Knölker’s Iron Complex: An Efficient In Situ Generated Catalyst for Reductive Amination of Alkyl Aldehydes and Amines

Pagnoux‐Ozherelyeva, Anastassiya; Pannetier, Nicolas; Mbaye, Mbaye Diagne; Gaillard, Sylvain; Renaud, Jean‐Luc

doi:10.1002/anie.201201360

Cited by 163 publications

(64 citation statements)

References 81 publications

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“…As reported during our preliminary study, the tricarbonyl complex is not active in catalysis 12. The active species is the iron(II) hydride complex, which is usually prepared through the Hieber reaction, namely, treatment of 1 with aqueous sodium hydroxide followed by an acidic workup with phosphoric acid 13.…”

Section: Resultsmentioning

confidence: 84%

“…Even the Morris iron complexes, known to be efficient either in hydrogenation or hydride‐transfer reduction of acetophenone,22–24 proved to be poorly active or inactive in reductive amination. But, to our delight, Knölker’s complex yielded the alkylated amine with total conversion 12. The hydride complex is indeed the active catalyst but it is air sensitive and decomposes quickly after exposure to air.…”

Section: Resultsmentioning

confidence: 98%

“…We have recently reported that Knölker’s complex catalysed the reductive amination of aliphatic carbonyl compounds using molecular hydrogen as reducing agent (Scheme ) 12…”

Section: Introductionmentioning

confidence: 99%

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Bifunctional (Cyclopentadienone)Iron–Tricarbonyl Complexes: Synthesis, Computational Studies and Application in Reductive Amination

Moulin

Dentel

Pagnoux‐Ozherelyeva

et al. 2013

Chemistry A European J

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120

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Reductive amination under hydrogen pressure is a valuable process in organic chemistry to access amine derivatives from aldehydes or ketones. Knölker's complex has been shown to be an efficient iron catalyst in this reaction. To determine the influence of the substituents on the cyclopentadienone ancillary ligand, a series of modified Knölker's complexes was synthesised and fully characterised. These complexes were also transformed into their analogous acetonitrile iron-dicarbonyl complexes. Catalytic activities of these complexes were evaluated and compared in a model reaction. The scope of this reaction is also reported. For mechanistic insights, deuterium-labelling experiments and DFT calculations were undertaken and are also presented.

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Section: Resultsmentioning

confidence: 84%

Section: Resultsmentioning

confidence: 98%

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Bifunctional (Cyclopentadienone)Iron–Tricarbonyl Complexes: Synthesis, Computational Studies and Application in Reductive Amination

Moulin

Dentel

Pagnoux‐Ozherelyeva

et al. 2013

Chemistry A European J

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120

121

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“…Intermediate Complex D further undergoes β‐hydride elimination, leading to Fe−H complex E . Condensation of the liberated aldehyde with an amine occurs to form the imine/iminium ion, which following a reduction with the iron–hydride complex E (possibly it operates through outer‐sphere mechanism) leads to allylic amination product 3 and regeneration of the catalyst B .…”

Section: Figurementioning

confidence: 99%

Iron‐Catalyzed Allylic Amination Directly from Allylic Alcohols

Emayavaramban

Roy

Sundararaju

2016

Chemistry A European J

107

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Allylic amination, directly from alcohols, has been demonstrated without any Lewis acid activators using an efficient and regiospecific molecular iron catalyst. Various amines and alcohols were employed and the reaction proceeded through the oxidation/reduction (redox) pathway. A direct one-step synthesis of common drugs, such as cinnarizine and nafetifine, was exhibited from cinnamyl alcohol that produced water as side product.

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“…[17] Importantly, Knçlker's complexes can be easily produced in situ and have been successfully applied in various organic redox reactions. [18] Owing to their uniquely powerful redox catalyst properties, they possess great potential as efficient WRCs in the presence of a heteroleptic CuPS (Scheme 1). We report herein on the use of a series of Knçlker iron complexes as mimics for mononuclear iron-based hydrogenases, which have proved to be highly active catalysts for water reduction.…”

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confidence: 99%

Efficient Photocatalytic Water Reduction Using In Situ Generated Knölker's Iron Complexes

et al. 2016

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In situ generated iron-based Knçlker complexes were found to be efficient catalysts in a fully non-noble metal Cu-Fe photocatalytic water reduction system. These mononuclear iron catalysts were able to generate hydrogen up to 15 times faster than previously reported [Fe 3 (CO) 12 ]. A reductive quenching mechanism was shown to operate by fluorescence experiments.Artificial photosynthesis is considered to offer solutions for the current energy crisis and to decrease environmental pollution, because it directly converts sunlight energy into chemical energy. Among the various concepts, the most direct and clean method to convert photochemical energy into chemicals is the splitting of water into O 2 and H 2 .[1] Despite tremendous effort in this area, [2] significant challenges for its application still exist owing to low efficiencies of the light absorption materials, [3] redox catalysts, [4] and full-cell systems. [5] To improve current systems and to gain better understanding of the overall water-splitting process, the individual half reactions (proton reduction and water oxidation) are generally studied separately. Over the past decades, numerous, highly active, water reduction catalysts (WRCs) for photocatalytic hydrogen generation have been developed, [6] most of which are derived from precious metals such as platinum, [7] palladium, [8] rhodium, [9] and ruthenium.[10] As a result of the high price and limited availability of these precious metals, the development of WRCs based on biorelevant or earth-abundant transition metals is highly desirable. Recently, non-noble metal alternatives, for example, cobalt [11] and nickel [12] complexes, have been examined as active hydrogen-generation catalysts. In addition, nature has developed an iron-based hydrogenase (with up to 9000 molecules of H 2 per second and site) for proton reduction, [13] which makes it appealing for WRC applications. [14] In 2009, Beller demonstrated that simple, cheap, and readily available iron carbonyls can act as WRCs.[15] In combination with a noble metal photosensitizer (PS), [Ir(bpy)(ppy) 2 ]PF 6 (bpy: 2,2'-bipyridyl; ppy: 2-phenylpyridine), high activities were achieved. This was followed by a new non-noble metal water reduction system that employed [Fe 3 (CO) 12 ] as a WRC and a heteroleptic copper complex as PS. Both oxidative and reductive quenching pathways of the excited state of the copper(I) photosensitizer (CuPS) were confirmed in this Cu-Fe system.[16] Herein, we envisioned that mononuclear iron tricarbonyl cyclopentadienone complexes might become an efficient substitute for [Fe 3 (CO) 12 ]. In general, Knçlker's precursor complexes are stable under contact with air and water and are easily accessible from simple and cheap precursors.[17] Importantly, Knçlker's complexes can be easily produced in situ and have been successfully applied in various organic redox reactions.[18] Owing to their uniquely powerful redox catalyst properties, they possess great potential as efficient WRCs in the presence of a heteroleptic C...

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Knölker’s Iron Complex: An Efficient In Situ Generated Catalyst for Reductive Amination of Alkyl Aldehydes and Amines

Abstract: An aminated series: a well-defined iron-catalyzed reductive amination reaction of aldehydes and ketones with aliphatic amines using molecular hydrogen is presented. Under mild conditions, good yields for a broad range of alkyl ketones as well as aldehydes were achieved.

Cited by 163 publications

References 81 publications

Bifunctional (Cyclopentadienone)Iron–Tricarbonyl Complexes: Synthesis, Computational Studies and Application in Reductive Amination

Bifunctional (Cyclopentadienone)Iron–Tricarbonyl Complexes: Synthesis, Computational Studies and Application in Reductive Amination

Iron‐Catalyzed Allylic Amination Directly from Allylic Alcohols

Efficient Photocatalytic Water Reduction Using In Situ Generated Knölker's Iron Complexes

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