Iron(II)‐Catalyzed Asymmetric Hydrosilylation of Acetophenone

Flückiger, Michelle; Togni, Antonio

doi:10.1002/ejoc.201100550

Cited by 41 publications

(20 citation statements)

References 48 publications

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“…Togni has shown that an in-situ-formed catalyst from cyclopentadienyl-bearing chiral diamine (L26) and Fe(acac) 2 promoted the reduction of ketones affording the corresponding alcohols with conversion up to 99% but with low to moderate ee up to 37% (Scheme 70). 296 Pincer-type iron complexes, which are usually more stable and efficient in hydrogenation, were also extensively reported in hydrosilylation of carbonyl compounds.…”

Section: Aldehydes and Ketonesmentioning

confidence: 99%

Iron Catalysis in Reduction and Hydrometalation Reactions

2018

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The last two decades have seen an impressive improvement of the use of iron as a fascinating and valuable alternative transition metal in homogeneous catalysis in terms of sustainability and economy. It was efficiently used in catalytic organic synthetic transformations, which in particular include the reduction of unsaturated bonds. This review summarizes the fast development and the recent advances in selective reductions of olefins, alkynes, carbonyl and carboxylic derivatives, imines, and nitro compounds promoted by iron catalysts. The topical hydrogen-borrowing reactions and hydroboration of unsaturated compounds are also reported. It is hoped that this account not only provides an overview of the state of the art in iron catalysis but also stimulates the development of superior greener catalytic systems in the near future.

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Section: Aldehydes and Ketonesmentioning

confidence: 99%

Iron Catalysis in Reduction and Hydrometalation Reactions

2018

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“…Coordinatively unsaturated transition metal (TM) carbonyls are known to catalyze various processes, primarily the hydrogenation, isomerization, and hydroformylation of olefins, − C–H bond activation, and Fischer–Tropsch and water–gas-shift reactions. ,, Iron carbonyls are widely used in manufacturing new materials and epitaxial layers . Fe(CO) 5 is particularly used in preparation of carbon nanotubes via the catalytic chemical vapor deposition, where molecular hydrogen plays an important role in the growth and microstructure of nanotubes .…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Iron Carbonyl-Catalyzed Hydrogenation of Ethylene. 1. Theoretical Exploration of Molecular Pathways

Asatryan

Ruckenstein

2013

J. Phys. Chem. A

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The hydrogenation of alkenes catalyzed by metal carbonyls is an intricate process involving reactions of various isomers of labile π- and σ-complexes, hydrides, dihydrides, and their radicals. Two general mechanisms have been suggested in the literature regarding the catalytic hydrogenation of simple alkenes by photochemically activated iron pentacarbonyl: a molecular mechanism that involves the sequential replacement of two carbonyl ligands by hydrogen and unsaturated ligands, and a radical mechanism involving the EPR-identified iron carbonyl hydride radicals. Even though significant results were obtained in numerous experiments and few theoretical studies, these mechanisms remain phenomenological, without detailed information regarding the potential energy surfaces (PES) and the elementary processes. Several major issues also remain open. It is still unclear, for instance, whether the ethane can be formed via a monomolecular reaction of ethyl hydride isomer intermediates HFe(CO)3(C2H5) or the only way to produce C2H6 is a bimolecular reaction assisted by a second ethylene. It is also uncertain if a dihydride or a dihydrogen complex is operating in olefin hydrogenation. To gain insight into these processes, a detailed theoretical examination of various PES for gas-phase reactions of ethylene with potential metallocomplex reagents to primary and secondary products (both singlet and triplet electronic states) was performed using DFT and ab initio methods. Calculations have been carried out for a set of reactions of ethylene with all possible isomers of tricarbonyliron hydrogenates, viz., dihydrides of trans-, cis-, and gauche-configurations (isomers with respect to the two hydridic atoms), and two nonclassical singlet and two triplet dihydrogen complexes, some of them being identified for the first time. The hydrogenation pathways (both molecular and radical) are shown to be strongly stereoselective and dependent on the spin configurations of the initial reagents. The combination of various dihydride isomers with C2H4 as separate reaction channels allowed us to explore relevant PES cross sections and to identify corresponding stereoregulated elementary processes. The reaction channels can alternatively start from the association of ethylene with dihydrogen tricarbonyliron complexes and may involve intersystem crossings with triplet pathways, followed by that of the corresponding singlet PES. Various interconversion and isomerization processes involving single-olefin adducts were found to precede the major ethane-elimination reactions (through both monomolecular and second-ethylene-assisted pathways). Monomolecular processes are suggested to occur under appropriate conditions. The stereospecific mechanistic results and thermochemical parameters constitute a basis for developing detailed kinetic models for iron-carbonyl catalysis.

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“…Recently, nontoxic and cheap, but achiral, iron catalysts have been mainly used in hydrogenation, hydrosilylation, and cross-coupling reactions . In contrast, only a handful of chiral catalysts have been developed for enantioselective transformations such as hydrosilylation, direct H 2 -hydrogenation (AH), and transfer hydrogenation − of ketones (ATH). Despite spectacular advances, the stability of iron catalysts is still a major issue.…”

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confidence: 99%

Isonitrile Iron(II) Complexes with Chiral N₂P₂ Macrocycles in the Enantioselective Transfer Hydrogenation of Ketones

Bigler

Mezzetti

2014

Org. Lett.

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Iron(II)‐Catalyzed Asymmetric Hydrosilylation of Acetophenone

Cited by 41 publications

References 48 publications

Iron Catalysis in Reduction and Hydrometalation Reactions

Iron Catalysis in Reduction and Hydrometalation Reactions

Mechanism of Iron Carbonyl-Catalyzed Hydrogenation of Ethylene. 1. Theoretical Exploration of Molecular Pathways

Isonitrile Iron(II) Complexes with Chiral N₂P₂ Macrocycles in the Enantioselective Transfer Hydrogenation of Ketones

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Iron(II)‐Catalyzed Asymmetric Hydrosilylation of Acetophenone

Cited by 41 publications

References 48 publications

Iron Catalysis in Reduction and Hydrometalation Reactions

Iron Catalysis in Reduction and Hydrometalation Reactions

Mechanism of Iron Carbonyl-Catalyzed Hydrogenation of Ethylene. 1. Theoretical Exploration of Molecular Pathways

Isonitrile Iron(II) Complexes with Chiral N2P2 Macrocycles in the Enantioselective Transfer Hydrogenation of Ketones

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Isonitrile Iron(II) Complexes with Chiral N₂P₂ Macrocycles in the Enantioselective Transfer Hydrogenation of Ketones