Diverse Reactivity Manifolds of Alkynyl Enone- and Alkynyl Enal-Derived Nickelacycles:  Discovery of Nickel-Promoted [3+2] and [2+1] Cycloadditions

Chowdhury, Sanjoy K.; Amarasinghe, Kande K. D.; Heeg, and Mary Jane; Montgomery, John

doi:10.1021/ja0012624

Cited by 51 publications

(8 citation statements)

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“…Furthermore, complex 2 was observed to demonstrate reactivity that closely parallels the nickel-catalyzed and nickel-promoted chemistry of alkynyl enal 1 . For instance, treatment of complex 2 with dimethylzinc affords a 71% isolated yield of aldehyde 3 , in direct analogy to the catalytic alkynyl enone/organozinc couplings that we extensively developed (Scheme ). 13a,b, Likewise, alkylative cycloadditions of 2 with methyl iodide and benzaldehyde proceeded in direct analogy to the one-pot procedures recently developed 13c to allow the efficient production of 4 and 5 in 69% and 68% yields, respectively.…”

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confidence: 99%

“…Our group has recently contributed to the area of late-metal-catalyzed enyne cyclizations . These reports have included a variety of nickel-catalyzed or -promoted processes involving alkynyl enones, such as alkylative cyclizations,13a reductive cyclizations,13a [2 + 2 + 2] cycloadditions,13b [3 + 2] alkylative cycloadditions,13c and [2 + 1] oxidative cycloadditions 13c. The intermolecular versions of several of these processes have been extensively developed by Ikeda 12b.…”

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confidence: 99%

“…Whereas several mechanisms may be envisioned for these processes, the formation of a reactive nickel metallacycle has emerged as the most reasonable mechanistic model on the basis of the data obtained to date. Our most recent studies demonstrated that treatment of equimolar quantities of Ni(COD) 2 and tetramethylethylenediamine (tmeda) with an alkynyl enone afforded a complex in situ that demonstrated reactivity consistent with the proposed metallacycle 13c. However, no direct evidence for formation of the proposed nickel metallacycle was initially obtained.…”

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Structure of an η¹ Nickel O-Enolate: Mechanistic Implications in Catalytic Enyne Cyclizations

et al. 2001

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Structure of an η¹ Nickel O-Enolate: Mechanistic Implications in Catalytic Enyne Cyclizations

et al. 2001

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“…The formation of five‐membered azanickelacycles from imines and alkynes similar to A were described recently by Ogoshi et al 10a. Many other five‐membered metallacycles11 containing an oxygen atom10b,c or only carbon atoms11b–e were observed or proposed as key catalytic intermediates. The formation of a nickelacycle by the addition of two π components is generally regioselective, with the carbon atom having an electron‐drawing functionality near to the metal center 4.…”

Section: Nickel‐catalyzed Reductive Coupling Reaction Of Imines and Cmentioning

confidence: 62%

Regioselective Synthesis of γ‐Amino Esters, Nitriles, Sulfones, and Pyrrolidinones by Nickel‐Catalyzed Reductive Coupling of Aldimines and Activated Alkenes

Yeh¹,

Korivi²,

Cheng³

2008

Angewandte Chemie

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The transition-metal-catalyzed regioselective coupling of two organic p components via a five-membered metallacycle intermediate is one method for the construction of CÀC bonds and the synthesis of molecules with multiple functional groups. Among these reactions, the reductive coupling of alkyne/alkyne [1a] alkene/alkyne, [1b,c,i,j] and alkene/alkene [1a] couples has been widely explored by us and others. Similarly, the coupling of alkene/carbonyl [1d] and alkyne/carbonyl [1e-h] couples catalyzed by metal complexes has more recently also attracted attention. In comparison, the use of an imine derivative as one of the p components has only rarely been explored. [2,3] Rhodium- [2a-c] and organo-catalyzed [2d,e] coupling reactions of conjugated alkenes with activated imines were found to give Baylis-Hillman-type products in which a CÀC bond was formed between the a-carbon atom of the alkene and the carbon atom of the imine. There is no report of an analogous metal-catalyzed coupling reaction occurring at the b-carbon atom of the alkene.[3] Our efforts to develop methods for the reductive coupling of two p components [1b,c, 4a] prompted us to investigate the coupling reaction of conjugated alkenes and imines. Herein, we report an efficient eneimine reductive coupling reaction catalyzed by a nickel-1,10-phenanthroline complex to give various substituted g-amino esters, [5i,j] g-aminonitriles, [5k,l] g-aminosulfones, and pyrrolidinones.[5] These products are all g-aminobutyric acid (GABA) derivatives, which are known to exhibit a wide range of biological properties [6] and have found various industrial applications.[6] In contrast to the base- [2d] and metal-catalyzed reactions, our ene-imine coupling reaction yields saturated products in which a C À C bond is formed at the b-carbon atom of conjugated alkenes.The success of the reductive ene-imine coupling reaction depends greatly on the choice of the ligand and metal. When 4-fluorobenzaldimine 1 a was treated with ethyl acrylate in acetonitrile in the presence of [CoI 2 (dppe)] (dppe = 1,2-bis(diphenyphosphanyl)ethane) or [NiBr 2 (dppe)], Zn, and H 2 O at 808C, only a trace of the reductive coupling product 3 a was observed. Fortunately, when we changed the catalyst to [NiI 2 (phen)], [NiBr 2 (bipy)], [NiCl 2 (bipy)], or [NiBr 2 -(phen)] (phen = 1,10-phenanthroline, bipy = 2,2'-bipyridine), the expected product 3 a was formed in yields of 55, 75, 37, or 99 %, respectively. The yields of 3 a were determined by integration of the 1 H NMR signals, using mesitylene as the internal standard. The nickel complex [NiBr 2 (tmeda)] (tmeda = tetramethylethylenediamine), which has an electron-rich nitrogen ligand, did not give the desired product. Also, phenanthroline or zinc alone did not catalyze the reaction. Surprisingly, these studies show that phosphines are not suitable ligands in the present catalytic reaction, but that bipyridine-type ligands, particularly phen, are essential.

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“…Nevertheless, late transition metal-catalyzed reactions of aldehydes and imines that are likely to occur by insertion of aldehydes or imines have emerged recently. For example, additions of aryl and vinyl groups to α,β-unsaturated carbonyl compounds, aldehydes, and imines catalyzed by rhodium , and other late metals − have become a versatile method for the construction of new carbon−carbon bonds. Few studies have been conducted to reveal the mechanism of the additions to aldehydes and imines, but insertions of aldehydes, ketones, and imines into late metal carbon bonds have been proposed to account for the formation of diarylmethanol or diarylmethylamine products (Scheme ).…”

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confidence: 99%

Reactions of an Arylrhodium Complex with Aldehydes, Imines, Ketones, and Alkynones. New Classes of Insertion Reactions

Krug

Hartwig

2004

Organometallics

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Organorhodium complexes of the general formula (DPPE)Rh(pyridine)(R) (R ) p-tol (2a) and CH 2 SiMe 3 (2b), DPPE ) 1,2-bis(diphenylphosphino)ethane) were prepared from [(DPPE)-Rh(µ-Cl)] 2 , pyridine, and p-tolyllithium or Me 3 SiCH 2 MgCl. Complex 2a inserted the electronpoor aldimines (p-tol)CHdN(C 6 H 4 -p-CO 2 Me) (3a-Tol) and (Ph)CHdN(C 6 H 4 -p-CO 2 Me) (3a-Ph) to give amide complexes that were isolated directly or trapped with PEt 3 . In contrast, the reaction of aryl complex 2a with the electron-neutral and electron-rich imines PhCHd NPh (3b) and (p-tol)CHdN(C 6 H 4 -p-OMe) (3c) did not form stable amide products. Instead, the amide from insertion of imines 3b or 3c underwent β-hydrogen elimination, followed by metalation of the resulting ketimine. The reaction of 2a with 3a-Ph was first order in arylrhodium complex and inverse first order in the concentration of pyridine. Aldehydes that cannot enolize, such as PhCHO and Me 3 CCHO, inserted into the Rh-aryl bond of 2a to form ketones and esters. The esters were formed from insertion of a second aldehyde into the Rh-O bond of an intermediate alkoxide, followed by β-hydride elimination. Complex 2a underwent proton transfer with acetophenone to give π-oxaallyl complex 24 and with water to generate toluene and the dimeric hydroxide [(DPPE)Rh(µ-OH)] 2 (36). It also reacted with the tert-butyl-substituted ynone 25 to form a product that contained a metalated isobutyl group. Quenching the reaction between aryl complexes 2a and 3a-Ph with H 2 O instead of PEt 3 also formed hydroxide 36 and the diarylmethylamine (Ph)(p-tol)CH-NH(C 6 H 4 -p-CO 2 -Me) (35).

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Diverse Reactivity Manifolds of Alkynyl Enone- and Alkynyl Enal-Derived Nickelacycles: Discovery of Nickel-Promoted [3+2] and [2+1] Cycloadditions

Cited by 51 publications

References 15 publications

Structure of an η¹ Nickel O-Enolate: Mechanistic Implications in Catalytic Enyne Cyclizations

Structure of an η¹ Nickel O-Enolate: Mechanistic Implications in Catalytic Enyne Cyclizations

Regioselective Synthesis of γ‐Amino Esters, Nitriles, Sulfones, and Pyrrolidinones by Nickel‐Catalyzed Reductive Coupling of Aldimines and Activated Alkenes

Reactions of an Arylrhodium Complex with Aldehydes, Imines, Ketones, and Alkynones. New Classes of Insertion Reactions

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Diverse Reactivity Manifolds of Alkynyl Enone- and Alkynyl Enal-Derived Nickelacycles: Discovery of Nickel-Promoted [3+2] and [2+1] Cycloadditions

Cited by 51 publications

References 15 publications

Structure of an η1 Nickel O-Enolate: Mechanistic Implications in Catalytic Enyne Cyclizations

Structure of an η1 Nickel O-Enolate: Mechanistic Implications in Catalytic Enyne Cyclizations

Regioselective Synthesis of γ‐Amino Esters, Nitriles, Sulfones, and Pyrrolidinones by Nickel‐Catalyzed Reductive Coupling of Aldimines and Activated Alkenes

Reactions of an Arylrhodium Complex with Aldehydes, Imines, Ketones, and Alkynones. New Classes of Insertion Reactions

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Structure of an η¹ Nickel O-Enolate: Mechanistic Implications in Catalytic Enyne Cyclizations

Structure of an η¹ Nickel O-Enolate: Mechanistic Implications in Catalytic Enyne Cyclizations