineate mechanistically, especially when paramagnetic intermediates are involved. We have accordingly attempted to understand some of the structural and electronic factors of the precatalysts that potentially impact on the reactivity of 1-9 using a combination of DFT simulations and solid angle calculations. By combining the information from the experimental kinetics and insights gained from DFT simulations we have proposed a 4-step catalytic cycle (after induction) that accounts ...

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Ruthenium-Catalysed Asymmetric Reduction of Ketones

Cited by 52 publications

References 0 publications

Synthesis of a novel magnetic nanocatalyst based on rhodium complex for transfer hydrogenation of ketone

Synthesis of a novel magnetic nanocatalyst based on rhodium complex for transfer hydrogenation of ketone

Ruthenium(II)-Arene Complexes of the Water-Soluble Ligand CAP as Catalysts for Homogeneous Transfer Hydrogenations in Aqueous Phase

Structural, kinetic, and DFT studies of the transfer hydrogenation of ketones mediated by (pyrazole)pyridine iron(ii) and nickel(ii) complexes

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