Asymmetric heterogeneous catalytic hydrogenation; is it a useful tool for the synthetic organic chemist?

Tungler, Antal; Sı́pos, É.; Háda, Viktor

doi:10.3998/ark.5550190.0005.718

Cited by 16 publications

(1 citation statement)

References 60 publications

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“…(Immobilized chiral metal complexes traditionally belong to homogeneous catalysis and will not be discussed here.) The progress in the past years in heterogeneous enantioselective catalysis is indicated by the rapidly growing number of scientific publications and also by the expanding circle of highly enantioselective synthetic applications (for recent general reviews, see refs [1][2][3][4][5]. The relevance of chirally modified metals in asymmetric synthesis induced a flourishing of surface science studies aimed at understanding the fundamental properties of chiral surfaces.…”

Section: Introductionmentioning

confidence: 99%

Asymmetric Catalysis at Chiral Metal Surfaces

2007

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He continued his academic carrier at the Organic Chemical Technology Research Group of the Hungarian Academy of Sciences. In 1990, he moved to ETH Zurich, where he is currently a scientist. He was awarded a D.Sc. degree in 1994 by the Hungarian Academy of Sciences. His main scientific interests are the application of heterogeneous catalysts in the synthesis of fine chemicals, including asymmetric catalysis, oxidation, and hydrogenation reactions, and the application of electrochemical methods in catalysis.

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Section: Introductionmentioning

confidence: 99%

Asymmetric Catalysis at Chiral Metal Surfaces

2007

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Asymmetrische heterogene Katalyse

2006

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Knapper werdende Rohstoffe und ein zunehmender Bedarf an enantiomerenreinen Verbindungen machen die Katalyse und insbesondere die heterogene asymmetrische Katalyse zu einer Schlüsseltechnologie. Von den Anfängen, der Verwendung chiraler Biopolymere wie Seide als Träger für Metallkatalysatoren, zu den modernen Forschungsfeldern hat sich das Gebiet rasant entwickelt. Mesoporöse Träger, nichtkovalente Immobilisierung, metall‐organische Katalysatoren, chirale Modifikatoren: viele Gebiete sind im Aufbruch. Dass hierbei von den Katalysatoren mehr geleistet wird, als nur leichte Abtrennung und Wiederverwendung zu ermöglichen, zeigt dieser Aufsatz. So können z. B. bessere Aktivitäten und Selektivitäten als bei der homogenen Katalyse und zudem neuartige, effiziente Reaktionsmechanismen erhalten werden. Besonders spektakulär ist aber der Ausblick auf hochgeordnete metall‐organische Katalysatoren, die “rational” entwickelt, synthetisiert und strukturell eindeutig charakterisiert werden können, um maßgeschneiderte Katalysatoren zu erhalten.

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Heterogeneous Enantioselective Hydrogenation of Aromatic Ketones Catalyzed by Cinchona‐ and Phosphine‐Modified Iridium Catalysts

Yang

et al. 2008

Angewandte Chemie

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Dedicated to the Catalysis Society of Japan on the occasion of the 50th anniversary Heterogeneous catalytic systems for asymmetric reactions are fascinating because of their potential in synthetic applications.[1] However, because of the high substrate specificity of these catalysts, the complexity of the task at hand, and the difficulties in understanding and designing the catalytic reactions, there have been just three established systems reported.[1a] One system identified for asymmetric hydrogenation is the cinchona-modified Pt/Al 2 O 3 for asymmetric hydrogenation of a-keto esters, which was developed by Orito et al. in 1979. [2] Baiker et al. successfully used this catalyst in the asymmetric hydrogenation of activated aromatic ketones.[3] However, when considering the asymmetric hydrogenation of simple aromatic ketones and derivatives, which are among the most fundamental subjects in modern synthetic chemistry, few successful heterogeneous catalytic examples are reported.Chiral modifiers are the origin of the enantioselectivity in most heterogeneous catalytic reactions, and natural cinchona alkaloids and their derivatives have been widely used as versatile chiral catalysts, ligands, column packing, and chiral shift reagents.[4] Two of the three most well-known heterogeneous catalytic systems in asymmetric reactions are based on natural cinchona alkaloids and their derivatives as the chiral modifiers. [2,5] Stabilizers, which are widely used in preparing nanometal catalysts, including amines, [6] phosphines, [7] and thiols, [8] have been gradually introduced into supported catalysts in recent years. We previously reported polyvinylpyrrolidone (PVP) and cinchona-stabilized Rh in the asymmetric hydrogenation of a-keto esters, in which moderate to good enantioselectivities were obtained.[9] Meanwhile, little attention has been paid to the preparation of supported metal catalysts stabilized by phosphines. Reported herein is a Ph 3 Pstabilized Ir/SiO 2 catalyst system modified by a chiral diamine, derived from cinchona alkaloids, for the asymmetric hydrogenation of simple aromatic ketones and their derivatives; the results are compared to known homogeneous catalysts.[10] To the best of our knowledge, this is the first report of the asymmetric hydrogenation of simple aromatic ketones with a greater than 95 % ee by using a new heterogeneous catalyst. This report is also the first successful example of the asymmetric hydrogenation of simple aromatic ketones employing Ir and H 2 .The high-resolution transmission electron microscopy (HRTEM) picture ( Figure 1 in the Supporting Information) of 3 %Ir/SiO 2 /2tpp (tpp = triphenylphosphine) showed that Ir is highly dispersed on the SiO 2 as an amorphous agglomerate. The X-ray photoelectron spectroscopy (XPS) analysis indicated that the metal component is present in a reduced state (Ir 4f 7/2 core level centered at 61.6 eV) compared to Ir 0 (Ir 4f 7/2 core level centered at 60.8 eV), [11] and the binding energy (103.5 eV) of Si 2p is similar to the expected value (103.4 ...

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Asymmetric heterogeneous catalytic hydrogenation; is it a useful tool for the synthetic organic chemist?

Abstract: The evaluation of different asymmetric hydrogenation methods is presented: the use of anchored chiral transition metal complexes modified metal catalysts and diastereoselective reactions, partly with chiral synthons. Recent results and perspectives are summarized.

Cited by 16 publications

References 60 publications

Asymmetric Catalysis at Chiral Metal Surfaces

Asymmetric Catalysis at Chiral Metal Surfaces

Asymmetrische heterogene Katalyse

Heterogeneous Enantioselective Hydrogenation of Aromatic Ketones Catalyzed by Cinchona‐ and Phosphine‐Modified Iridium Catalysts

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