Forming a ruthenium isomerisation catalyst from Grubbs II: a DFT study

Young, Allan; Vincent, Mark A.; Hillier, Ian H.; Percy, Jonathan M.; Tuttle, Tell

doi:10.1039/c4dt00464g

Cited by 10 publications

(12 citation statements)

References 30 publications

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“…Notably, the olefination of oximes also proceeds in more coordinating solvents including acetonitrile, tetrahydrofuran, acetone, and dimethylsulfoxide, albeit in overall lower yields ranging from 51 % [d] Addition of MeOH to Grubbs-type Ru alkylidene catalysts leads to formation of Ru hydride species which isomerize the olefin product 15 resulting in lower yield at extended reaction times. [42,43] Angewandte to 74 % (Table 3, Entries 5-8). Productive olefination of adamantyl oxime 32 was also observed in methanol to form cyclopentene 15 in 47 % yield after 2 hours at 60 °C but resulted in lower yield of 35 % at 16 hours, presumably due to olefin isomerization (Table 3, Entry 9).…”

Section: Methodsmentioning

confidence: 99%

Hydrazone and Oxime Olefination via Ruthenium Alkylidenes

et al. 2022

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We describe the development of an efficient method for the olefination of hydrazones and oximes.The key design approach that enables this transformation is tuning of the energy/polarity of C=N π-bonds by employing heteroatom functionalities (NR 2 , OR). The resulting hydrazones or oximes facilitate olefination with ruthenium alkylidenes. Through this approach, we show that air-stable, commercially available ruthenium alkylidenes provide access to functionalized alkenes (20 examples) in ring-closing reactions with yields up to 88 %.

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Section: Methodsmentioning

confidence: 99%

Hydrazone and Oxime Olefination via Ruthenium Alkylidenes

et al. 2022

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“…In addition, thermolysis of these species leads to ruthenium hydride species (such as 62 and 63) which may isomerise substrate and product alkenes. 139,[142][143][144][145][146] The reaction of Piers2 with 1,1-dichloroethene leads to the halide bridged complex 64 (Scheme 29). 147 In addition, catalytically-inactive species 58, 59, 65 and 66 have been obtained from the reaction of vinyl halides and vinyl esters with metathesis pre-catalysts (Scheme 30).…”

Section: Electron-rich Alkenesmentioning

confidence: 99%

Key processes in ruthenium-catalysed olefin metathesis

et al. 2014

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While the fundamental series of [2+2]cycloadditions and retro[2+2]cycloadditions that make up the pathways of ruthenium-catalysed metathesis reactions is well-established, the exploration of mechanistic aspects of alkene metathesis continues. In this Feature Article, modern mechanistic studies of the alkene metathesis reaction, catalysed by well-defined ruthenium complexes, are discussed. Broadly, these concern the processes of pre-catalyst initiation, propagation and decomposition, which all have a considerable impact on the overall efficiency of metathesis reactions.

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“…This ruthenium complex undergoes a third hydride transfer and leads, after recoordination of the dissociated PCy 3 ligand, to the formation of the reported hydrido carbonyl complex (Scheme 2 ). 6 , 9 …”

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confidence: 99%

From a Decomposition Product to an Efficient and Versatile Catalyst: The [Ru(η⁵-indenyl)(PPh₃)₂Cl] Story

2014

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ConspectusOne of the most important challenges in catalyst design is the synthesis of stable promoters without compromising their activity. For this reason, it is important to understand the factors leading to decomposition of such catalysts, especially if side-products negatively affect the activity and selectivity of the starting complex. In this context, the understanding of termination and decomposition processes in olefin metathesis is receiving significant attention from the scientific community. For example, the decomposition of ruthenium olefin metathesis precatalysts in alcohol solutions can occur during either the catalyst synthesis or the metathesis process, and such decomposition has been found to be common for Grubbs-type precatalysts. These decomposition products are usually hydridocarbonyl complexes, which are well-known to be active in several transformations such as hydrogenation, terminal alkene isomerization, and C–H activation chemistry. The reactivity of these side products can be unwanted, and it is therefore important to understand how to avoid them and maybe also important to keep an open mind and think of ways to use these in other catalytic reactions.A showcase of these decomposition studies is reported in this Account. These reports analyze the stability of ruthenium phenylindenylidene complexes, highly active olefin metathesis precatalysts, in basic alcohol solutions. Several different decomposition processes can occur under these conditions depending on the starting complex and the alcohol used. These indenylidene-bearing metathesis complexes display a completely different behavior compared with that of other metathesis precatalysts and show an alternative competitive alcoholysis pathway, where rather than forming the expected hydrido carbonyl complexes, the indenylidene fragment is transformed into a η1-indenyl, which then rearranges to its η5-indenyl form. In particular, [RuCl(η5-(3-phenylindenylidene)(PPh3)2] has been found to be extremely active in numerous transformations (at least 20) as well as compatible with a broad range of reaction conditions, rendering it a versatile catalytic tool. It should be stated that the η5-phenyl indenyl ligand shows enhanced catalytic activity over related half-sandwich ruthenium complexes. The analogous half-sandwich (cyclopentadienyl and indenyl) ruthenium complexes show lower activity in transfer hydrogenation and allylic alcohol isomerization reactions. In addition, this catalyst allows access to new phenylindenyl ruthenium complexes, which can be achieved in a very straightforward manner and have been successfully used in catalysis. This Account provides an overview of how mechanistic insights into decomposition and stability of a well-known family of ruthenium metathesis precatalysts has resulted in a series of novel and versatile ruthenium complexes with unexpected reactivity.

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Forming a ruthenium isomerisation catalyst from Grubbs II: a DFT study

Cited by 10 publications

References 30 publications

Hydrazone and Oxime Olefination via Ruthenium Alkylidenes

Hydrazone and Oxime Olefination via Ruthenium Alkylidenes

Key processes in ruthenium-catalysed olefin metathesis

From a Decomposition Product to an Efficient and Versatile Catalyst: The [Ru(η⁵-indenyl)(PPh₃)₂Cl] Story

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Forming a ruthenium isomerisation catalyst from Grubbs II: a DFT study

Cited by 10 publications

References 30 publications

Hydrazone and Oxime Olefination via Ruthenium Alkylidenes

Hydrazone and Oxime Olefination via Ruthenium Alkylidenes

Key processes in ruthenium-catalysed olefin metathesis

From a Decomposition Product to an Efficient and Versatile Catalyst: The [Ru(η5-indenyl)(PPh3)2Cl] Story

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From a Decomposition Product to an Efficient and Versatile Catalyst: The [Ru(η⁵-indenyl)(PPh₃)₂Cl] Story