Asymmetrische Katalyse mit hinsichtlich Struktur und Funktion gezielt entworfenen Molekülen: die chemo- und stereoselektive Hydrierung von Ketonen

Noyori, Ryoji; Ohkuma, Takeshi

doi:10.1002/1521-3757(20010105)113:1<40::aid-ange40>3.0.co;2-k

Cited by 408 publications

(11 citation statements)

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“…The key mechanistic steps usually include a reversible switching between the coordination modes of the ligands that are bound to the catalytically active metal center (Scheme 1).For example, metal-amide/metal-amine interconversion, originally described by Noyori and Ikariya, [1] led to the discovery of very efficient asymmetric hydrogenation catalysts. [2] Aromatization/dearomatization in heteroaromatic PNP and PNN pincer ligands made nonoxidative activation of HÀH, [3] CÀH, [4] and NÀH [5] bonds possible and a family of hydrogenation/dehydrogenation catalysts was established by Milstein. [6] Nonaromatic switchable PNP pincer systems have been proven to facilitate heterolytic bond cleavage and catalyze transfer [7] and acceptorless dehydrogenation/hydrogenation reactions.…”

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confidence: 99%

Ligand–Metal Cooperating PC(sp³)P Pincer Complexes as Catalysts in Olefin Hydroformylation

Musa

Filippov

Belkova

et al. 2013

Chemistry A European J

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In recent years, metal complexes, in which both the metal center and the ligand play active and cooperative roles, have emerged as very promising catalysts, capable of activating and forming chemical bonds through nonoxidative pathways (i.e., alternative to the conventional oxidative addition/reductive elimination sequence). The key mechanistic steps usually include a reversible switching between the coordination modes of the ligands that are bound to the catalytically active metal center (Scheme 1).For example, metal-amide/metal-amine interconversion, originally described by Noyori and Ikariya, [1] led to the discovery of very efficient asymmetric hydrogenation catalysts. [2] Aromatization/dearomatization in heteroaromatic PNP and PNN pincer ligands made nonoxidative activation of HÀH, [3] CÀH, [4] and NÀH [5] bonds possible and a family of hydrogenation/dehydrogenation catalysts was established by Milstein. [6] Nonaromatic switchable PNP pincer systems have been proven to facilitate heterolytic bond cleavage and catalyze transfer [7] and acceptorless dehydrogenation/hydrogenation reactions. [8] So far, ligand-metal cooperation relies on a dynamic interplay between carbometalated and a-or b-H eliminated species in electron rich CA C H T U N G T R E N N U N G (sp 3 )-metalated pincer complexes, [9] as well as on keto-enol [10] or lactam-lactim tautomerism. [11] These systems established a basis for the design of mild catalysts for nonoxidative (de)hydrogenation processes [12] and chemoselective H/D exchange. [13] The examples are impressive, however, they provide only a hint of the real synthetic potential concealed in ligandmetal cooperation. Therefore, we strongly believe that further extension of this concept to new reaction schemes will eventually lead to the discovery of conceptually novel catalysis.Herein, we wish to report on the development of Ir III -and Rh III -based catalysts that are capable of promoting olefin hydroformylation through the unprecedented metal-ligand cooperating mechanism. In our previous work, we developed the Ir III PCA C H T U N G T R E N N U N G (sp 3 )P pincer complex 1, which forms molecular hydrogen by an intramolecular interaction that involves both the metal center (hydride) and a polar O-based ligand sidearm (Scheme 2). [14] The catalyst showed very high activity in the acceptorless dehydrogenation of primary and secondary alcohols. We also observed that the release of molecular hydrogen is efficiently intercepted by the presence of unsaturated substrates.Based on this observation, we hypothesized that the hydroformylation of double bonds may proceed through a reversed metal-ligand cooperating mechanism (Scheme 3). The hypothetical catalytic cycle is likely to include the following elementary steps: i) heterolytic nonoxidative H 2 activation by the species a through alkoxide ring-opening to form the M À H complex b; ii) migratory insertion of an alkene into the Ir À H bond, resulting in the formation of c; iii) carbonylation of c, followed by migratory insertion of CO into th...

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confidence: 99%

Ligand–Metal Cooperating PC(sp³)P Pincer Complexes as Catalysts in Olefin Hydroformylation

Musa

Filippov

Belkova

et al. 2013

Chemistry A European J

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“…[1] However, this concept of a metal and its ligand acting in concert is still strongly under-explored in synthetic chemistry with first-row transition metals, although for heavier analogues this has provided new routes to the formation and functionalization of useful building blocks. [2] Recently, a family of pincer ligands [3] was demonstrated to enable cooperative catalysis. [4] Strikingly, relatively little attention has been paid to the chemistry of Fe, [5] Co, [6,7] and Ni [8][9][10] with these noninnocent ligand frameworks relative to the elegant reactivity detailed for their heavier congeners.…”

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Dinuclear Copper(I) Thiolate Complexes with a Bridging Noninnocent PNP Ligand

Vlugt

Pidko

Bauer

et al. 2011

Chemistry A European J

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Noninnocent, but not guilty: The versatile PNPtBu scaffold acts as a noninnocent, pseudobridging ligand toward CuX (ratio 1:2), resulting in a 1D‐coordination chain. Ligand dearomatization by using base and subsequent addition of thiols leads to the unique, asymmetrically substituted, dinuclear Cu species with reactive Br coligands and the versatile PNPtBu ligand that bridges the two Cu centers (see scheme).

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“…Owing to their structure which is similar to that of Noyori's complex 4, 34 the Ru compounds exhibit catalytic activity for hydrogenation reactions. Multiple cyclic voltammetry for redox screening was applied to a library of 36 Ru͑II͒ complexes 1-3 ͑Fig.…”

Section: F Redox Screening Of Compound Librariesmentioning

confidence: 96%

Combinatorial microelectrochemistry: Development and evaluation of an electrochemical robotic system

Erichsen

Reiter

Ryabova

et al. 2005

Review of Scientific Instruments

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Articles you may be interested inIn operando observation system for electrochemical reaction by soft X-ray absorption spectroscopy with potential modulation method Rev. Sci. Instrum. 85, 104105 (2014); 10.1063/1.4898054 Sonochemically precipitated spinel Co 3 O 4 and NiCo 2 O 4 nanostructures as an electrode materials for supercapacitor AIP Conf. Proc. 1512, 1216 (2013); 10.1063/1.4791488Pt metal-CeO 2 interaction: Direct observation of redox coupling between Pt 0 / Pt 2 + / Pt 4 + and Ce 4 + / Ce 3 + states in Ce 0.98 Pt 0.02 O 2 − δ catalyst by a combined electrochemical and x-ray photoelectron spectroscopy study An electrochemical robotic system using standard microtiter plates as reaction wells for potentiostatic and galvanostatic electrosynthesis and high-throughput electroanalysis was conceived and realized using stepmotor driven positioning stages in combination with a flexible software. Electrode bundles specifically adapted to the experimental needs are accurately positioned in the wells of a microtiter plate followed by the automatic performance of sequences of electrosynthetic or electroanalytical techniques. The system allows us to work under inert-gas atmosphere, in aqueous and organic solvents, and to add or remove solutions by means of integrated syringe pumps. A specifically developed script language permits the user to perform very complex experimental sequences in the different wells of the microtiter plate. The hardware and software features of the developed electrochemical robotic system, the design of suitable electrode arrangements for electrosynthesis and electroanalytical techniques, as well as the reproducibility in aqueous and organic electrolytes are described. The performance of the system is demonstrated by redox screening of a Ru-complex library and by electrosynthesis with in situ analysis of a compound library.

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Asymmetrische Katalyse mit hinsichtlich Struktur und Funktion gezielt entworfenen Molekülen: die chemo- und stereoselektive Hydrierung von Ketonen

Cited by 408 publications

References 353 publications

Ligand–Metal Cooperating PC(sp³)P Pincer Complexes as Catalysts in Olefin Hydroformylation

Ligand–Metal Cooperating PC(sp³)P Pincer Complexes as Catalysts in Olefin Hydroformylation

Dinuclear Copper(I) Thiolate Complexes with a Bridging Noninnocent PNP Ligand

Combinatorial microelectrochemistry: Development and evaluation of an electrochemical robotic system

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Asymmetrische Katalyse mit hinsichtlich Struktur und Funktion gezielt entworfenen Molekülen: die chemo- und stereoselektive Hydrierung von Ketonen

Cited by 408 publications

References 353 publications

Ligand–Metal Cooperating PC(sp3)P Pincer Complexes as Catalysts in Olefin Hydroformylation

Ligand–Metal Cooperating PC(sp3)P Pincer Complexes as Catalysts in Olefin Hydroformylation

Dinuclear Copper(I) Thiolate Complexes with a Bridging Noninnocent PNP Ligand

Combinatorial microelectrochemistry: Development and evaluation of an electrochemical robotic system

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Ligand–Metal Cooperating PC(sp³)P Pincer Complexes as Catalysts in Olefin Hydroformylation

Ligand–Metal Cooperating PC(sp³)P Pincer Complexes as Catalysts in Olefin Hydroformylation