Ru-based Z-selective metathesis catalysts with modified cyclometalated carbene ligands

Bronner, Sarah M.; Herbert, Myles B.; Patel, Paresma; Marx, Vanessa M.; Grubbs, Robert H.

doi:10.1039/c4sc01541j

Cited by 43 publications

(28 citation statements)

References 57 publications

(43 reference statements)

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“…Complex 11 showed good activity and retained high Z-selectivity in the homodimerization of allylbenzene, but it generated the undesired β-methylstyrene through isomerization of the olefin in the starting material [40]. Catalyst 12 displayed low to poor activity and modest Z-selectivity [40]. Complexes 13 and 14 both displayed good selectivity, but 13 showed superior activity to 14 [41].…”

Section: Cyclometalated Catalysts Developmentmentioning

confidence: 99%

“…The metathesis activity of these complexes was evaluated using standard terminal olefin homodimerization reactions of allylbenzene, 4-penten-1-ol, or methyl-10-undecenoate. Complex 10, possessing a 6-membered NHC, was found to be inactive in the test reactions [40]. Complex 11 showed good activity and retained high Z-selectivity in the homodimerization of allylbenzene, but it generated the undesired β-methylstyrene through isomerization of the olefin in the starting material [40].…”

Section: Cyclometalated Catalysts Developmentmentioning

confidence: 99%

“…Complex 10, possessing a 6-membered NHC, was found to be inactive in the test reactions [40]. Complex 11 showed good activity and retained high Z-selectivity in the homodimerization of allylbenzene, but it generated the undesired β-methylstyrene through isomerization of the olefin in the starting material [40]. Catalyst 12 displayed low to poor activity and modest Z-selectivity [40].…”

Section: Cyclometalated Catalysts Developmentmentioning

confidence: 99%

“…It was postulated that the monodentate nature of the chloride ligand allows metathesis to proceed through a bottom-bound ruthenacycle, thus favoring E-products. Complex 18 featuring a nitrite X-type ligand Efforts to improve the reactivity and selectivity of cyclometalated catalysts 6 and 9 have resulted in the preparation of novel cyclometalated complexes with varying carbene moieties including those with chelating N-substituents beyond N-1-adamantyl ( Figure 5) [39][40][41]. The metathesis activity of these complexes was evaluated using standard terminal olefin homodimerization reactions of allylbenzene, 4-penten-1-ol, or methyl-10-undecenoate.…”

Section: Cyclometalated Catalysts Developmentmentioning

confidence: 99%

“…The desired CM products were isolated in moderate yield, but high levels of Z-selectivity were observed. As modifications were made to the cyclometalated catalysts, new scaffolds were assessed ( Table 2, entries 2-4), but 9 proved to be the best catalyst to date [37][38][39][40]42]. of ethylene, driving the reaction forward.…”

Section: Z-selective Cross Metathesismentioning

confidence: 99%

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Recent Advancements in Stereoselective Olefin Metathesis Using Ruthenium Catalysts

2017

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Olefin metathesis is a prevailing method for the construction of organic molecules. Recent advancements in olefin metathesis have focused on stereoselective transformations. Ruthenium olefin metathesis catalysts have had a particularly pronounced impact in the area of stereoselective olefin metathesis. The development of three categories of Z-selective olefin metathesis catalysts has made Z-olefins easily accessible to both laboratory and industrial chemists. Further design enhancements to asymmetric olefin metathesis catalysts have streamlined the construction of complex molecules. The understanding gained in these areas has extended to the employment of ruthenium catalysts to stereoretentive olefin metathesis, the first example of a kinetically E-selective process. These advancements, as well as synthetic applications of the newly developed catalysts, are discussed.

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Section: Cyclometalated Catalysts Developmentmentioning

confidence: 99%

Section: Cyclometalated Catalysts Developmentmentioning

confidence: 99%

Section: Cyclometalated Catalysts Developmentmentioning

confidence: 99%

Section: Cyclometalated Catalysts Developmentmentioning

confidence: 99%

Section: Z-selective Cross Metathesismentioning

confidence: 99%

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Recent Advancements in Stereoselective Olefin Metathesis Using Ruthenium Catalysts

2017

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Recent Developments in Z‐Selective Olefin Metathesis Reactions by Molybdenum, Tungsten, Ruthenium, and Vanadium Catalysts

Dawood

Nomura

2021

Adv Synth Catal

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This review article summarizes reports for Z‐selective olefin metathesis reactions by molybdenum, tungsten, ruthenium, and vanadium catalysts. It is clearly demonstrated that the ligand modifications play essential roles in achieving the stereospecific olefin metathesis reactions. In particular, Mo‐ and W‐alkylidene based complex catalysts having pyrrolide‐aryloxide [or bis(aryloxide)] were highly effective in the efficient enantioselective ring opening/cross‐metathesis (EROCM), cross metathesis (CM), homodimerization, ring‐opening metathesis polymerization (ROMP), and in ring closing metathesis (RCM) with high Z‐ selectivities (∼>98%). Ruthenium‐carbene catalysts having cycloadamantyl, catechothiolate, phenolate and thiophenolate ligands display pronounced Z‐selectivity (>98%) in efficient CM, ROCM, AROCM, RCM, ROMP reactions. Halogenated (arylimido)‐alkoxo vanadium‐alkylidenes were thermally robust and effective for efficient highly cis‐specific ROMP of cyclic olefins to afford end‐functionalized ring‐opened polymers.

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Z‐Selektive Kreuzmetathese mit Ruthenium‐Katalysatoren: Anwendung in der Synthese und mechanistische Aspekte

Herbert

Grubbs

2015

Angewandte Chemie

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Die Olefin-Kreuzmetathese (CM) wurde intensiv in der Synthese komplexer Naturstoffe und anderer Verbindungen genutzt, wobei generell das thermodynamisch begünstigte E-(oder trans) C-C-Doppelbindungsisomer entsteht. [1] Olefin-Kreuzmetathesen verlaufen über eine [2+2]-Cycloaddition zwischen einem Olefin und einem Metall-Alkylidenkomplex, wobei eine Metallacyclobutan-Zwischenstufe gebildet wird, die unter Cycloreversion ein neues Alken bildet (Schema 1).Studien zur Struktur und Stabilität substituierter Metallacyclobutane haben zur Entwicklung von Katalysatoren ge-führt, die in der Lage sind, Z-(oder cis) Olefine mit hoher Stereoselektivität zu erzeugen. [2] Dies wurde zuerst von Schrock und Hoveyda berichtet, denen es gelang, Monoaryloxid-Pyrrolidkomplexe mit Wolfram und Molybdän zu entwickeln, die einige Z-selektive Kreuzmetathesen begünstigen. [3] Vor kurzem wurde eine Serie von Ruthenium-Katalysatoren mit cyclometallierten N-heterocyclischen Carbenliganden (NHCs) beschrieben, die die Z-selektive Olefin-Metathese begünstigen. [4] Katalysatoren 1-3 sind drei der am besten untersuchten Z-selektiven Olefin-Metathesekatalysatoren, sie sind mittels C-H-Aktivierung des N-Adamantyl-Substituenten des NHC-Liganden zugänglich (Abbildung 1). [5] Katalysator 1 weist eine N-Mesityl(Mes)-Gruppe als nicht chelatisierten Substituenten des NHC-Liganden auf, als X-Typ-Ligand fungiert Pivalat. Katalysator 1 katalysiert die Homodimerisierung von endständigen Olefinen mit einer Selektivität von ca. 90 % zugunsten des Z-Olefins, bei einer geringen Katalysatorbeladung von 1 Mol-%. Durch Austausch des Pivalat-gegen einen Nitratliganden wird Katalysator 2 erhalten, der sich durch eine erhçhte Z-Selektivität von ca. 95 % in einer Vielzahl von Homodimerisierungsreaktionen auszeichnet. Wird der nicht chelatisierte Substituent Die Olefin-Kreuzmetathese ist eine besonders nützliche Reaktion, die intensiv in der Synthese von komplexen Verbindungen genutzt wurde. Bis vor kurzem war es jedoch nicht mçglich, Z-Olefine mit dieser Methode herzustellen. Mit der Entdeckung und Entwicklung dreier Klassen von Ruthenium-Katalysatoren wurde die Synthese von Z-Olefinen mittels Kreuzmetathese nun ermçglicht und wird zunehmend populärer. Insbesondere Ruthenium-Komplexe mit cyclometallierten NHC-Liganden, die in unserem Labor entwickelt wurden, konnten erfolgreich in verschiedenen Kreuzmetathesen eingesetzt werden. Sie zeichnen sich durch eine hohe Aktivität und nahezu vollständige Z-Selektivität aus. Dieser Kurzaufsatz gibt einen Überblick über die bisher untersuchten Kreuzmetathesereaktionen. Schema 1. Mechanismus der Olefinmetathese.Abbildung 1. Cyclometallierte Ruthenium-Katalysatoren für die Z-selektive Olefinmetathese.

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Ru-based Z-selective metathesis catalysts with modified cyclometalated carbene ligands

Cited by 43 publications

References 57 publications

Recent Advancements in Stereoselective Olefin Metathesis Using Ruthenium Catalysts

Recent Advancements in Stereoselective Olefin Metathesis Using Ruthenium Catalysts

Recent Developments in Z‐Selective Olefin Metathesis Reactions by Molybdenum, Tungsten, Ruthenium, and Vanadium Catalysts

Z‐Selektive Kreuzmetathese mit Ruthenium‐Katalysatoren: Anwendung in der Synthese und mechanistische Aspekte

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