Transition-Metal-Catalyzed Arene Alkylation and Alkenylation: Catalytic Processes for the Generation of Chemical Intermediates

Gunnoe, T. Brent; Schinski, William L.; Jia, Xiaofan; Zhu, Weihao

doi:10.1021/acscatal.0c03494

Cited by 16 publications

(22 citation statements)

References 137 publications

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“…Molecular complexes based on Ru, − Pd, − Ni, , Ir, − and Pt − have been reported to catalyze olefin hydroarylation (to produce alkyl arenes) and oxidative olefin hydroarylation (to produce alkenyl arenes) using unactivated arenes and olefins. Our group and others have reported Rh catalyzed aromatic C–H activation − and arene alkenylation using hydrocarbon substrates, ,− and we recently demonstrated oxidative olefin hydroarylation using [(η 2 -C 2 H 4 ) 2 Rh(μ-OAc)] 2 ( 1 ) as the catalyst precursor. ,− These reactions incorporate the Rh catalyst precursor, arene, olefin and CuX 2 (X = carboxylate such as acetate, pivalate and 2-ethylhexanoate) and are generally heated between 150 and 165 °C. Potential advantages of the Rh-catalyzed alkenyl arene formation include: (a) selectivity for linear 1-aryl alkenes (>8:1 linear/branched ratio in most cases); (b) broad substrate scope including electron-deficient arenes; (c) under some reaction conditions, quantitative yield based on Cu(II) oxidants as the limiting reagent; and (d) aerobic oxidation by recycling Cu(II) with air, either during catalysis or in a step separate from catalysis.…”

Section: Introductionmentioning

confidence: 99%

Mechanistic Studies of Styrene Production from Benzene and Ethylene Using [(η²-C₂H₄)₂Rh(μ-OAc)]₂ as Catalyst Precursor: Identification of a Bis-Rh^I Mono-Cu^II Complex As the Catalyst

et al. 2021

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We report a combined experimental and computational study focused on the mechanism of oxidative conversion of benzene and ethylene to styrene using [(η2-C2H4)2Rh(μ-OAc)]2 as the catalyst precursor in the presence of Cu(OPiv)2 (OPiv = pivalate). Using [(η2-C2H4)2Rh(μ-OAc)]2 as the catalyst precursor, ∼411 turnovers of styrene are observed after 1 h, giving an apparent turnover frequency of ∼0.11 s–1 (calculated assuming the binuclear structure is maintained in the active catalyst). We identify the catalyst resting state to be [(η2-C2H4)2RhI(μ-OPiv)2]2(μ-Cu), which is a heterotrinuclear molecular complex in which a central CuII atom bridges two Rh moieties. At high Rh concentration in the presence of Cu(OPiv)2 and pivalic acid (HOPiv), the trinuclear complex [(η2-C2H4)2RhI(μ-OPiv)2]2(μ-Cu) converts to the binuclear Rh(II) complex [(HOPiv)RhII(μ-OPiv)2]2, which has been identified by 1H NMR spectroscopy and single crystal X-ray diffraction. The binuclear Rh(II) [(HOPiv)RhII(μ-OPiv)2]2 is not a catalyst for styrene production, but under catalytic conditions [(HOPiv)RhII(μ-OPiv)2]2 can be partially converted to the active catalyst, the Rh–Cu–Rh complex [(η2-C2H4)2RhI(μ-OPiv)2]2(μ-Cu), following an induction period of ∼6 h. Using quantum chemical calculations, we sampled possible mononuclear and binuclear Rh species, finding that the binuclear Rh(II) [(HOPiv)RhII(μ-OPiv)2]2 paddle-wheel is a low energy global minimum, which is consistent with experimental observations that [(HOPiv)RhII(μ-OPiv)2]2 is not a catalyst for styrene formation. Further, we investigated the mechanism of styrene production starting from [(η2-C2H4)2RhI(μ-OAc)2]2(μ-Cu), [(η2-C2H4)2Rh(μ-OAc)]2, and (η2-C2H4)2Rh(κ2-OAc). For all reaction pathways studied, the predicted activation barriers for styrene formation from [(η2-C2H4)2Rh(μ-OAc)]2 and (η2-C2H4)2Rh(κ2-OAc) are too high compared to experimental kinetics. In contrast, the overall activation barrier for styrene formation predicted by DFT from the Rh–Cu–Rh complex [(η2-C2H4)2RhI(μ-OPiv)2]2(μ-Cu) is in agreement with experimentally determined rates of catalysis. Based on these results, we conclude that incorporation of Cu(II) into the active Rh–Cu–Rh catalyst reduces the activation barrier for benzene C–H activation, O–H reductive elimination, and ethylene insertion into the Rh–Ph bond.

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Section: Introductionmentioning

confidence: 99%

Mechanistic Studies of Styrene Production from Benzene and Ethylene Using [(η²-C₂H₄)₂Rh(μ-OAc)]₂ as Catalyst Precursor: Identification of a Bis-Rh^I Mono-Cu^II Complex As the Catalyst

et al. 2021

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“… Also, our group has disclosed a series of studies using Rh catalysts (Scheme ). − Notable features of these reactions include (1) the use of Cu(II) oxidants, for which we have demonstrated regeneration by dioxygen from air, ,, (2) the conversion of electron-deficient arenes, and (3) the selective formation of anti-Markovnikov addition products, 1-arylalkenes, with a >8/1 anti-Markovnikov/Markovnikov ratio in most reactions and higher selectivity under some conditions. ,, In an extension of Rh-catalyzed arene alkenylation, we recently reported oxidative conversion of unactivated arenes and alkenes to alkenylarenes using unpurified air or O 2 as the sole oxidant . This protocol uses a simple RhCl 3 salt ( 10 ) as a catalyst precursor, and >1000 TOs of styrene was demonstrated; however, under aerobic conditions benzaldehyde forms from the oxidation of styrene and is a major side product at high styrene TOs.…”

Section: Introductionmentioning

confidence: 99%

Advances in Group 10 Transition-Metal-Catalyzed Arene Alkylation and Alkenylation

Zhu

Gunnoe

2021

J. Am. Chem. Soc.

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On a large scale, the dominant method to produce alkyl arenes has been arene alkylation from arenes and olefins using acid-based catalysis. The addition of arene C−H bonds across olefin CC bonds catalyzed by transition-metal complexes through C−H activation and olefin insertion into metal−aryl bonds provides an alternative approach with potential advantages. This Perspective presents recent developments of olefin hydroarylation and oxidative olefin hydroarylation catalyzed by molecular complexes based on group 10 transition metals (Ni, Pd, Pt). Emphasis is placed on comparisons between Pt catalysts and other group 10 metal catalysts as well as Ru, Ir, and Rh catalysts.

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“…Furthermore, the procedure might enable a straightforward and scalable synthesis of super linear alkylbenzene (SLAB) surfactants like 8. [18] Herein, we demonstrate that benzylic sodium intermediates prepared by this continuous flow Scheme 1. a) On-demand continuous flow generation of (2ethylhexyl)sodium (1) and subsequent in-line Br/Na-exchange and directed metalation. b) Lateral metalations of methylarenes using in continuous flow prepared (2-ethylhexyl)sodium (1) and subsequent use of the benzylic sodiums for additive free Wurtz-type-couplings, oxetane, epoxide openings and addition to carbonyl derivatives.…”

Section: Introductionmentioning

confidence: 89%

Continuous Flow Preparation of Benzylic Sodium Organometallics

et al. 2022

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We report a lateral sodiation of alkyl(hetero)arenes using on‐demand generated hexane‐soluble (2‐ethylhexyl)sodium (1) in the presence of TMEDA. (2‐Ethylhexyl)sodium (1) is prepared via a sodium packed‐bed reactor and used for metalations at ambient temperature in batch as well as in continuous flow. The resulting benzylic sodium species are subsequently trapped with various electrophiles including carbonyl compounds, epoxides, oxetane, allyl/benzyl chlorides, alkyl halides and alkyl tosylates. Wurtz‐type couplings with secondary alkyl halides and tosylates proceed under complete inversion of stereochemistry. Furthermore, the utility of this lateral sodiation is demonstrated in the synthesis of pharmaceutical relevant compounds. Thus, fingolimod is prepared from p‐xylene applying the lateral sodiation twice. In addition, 7‐fold isotopically labeled salmeterol‐d7 and fenpiprane as well as precursors to super linear alkylbenzene (SLAB) surfactants are prepared.

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Transition-Metal-Catalyzed Arene Alkylation and Alkenylation: Catalytic Processes for the Generation of Chemical Intermediates

Cited by 16 publications

References 137 publications

Mechanistic Studies of Styrene Production from Benzene and Ethylene Using [(η²-C₂H₄)₂Rh(μ-OAc)]₂ as Catalyst Precursor: Identification of a Bis-Rh^I Mono-Cu^II Complex As the Catalyst

Mechanistic Studies of Styrene Production from Benzene and Ethylene Using [(η²-C₂H₄)₂Rh(μ-OAc)]₂ as Catalyst Precursor: Identification of a Bis-Rh^I Mono-Cu^II Complex As the Catalyst

Advances in Group 10 Transition-Metal-Catalyzed Arene Alkylation and Alkenylation

Continuous Flow Preparation of Benzylic Sodium Organometallics

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Transition-Metal-Catalyzed Arene Alkylation and Alkenylation: Catalytic Processes for the Generation of Chemical Intermediates

Cited by 16 publications

References 137 publications

Mechanistic Studies of Styrene Production from Benzene and Ethylene Using [(η2-C2H4)2Rh(μ-OAc)]2 as Catalyst Precursor: Identification of a Bis-RhI Mono-CuII Complex As the Catalyst

Mechanistic Studies of Styrene Production from Benzene and Ethylene Using [(η2-C2H4)2Rh(μ-OAc)]2 as Catalyst Precursor: Identification of a Bis-RhI Mono-CuII Complex As the Catalyst

Advances in Group 10 Transition-Metal-Catalyzed Arene Alkylation and Alkenylation

Continuous Flow Preparation of Benzylic Sodium Organometallics

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Mechanistic Studies of Styrene Production from Benzene and Ethylene Using [(η²-C₂H₄)₂Rh(μ-OAc)]₂ as Catalyst Precursor: Identification of a Bis-Rh^I Mono-Cu^II Complex As the Catalyst

Mechanistic Studies of Styrene Production from Benzene and Ethylene Using [(η²-C₂H₄)₂Rh(μ-OAc)]₂ as Catalyst Precursor: Identification of a Bis-Rh^I Mono-Cu^II Complex As the Catalyst