Enantioselective Olefin Metathesis

Stenne, Brice; Collins, Shawn K.

doi:10.1002/9781118711613.ch6

Cited by 16 publications

(19 citation statements)

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“…[28] Another important specialized application of chiral uNHC based catalysts is the enantioselective olefin metathesis. [29] This transformation is not presented in Scheme 1 but will be discussed later in this Review (in section 3.2).…”

Section: Key Applications Of Unhc Bearing Catalystsmentioning

confidence: 99%

“…Several studies utilizing chiral uNHC-based ruthenium catalysts were aimed at the synthesis of enantiopure compounds via the desymmetrization of prochiral molecules by olefin metathesis. [29] For instance, Colins and co-workers introduced Grubbs and Hoveyda-type ruthenium complexes bearing enantiopure uNHC ligands. [47] As an example, Ru41 with an optically pure chiral uNHC substituted with one methyl group and one 2-(isopropyl)phenyl arm and two tert-Bu substituents Scheme 7.…”

Section: Ru Complexes Featuring Chiral Unhc: An Opportunity For Asymmetry Inductionmentioning

confidence: 99%

“…[3b,39] The catalysts Ru29 and Ru33-34 proved to be perfectly stable in ethylene atmosphere and this feature, in addition to the selectivity already observed, led us to test them in ethenolysis of bio-sourced fatty acid esters such as ethyl oleate (27) (Scheme 5). Under industrial relevant conditions, i. e. low catalyst loading of 0.005 mol % (50 ppm of [Ru]) and 20 bars of ethylene of purity 4.5, ethenolysis of ethyl oleate (27) proceeded with conversion ranging from 48 to 67 % leading to ethyl dec-9-enoate (28) and 1-decene (29) with excellent selectivity (> 97 %). It shall be however noted that catalysts such as Ru35, bearing so-called cyclic alkylamino carbene (CAAC) ligands-specially designed for ethenolysis-usually provide even better results in this reaction.…”

Section: P E R S O N a L A C C O U N T T H E C H E M I C A L R E C O R Dmentioning

confidence: 99%

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Ruthenium Complexes Featuring Unsymmetrical N‐Heterocyclic Carbene Ligands–Useful Olefin Metathesis Catalysts for Special Tasks

Monsigny

Kajetanowicz

Grela

2021

The Chemical Record

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This review describes a distinct class of ruthenium olefin metathesis catalysts featuring unsymmetrical N-heterocyclic carbene (uNHC) ligands, from its historical beginning to the present state of the art. Thanks to advantageous traits, such as pronounced thermodynamic stability, chemical latency, outstanding selectivity, and compatibility with green solvents, these catalysts led to good results in a number of specialized metathesis transformations. Therefore, while being a niche, the uNHC complexes can potentially be implemented in a number of industrial processes, such as valorization of Fischer-Tropsch olefin fractions, ethenolysis of renewable products, and modern pharmaceutical production.

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Section: Key Applications Of Unhc Bearing Catalystsmentioning

confidence: 99%

Section: Ru Complexes Featuring Chiral Unhc: An Opportunity For Asymmetry Inductionmentioning

confidence: 99%

Section: P E R S O N a L A C C O U N T T H E C H E M I C A L R E C O R Dmentioning

confidence: 99%

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Ruthenium Complexes Featuring Unsymmetrical N‐Heterocyclic Carbene Ligands–Useful Olefin Metathesis Catalysts for Special Tasks

Monsigny

Kajetanowicz

Grela

2021

The Chemical Record

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“…However, these carbenes were not immobilized at all or were immobilized on current silica only. This remains a great challenge, especially the immobilization of new carbenes with high stereoselectivity [88] and even enantioselectivity [89] as homogeneous catalysts. Another major challenge is the development of heterogeneous catalysts for alkyne and enyne metathesis.…”

Section: Discussionmentioning

confidence: 99%

SBA-15 as a Support for Effective Olefin Metathesis Catalysts

Balcar

Čejka

2019

Catalysts

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Olefin metathesis is the catalytic transformation of olefinic substrates, finding a wide range of applications in organic synthesis. The mesoporous molecular sieve Santa Barbara Amorphous (SBA-15) has proven to be an excellent support for metathesis catalysts thanks to its regular mesoporous structure, high BET area, and large pore volume. A survey of catalysts consisting of (i) molybdenum and tungsten oxides on SBA-15, and (ii) molybdenum and ruthenium organometallic complexes (Schrock and Grubbs-type carbenes) on SBA-15 is provided together with their characterization and catalytic performance in various metathesis reactions. The comparison with catalysts based on other supports demonstrates the high quality of the mesoporous molecular sieve SBA-15 as an advanced catalyst support.

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“… 5 With a plethora of options to form and reshape carbon–carbon double bonds, olefin metathesis is the method of choice for the synthesis of macrocycles 6 and heavy-duty polymeric materials 7 and even for the preparation of simple commodity chemicals from oil waste products and biomass. 8 The flexible framework of ruthenium-based complexes has opened up many research avenues for the development of task-specific catalysts, 9 such as catalysts embedded with asymmetric ligands for enantioselective olefin metathesis reactions, 10 catalysts that specialize in ring-closing metathesis (RCM) of macrocyclic structures, 11 catalysts for Z -selective 12 and stereoretentive 13 olefin metathesis reactions, and fast-initiating catalysts for ring-opening metathesis polymerization (ROMP). 14 Slow-initiating or latent metathesis catalysts are an important class of initiators that require the application of an external stimulus (heat, light, mechanical force, etc.)…”

Section: Introductionmentioning

confidence: 99%

Light-Activated Olefin Metathesis: Catalyst Development, Synthesis, and Applications

et al. 2020

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Conspectus The most important means for tuning and improving a catalyst’s properties is the delicate exchange of the ligand shell around the central metal atom. Perhaps for no other organometallic-catalyzed reaction is this statement more valid than for ruthenium-based olefin metathesis. Indeed, even the simple exchange of an oxygen atom for a sulfur atom in a chelated ruthenium benzylidene about a decade ago resulted in the development of extremely stable, photoactive catalysts. This Account presents our perspective on the development of dormant olefin metathesis catalysts that can be activated by external stimuli and, more specifically, the use of light as an attractive inducing agent. The insight gained from a deeper understanding of the properties of cis -dichlororuthenium benzylidenes opened the doorway for the systematic development of new and efficient light-activated olefin metathesis catalysts and catalytic chromatic-orthogonal synthetic schemes. Following this, ways to disrupt the ligand-to-metal bond to accelerate the isomerization process that produced the active precatalyst were actively pursued. Thus, we summarize herein the original thermal activation experiments and how they brought about the discoveries of photoactivation in the sulfur-chelated benzylidene family of catalysts. The specific wavelengths of light that were used to dissociate the sulfur–ruthenium bond allowed us to develop noncommutative catalytic chromatic-orthogonal processes and to combine other photochemical reactions with photoinduced olefin metathesis, including using external light-absorbing molecules as “sunscreens” to achieve novel selectivities. Alteration of the ligand sphere, including modifications of the N-heterocyclic carbene (NHC) ligand and the introduction of cyclic alkyl amino carbene (CAAC) ligands, produced more efficient light-induced activity and special chemical selectivity. The use of electron-rich sulfoxides and, more prominently, phosphites as the agents that induce latency widened the spectrum of light-induced olefin metathesis reactions even further by expanding the colors of light that may now be used to activate the catalysts, which can be used in applications such as stereolithography and 3D printing of tough metathesis-derived polymers.

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Enantioselective Olefin Metathesis

Cited by 16 publications

References 105 publications

Ruthenium Complexes Featuring Unsymmetrical N‐Heterocyclic Carbene Ligands–Useful Olefin Metathesis Catalysts for Special Tasks

Ruthenium Complexes Featuring Unsymmetrical N‐Heterocyclic Carbene Ligands–Useful Olefin Metathesis Catalysts for Special Tasks

SBA-15 as a Support for Effective Olefin Metathesis Catalysts

Light-Activated Olefin Metathesis: Catalyst Development, Synthesis, and Applications

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