The Impact of Oxygen on Leading and Emerging Ru-Carbene Catalysts for Olefin Metathesis: An Unanticipated Correlation Between Robustness and Metathesis Activity

Ton, Stephanie J.; Fogg, Deryn E.

doi:10.1021/acscatal.9b03285

Cited by 32 publications

(36 citation statements)

References 58 publications

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“… 9 Recently, also catalysts containing cyclic-(alkyl)(amino)-carbenes (CAAC) gained more and more popularity. 10 − 13 What is more, Lemcoff et al proved that some of the latter are excellent in reducing double bond isomerization at high temperatures. 14 …”

Section: Introductionmentioning

confidence: 99%

4-Methyltetrahydropyran as a Convenient Alternative Solvent for Olefin Metathesis Reaction: Model Studies and Medicinal Chemistry Applications

Nienałtowski

Krzesiński

Baumert

et al. 2020

ACS Sustainable Chem. Eng.

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A number of metathesis reactions were successfully conducted in 4-methyltetrahydropyran, including both standard model dienes, as well as more complex substrates, such as analogues of biologically active compounds and active pharmaceutical ingredients. To place this solvent in a context of pharmaceutical R + D, larger-scale syntheses of SUAM 1221, a prolyl endopeptidase inhibitor with potential application in Alzheimer disease treatment, and a derivative of sildenafil, an analogue of the popular Viagra drug, were executed. In the latter case, despite all the setup being made in air, the metathesis reaction at a 33 g scale proceeded very well with relatively low catalyst loading and without need of aqueous workup or column chromatography.

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Section: Introductionmentioning

confidence: 99%

4-Methyltetrahydropyran as a Convenient Alternative Solvent for Olefin Metathesis Reaction: Model Studies and Medicinal Chemistry Applications

Nienałtowski

Krzesiński

Baumert

et al. 2020

ACS Sustainable Chem. Eng.

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“… 50 More recently, a new generation of CAAC complexes was reported by Skowerski and Fogg showing exceptional catalytic efficiency and remarkable stability. 51 To examine the effect of CAAC ligands on sulfur-chelated complexes, four new sulfur-chelated complexes bearing CAAC ligands were prepared ( Figure 12 ). 52 …”

Section: Exploring the Effects Of Altering The N-heterocyclic Carbenementioning

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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“…Catalytic reactions are sensitive to a wide range of experimental conditions, even in homogeneous systems. [1][2][3][4][5][6][7][8][9] These conditions include variables, such as concentration of reactants and catalyst, [10] stirring rate, [11] reaction time and temperature, [12] which contribute to the outcome of a catalytic system after optimization. This study focuses on the influence of stirring in a small-scale crosscoupling reaction.…”

Section: Introductionmentioning

confidence: 99%

Standardized Stirring for Small Scale Surveys

Omari¹,

Paul²,

McIndoe³

2021

Preprint

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Stirring rates in heterogeneous catalytic reactions have an effect on reaction rates. When conducting small-scale surveys using a single central stir plate, reaction vessels in different positions experience slightly different levels and patterns of agitation. We probed this effect by running the same reaction 40 times, varying the stir rate (fast/slow) and the vial position using two 3D printed vial holders. We found variability of conversion (measured mass spectrometrically) to be approximately two times higher for vials placed at different distances, but the effect was relatively small and could be minimized by using a high stir rate. For those experimenters wishing to completely eliminate differential stirring as a cause for variation in results, the 3D printed circular array we designed is recommended over a conventional rectangular array.

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The Impact of Oxygen on Leading and Emerging Ru-Carbene Catalysts for Olefin Metathesis: An Unanticipated Correlation Between Robustness and Metathesis Activity

Cited by 32 publications

References 58 publications

4-Methyltetrahydropyran as a Convenient Alternative Solvent for Olefin Metathesis Reaction: Model Studies and Medicinal Chemistry Applications

4-Methyltetrahydropyran as a Convenient Alternative Solvent for Olefin Metathesis Reaction: Model Studies and Medicinal Chemistry Applications

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

Standardized Stirring for Small Scale Surveys

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