Nickel-Catalyzed Enantioselective Reductive Cross-Coupling Reactions

ACS Catalysis, Journal Year: 2020, Volume and Issue: 10(15), P. 8237 - 8246

Published: June 24, 2020

Nickel-catalyzed reductive cross-coupling reactions have emerged as powerful methods to join two electrophiles. These proven particularly useful for the coupling of sec-alkyl electrophiles form stereogenic centers; however, development enantioselective variants remains challenging. In this Perspective, we summarize progress that has been made toward Ni-catalyzed reactions.

Language: Английский

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Nickel-Catalyzed Dicarbofunctionalization of Alkenes

ACS Catalysis, Journal Year: 2020, Volume and Issue: 10(15), P. 8542 - 8556

Published: July 2, 2020

1,2-Dicarbofunctionalization of alkenes has emerged as an efficient synthetic strategy for preparing substituted molecules by coupling readily available with electrophiles and/or nucleophiles. Nickel complexes serve effective catalysts owing to their tendency undergo facile oxidative addition and slow β-hydride elimination, capability access both two-electron radical pathways. Two-component alkene functionalization reactions have achieved high chemo-, regio-, stereoselectivities tethering one the partners substrate. Three-component reactions, however, often incorporate directing groups control selectivity. Only a few examples directing-group-free difunctionalizations unactivated been reported. Therefore, great opportunities exist development three-component difunctionalization broad substrate scopes tunable stereoselectivities.

Language: Английский

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Mechanisms of Nickel-Catalyzed Coupling Reactions and Applications in Alkene Functionalization

Accounts of Chemical Research, Journal Year: 2020, Volume and Issue: 53(4), P. 906 - 919

Published: April 2, 2020

ConspectusNickel complexes exhibit distinct properties from other group 10 metals, including a small nuclear radius, high paring energy, low electronegativity, and redox potentials. These enable Ni catalysts to accommodate stabilize paramagnetic intermediates, access radical pathways, undergo slow β-H elimination. Our research program investigates how each of these fundamental attributes impact the catalytic Ni, in particular context alkene functionalization.Alkenes are versatile functional groups, but stereoselective carbofunctionalization reactions alkenes have been underdeveloped. This challenge may derive difficulty controlling selectivity via traditional two-electron migratory insertion pathways. could lead different stereodetermining steps mechanisms, allowing molecular scaffolds that otherwise difficult prepare. For example, an asymmetric diarylation reaction developed by our relies upon Ni(III) intermediates control enantioselectivity give library chiral α,α,β-triarylethane molecules with biological activity.Mechanistic studies on two-component reductive 1,2-difunctionalization shed light origin cross-electrophile selectivity, as C sp2 sp3 electrophiles independently activated at Ni(I) respectively. Catalyst reduction has identified be turnover-limiting step this system. A closer investigation formation using (Xantphos)Ni(I)Ar model complex reveals initiates concerted halogen-abstraction pathway.The potentials allowed us develop reductive, trans-selective diene cyclization, wherein classic mechanism operates Ni(I)/Ni(III) platform, accounting for chemo- stereoselectivity. found applications efficient synthesis pharmaceutically relevant molecules, such 3,4-dimethylgababutin.The tendency one-electron processes prompted explore dinuclear Ni-mediated bond formations. provide insight into Ni–Ni bonding two metal centers react cooperatively promote C–C, C–X, N–N forming elimination.Finally, isolation β-agostic Pd X-ray neutron diffraction characterization highly reactive molecules. The parameters serve unambiguous evidence interactions help rationalize slower elimination relative Pd. Overall, elucidated several contexts. Greater mechanistic understanding facilitates catalyst design helps reactivity Ni-catalyzed functionalization reactions.

Language: Английский

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Enantioselective Three-Component Fluoroalkylarylation of Unactivated Olefins through Nickel-Catalyzed Cross-Electrophile Coupling

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(21), P. 9604 - 9611

Published: May 11, 2020

A nickel-catalyzed, enantioselective, three-component fluoroalkylarylation of unactivated alkenes with aryl halides and perfluoroalkyl iodides has been described. This cross-electrophile coupling protocol utilizes a chiral nickel/BiOx system as well pendant chelating group to facilitate the challenging three-component, asymmetric difunctionalization alkenes, providing direct access valuable β-fluoroalkyl arylalkanes high efficiency excellent enantioselectivity. The mild conditions allow for broad substrate scope good functional toleration.

Language: Английский

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Asymmetric Ni-Catalyzed Radical Relayed Reductive Coupling

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(31), P. 13515 - 13522

Published: June 29, 2020

Alkene dicarbofunctionalizations enable the streamlined construction of aliphatic structures and have thus been subject intense research efforts. Despite significant progress, catalytic asymmetric variants remain scarce. Inspired by advantages reductive cross-coupling approaches, we present here a highly efficient intermolecular Ni-catalyzed dicarbofunctionalization alkenes. Two distinct readily available electrophiles, namely, Csp2- Csp3-halides, are added simultaneously across variety olefins (vinyl amides, vinyl boranes, phosphonates) at room temperature in regio- enantioselective manner. The reaction, devoid sensitive organometallic reagents, takes advantage an situ generated chiral alkyl Ni(III)-intermediate to ensure stereodefined outcome Csp3–Csp2 bond-forming reaction. An (l)-(+)-isoleucine bisoxazoline ligand presence coordinating sites on alkene key for successful these "asymmetric radical relayed couplings" (ARRRCs). Further, multiple transformations amides obtained this process showcase potential new methodology straightforward assembly building blocks such as primary secondary amines oxazolines, highlighting its synthetic utility.

Language: Английский

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Mechanism of Ni-Catalyzed Reductive 1,2-Dicarbofunctionalization of Alkenes

Journal of the American Chemical Society, Journal Year: 2019, Volume and Issue: 141(44), P. 17937 - 17948

Published: Oct. 7, 2019

Ni-catalyzed cross-electrophile coupling reactions have emerged as appealing methods to construct organic molecules without the use of stoichiometric organometallic reagents. The mechanisms are complex: plausible pathways, such "radical chain" and "sequential reduction" mechanisms, dependent on sequence activation electrophiles. A combination kinetic, spectroscopic, studies reveals that a Ni-catalyzed, reductive 1,2-dicarbofunctionalization alkenes proceeds through pathway. reduction Ni by Zn is turnover-limiting step, consistent with Ni(II) intermediates catalyst resting-state. only sufficient reduce (phen)Ni(II) Ni(I) species. As result, commonly proposed Ni(0) absent under these conditions. (Phen)Ni(I)–Br selectively activates aryl bromides via two-electron oxidation addition, whereas alkyl activated (phen)Ni(I)–Ar single-electron afford radicals. These findings could provide insight into achieving selectivity between different

Language: Английский

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Nickel/Photo-Cocatalyzed Asymmetric Acyl-Carbamoylation of Alkenes

Journal of the American Chemical Society, Journal Year: 2020, Volume and Issue: 142(5), P. 2180 - 2186

Published: Jan. 23, 2020

An unprecedented asymmetric acyl-carbamoylation of pendant alkenes tethered on aryl carbamic chlorides with both aliphatic and aromatic aldehydes has been developed via the cooperative catalysis a chiral nickel-PHOX complex tetrabutylammonium decatungstate. This reaction represents first example merging hydrogen-atom-transfer photochemistry transition metal in difunctionalization alkenes. Using this protocol, variety oxindoles bearing challenging quaternary stereogenic center are furnished under mild conditions highly enantioselective manner.

Language: Английский

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Nickel‐CatalyzedDicarbofunctionalization of Alkenes^†

Chinese Journal of Chemistry, Journal Year: 2020, Volume and Issue: 38(11), P. 1371 - 1394

Published: June 16, 2020

As a straightforward strategy for rapidly increasing molecular complexity, dicarbofunctionalization of alkenes has attracted substantial interests organic synthesis, medicine chemistry, and materials science. Nickel‐catalyzed cascade dicarbofunctionalizations have been flourished in this area recently, nickel‐mediated radical pathways particularly offer new opportunities conjunctive cross‐couplings with alkyl coupling partners. Herein, we give comprehensive review nickel‐catalyzed through historical perspective, including intermolecular three‐component reactions intramolecular reactions. Among the discussed review, carbometallation/cross‐coupling process addition/cross‐coupling are two major alkenes. The oxidative cyclization 1,2‐metallate shift processes also selectively discussed. These methods overcome limitations associated using noble metals field, providing an efficient access to structurally diversified molecules.

Language: Английский

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Visible-Light-Driven Catalytic Reductive Carboxylation with CO₂

ACS Catalysis, Journal Year: 2020, Volume and Issue: 10(19), P. 10871 - 10885

Published: Aug. 28, 2020

Carbon dioxide (CO2) is an important C1 source for the generation of carboxylic acids and derivatives. Stoichiometric catalytic carboxylation nucleophiles, including organometallic reagents, with CO2 has been widely investigated. Since many kinds reagents are prepared from electrophiles, transition-metal-catalyzed direct diverse electrophiles attracted much attention high step economy user-friendly protocols. Although significant progress achieved, use stoichiometric metallic or pyrophoric reductants common. The renaissance photochemistry seen numerous efforts devoted to light-driven CO2, which become one most active directions in this field. In Perspective, we summarize recent advances visible-light-driven reductive substrates, such as unsaturated hydrocarbons, organic (pseudo)halides, imines, presence mild electron donors, amines, Hantzsch esters, formates. We highlight mechanisms reactions, can proceed absence a photoredox catalyst dual visible light photoredox/transition metal system. also discuss future field offer some insight into challenges that remain.

Language: Английский

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Nickel‐Catalyzed Asymmetric Reductive Arylalkylation of Unactivated Alkenes

Angewandte Chemie International Edition, Journal Year: 2019, Volume and Issue: 58(20), P. 6722 - 6726

Published: March 20, 2019

Abstract Reported is an asymmetric reductive dicarbofunctionalization of unactivated alkenes. Under the catalysis a Ni/BOX system, various aryl bromides, incorporating pendant olefinic unit, were successfully reacted with array primary alkyl bromides in presence Zn as reductant, furnishing series benzene‐fused cyclic compounds bearing quaternary stereocenter high enantioselectivities. Notably, this reaction avoids use pregenerated organometallics and demonstrates tolerance sensitive functionalities. The preliminary mechanistic investigations reveal that Ni‐catalyzed proceeds cascade consisting migratory insertion cross‐coupling nickel(I)‐mediated intramolecular 5‐ exo cyclization enantiodetermining step.

Language: Английский

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