Metal/Metal Dual Catalysis in C−H Activation

Zhang, Qijing; Wang, Chengming

doi:10.1002/ejoc.202200431

Cited by 12 publications

(6 citation statements)

References 77 publications

(41 reference statements)

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“…Very importantly, BINOL can be efficiently converted into product 7 e, which cannot be accessed via a typical hypervalent iodine(III)-promoted dearomatization, because that leads to the formation of other, more oxidized derivatives. [22] Unfortunately, both enantiopure BINOL and its 3,3'-diphenyl version were found to yield the corresponding products 7 e and 7 f as racemates. [27] 6,6'-and 7,7'-dibromo-BINOLs could also be dearomatized to products 7 g and 7 h, in 62 % and 32 % yield, respectively.…”

Section: Entrymentioning

confidence: 99%

“…Importantly, the latter are not accessible through the application of hypervalent iodine oxidants, as these lead to an over-oxidation of the BINOL moiety. [22] Moreover, to gain comprehensive understanding of the reaction mechanism, and uncover the potential and limitations of the method, we performed thorough density functional theory (DFT) calculations. These provide insight into the origins of its chemo-and regioselectivity, in particular with respect to the side-functionalization at a benzylic position.…”

Section: Introductionmentioning

confidence: 99%

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Electrochemical Dearomatizing Methoxylation of Phenols and Naphthols: Synthetic and Computational Studies

Tomczyk,

Kalek

2024

Chemistry A European J

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The electrochemical oxidative dearomatizing methoxylation of phenols and naphthols was developed. It provides an alternative route for the preparation of methoxycyclohexadienones, important and versatile synthetic intermediates, that eliminates the need for stoichiometric high‐energy chemical oxidants and generates hydrogen as a sole by‐product. The reaction proceeds in a simple constant current mode, in an undivided cell, and it employs standardized instrumentation. A collection of methoxycyclohexadienones derived from various 2,4,6‐tri‐substituted phenols and 1‐substituted‐2‐naphthols was obtained in moderate to excellent yields. These include a complex derivative of estrone, as well as methoxylated dearomatized 1,1′‐bi‐2‐naphthols (BINOLs). The mechanism of the reaction was subject to profound investigations using density functional theory calculations. In particular, the reactivity of two key intermediates, phenoxyl radical and phenoxenium ion, was carefully examined. The obtained results shed light on the pathway leading to the desired product and rationalize experimentally observed selectivities regarding a side benzylic methoxylation and the preference for the functionalization at the para over the ortho position. They also uncover the structure‐selectivity relationship, inversely correlating the steric bulk of the substrate with its propensity to undergo the side‐reaction. Moreover, the loss of stereochemical information from enantiopure BINOL substrates during the reaction is rationalized by the computations.

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Section: Entrymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Electrochemical Dearomatizing Methoxylation of Phenols and Naphthols: Synthetic and Computational Studies

Tomczyk,

Kalek

2024

Chemistry A European J

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“…Multimetallic catalysis is poised to be an essential strategy to address these challenges, and it is primed for wider exploration and study. Indeed, a large and growing amount of literature in the areas of synergistic, cooperative, and multimetallic catalysis demonstrates a shift in reaction development from single-catalyst systems to more complex ones. − , In order for multimetallic catalysis to reach its full potential, the discovery of new systems and an improved understanding of how functional systems work is required. As we have shown, many of these lessons can be learned from established C–C bond-forming reactions that have facilitated cross couplings, ring openings, and polymerizations.…”

Section: Future Outlookmentioning

confidence: 99%

“…However, a single-metal catalyst can be limiting when reaction steps of a transformation have competing requirements, such as oxidative addition and reductive elimination (Figure A). A solution to these cases is multimetallic catalysis (Figure B), a process in which two or more metal catalysts work in concert to enable a single synthetic transformation. − This catalytic strategy is distinct from orthogonal tandem catalysis, when sequential , independent reactions occur in the same flask, each catalyzed by a single catalyst. − In a multimetallic system, both metals operate simultaneously, rather than sequentially: both metals are necessary for catalytic turnover. Reactions can be distinguished by how the two metals interact (Figure B).…”

Section: Introductionmentioning

confidence: 99%

Multimetallic-Catalyzed C–C Bond-Forming Reactions: From Serendipity to Strategy

Ackerman-Biegasiewicz

Kariofillis

Weix

2023

J. Am. Chem. Soc.

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The use of two or more metal catalysts in a reaction is a powerful synthetic strategy to access complex targets efficiently and selectively from simple starting materials. While capable of uniting distinct reactivities, the principles governing multimetallic catalysis are not always intuitive, making the discovery and optimization of new reactions challenging. Here, we outline our perspective on the design elements of multimetallic catalysis using precedent from well-documented C–C bond-forming reactions. These strategies provide insight into the synergy of metal catalysts and compatibility of the individual components of a reaction. Advantages and limitations are discussed to promote further development of the field.

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“…A bimetallic catalyst involves two metals acting synergistically to provide a better yield and selectivity of the product compared to those of any one of them. Although most bimetallic catalysts reported until date are based on heterogeneous catalysis, − there are some reports of their discrete molecular species being involved and detected in homogeneous catalysis, especially in C–H activation processes. , …”

Section: Introductionmentioning

confidence: 99%

Acetoxy Group-Directed Regioselective C2 Alkenylation of Indoles via Pd–Ag Bimetallic Catalysis

Paul,

Sengupta,

Sarkar

et al. 2023

J. Org. Chem.

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Regioselective C−H functionalizations of indoles reported to date with directing groups at C3 mainly rely on functional groups that are linked to the indole via C−C bonds. However, groups that are linked to the indole core by C−X linkages are also attractive due to the possibility of further modifications of the C−X bond. Herein, we report a 3-acetoxy directing group for the regioselective C2 alkenylation of indoles via a C−H activation-based, cross-dehydrogenative, oxidative Heck-type reaction. The reaction is catalyzed by Pd(II) and Ag(I) with stoichiometric Cu(II) as the oxidant and provides the 2-alkenylated indoles in yields of 52−84%. The reaction conditions are compatible with several functional groups at different positions as well as different N-protecting groups or free NH groups on the indole core. With respect to the alkene coupling partners, the reactions are successful with acrylates, vinyl sulfates, and phosphates. Specifically designed experiments, as well as density functional theory (DFT) computational studies, reveal that a heterodinuclear [Pd(μ-OAc) 3 Ag] bimetallic species is the actual catalyst responsible for the C−H alkenylation. A mechanistic path involving this catalytic species was also found to be favorable over other possible pathways for explaining the observed regioselectivity through DFT studies.

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Metal/Metal Dual Catalysis in C−H Activation

Cited by 12 publications

References 77 publications

Electrochemical Dearomatizing Methoxylation of Phenols and Naphthols: Synthetic and Computational Studies

Electrochemical Dearomatizing Methoxylation of Phenols and Naphthols: Synthetic and Computational Studies

Multimetallic-Catalyzed C–C Bond-Forming Reactions: From Serendipity to Strategy

Acetoxy Group-Directed Regioselective C2 Alkenylation of Indoles via Pd–Ag Bimetallic Catalysis

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