First Examples of Improved Catalytic Asymmetric C−C Bond Formation Using the Monodentate Ligand Combination Approach

Duursma, Ate; Hoen, Rob; Schuppan, Julia; Hulst, Ron; Minnaard, and Adriaan J.; Feringa, Ben L.

doi:10.1021/ol035106o

Cited by 139 publications

(47 citation statements)

References 24 publications

(21 reference statements)

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“…[220] In the case of a simple ML 2 model with a mixture of two different enantiopure monodentate ligands, L x and L y , three types of catalysts, Classical nonlinear effects can be considered to result from a library of complexes built from two enantiomeric ligands (ML 2 , ML 3 , ML 4 etc). The use of a mixture of different ligands creates a more complicated library of complexes, which can give rise to interesting nonlinear effects.…”

Section: Mixtures Of Nondiastereomeric Chiral Complexesmentioning

confidence: 99%

Nonlinear Effects in Asymmetric Catalysis

Satyanarayana¹,

Abraham²,

Kagan³

2008

Angew Chem Int Ed

488

273

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There is a need for the preparation of enantiomerically pure compounds for various applications. An efficient approach to achieve this goal is asymmetric catalysis. The chiral catalyst is usually prepared from a chiral auxiliary, which itself is derived from a natural product or by resolution of a racemic precursor. The use of non-enantiopure chiral auxiliaries in asymmetric catalysis seems unattractive to preparative chemists, since the anticipated enantiomeric excess (ee) of the reaction product should be proportional to the ee value of the chiral auxiliary (linearity). In fact, some deviation from linearity may arise. Such nonlinear effects can be rich in mechanistic information and can be synthetically useful (asymmetric amplification). This Review documents the advances made during the last decade in the use of nonlinear effects in the area of organometallic and organic catalysis.

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Section: Mixtures Of Nondiastereomeric Chiral Complexesmentioning

confidence: 99%

Nonlinear Effects in Asymmetric Catalysis

Satyanarayana¹,

Abraham²,

Kagan³

2008

Angew Chem Int Ed

488

273

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“…Bei Verwendung von nur einem chiralen Liganden tritt oft auch der gegenteilige Effekt auf. [102,103] Mit Gemischen verschiedener chiraler einzähniger Phosphonite L13-L14 konnten bei der Rh-katalysierten Hydrierung der substituierten Alkene 14 bessere Enantioselektivitäten erzielt werden als mit nur einem chiralen Liganden (Schema 4). [94,100] Der gleiche Ansatz wurde auch auf andere Umsetzungen angewendet, beispielsweise die C-C-Verknüpfung (siehe unten).…”

Section: Phosphoramidite: Struktur Synthese Und Eigenschaftenunclassified

Phosphoramidite: privilegierte Liganden in der asymmetrischen Katalyse

2010

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Die asymmetrische Katalyse mit Übergangsmetallkomplexen ist die Grundlage unzähliger stereoselektiver Umwandlungen und hat damit das Bild der modernen Synthesechemie gewandelt. Der Schlüssel zum Erfolg war die Entwicklung chiraler Liganden zur Kontrolle der Regio‐, Diastereo‐ und Enantioselektivität. Dabei haben sich Phosphoramidite als eine äußerst vielseitige und leicht zugängliche Klasse von chiralen Liganden erwiesen. Ihre modulare Struktur ermöglicht die Herstellung von Ligandenbibliotheken und erleichtert die Feinabstimmung für eine bestimmte katalytische Reaktion. Phosphoramidite bewirken oft außerordentlich hohe Stereoselektivitäten, und ihre einzähnige Natur ist in der kombinatorischen Katalyse, die gemischte Liganden verwendet, unverzichtbar. In diesem Aufsatz werden neue Entwicklungen in der asymmetrischen Katalyse mit Phosphoramiditen diskutiert, wobei der Schwerpunkt auf der Bildung von Kohlenstoff‐ Kohlenstoff‐ und Kohlenstoff‐Heteroatom‐Bindungen liegt.

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“…In particular, excellent results were achieved in the addition to a,b-unsaturated carbonyl compounds. [3] However, despite the great synthetic importance of nitro compounds, [4] it is surprising that far fewer studies reported the efficient asymmetric addition of boronic acids to nitroalkenes, most likely because of the difficulty in controlling the reaction stereoselectivity.[5] In fact, high enantioselectivities were only achieved by the Hayashi group in the asymmetric addition of organoboronic acids to a-substituted 1-nitroalkenes using a rhodium/binap (binap = 2,2-bis(diphenylphosphanyl)-1,1 -binaphthyl) catalyst.[6] In other reports, [7] low levels of enantiomeric enrichment (< 50 % ee) were often observed with general 1-nitroalkene substrates that lack a substitutents. Therefore, the development of a capable catalyst system for efficient asymmetric boronic acid addition to nitroalkenes is highly desirable.…”

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confidence: 99%

Rhodium‐Catalyzed Asymmetric Conjugate Addition of Organoboronic Acids to Nitroalkenes Using Chiral Bicyclo[3.3.0] Diene Ligands

et al. 2010

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In recent years, the use of transition-metal-catalyzed reactions have been an important and general method in carbonÀ carbon and carbonÀheteroatom bond-forming synthesis. [1] Among them, the rhodium-catalyzed asymmetric conjugate addition of organoboronic acids to electron-deficient olefins, pioneered by Miyaura, Hayashi, and co-workers, [2] has been established as one of the most powerful and convenient tools for the enantioselective synthesis of b-substituted functionalized compounds. In particular, excellent results were achieved in the addition to a,b-unsaturated carbonyl compounds. [3] However, despite the great synthetic importance of nitro compounds, [4] it is surprising that far fewer studies reported the efficient asymmetric addition of boronic acids to nitroalkenes, most likely because of the difficulty in controlling the reaction stereoselectivity.[5] In fact, high enantioselectivities were only achieved by the Hayashi group in the asymmetric addition of organoboronic acids to a-substituted 1-nitroalkenes using a rhodium/binap (binap = 2,2-bis(diphenylphosphanyl)-1,1 -binaphthyl) catalyst.[6] In other reports, [7] low levels of enantiomeric enrichment (< 50 % ee) were often observed with general 1-nitroalkene substrates that lack a substitutents. Therefore, the development of a capable catalyst system for efficient asymmetric boronic acid addition to nitroalkenes is highly desirable. Herein, we report our preliminary results on the rhodium-catalyzed asymmetric addition of organoboronic acids to nitroalkenes that lack a substitutents; high enantiocontrol is afforded using chiral bicyclo[3.3.0] diene ligands.In 2007, we reported our discovery of a new family of C 2 -symmetric chiral diene ligands bearing a simple bicyclo[3.3.0] backbone; these ligands were successfully applied in the rhodium-catalyzed enantioselective arylation of N-tosylarylimines and the 1,4-addition of arylboronic acids to a,bunsaturated carbonyl compounds under mild conditions. [8] Inspired by these successes, we wondered whether these rhodium/diene complexes could also act as effective catalysts for the asymmetric addition of boronic acids to nitroalkenes. In spite of the recent significant advances, there has been no report on the use of chiral diene ligands [9] in this field. Our initial investigation was carried out by examining the reaction of nitrostyrene 2 with para-anisylboronic acid (3) in the presence of chiral diene ligand 1 a (3 mol %) under the reaction conditions previously reported [8a] for the arylation of N-tosylarylimines with arylboronic acids (Scheme 1). However, the result was disappointing. The addition product 4 a was obtained in only 9 % yield, albeit with moderate enantioselectivity (40 %), and a large amount of starting material 2 was recovered. Considering the known catalytic cycle for the 1,4-addition of organoboron reagents to activated alkenes, [10] it is likely that the low yield can be attributed to poor catalyst regeneration from its rhodium nitronate intermediate in the hydrolysis step. Indeed, we ...

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First Examples of Improved Catalytic Asymmetric C−C Bond Formation Using the Monodentate Ligand Combination Approach

Cited by 139 publications

References 24 publications

Nonlinear Effects in Asymmetric Catalysis

Nonlinear Effects in Asymmetric Catalysis

Phosphoramidite: privilegierte Liganden in der asymmetrischen Katalyse

Rhodium‐Catalyzed Asymmetric Conjugate Addition of Organoboronic Acids to Nitroalkenes Using Chiral Bicyclo[3.3.0] Diene Ligands

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