Hydrogenative Cycloisomerization and Sigmatropic Rearrangement Reactions of Cationic Ruthenium Carbenes Formed by Catalytic Alkyne <i>gem</i>‐Hydrogenation

Biberger, Tobias; Hess, Stephan N.; Leutzsch, Markus; Fürstner, Alois

doi:10.1002/anie.202113827

Cited by 14 publications

(6 citation statements)

References 70 publications

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“…As mentioned in the Introduction , gem -hydrogenation empowers various types of transformations including cyclopropanation, metathesis, skeletal rearrangements, and various heterocycle syntheses; 1 − 12 C–H insertion was late to appear on scene. 8 In view of this history, the ease of the reaction, as manifested in the examples outlined above, is all the more striking.…”

Section: Resultsmentioning

confidence: 99%

“… The conversion of the receiving C atom into a methylene group is accompanied by the formation of a discrete metal carbene at the adjacent position. For the time being, such “ gem -hydrogention” reactions have been accomplished with [Cp X RuCl] (or closely related metal fragments) , as well as with [NHC(η 6 -cymene)RuCl 2 ]; this latter system is photochemically driven and opens an unconventional entry into second-generation Grubbs-type catalysts. , The use of [Cp X RuCl], in contrast, provides access to piano-stool ruthenium carbene complexes, the electrophilic character of which manifests itself in multifarious reactivity (Scheme ): so far, it could be harnessed in the form of hydrogenative cyclopropanation, , hydrogenative metathesis, , hydrogenative heterocycle syntheses, , hydrogenative ring expansion reactions, and hydrogenative rearrangements, − all of which are conceptually new types of transformations; some of them are even counterintuitive when judged on the basis of conventional chemical logic…”

Section: Introductionmentioning

confidence: 99%

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C–H Insertion via Ruthenium Catalyzedgem-Hydrogenation of 1,3-Enynes

et al. 2022

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gem -Hydrogenation of an internal alkyne with the aid of [Cp*RuCl] 4 as the precatalyst is a highly unorthodox transformation, in which one C atom of the triple bond is transformed into a methylene group, whereas the second C atom gets converted into a ruthenium carbene. In the case of 1,3-enynes bearing a propargylic steering substituent as the substrates, the reaction occurs regioselectively, giving rise to vinyl carbene complexes that adopt interconverting η 1 /η 3 -binding modes in solution; a prototypical example of such a reactive intermediate was characterized in detail by spectroscopic means. Although both forms are similarly stable, only the η 3 -vinyl carbene proved kinetically competent to insert into primary, secondary, or tertiary C–H bonds on the steering group itself or another suitably placed ether, acetal, orthoester, or (sulfon)amide substituent. The ensuing net hydrogenative C–H insertion reaction is highly enabling in that it gives ready access to spirocyclic as well as bridged ring systems of immediate relevance as building blocks for medicinal chemistry. Moreover, the reaction scales well and lends itself to the formation of partly or fully deuterated isotopologues. Labeling experiments in combination with PHIP NMR spectroscopy (PHIP = parahydrogen induced polarization) confirmed that the reactions are indeed triggered by gem -hydrogenation, whereas kinetic data provided valuable insights into the very nature of the turnover-limiting transition state of the actual C–H insertion step.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

C–H Insertion via Ruthenium Catalyzedgem-Hydrogenation of 1,3-Enynes

et al. 2022

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“…OPSY (only parahydrogen spectroscopy) is a gradient-based PHIP NMR method, which can selectively observe the polarized signals while the thermally polarized signals are filtered. Based on this method, the spectra can be “cleared”, leading to enhanced sensitivity. , Besides, PhD-PHIP (parahydrogen discriminated-PHIP) can act as an acquisition block that prevents signal cancellation in the presence of magnetic field inhomogeneities to increase the resolution and sensitivity of the spectra …”

Section: Conclusion and Prospectsmentioning

confidence: 99%

Understanding Heterogeneous Catalytic Hydrogenation by Parahydrogen-Induced Polarization NMR Spectroscopy

Wang

et al. 2023

ACS Catal.

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Parahydrogen-induced polarization (PHIP) is an NMR hyperpolarization technique with the ability to increase the NMR sensitivity by serval orders. The generation of hyperpolarization in hydrogenation reactions is associated with a pairwise addition behavior, which is sensitive to the properties of catalysts and the reaction process, making it a powerful tool for the characterization of catalyst properties and elucidation of reaction mechanisms. In this Perspective, we provide an in-depth overview of the heterogeneous PHIP (HET-PHIP) technique and its application in heterogeneous catalytic hydrogenation. The fundamentals of HET-PHIP are introduced. We describe how HET-PHIP can be used to obtain information about the morphology and electronic properties of supported monometallic catalysts, bimetallic catalysts, and zeolites as well as the facet effect and strong metal–support interaction (SMSI) effect in hydrogenation. Advances in the mechanistic understanding of catalytic hydrogenations by using HET-PHIP are discussed with representative work. We propose the current limitations and prospects of the HET-PHIP technique in catalytic hydrogenation reactions.

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“…Furthermore, we systematically investigated the effect of different groups on the final migration step and whether it is possible to use a substrate with an OAc group (69b); 37 the use of an OAc group (71) in hydrogenative rearrangement has been realized by Furstner (Figure 9g,h). 38 Inspired by our computed low-barrier boryl migration (63B → 64B), 37 we further conducted DFT MD simulations to scrutinize the reaction dynamics from the rate-determining first migration TS zone (TS5B; Figure 9f). Our simulations suggested that C β −H bond formation is extremely fast (9−51 fs), whereas C β −B bond formation could essentially occur within 1 ps in ∼24% of the productive trajectories (with a time gap of ∼430−965 fs between these two bond-formation processes).…”

Section: Dispersion-controlled Enantioselective Pd(ii)-catalyzed Dibo...mentioning

confidence: 99%

“…Moreover, crossover experiments using a mixture of H 2 and D 2 indicated that the two hydrogen atoms for geminal hydrogenation originate from the same H 2 molecule (Figure e), which is also consistent with our mechanism. Furthermore, we systematically investigated the effect of different groups on the final migration step and whether it is possible to use a substrate with an OAc group ( 69b ); the use of an OAc group ( 71 ) in hydrogenative rearrangement has been realized by Fürstner (Figure g,h) …”

Section: Hydrofunctionalizationsmentioning

confidence: 99%

New Insights and Predictions into Complex Homogeneous Reactions Enabled by Computational Chemistry in Synergy with Experiments: Isotopes and Mechanisms

Lan

Yang

et al. 2022

Acc. Chem. Res.

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Conspectus Homogeneous catalysis and biocatalysis have been widely applied in synthetic, medicinal, and energy chemistry as well as synthetic biology. Driven by developments of new computational chemistry methods and better computer hardware, computational chemistry has become an essentially indispensable mechanistic “instrument” to help understand structures and decipher reaction mechanisms in catalysis. In addition, synergy between computational and experimental chemistry deepens our mechanistic understanding, which further promotes the rational design of new catalysts. In this Account, we summarize new or deeper mechanistic insights (including isotope, dispersion, and dynamical effects) into several complex homogeneous reactions from our systematic computational studies along with subsequent experimental studies by different groups. Apart from uncovering new mechanisms in some reactions, a few computational predictions (such as excited-state heavy-atom tunneling, steric-controlled enantioswitching, and a new geminal addition mechanism) based on our mechanistic insights were further verified by ensuing experiments. The Zimmerman group developed a photoinduced triplet di-π-methane rearrangement to form cyclopropane derivatives. Recently, our computational study predicted the first excited-state heavy-atom (carbon) quantum tunneling in one triplet di-π-methane rearrangement, in which the reaction rates and 12C/13C kinetic isotope effects (KIEs) can be enhanced by quantum tunneling at low temperatures. This unprecedented excited-state heavy-atom tunneling in a photoinduced reaction has recently been verified by an experimental 12C/13C KIE study by the Singleton group. Such combined computational and experimental studies should open up opportunities to discover more rare excited-state heavy-atom tunneling in other photoinduced reactions. In addition, we found unexpectedly large secondary KIE values in the five-coordinate Fe(III)-catalyzed hetero-Diels–Alder pathway, even with substantial C–C bond formation, due to the non-negligible equilibrium isotope effect (EIE) derived from altered metal coordination. Therefore, these KIE values cannot reliably reflect transition-state structures for the five-coordinate metal pathway. Furthermore, our density functional theory (DFT) quasi-classical molecular dynamics (MD) simulations demonstrated that the coordination mode and/or spin state of the iron metal as well as an electric field can affect the dynamics of this reaction (e.g., the dynamically stepwise process, the entrance/exit reaction channels). Moreover, we unveiled a new reaction mechanism to account for the uncommon Ru(II)-catalyzed geminal-addition semihydrogenation and hydroboration of silyl alkynes. Our proposed key gem-Ru(II)–carbene intermediates derived from double migrations on the same alkyne carbon were verified by crossover experiments. Additionally, our DFT MD simulations suggested that the first hydrogen migration transition-state structures may directly and quickly form the key gem-Ru–carbene structu...

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Hydrogenative Cycloisomerization and Sigmatropic Rearrangement Reactions of Cationic Ruthenium Carbenes Formed by Catalytic Alkyne gem‐Hydrogenation

Cited by 14 publications

References 70 publications

C–H Insertion via Ruthenium Catalyzedgem-Hydrogenation of 1,3-Enynes

C–H Insertion via Ruthenium Catalyzedgem-Hydrogenation of 1,3-Enynes

Understanding Heterogeneous Catalytic Hydrogenation by Parahydrogen-Induced Polarization NMR Spectroscopy

New Insights and Predictions into Complex Homogeneous Reactions Enabled by Computational Chemistry in Synergy with Experiments: Isotopes and Mechanisms

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