Metathesis of norbornene-derivatives bearing trimethylsilyl groups using Ru-alkylidene catalysts: An experimental and computational study

Zárate-Saldaña, Daniel; Landeros‐Rivera, Bruno; Cruz-Morales, Jorge A.; Gutiérrez, Selena

doi:10.1016/j.jorganchem.2020.121206

Cited by 5 publications

(3 citation statements)

References 35 publications

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“…We verified the absence of a transition state by additional scan calculations with B3PW91 , and TPSS0 , hybrid DFT methods (Figure S5, Supporting Information). Cycloreversion without a transition state is known for metathesis reaction with a Ru-based catalyst …”

Section: Resultsmentioning

confidence: 99%

“…Cycloreversion without a transition state is known for metathesis reaction with a Ru-based catalyst. 62 In intermediate 3, the second alkene group approaches the Mo−C bond, while it initially pointed in a different direction in metallacyclobutane 2. A conformational rearrangement of the Overall, the energies along the syn and anti-pathways of the main catalytic cycle are very similar (see Figure 4).…”

Section: Resultsmentioning

confidence: 99%

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Reaction Mechanism of Ring-Closing Metathesis with a Cationic Molybdenum Imido Alkylidene N-Heterocyclic Carbene Catalyst

et al. 2020

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DFT calculations were carried out to explore all relevant pathways for the ring-closing metathesis (RCM) reaction of a cationic molybdenum imido alkylidene N-heterocyclic carbene (NHC) catalyst with α,ω-dienes. Besides the catalytic cycle, which produces the desired cycloalkene in two consecutive metathesis steps, the initiation, a nonproductive cycle, and a degenerative catalytic path were also investigated. On the basis of the approaching face of the diene, two further possibilities were considered for all pathways: synand anti-addition. Steric repulsion on the metallacyclobutane ring of the trigonal-bipyramidal (TBP) intermediate appears to be one of the important influencing factors. We found the nonproductive cycle to compete with the catalytic conversion of the substrate. The TBP intermediate formed during the catalytic cycle is energetically lower than the corresponding TBP intermediate of the nonproductive cycle. However, the barriers for the nonproductive cycle are slightly lower than the barrier for the catalytic cycle. Thus, the nonproductive cycle can be expected to be used during catalysis, but it will only have a weak detrimental effect on the turnover rate because it is faster than the catalytic cycle. Of the four different initiation paths, the α-anti-addition path was found to be the energetically most favorable one. Notably, the catalyst was found to be fairly stable against degradation via β-hydride (β-H) transfer to the metal. High activation barriers for the conversion of the TBP intermediate to a square-pyramidal (SP)-based intermediate and a higher energy of a later intermediate suggest a stability of catalyst against degradation. A very high barrier for β-H transfer also disfavors the degradation reaction. The 1 H NMR spectrum of the reaction between [Mo(N-2,6-Me 2 -C 6 H 3 )(CHCMe 2 Ph)(IMes)(OCH(CF 3 ) 2 ) + B(Ar F ) 4 − ] and 1,7-octadiene confirms the absence of any β-H transfer.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Reaction Mechanism of Ring-Closing Metathesis with a Cationic Molybdenum Imido Alkylidene N-Heterocyclic Carbene Catalyst

et al. 2020

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“…Por otro lado, gracias al aporte de los catalizadores, se ha podido avanzar, y desarrollar nuevas rutas de síntesis (Kamel & Khattab, 2021;Kandathil et al, 2021). En ese sentido, la reacción de metátesis ha demostrado ser una herramienta muy poderosa y atractiva debido a su versatilidad y contribución en la química orgánica, la química verde y la química sostenible (Martínez et al, 2014;Zárate-Saldaña et al, 2020), especialmente, en las áreas de: petroquímica, oleoquímica, polímeros y productos de química fina; para la obtención de productos de interés comercial como: detergentes, feromonas, polímeros biodegradables, moléculas con actividad farmacológica, entre otros; siendo uno de los ejemplos con mayor impacto a nivel industrial, la síntesis del polioctenámero a base de norborneno (Vestenamer®), polímero empleado exitosamente en últimos años en la recuperación de petróleo en derrames acuíferos (Pineda et al, 2018).…”

Section: Introductionunclassified

Synthesis of heterogeneous metathesis catalysts for the development of sustainable processes

Gutiérrez-Flores

García-Barrera

Zárate-Saldaña

et al. 2022

Renew. energ. biomass sustain

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In recent decades, it has been tried to develop processes that involve the use of catalysts that can be recovered from the reaction medium, to make them green and sustainable. Approximately, 90 % of all processes in chemistry and petrochemicals use heterogeneous catalysts. In this sense, the supported heterogeneous catalysts present advantages in the purification of the products and the reduction of costs. In the present work, the synthesis of a new heterogeneous supported catalyst, highly active in the metathesis reaction, based on a ruthenium-alkylidene complex, was carried out. The new catalyst was obtained by anchoring of dichloro[1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene](benzylidene)(tricyclohexylphosphine)ruthenium (II) (second generation Grubbs) in various silylated polymeric gels, based on 2-norbornene-5,6-dicarboxylic anhydride (NDA) and cis-cyclooctene (CO) cross-linked with various percentages of 3-aminopropyltriethoxysilane (APTES) (5%, 15%, 100%). The new heterogeneous catalyst was successfully used in the depolymerization reaction via metathesis of natural rubber from Oaxaca (HNO), using 1-octene as CTA; observing the formation of liquid oligomers, achieving a decrease in molecular weight from 137.941 g/mol to 297 g/mol; proving, in this way, its high effectiveness.

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Application of the fractal model to estimate the diffusion and solubility of gases in non-porous membranes based on aromatic polynorbornene dicarboximides

et al. 2021

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Metathesis of norbornene-derivatives bearing trimethylsilyl groups using Ru-alkylidene catalysts: An experimental and computational study

Cited by 5 publications

References 35 publications

Reaction Mechanism of Ring-Closing Metathesis with a Cationic Molybdenum Imido Alkylidene N-Heterocyclic Carbene Catalyst

Reaction Mechanism of Ring-Closing Metathesis with a Cationic Molybdenum Imido Alkylidene N-Heterocyclic Carbene Catalyst

Synthesis of heterogeneous metathesis catalysts for the development of sustainable processes

Application of the fractal model to estimate the diffusion and solubility of gases in non-porous membranes based on aromatic polynorbornene dicarboximides

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