Unifying Metal and Brønsted Acid Catalysis—Concepts, Mechanisms, and Classifications

Rueping, Magnus; Koenigs, René M.; Atodiresei, Iuliana

doi:10.1002/chem.201001140

Cited by 425 publications

(106 citation statements)

References 111 publications

(151 reference statements)

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“…As part of our ongoing work on the development of asymmetric carbene insertion reactions, [15] we report herein the asymmetric NÀH insertion reaction cooperatively catalyzed by dirhodium(II) carboxylates and chiral spiro phosphoric acids (SPAs). [16] Excellent reactivity and high enantioselectivity (up to 95 % ee) were achieved in the presence of as little as 0.1 mol % of catalyst.…”

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confidence: 97%

Asymmetric NH Insertion Reaction Cooperatively Catalyzed by Rhodium and Chiral Spiro Phosphoric Acids

et al. 2011

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Nitrogen-containing organic compounds, such as a-amino acids and alkaloids, are important biologically active compounds, thus the development of efficient and enantioselective methods for the construction of carbon-nitrogen bonds is a fundamental goal in modern organic synthesis.[1] Transitionmetal-catalyzed carbene insertion into N À H bonds is one of the most efficient methods to construct carbon-nitrogen bonds [2] and the development of asymmetric versions of the NÀH insertion reaction has attracted considerable attention. [3] In initial studies, chiral dirhodium catalysts were tested in intramolecular [4] and intermolecular [5] NÀH insertion reactions, however, only low to modest enantioselectivities (< 50 % ee) were achieved. Since these reports, other transition metals including copper and silver have been used as catalysts, and gave enantioselectivities up to 48 % ee.[6]Recently, we reported a highly enantioselective NÀH insertion reaction (up to 98 % ee) using a copper complex with chiral spiro bisoxazoline ligands.[7] Subsequently, two other types of chiral copper catalysts have been developed, one with a planar chiral bipyridine ligand [8] and the other with a binolderivative ligand, [9] and both of these catalysts give high enantioselectivities in NÀH insertion reactions.Although progress on copper-catalyzed asymmetric NÀH insertion reactions has been substantial, they still have serious limitations. For instance, all the copper-catalyzed N À H insertion reactions require high catalyst loading (5-10 mol %) for satisfactory yields and enantioselectivities, thus more-efficient chiral catalysts are highly desirable. Because the activity of dirhodium(II) catalysts is usually superior to that of copper catalysts in nonenantioselective NÀ H insertion reactions, [10] the possibility of using dirhodium catalysts to achieve highly enantioselective N À H insertion reactions is an intriguing one. Recently, Saito et al. [11] reported that dirhodium(II) carboxylates and cinchona alkaloids cooperatively catalyze the asymmetric NÀH insertion reactions of a-diazo-a-arylacetates with anilines. The combined catalysts exhibit excellent reactivity but only modest enantioselectivity (up to 71 % ee). It is generally accepted that the rhodium-catalyzed N À H insertion most likely proceeds via an ylide intermediate (Scheme 1 A).[2a] We speculated that the subsequent protontransfer step could be facilitated by a chiral phosphoric acid [12] species via a seven-membered-ring transition state, and that, consequently, chiral induction could be accomplished in this step (Scheme 1 B). The groups of Yu [13] and Platz [14] have reported that either water or alcohols can assist proton transfer in OÀH insertion reactions, as indicated by density functional theory calculations and ultrafast time-resolved IR spectroscopy studies. These studies stimulated our interest in exploring asymmetric N À H insertion in the presence of a proton-transfer catalyst. As part of our ongoing work on the development of asymmetric carbene insertion reaction...

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Asymmetric NH Insertion Reaction Cooperatively Catalyzed by Rhodium and Chiral Spiro Phosphoric Acids

et al. 2011

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“…the merging of organo-and metal catalysis). [9] A full overview of the enormous and rapidly expanding topic of organocatalytic one-pot reactions is outside the scope of this Minireview; instead, key success criteria and future perspectives are discussed. Moreover, a new method for the systematic classification and naming of one-pot reactions is introduced.…”

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confidence: 99%

A Simple Recipe for Sophisticated Cocktails: Organocatalytic One‐Pot Reactions—Concept, Nomenclature, and Future Perspectives

2011

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Asymmetric organocatalysis has been successfully incorporated in many multistep one-pot sequences to provide simple access to structurally complex target molecules in a highly stereoselective fashion. The key feature behind this success is the ability of organocatalyzed reactions to proceed efficiently in the presence of large amounts of spectator reagents. Additionally, owing to their organic nature and substoichiometric presence, organocatalysts are also expected to become innocent bystanders in subsequent transformations. In this Minireview, an easy-to-use classification and nomenclatural system that is capable of systematically and informatively describing each one-pot reaction is introduced, and selected important contributions within the field of organocatalytic one-pot reactions are reviewed according to this new system. Finally, future developments and perspectives in the field are discussed.

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“…[8] Zu verwandten Themen existieren mehrere exzellente und sehr detaillierte Übersichtsartikel (beispielsweise zur Vereinigung von Organo-und Metallkatalyse). [9] Eine erschçpfende Übersicht über das enorm schnell expan- Zur Vervollständigung des Klassifizierungssystems wird jede Eintopf-Transformation mit einem "Fingerprint"-Parameter versehen, der die Zahl der gebildeten Bindungen angibt. Dieser Parameter fasst die Eintopf-Reaktionskaskaden zusammen indem er sie mit der Summe der gebildeten Bindungen im Verlauf der Kaskade in Relation setzt.…”

Section: Introductionunclassified

Ein einfaches Rezept für raffinierte Cocktails: organokatalysierte Eintopf‐Reaktionen – Konzept, Nomenklatur und Ausblick

Albrecht¹,

Jiang²,

Jørgensen³

2011

Angewandte Chemie

122

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Die asymmetrische Organokatalyse konnte erfolgreich in vielen mehrstufigen Eintopf‐Sequenzen eingebunden werden und stellt so einen einfachen, hoch stereoselektiven Zugang zu strukturell komplexen Zielmolekülen dar. Der Schlüssel zu diesem Erfolg liegt in der Eigenschaft organokatalysierter Reaktionen, auch in Gegenwart großer Mengen unbeteiligter Reagentien effizient zu verlaufen. Da der Organokatalysator in substöchiometrischen Mengen vorliegt und es sich um ein organisches Molekül handelt, kann man erwarten, dass er sich in nachfolgenden Reaktionen ebenfalls als passiver Zuschauer verhält. In diesem Kurzaufsatz wird ein einfach anzuwendendes Klassifizierungs‐ und Nomenklatursystem vorgestellt, das die systematische und aussagekräftige Beschreibung von Eintopf‐Reaktionen ermöglicht, und ausgewählte Beiträge aus dem Feld der organokatalysierten Eintopf‐Reaktionen werden gemäß diesem System besprochen. Zum Schluss wird ein Ausblick auf zukünftige Entwicklungen gegeben.

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Unifying Metal and Brønsted Acid Catalysis—Concepts, Mechanisms, and Classifications

Cited by 425 publications

References 111 publications

Asymmetric NH Insertion Reaction Cooperatively Catalyzed by Rhodium and Chiral Spiro Phosphoric Acids

Asymmetric NH Insertion Reaction Cooperatively Catalyzed by Rhodium and Chiral Spiro Phosphoric Acids

A Simple Recipe for Sophisticated Cocktails: Organocatalytic One‐Pot Reactions—Concept, Nomenclature, and Future Perspectives

Ein einfaches Rezept für raffinierte Cocktails: organokatalysierte Eintopf‐Reaktionen – Konzept, Nomenklatur und Ausblick

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