Ligand-Controlled Nickel-Catalyzed Reductive Relay Cross-Coupling of Alkyl Bromides and Aryl Bromides

ACS Catalysis, Год журнала: 2017, Номер 8(1), С. 310 - 313

Опубликована: Дек. 1, 2017

1,1-Diarylalkanes are important structural frameworks which widespread in biologically active molecules. Herein, we report a reductive relay cross-coupling of alkyl bromides with aryl by nickel catalysis simple nitrogen-containing ligand. This method selectively affords 1,1-diarylalkane derivatives good to excellent yields and regioselectivity.

Язык: Английский

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Photochemical Nickel-Catalyzed Reductive Migratory Cross-Coupling of Alkyl Bromides with Aryl Bromides

Organic Letters, Год журнала: 2018, Номер 20(7), С. 1880 - 1883

Опубликована: Март 21, 2018

A novel method to access 1,1-diarylalkanes from readily available, nonactivated alkyl bromides and aryl via visible-light-driven nickel iridium dual catalysis, wherein diisopropylamine ( iPr2NH) is used as the terminal stoichiometric reductant, reported. Both primary secondary can be successfully transformed into migratory benzylic arylation products with good selectivity. Additionally, this showcases tolerance toward a wide array of functional groups presence bases.

Язык: Английский

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Mechanism and Origins of Ligand-Controlled Stereoselectivity of Ni-Catalyzed Suzuki–Miyaura Coupling with Benzylic Esters: A Computational Study

Journal of the American Chemical Society, Год журнала: 2017, Номер 139(37), С. 12994 - 13005

Опубликована: Авг. 25, 2017

Nickel catalysts have shown unique ligand control of stereoselectivity in the Suzuki–Miyaura cross-coupling boronates with benzylic pivalates and derivatives involving C(sp3)–O cleavage. The SIMes (1,3-dimesityl-4,5-dihydroimidazol-2-ylidene) produces stereochemically inverted C–C coupling product, while tricyclohexylphosphine (PCy3) delivers retained stereochemistry. We explored mechanism origins ligand-controlled density functional theory (DFT) calculations. oxidative addition determines two competing transition states, an SN2 back-side attack type state that inverts stereogenic center a concerted through cyclic state, which provides stereoretention. key difference between states is substrate–nickel–ligand angle distortion; controls selectivity by differentiating ease this distortion. For PCy3 ligand, nickel–ligand interaction involves mainly σ-donation, does not require significant energy penalty for facile distortion allows favorable leading to extra d–p back-donation from nickel coordinating carbene increases rigidity bond, corresponding more difficult. This makes unfavorable SN2-type stereoinversion.

Язык: Английский

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Enantioselective Formation of CF₃-Bearing All-Carbon Quaternary Stereocenters via C–H Functionalization of Methanol: Iridium Catalyzed Allene Hydrohydroxymethylation

Journal of the American Chemical Society, Год журнала: 2017, Номер 139(24), С. 8114 - 8117

Опубликована: Июнь 12, 2017

Using an iridium catalyst modified by PhanePhos, CF3-allenes react with methanol to form branched products of hydrohydroxymethylation as single regioisomers excellent levels enantiomeric enrichment. This hydrogen autotransfer process enables catalytic enantioselective formation acyclic CF3-bearing all-carbon quaternary stereocenters in the absence stoichiometric metals or byproducts.

Язык: Английский

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Enantioselective Construction of Acyclic Quaternary Carbon Stereocenters: Palladium-Catalyzed Decarboxylative Allylic Alkylation of Fully Substituted Amide Enolates

Journal of the American Chemical Society, Год журнала: 2017, Номер 139(28), С. 9615 - 9620

Опубликована: Июнь 19, 2017

We report a divergent and modular protocol for the preparation of acyclic molecular frameworks containing newly created quaternary carbon stereocenters. Central to this approach is sequence composed (1) regioselective -retentive allyloxycarbonyl-trapped fully substituted stereodefined amide enolates (2) enantioselective palladium-catalyzed decarboxylative allylic alkylation reaction using novel bisphosphine ligand.

Язык: Английский

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Ni-Catalyzed Arylboration of Unactivated Alkenes: Scope and Mechanistic Studies

Journal of the American Chemical Society, Год журнала: 2019, Номер 141(23), С. 9391 - 9400

Опубликована: Июнь 4, 2019

A method for the Ni-catalyzed arylboration of unactivated monosubstituted, 1,1-disubstituted, and trisubstituted alkenes is disclosed. The reaction notable in that it converts highly substituted alkenes, aryl bromides, diboron reagents to products contain a quaternary carbon synthetically versatile carbon-boron bond with control stereoselectivity regioselectivity. In addition, demonstrated be useful synthesis saturated nitrogen heterocycles, which are important motifs pharmaceutical compounds. Finally, due unusual reactivity demonstrated, mechanistic details were studied both computational experimental techniques.

Язык: Английский

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Quaternary Centers by Nickel‐Catalyzed Cross‐Coupling of Tertiary Carboxylic Acids and (Hetero)Aryl Zinc Reagents

Angewandte Chemie International Edition, Год журнала: 2019, Номер 58(8), С. 2454 - 2458

Опубликована: Янв. 9, 2019

Abstract This work bridges a gap in the cross‐coupling of aliphatic redox‐active esters with aryl zinc reagents. Previously limited to primary, secondary, and specialized tertiary centers, new protocol has been devised enable coupling general systems using nickel catalysis. The scope this operationally simple method is broad, it can be used simplify synthesis medicinally relevant motifs bearing quaternary centers.

Язык: Английский

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Migratory functionalization of unactivated alkyl bromides for construction of all-carbon quaternary centers via transposed tert-C-radicals

Nature Communications, Год журнала: 2020, Номер 11(1)

Опубликована: Сен. 25, 2020

Abstract Despite remarkable recent advances in transition-metal-catalyzed C(sp 3 )−C cross-coupling reactions, there remain challenging bond formations. One class of such reactions include the formation tertiary -C(sp bonds, presumably due to unfavorable steric interactions and competing isomerizations alkyl metal intermediates. Reported herein is a Ni-catalyzed migratory 3,3-difluoroallylation unactivated bromides at remote centers. This approach enables facile construction otherwise difficult prepare all-carbon quaternary Key success this transformation an unusual functionalization via chain walking most sterically hindered ) center substrate. Preliminary mechanistic radical trapping studies with primary suggest unique mode C-radical generation through chain-walking followed by Ni–C homolysis. strategy complementary existing coupling protocols tert -alkyl organometallic or halide reagents, it expedient centers from easily available starting materials.

Язык: Английский

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Reductive coupling of benzyl oxalates with highly functionalized alkyl bromides by nickel catalysis

Chemical Science, Год журнала: 2018, Номер 9(19), С. 4529 - 4534

Опубликована: Янв. 1, 2018

A nickel-catalyzed reductive Csp³–Csp³ coupling of benzyl oxalates with highly functionalized alkyl bromides was disclosed.

Язык: Английский

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Insight into Transmetalation Enables Cobalt-Catalyzed Suzuki–Miyaura Cross Coupling

ACS Central Science, Год журнала: 2016, Номер 2(12), С. 935 - 942

Опубликована: Дек. 1, 2016

Among the fundamental transformations that comprise a catalytic cycle for cross coupling, transmetalation from nucleophile to metal catalyst is perhaps least understood. Optimizing this elementary step has enabled first example of cobalt-catalyzed Suzuki-Miyaura coupling between aryl triflate electrophiles and heteroaryl boron nucleophiles. Key discovery was preparation characterization new class tetrahedral, high-spin bis(phosphino)pyridine cobalt(I) alkoxide aryloxide complexes, (iPrPNP)CoOR, optimizing their reactivity with 2-benzofuranylBPin (Pin = pinacolate). Cobalt compounds small substituents such as R methyl ethyl underwent swift at 23 °C but also proved kinetically unstable toward β-H elimination. Secondary alkoxides iPr or CH(Ph)Me balanced stability reactivity. Isolation structural product following transmetalation, (iPrPNP)Co(2-benzofuranyl), established planar, diamagnetic complex, demonstrating high- low-spin states rapidly interconvert during reaction. The insights studies in guided selection appropriate reaction conditions enable examples C-C bond formation neutral nucleophiles electrophiles, model successful proposed.

Язык: Английский

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