Synthesis of BC Ring-Systems of Taxol by Ring-Closing Metathesis

Bourgeois, Damien; Mahuteau, Jacqueline; Pancrazi, Ange; Nolan, Steven P.; Prunet, Joëlle

doi:10.1055/s-2000-6263

Cited by 59 publications

(27 citation statements)

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“…In the resulting π complex, B, an agostic interaction (indicated by a ''half'' arrow) might facilitate deprotonation at the allylic position leading to a σ-alkyl/π-allyl complex C, which reacts to give the carbene complex D. Dissociation of the isomerized alkene regenerates the catalytically active species A. [23] Scheme 2. Competing RCM and isomerization processes Scheme 3.…”

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confidence: 99%

“…Nolan, Prunet, et al have investigated the competition of ring closing metathesis and double bond isomerization in some detail for the model system 17. [23] Cyclooctene 18 and isomerization product 19 were obtained in varying amounts, and the composition of the reaction mixture depends strongly on the solvent, as illustrated in Scheme 2. Addition of small amounts of tricyclohexylphosphane oxide (POCy 3 ) completely suppresses the isomerization and leads to quantitative conversion into 18.…”

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confidence: 99%

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Catalysis at the Interface of Ruthenium Carbene and Ruthenium Hydride Chemistry: Organometallic Aspects and Applications to Organic Synthesis

2004

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Soon after the introduction of stable and defined ruthenium precatalysts for olefin metathesis it was discovered that double bond migrations may interfere with the metathesis reaction. This undesired side reaction has been attributed to the formation of ruthenium hydride species from metathesisactive ruthenium carbene species in situ. Over the past few years, several studies have indeed revealed the existence of pathways leading from ruthenium carbene to ruthenium hydride complexes. Furthermore, a number of examples have been published recently where typical precatalysts for olefin metathesis were found to promote non-metathesis trans- Olefin Metathesis and Non-Metathesis Side ReactionsThe discovery of stable and defined carbene complexes of molybdenum [1] and ruthenium [2] as efficient precatalysts for olefin metathesis has made this transformation one of the most important CϪC bond forming reactions.[3Ϫ8]Molybdenum-based complexes such as 1 are generally [a] formations efficiently in preparatively useful yields and selectivities, presumably via the in situ formation of ruthenium hydride species. These results open up a pathway to the development of novel catalyzed reaction sequences that combine ruthenium carbene-and ruthenium-hydride-mediated steps. This paper provides an overview of the field and covers organometallic aspects as well as synthetic applications.

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Catalysis at the Interface of Ruthenium Carbene and Ruthenium Hydride Chemistry: Organometallic Aspects and Applications to Organic Synthesis

2004

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“…We tested the construction of cycloheptenes to establish that the neopentylic position at C8 was not deleterious to this reaction. [46] Treatment of the alcohol 53a (1:1 mixture of epimers at C8) with the catalyst G1 furnished the cycloheptene 54a in 51 % yield, along with unwanted dimers. When the alcohol function was protected as a triethylsilyl ether in 53b, the yield increased to 93 %.…”

Section: Taxolmentioning

confidence: 99%

Progress in Metathesis Through Natural Product Synthesis

Prunet

2011

Eur J Org Chem

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101

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This article covers case studies in natural product syntheses with comments on various aspects of metathesis reactions and on how the difficulties encountered in these syntheses have led to better understanding of these reactions or to more effective reaction conditions and catalysts. Ring‐closingmetathesis leading to small and medium‐sized rings is discussed, followed by macrocycle formation, asymmetric ring‐closing metathesis, and cross metathesis.

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“…Die Cyclohexene trugen als 1,2-Substituenten einen Vinylrest in einer sterisch gehinderten Neopentylposition und eine flexible Hexenylkette. [37] Anhand einfacher Modellsubstrate, die keiner spezifischen konformativen Einschränkung unterliegen, konnte eindeutig nachgewiesen werden, dass das Vorliegen einer freien, ungeschützten OH-Funktion die Cyclisierung inhibiert. Die hohe Enthalpiebarriere konnte jedoch durch Verwendung des geschützten Triethylsilylethers überwunden werden.…”

Section: Anellierte Achtgliedrige Ringeunclassified

Selektiver Aufbau achtgliedriger Carbocyclen durch Ringschlussmetathese acyclischer Vorstufen

Michaut¹,

Rodríguez²

2006

Angewandte Chemie

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Bei der Synthese von Cyclooctanoiden kam es in jüngster Zeit zu bemerkenswerten Fortschrittten dank der Entwicklung von hochspezifisch wirkenden Reagentien und der Entdeckung neuartiger Reaktionen. Trotzdem bleibt der direkte Aufbau achtgliedriger Carbocyclen aus acyclischen Vorstufen eine Herausforderung, da entropische und enthalpische Faktoren für die Bildung von Ringen dieser Größe nachteilig sind. Dieser Kurzaufsatz beschreibt die Anwendung der Ringschlussmetathese (RCM) als eine neue Methode zur Synthese von Cyclooctanoiden.

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Synthesis of BC Ring-Systems of Taxol by Ring-Closing Metathesis

Cited by 59 publications

References 8 publications

Catalysis at the Interface of Ruthenium Carbene and Ruthenium Hydride Chemistry: Organometallic Aspects and Applications to Organic Synthesis

Catalysis at the Interface of Ruthenium Carbene and Ruthenium Hydride Chemistry: Organometallic Aspects and Applications to Organic Synthesis

Progress in Metathesis Through Natural Product Synthesis

Selektiver Aufbau achtgliedriger Carbocyclen durch Ringschlussmetathese acyclischer Vorstufen

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