Theoretical investigation of Ni(PMe3)4-catalyzed intermolecular hydroacylation of alkynes with benzaldehydes

Meng, Qingxi; Shen, Wei; He, Rongxing; Li, Ming

doi:10.1007/s11243-011-9533-8

Cited by 7 publications

(4 citation statements)

References 42 publications

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“…There would be obvious merits of developing a novel hydroacylation system that proceeds via an oxanickelacycle intermediate. First, unfavorable decarbonylation from an acylmetal intermediate, which could be generated via oxidative addition of a formyl group to the catalyst, , can be avoided since the target Ni system would proceed without the generation of an acylnickel intermediate . Decarbonylation is an inevitable side reaction in most of the reported catalyst systems with Pd and Rh, which causes a decrease in atom efficiency and deactivation of the catalyst via a coordination with carbon monoxide.…”

Section: Ni(0)-catalyzed Intramolecular Alkene Hydroacylationmentioning

confidence: 99%

Catalytic Transformation of Aldehydes with Nickel Complexes through η² Coordination and Oxidative Cyclization

2015

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Chemists no longer doubt the importance of a methodology that could activate and utilize aldehydes in organic syntheses since many products prepared from them support our daily life. Tremendous effort has been devoted to the development of these methods using main-group elements and transition metals. Thus, many organic chemists have used an activator-(aldehyde oxygen) interaction, namely, η(1) coordination, whereby a Lewis or Brønsted acid activates an aldehyde. In the field of coordination chemistry, η(2) coordination of aldehydes to transition metals by coordination of a carbon-oxygen double bond has been well-studied; this activation mode, however, is rarely found in transition-metal catalysis. In view of the distinctive reactivity of an η(2)-aldehyde complex, unprecedented reactions via this intermediate are a distinct possibility. In this Account, we summarize our recent results dealing with nickel(0)-catalyzed transformations of aldehydes via η(2)-aldehyde nickel and oxanickelacycle intermediates. The combination of electron-rich nickel(0) and strong electron-donating N-heterocyclic carbene (NHC) ligands adequately form η(2)-aldehyde complexes in which the aldehyde is highly activated by back-bonding. With Ni(0)/NHC catalysts, processes involving intramolecular hydroacylation of alkenes and homo/cross-dimerization of aldehydes (the Tishchenko reaction) have been developed, and both proceed via the simultaneous η(2) coordination of aldehydes and other π components (alkenes or aldehydes). The results of the mechanistic studies are consistent with a reaction pathway that proceeds via an oxanickelacycle intermediate generated by the oxidative cyclization with a nickel(0) complex. In addition, we have used the η(2)-aldehyde nickel complex as an effective activator for an organosilane in order to generate a silicate reactant. These reactions show 100% atom efficiency, generate no wastes, and are conducted under mild conditions.

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Section: Ni(0)-catalyzed Intramolecular Alkene Hydroacylationmentioning

confidence: 99%

Catalytic Transformation of Aldehydes with Nickel Complexes through η² Coordination and Oxidative Cyclization

2015

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“…Mechanistic studies on a number of selected of systems, ,,,,,,, coupled with computational investigations, − support oxidative addition of the aldehyde to give an acyl hydride being the first productive step, followed by alkene (or alkyne) coordination (Scheme ). Migratory insertion of the hydride, rather than the acyl, − is then proposed to occur to give an unobserved acyl alkyl (alkenyl) intermediate as either linear (1,2-insertion) or branched (2,1-insertion) regioisomers.…”

Section: Introductionmentioning

confidence: 99%

“…The synthesis of intermediates prior to reductive elimination for the most general class of catalysts used for hydroacylation, [Rh(chelating phosphine)] + , would give important structural and mechanistic data pertinent to C–C bond formation and linear/branched selectivity, and would also determine whether hydride migration or acyl migration (carbometalation) occursquestions that have only been addressed computationally. ,− As far as we are aware, such intermediates have not been experimentally reported for alkyne hydroacylation. Tanaka and Fu have reported mechanistic details of intramolecular alkynal hydroacylation, but no intermediates were isolated. − …”

Section: Introductionmentioning

confidence: 99%

Intermolecular Alkyne Hydroacylation. Mechanistic Insight from the Isolation of the Vinyl Intermediate That Precedes Reductive Elimination

et al. 2012

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The isolation of the branched alkenyl intermediate that directly precedes reductive elimination of the final α,β-unsaturated ketone product is reported for the hydroacylation reaction between the alkyne HCCArF (ArF = 3,5-(CF3)2C6H3) and the β-S-substituted aldehyde 2-(methylthio)benzaldehyde: [Rh(fac-κ3-DPEphos)(C(CH2)ArF)(C(O)C6H4SMe)2][CB11H12]. The structure of this intermediate shows that, in this system at least, hydride migration rather than acyl migration occurs. Kinetic studies on the subsequent reductive elimination to form the crystallographically characterized ketone-bound product [Rh(cis-κ2-DPEphos)(η2:η2,κ1-H2CC(ArF)C(O)(C6H4SMe)][CB11H12] yield the following activation parameters for reductive elimination, which follows first-order kinetics (k obs = (6.14 ± 0.04) × 10–5 s–1, 324 K): ΔH ⧧ = 95 ± 2 kJ mol–1, ΔS ⧧ = −32 ± 7 J K–1 mol–1, ΔG ⧧(298 K) = 105 ± 4 kJ mol–1. Mechanistic studies, including selective deuteration experiments, show that hydride insertion is not reversible and also reveal that an interesting isomerization process is occurring between the two branched alkenyl protons that is suggested to occur via a metallocyclopropene intermediate. During catalysis, the consumption of substrates and evolution of products follow pseudo zero-order kinetics. The observation of both linear and branched products under stoichiometric and catalytic regimes, in combination with kinetic modeling, allows for an overall mechanistic scheme to be presented. Partitioning of linear and branched pathways at the hydride insertion step occurs with an approximate 2:1 selectivity, while reductive elimination of the linear product is at least 3 orders of magnitude faster than that from the branched. An explanation for the large difference in rate of reductive elimination in this system, as recently outlined by Goldman, Krogh-Jespersen, and Brookhart, is that steric crowding in branched intermediates can slow C–C reductive elimination even though such species are higher in energy than their linear analogues, if the rotation of the vinyl group to the appropriate orientation is inhibited by steric crowding in the branched isomers.

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“…Tsuda and Saegusa et al reported Ni 0 /PR 3 -catalyzed intermolecular alkyne hydroacylation to give a,b-enones. [5,6] They proposed two possible reaction pathways: a) proceeds through an acyl nickel intermediate, and b) proceeds through an oxanickelacycle intermediate (Scheme 1). They concluded that the former was more plausible because of the formation of decarbonylated olefinic products in the reaction with benzaldehyde.…”

mentioning

confidence: 99%

Synthesis of Five‐ and Six‐Membered Benzocyclic Ketones through Intramolecular Alkene Hydroacylation Catalyzed by Nickel(0)/N‐Heterocyclic Carbenes

et al. 2012

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Transition-metal-catalyzed hydroacylation has been accepted as a promising synthetic method to form carbon-carbon bonds between an aldehyde and unsaturated compounds, such as alkenes, alkynes, and ketones. A number of catalyst systems have been developed, and high enatio-, regio-, and chemo-selectivity has been achieved.[1] Despite these extensive efforts and praiseworthy results, an inevitable side reaction persists: decarbonylation from an acyl metal intermediate, which causes a decrease in atom-efficiency and a deactivation of the catalyst through the coordination of carbon monoxide (Scheme

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Theoretical investigation of Ni(PMe3)4-catalyzed intermolecular hydroacylation of alkynes with benzaldehydes

Cited by 7 publications

References 42 publications

Catalytic Transformation of Aldehydes with Nickel Complexes through η² Coordination and Oxidative Cyclization

Catalytic Transformation of Aldehydes with Nickel Complexes through η² Coordination and Oxidative Cyclization

Intermolecular Alkyne Hydroacylation. Mechanistic Insight from the Isolation of the Vinyl Intermediate That Precedes Reductive Elimination

Synthesis of Five‐ and Six‐Membered Benzocyclic Ketones through Intramolecular Alkene Hydroacylation Catalyzed by Nickel(0)/N‐Heterocyclic Carbenes

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Theoretical investigation of Ni(PMe3)4-catalyzed intermolecular hydroacylation of alkynes with benzaldehydes

Cited by 7 publications

References 42 publications

Catalytic Transformation of Aldehydes with Nickel Complexes through η2 Coordination and Oxidative Cyclization

Catalytic Transformation of Aldehydes with Nickel Complexes through η2 Coordination and Oxidative Cyclization

Intermolecular Alkyne Hydroacylation. Mechanistic Insight from the Isolation of the Vinyl Intermediate That Precedes Reductive Elimination

Synthesis of Five‐ and Six‐Membered Benzocyclic Ketones through Intramolecular Alkene Hydroacylation Catalyzed by Nickel(0)/N‐Heterocyclic Carbenes

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Catalytic Transformation of Aldehydes with Nickel Complexes through η² Coordination and Oxidative Cyclization

Catalytic Transformation of Aldehydes with Nickel Complexes through η² Coordination and Oxidative Cyclization