Bench-Stable Nickel Precatalysts with Heck-type Activation

Weber, Jessica M.; Longstreet, Ashley R.; Jamison, Timothy F.

doi:10.1021/acs.organomet.8b00351

Cited by 30 publications

(16 citation statements)

References 21 publications

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“…Active nickel(0) species A was generated after reduction of actual catalyst NiCl 2 (PCy 3 ) 2 with trialkylaluminium and attacked the pre-activated silicon center of chlorosilane as nucleophile to furnish cationic Jamison and co-workers developed an air and moisture stable phosphine containing nickel(II) precatalyst featuring alkene-functionalized aryl ligands which activated via Heck-type conditions. [40] Authors shaped nickel(II) pre-catalyst in such a way where associated alkene chain was included in aryl ring. The nickel(II)-pre-catalyst was activated further with the help of triflate reagent.…”

Section: Intermolecular Heck Reactionsmentioning

confidence: 99%

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Emerging Nickel Catalysis in Heck Reactions: Recent Developments

Bhakta

Ghosh

2020

Adv Synth Catal

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The synthetic application of nickel catalysts in Heck-coupling reactions is quite prominent and noticeable of late in organic synthesis. It shows great interest over the other transition metal catalysts due to its unique characteristic that prepares them more significantly applicable in different fields of synthetic application. The usefulness of nickel-catalysts relies in the fact that they are abundant in nature, relatively less precious and environment friendly. Nickel plays pivotal role in different kind of Heck reactions known such as intramolecular-, intermolecular-, reductive-Heck type reaction producing mainly carbocycles and hetero cycles of biological significance. Carbocyclization or hetero-cyclization reaction occurred under optimized reaction conditions developed and come up with the formation of various structural building blocks of naturally occurring compounds. Via reductive Heck cyclization large membered ring of carbo-or hetero-cyclic system was formed which performed key role as building blocks in pharmaceutical synthesis and bioactive molecule formation. Intermolecular Heck type reactions were comparatively more explored. Silyl-Heck, carbonyl-Heck, and other miscellaneous type reactions were covered up through nickel-catalyzed intermolecular Heck reaction. Asymmetric versions of Heck-coupling reactions are also reported to proceed even with unactivated alkenes, offering molecules having quaternary stereogenic center in a regio-and enantioselective manner. This manuscript intends to cover these entire concepts.

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Section: Intermolecular Heck Reactionsmentioning

confidence: 99%

“…Jamison and co‐workers developed an air and moisture stable phosphine containing nickel(II) pre‐catalyst featuring alkene‐functionalized aryl ligands which activated via Heck‐type conditions [40] . Authors shaped nickel(II) pre‐catalyst in such a way where associated alkene chain was included in aryl ring.…”

Section: Intermolecular Heck Reactionsmentioning

confidence: 99%

Emerging Nickel Catalysis in Heck Reactions: Recent Developments

Bhakta

Ghosh

2020

Adv Synth Catal

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“…7 As opposite to Pd(0) and Pt(0), where dicoordinate complexes with phosphine and N-heterocyclic carbene (NHC) ligands are common, L2Ni(0) complexes were isolated exclusively with bulky NHC substituents, even though the phosphine analogs are commonly postulated active species in Ni(0)-Ni(II) catalytic cycles. 8,9 (NHC)2Ni(0) derivatives proved to be proficient precatalysts in a number of bond-forming transformations, 10 and their stoichiometric chemistry targeted mostly the related oxidative addition reactions leading to Ni(I) and Ni(II) complexes. 11 While L2Pt(0) moieties have been shown to act as lone pair donors in a variety of complexes, 12 there is no record of the lighter Ni congeners being able to emulate this binding mode.…”

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confidence: 99%

“…Synthesis of T-shaped Ni(0) complex 4. (11), Ni1-C 1.902(7), 1.884 (7), Ge1-Cl 2.340(2), 2.3363(18), Ni1···H 2.47(4), C1-Ni1-C19 167.2(3), C-Ni1-Ge1 92.96 (19), 97.26 (19), Cl1-Ge1-Cl2 94.69(4), Ge1-Ni1···H 172.8 (9).…”

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confidence: 99%

Nickel as a Lewis Base in a T‐Shaped Nickel(0) Germylene Complex Incorporating a Flexible Bis(NHC) Ligand

et al. 2018

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Flexible, chelating bis(NHC) ligand 2, able to accommodate both cis-and trans-coordination modes, was used to synthesize (2)Ni(η 2 -cod), 3. In reaction with GeCl2, this produced (2)NiGeCl2, 4, featuring a T-shaped Ni(0) and a pyramidal Ge center. Complex 4 could also be prepared from [(2)GeCl]Cl, 5, and Ni(cod)2, in a reaction that formally involved Ni-Ge transmetalation, followed by coordination of the extruded GeCl2 moiety to Ni. A computational analysis showed that 4 possesses considerable multiconfigurational character and the Ni→Ge bond is formed through σ-donation from the Ni 4s, 4p, and 3d orbitals to Ge. (NHC)2Ni(cod) complexes 9 and 10, as well as (NHC)2GeCl2 derivative 11, incorporating ligands that cannot accommodate a wide bite angle, failed to produce isolable Ni-Ge complexes. The isolation of (2)Ni(η 2 -Py), 12, provides further evidence for the reluctance of the (2)Ni(0) fragment to act as a σ-Lewis acid.

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“…31 This complex was not purified, but immediately treated with trimethylsilyl triflate (TMS-OTf), upon which a methallyl nickel triflate complex was rapidly formed. 32 The structure of this complex (P1) was unambiguously characterized using X-ray diffraction ( Figure 2). Under optimized reaction conditions, this precatalyst (P1) facilitated the C-N coupling reaction and provided the desired product in 98% yield in 2 h. Analysis of the crude reaction mixture (GC/MS) showed that N-methallyl aniline was formed during the reaction, consistent with activation of P1 through outersphere nucleophilic attack by aniline at the methallyl ligand.…”

Section: Resultsmentioning

confidence: 99%

The Quest for the Ideal Base: Rational Design of a Nickel Precatalyst Enables Mild, Homogeneous C–N Cross-Coupling

Liu

Dennis²,

Buchwald³

2020

Preprint

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Palladium-catalyzed amination reactions using soluble organic bases have provided a solution to the many issues associated with heterogeneous reaction conditions. Still, homogeneous C–N cross-coupling approaches cannot yet employ bases as weak and economical as trialkylamines. Furthermore, organic base-mediated methods have not been developed for Ni(0/II) catalysis, despite some advantages of such systems over analogous Pd-based catalysts. We designed a new air-stable and easily prepared Ni(II) precatalyst bearing an electron-deficient bidentate phosphine ligand that enables the cross-coupling of aryl triflates with aryl amines using triethylamine (TEA) as base. The method is tolerant of sterically-congested coupling partners, as well as those bearing base- and nucleophile-sensitive functional groups. With the aid of density functional theory (DFT) calculations, we determined that the electron-deficient auxiliary ligands decrease both the pKa of the Ni-bound amine and the barrier to reductive elimination from the resultant Ni(II)–amido complex. Moreover, we determined that precluding Lewis acid-base complexation between the Ni catalyst and the base, due to steric factors, is important for avoiding catalyst inhibition.

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Bench-Stable Nickel Precatalysts with Heck-type Activation

Abstract: Herein, we report the synthesis and characterization of a new class of air- and moisture-stable phosphine-containing nickel(II) precatalysts, which activate through a Heck-type mechanism. The activities of the precatalysts are demonstrated with a carbonyl–ene coupling reaction.

Cited by 30 publications

References 21 publications

Emerging Nickel Catalysis in Heck Reactions: Recent Developments

Emerging Nickel Catalysis in Heck Reactions: Recent Developments

Nickel as a Lewis Base in a T‐Shaped Nickel(0) Germylene Complex Incorporating a Flexible Bis(NHC) Ligand

The Quest for the Ideal Base: Rational Design of a Nickel Precatalyst Enables Mild, Homogeneous C–N Cross-Coupling

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