Ruthenium-Catalyzed Hydrodefluorination with Silane as the Directing and Reducing Group

Fang, Huaquan; He, Qiaoxing; Liu, Guixia; Huang, Zheng

doi:10.1021/acs.orglett.0c03530

Cited by 14 publications

(8 citation statements)

References 55 publications

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“…In 2020, Huang et al reported that the Ru-pincer complex catalyzed ortho-selective hydrodefluorination of polyfluoroarenes in which an in-built hydrosilane moiety plays a pivotal role as a directing group as well as a reductant (Scheme 20a). 85 The (pincer)Ru− H species initiates the catalysis via the oxidative addition of a H−Si to form a Ru(IV) species, 77 (Scheme 20b). The migration of an ortho F atom to a Si center, followed by C−Si bond cleavage, gives the aryne−Ru(IV) intermediate 78, which then undergoes hydrometalation or silylmetalation to form 79 or 79′.…”

Section: Directed C−f Bond Activation Inmentioning

confidence: 99%

Section: Directed C–f Bond Activation In Polyfluorinated Compoundsmentioning

confidence: 99%

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The Directing Group: A Tool for Efficient and Selective C–F Bond Activation

Das

Chatani

2021

ACS Catal.

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C−F bond activation is currently considered to be "a hot topic" in many different but interconnected fields of research, due to its inherent inertness and unique properties. While considerable progress has been made in this particular field of research, activating strong bonds, such as the C−F bond, continues to be a challenge. Because polyfluorinated compounds are commercially available, the functionalization of C−F bonds has been extensively studied for preparing partially fluorinated compounds, some of which are biologically active and are used as functionalized materials. However, chemo-and regioselective methods are still required to prepare useful partially fluorinated compounds. In addition, a new strategy for the activation of a C−F bond in less reactive monofluorinated compounds remains a need. Directed strategies have been extensively used in C−H bond activation chemistry to achieve high efficiency as well as a high regioselectivity. On the other hand, a directed strategy that is applicable to the activation of various unreactive bonds, such as C−O, C−N, C−F, and others is still needed, compared with directed C−H bond activation. In this Review, we focus on the directed strategy for the activation of inert C−F bonds.

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Section: Directed C−f Bond Activation Inmentioning

confidence: 99%

Section: Directed C–f Bond Activation In Polyfluorinated Compoundsmentioning

confidence: 99%

The Directing Group: A Tool for Efficient and Selective C–F Bond Activation

Das

Chatani

2021

ACS Catal.

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“…An increasing number of applications of fluoroaryl-containing compounds in materials, [1] agrochemicals, [2] and pharmaceuticals [3] encourages the development of new strategies to synthesize such classes of compounds. Procedures to functionalize fluorinated arenes and the conversion of fluoroarenes into more complex organic molecules has been reported using fluoroaryl boronates, [4,5] magnesium, [6] lithium, [7,8] zinc, [9,10] or silicon reagents, [11] as well as halides, [12] and carboxylic acids. [13] However, the development of synthetic procedures to modify fluoroarenes via direct CÀ F [14] or CÀ H [15] functionalization is highly desirable as it decreases the number of synthetic steps, waste, cost, and energy usage.…”

Section: Introductionmentioning

confidence: 99%

Pd‐Catalyzed Oxidative C−H Arylation of (Poly)fluoroarenes with Aryl Pinacol Boronates and Experimental and Theoretical Studies of its Reaction Mechanism

Budiman,

Putra,

Ramadhan

et al. 2024

Chemistry An Asian Journal

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We report the synergistic combination of Pd(OAc)2 and Ag2O for the oxidative C–H arylation of (poly)fluoroarenes with aryl pinacol boronates (Ar‐Bpin) in DMF as the solvent. This procedure can be conducted easily in air, and without using additional ligands, to afford the fluorinated unsymmetrical biaryl products in up to 98% yield. Experimental studies suggest that the formation of [PdL2(C6F5)2] in DMF as coordinating solvent does not take place under the reaction conditions as it is stable to reductive elimination and thus would deactivate the catalyst. Thus, the intermediate [Pd(DMF)2(ArF)(Ar)] must be formed selectively to give desired arylation products. DFT calculations predict a low barrier (5.87 kcal/mol) for the concerted metalation deprotonation (CMD) process between C6F5H and the Pd(II) species formed after transmetalation between the Pd(II)X2 complex and aryl‐Bpin forms a Pd‐Arrich species; thus a Pd(Arrich)(Arpoor) complex is generated selectively which undergoes reductive elimination to generate the unsymmetrical biaryl product.

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“…Low-valent transition-metal complexes are commonly used to activate aromatic C(sp 2 )–F bonds. , Using transition-metal complexes, e.g., Pd, Ni, Ru, and Fe, − in the presence of silane reductants, fluoroarenes can proceed to hydrodefluorination. For aliphatic C(sp 3 )–F bond activation, strong main-group electrophiles, particularly silylium ions, R 3 Si + , were employed to heterolytically cleave the C–F bond .…”

Section: Introductionmentioning

confidence: 99%

Mechanisms of the Ruthenium Sulfur Complex in Generation and Stabilization of Silicon and Aluminum Electrophiles for C(sp³)–F Bond Activation

Worakul

Surawatanawong

2023

Organometallics

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C−F bond transformation has attracted much attention in chemical synthesis. For aliphatic C(sp 3 )−F activation, strong main-group electrophiles are commonly employed to abstract the fluoride. Herein, we performed density functional calculations to gain insights into the hydrodefluorination of CF 3substituted aniline derivatives, CF 3 (C 6 H 4 )NMe 2 , by the Ru−S complex 1, [(PEt 3 )Ru(DmpS)] + (DmpS = 2,6-dimesitylphenyl thiolate) with HSiMe 2 Ph. The mechanism involves three main steps: (i) Si−H bond activation to generate Ru−H with the thiosilane ligand, (ii) fluoride abstraction by the sulfur-supported silylium ( + SiMe 2 Ph) to generate + CF 2 (C 6 H 4 )NMe 2 , and (iii) hydride transfer from the Ru−H to the carbocation to generate the first hydrodefluorination product, CF 2 H(C 6 H 4 )NMe 2 . To form the fully hydrodefluorinated product, the second and the third fluoride abstractions proceed with lower energy barriers than the first fluoride abstraction, which is the rate-determining step. As the Si−H activation generates Ru−H with the thiosilane ligand, the Si−S bond must be cleaved to generate the active silylium moiety for the fluoride abstraction. In contrast, the Al−H activation of HAl i Bu 2 leads to the formation of Ru−H with the alumenium ( + Al i Bu 2 ), stabilized by the donation from both σ(Ru−H) and sulfur lone pair. Upon fluoride abstraction, the donation from the sulfur lone pair to the alumenium remains while that from σ(Ru−H) is loosened and simply replaced by the donation from the fluoride. The fluoride abstraction by the alumenium has a higher interaction and also involves less structural change than that by the silylium. This corresponds with the higher activity for the C−F bond activation when HAl i Bu 2 is used. The insights into the difference in the structures and activities in the fluoride abstraction by the silicon and the aluminum electrophiles, generated and stabilized by the Ru−S complex 1, will assist with the development of catalysts for C−F bond activation.

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Ruthenium-Catalyzed Hydrodefluorination with Silane as the Directing and Reducing Group

Cited by 14 publications

References 55 publications

The Directing Group: A Tool for Efficient and Selective C–F Bond Activation

The Directing Group: A Tool for Efficient and Selective C–F Bond Activation

Pd‐Catalyzed Oxidative C−H Arylation of (Poly)fluoroarenes with Aryl Pinacol Boronates and Experimental and Theoretical Studies of its Reaction Mechanism

Mechanisms of the Ruthenium Sulfur Complex in Generation and Stabilization of Silicon and Aluminum Electrophiles for C(sp³)–F Bond Activation

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Ruthenium-Catalyzed Hydrodefluorination with Silane as the Directing and Reducing Group

Cited by 14 publications

References 55 publications

The Directing Group: A Tool for Efficient and Selective C–F Bond Activation

The Directing Group: A Tool for Efficient and Selective C–F Bond Activation

Pd‐Catalyzed Oxidative C−H Arylation of (Poly)fluoroarenes with Aryl Pinacol Boronates and Experimental and Theoretical Studies of its Reaction Mechanism

Mechanisms of the Ruthenium Sulfur Complex in Generation and Stabilization of Silicon and Aluminum Electrophiles for C(sp3)–F Bond Activation

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Mechanisms of the Ruthenium Sulfur Complex in Generation and Stabilization of Silicon and Aluminum Electrophiles for C(sp³)–F Bond Activation