Reactivity and Selectivity in Ruthenium Sulfur‐Chelated Diiodo Catalysts

Nechmad, Noy B.; Kobernik, Victoria; Tarannam, Naziha; Phatake, Ravindra S.; Eivgi, Or; Kozuch, Sebastian; Lemcoff, N. Gabriel

doi:10.1002/anie.202014929

Cited by 17 publications

(26 citation statements)

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“…This strategy was previously implemented by Hoveyda et al via the substitution of chlorides by a catechothiolate ligand (see Scheme c), which resulted in a highly Z -selective catalyst and high yields for ROMP and ROCM . It is observed that this approach focused on stereoselectivity differs from other sulfur chelates previously reported, in which the ether R 2 O→Ru in HG catalysts is replaced by a thioether R 2 S→Ru, resulting in enhancements in the catalytic activity. − It should be clarified, however, that we aimed at the formation of an active species that resembles the structure depicted in Scheme b. In this regard, several authors have previously reported predictive catalysis based on DFT calculations verified by experimental evidence. − …”

Section: Introductionmentioning

confidence: 98%

Olefin Metathesis Catalyzed by a Hoveyda–Grubbs-like Complex Chelated to Bis(2-mercaptoimidazolyl) Methane: A Predictive DFT Study

Martínez

Trzaskowski

2022

J. Phys. Chem. A

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Although highly selective complexes for the cross-metathesis of olefins, particularly oriented toward the productive metathesis of Z -olefins, have been reported in recent years, there is a constant need to design and prepare new and improved catalysts for this challenging reaction. In this work, guided by density functional theory (DFT) calculations, the performance of a Ru-based catalyst chelated to a sulfurated pincer in the olefin metathesis was computationally assessed. The catalyst was designed based on the Hoveyda–Grubbs catalyst (SIMes)Cl 2 Ru(=CH–o–O i PrC 6 H 4 ) through the substitution of chlorides with the chelator bis(2-mercaptoimidazolyl)methane. The obtained thermodynamic and kinetic data of the initiation phase through side- and bottom-bound mechanisms suggest that this system is a versatile catalyst for olefin metathesis, as DFT predicts the highest energy barrier of the catalytic cycle of ca. 20 kcal/mol, which is comparable to those corresponding to the Hoveyda–Grubbs-type catalysts. Moreover, in terms of the stereoselectivity evaluated through the propagation phase in the metathesis of propene–propene to 2-butene, our study reveals that the Z isomer can be formed under a kinetic control. We believe that this is an interesting outcome in the context of future exploration of Ru-based catalysts with sulfurated chelates in the search for high stereoselectivity in selected reactions.

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Section: Introductionmentioning

confidence: 98%

Olefin Metathesis Catalyzed by a Hoveyda–Grubbs-like Complex Chelated to Bis(2-mercaptoimidazolyl) Methane: A Predictive DFT Study

Martínez

Trzaskowski

2022

J. Phys. Chem. A

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“… 17 − 20 Generally, ROMP offers access to single-structure, functional oligomers or polymers. 8 , 18 , 19 , 21 − 25 In that regards, controlling the stereoselectivity in ROMP is an ultimate driving force in catalyst design because the tacticity of a polymer is intricately linked to its properties. 23 In the case of norborn-2-ene (NBE), four different regular polymers can be formed (see Scheme 1 (left)); these are cis -syndiotactic ( cis -st), cis -isotactic ( cis -it), trans -syndiotactic ( trans -st), and trans -isotactic ( trans -it).…”

Section: Introductionmentioning

confidence: 99%

“…Olefin metathesis has become a key reaction in the formation of carbon–carbon bonds. − The success can be attributed to the development of Mo- and W-based Schrock and Ru-based Grubbs initiators, which allow for such selective C–C coupling reactions under mild conditions and provide access to well-defined polymers with tunable properties. ,− Although more reactive, the fast deactivation of Mo-based catalysts in comparison to Ru-based catalysts prevented so far their broader use . By contrast, neutral, pentacoordinated and cationic, tetracoordinated Mo imido alkylidene N -heterocyclic carbene (NHC) complexes show improved stability not only toward oxygen, water, and protic substrates but also toward high temperatures without sacrificing reactivity and productivity. − Indeed, these catalysts are characterized by an impressive functional group tolerance and allow for olefin metathesis reactions with hydroxyl-, carboxyl-, aldehyde-, ether-, and amine-containing substrates .…”

Section: Introductionmentioning

confidence: 99%

“…By contrast, neutral, pentacoordinated and cationic, tetracoordinated Mo imido alkylidene N -heterocyclic carbene (NHC) complexes show improved stability not only toward oxygen, water, and protic substrates but also toward high temperatures without sacrificing reactivity and productivity. − Indeed, these catalysts are characterized by an impressive functional group tolerance and allow for olefin metathesis reactions with hydroxyl-, carboxyl-, aldehyde-, ether-, and amine-containing substrates . Apart from their high activity , they also show remarkable stereoselectivity in ring-opening metathesis polymerization (ROMP), allowing the synthesis of highly tactic polymers. − Generally, ROMP offers access to single-structure, functional oligomers or polymers. ,,,− In that regards, controlling the stereoselectivity in ROMP is an ultimate driving force in catalyst design because the tacticity of a polymer is intricately linked to its properties . In the case of norborn-2-ene (NBE), four different regular polymers can be formed (see Scheme (left)); these are cis -syndiotactic ( cis -st), cis -isotactic ( cis -it), trans -syndiotactic ( trans -st), and trans -isotactic ( trans -it).…”

Section: Introductionmentioning

confidence: 99%

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On the Origin of E-Selectivity in the Ring-Opening Metathesis Polymerization with Molybdenum Imido Alkylidene N-Heterocyclic Carbene Complexes

2021

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The understanding and control of stereoselectivity is a central aspect in ring-opening metathesis polymerization (ROMP). Herein, we report detailed quantum chemical studies on the reaction mechanism of E -selective ROMP of norborn-2-ene (NBE) with Mo( N -2,6-Me 2 -C 6 H 3 )(CHCMe 3 )(IMes)(OTf) 2 ( 1 , IMes = 1,3-dimesitylimidazol-2-ylidene) as a first step to stereoselective polymerization. Four different reaction pathways based on an ene syn or ene anti approach of NBE to either the syn - or anti -isomer of the neutral precatalyst have been studied. In contrast to the recently established associative mechanism with a terminal alkene, where a neutral olefin adduct is formed, NBE reacts directly with the catalyst via [2 + 2] cycloaddition to form molybdacyclobutane with a reaction barrier about 30 kJ mol –1 lower in free energy than via the formation of a catalyst–monomer adduct. However, the direct cycloaddition of NBE was only found for one out of four stereoisomers. Our findings strongly suggest that this stereoselective approach is responsible for E -selectivity and point toward a substrate-specific reaction mechanism in olefin metathesis with neutral Mo imido alkylidene N -heterocyclic carbene bistriflate complexes.

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“…Hydrogen atoms and solvent molecules were omitted for clarity. [21] Scheme 1. Reaction Scheme of 1,7-octadiene and DCPD derivatives in the presence of Ru-S-CF 3 -I.…”

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confidence: 99%

Reactivity and Selectivity in Ruthenium Sulfur‐Chelated Diiodo Catalysts

et al. 2021

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A trifluoromethyl sulfur‐chelated ruthenium benzylidene, Ru‐S‐CF3‐I, was synthesized and characterized. This latent precatalyst provides a distinct activity and selectivity profiles for olefin metathesis reactions depending on the substrate. For example, 1,3‐divinyl‐hexahydropentalene derivatives were efficiently obtained by ring‐opening metathesis (ROM) of dicyclopentadiene (DCPD). Ru‐S‐CF3‐I also presented a much more effective photoisomerization process from the inactive cis‐diiodo to the active trans‐diiodo configuration after exposure to 510 nm (green light), allowing for a wide scope of photoinduced olefin metathesis reactions. DFT calculations suggest a faster formation and enhanced stability of the active trans‐diiodo species of Ru‐S‐CF3‐I compared with Ru‐S‐Ph‐I, explaining its higher reactivity. In addition, the photochemical release of chloride anions by irradiation of Cl‐BODIPY in the presence of DCPD derivatives with diiodo Ru benzylidenes, led to in situ generation of chloride complexes, which quickly produced the corresponding cross‐linked polymers. Thus, novel selective pathways that use visible light to guide olefin metathesis based synthetic sequences is presented.

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Reactivity and Selectivity in Ruthenium Sulfur‐Chelated Diiodo Catalysts

Cited by 17 publications

References 64 publications

Olefin Metathesis Catalyzed by a Hoveyda–Grubbs-like Complex Chelated to Bis(2-mercaptoimidazolyl) Methane: A Predictive DFT Study

Olefin Metathesis Catalyzed by a Hoveyda–Grubbs-like Complex Chelated to Bis(2-mercaptoimidazolyl) Methane: A Predictive DFT Study

On the Origin of E-Selectivity in the Ring-Opening Metathesis Polymerization with Molybdenum Imido Alkylidene N-Heterocyclic Carbene Complexes

Reactivity and Selectivity in Ruthenium Sulfur‐Chelated Diiodo Catalysts

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