A ruthenium racemisation catalyst for the synthesis of primary amines from secondary amines

Pingen, Dennis; Altıntaş, Çiğdem; Schaller, Max; Vogt, Dieter

doi:10.1039/c6dt01525e

Cited by 8 publications

(3 citation statements)

References 34 publications

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“…The acidic proton on the hydroxycyclopentadienyl ligand was suspected to be related to the high RWGS activity. Accordingly, by replacing the hydroxyl group with the phenyl substituent, complex 4 was synthesized for comparing with Shov’s catalyst. As expected, the TON CO dropped from 89 to 11 even in the presence of LiCl when applying complex 4 as the catalyst.…”

Section: Resultsmentioning

confidence: 99%

Selectivity Switching of CO₂ Hydrogenation from HCOOH to CO with an In Situ Formed Ru–Li Complex

et al. 2021

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Herein, we report the role of alkali halide salt in regulating the pathway of CO 2 hydrogenation in the presence of Shvo's complex. Particularly, the collaboration of Shvo's complex with LiCl exhibited as a highly efficient catalyst for CO 2 hydrogenation to CO instead of the kinetically favorable product HCOOH under mild conditions. The reaction can be initiated at 45 °C with CO as the dominant product, and the rate of CO formation was almost 80 times to that in the absence of LiCl at 60 °C. Under optimized conditions, the TON CO could reach 1555 at 160 °C, much higher than the reported results of the most efficient Ru-based homogeneous catalyst. Density functional theory calculations demonstrated that the cooperation of the alkali cation and chloride anion contributed to reducing the energy barrier of CO 2 activation to form the key Ru−CO 2 H intermediate. An in situ formed mixed Ru−Li complex (5) has been characterized by X-ray crystallography, highlighting the indispensability of electrostatic interactions between LiCl and Shvo's complex for enhanced reactivity and altered selectivity.

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Section: Resultsmentioning

confidence: 99%

Selectivity Switching of CO₂ Hydrogenation from HCOOH to CO with an In Situ Formed Ru–Li Complex

et al. 2021

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“…Beller and co-workers, as well as our research group, reported that secondary and tertiary amines can also be catalytically cleaved with ammonia following deaminative coupling. [2,10] The homogeneously catalyzed amination of alcohols offers some advantages for the synthesis of primary amines compared to heterogeneous systems: The use of molecular hydrogen is not required, and milder reaction conditions can be used, leading to more selective syntheses of primary amines, as shown by the groups of Milstein, Fujita, Beller and Schaub, and our research group. [6,11,[12][13][14][15][16][17] For example, different studies on the amination of 1-octanol (1) with ammonia (Table 1) already showed that the combination of ruthenium precursors like HRuCl(CO)(PPh 3 ) 3 and unique ligands like the Milstein-Ligand (L1) and Triphos (L2) yield primary amines with high selectivities, good catalytic activity only using a slight ammonia excess(Table 1, entries 1 and 2).…”

Section: Introductionmentioning

confidence: 92%

“…However, their formation is highly dependent on the sterical demand of the substrate. Beller and co‐workers, as well as our research group, reported that secondary and tertiary amines can also be catalytically cleaved with ammonia following deaminative coupling [2,10] …”

Section: Introductionmentioning

confidence: 95%

Selective Synthesis of Primary Amines by Kinetic‐based Optimization of the Ruthenium‐Xantphos Catalysed Amination of Alcohols with Ammonia

et al. 2022

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The selective synthesis of primary amines directly from several alcohols and ammonia using a homogeneous catalyst based on HRuCl(CO)(PPh 3 ) 3 and Xantphos is presented. The key to success was the detailed understanding of all mutually influencing parameters such as temperature, ammonia excess, and substrate concentration. These studies were supported by the determination of the kinetics, which allowed the reaction order to be calculated as 0.7. Furthermore, the kinetic model derived from the mechanism was confirmed. After measuring reaction profiles for all influencing parameters, optimized conditions were obtained, which finally allowed the amination of aliphatic, cyclic, as well as primary and secondary alcohols with selectivities to the desired primary amine exceeding 90 % at quantitative alcohol conversion with only minimal formation of the undesired secondary amines. Furthermore, the catalytic activity of the commercially available and robust Xantphos system was drastically improved, corresponding to a turnover frequency (TOF) > 60 h À 1 after 30 minutes and a turnover number (TON) of 120.

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Triazolylidene‐Iridium Complexes with a Pendant Pyridyl Group for Cooperative Metal–Ligand Induced Catalytic Dehydrogenation of Amines

Valencia

Pereira

Müller‐Bunz

et al. 2017

Chemistry A European J

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Two iridium(III) complexes containing a C,N-bidentate pyridyl-triazolylidene ligand were prepared that are structurally very similar but differ in their pendant substituent. Whereas complex 1 contains a non-coordinating pyridyl unit, complex 2 has a phenyl group on the triazolylidene substituent. The presence of the basic pyridyl unit has distinct effects on the catalytic activity of the complex in the oxidative dehydrogenation of benzylic amines, inducing generally higher rates, higher selectivity towards formation of imines versus secondary amines, and notable quantities of tertiary amines when compared to the phenyl-functionalized analogue. The role of the pyridyl functionality has been elucidated from a set of stoichiometric experiments, which demonstrate hydrogen bonding between the pendant pyridyl unit and the amine protons of the substrate. Such N ⋅⋅⋅H-N interactions are demonstrated by X-ray diffraction analysis, H NMR, and IR spectroscopy, and suggest a pathway of substrate bond-activation that involves concerted substrate binding through the Lewis acidic iridium center and the Lewis basic pyridyl site appended to the triazolylidene ligand, in agreement with ligand-metal cooperative substrate activation.

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A ruthenium racemisation catalyst for the synthesis of primary amines from secondary amines

Cited by 8 publications

References 34 publications

Selectivity Switching of CO₂ Hydrogenation from HCOOH to CO with an In Situ Formed Ru–Li Complex

Selectivity Switching of CO₂ Hydrogenation from HCOOH to CO with an In Situ Formed Ru–Li Complex

Selective Synthesis of Primary Amines by Kinetic‐based Optimization of the Ruthenium‐Xantphos Catalysed Amination of Alcohols with Ammonia

Triazolylidene‐Iridium Complexes with a Pendant Pyridyl Group for Cooperative Metal–Ligand Induced Catalytic Dehydrogenation of Amines

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A ruthenium racemisation catalyst for the synthesis of primary amines from secondary amines

Cited by 8 publications

References 34 publications

Selectivity Switching of CO2 Hydrogenation from HCOOH to CO with an In Situ Formed Ru–Li Complex

Selectivity Switching of CO2 Hydrogenation from HCOOH to CO with an In Situ Formed Ru–Li Complex

Selective Synthesis of Primary Amines by Kinetic‐based Optimization of the Ruthenium‐Xantphos Catalysed Amination of Alcohols with Ammonia

Triazolylidene‐Iridium Complexes with a Pendant Pyridyl Group for Cooperative Metal–Ligand Induced Catalytic Dehydrogenation of Amines

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Selectivity Switching of CO₂ Hydrogenation from HCOOH to CO with an In Situ Formed Ru–Li Complex

Selectivity Switching of CO₂ Hydrogenation from HCOOH to CO with an In Situ Formed Ru–Li Complex