Thermolytic reactions of esters. Part II. Structural effects in the radical decomposition of simple allyl esters

Louw, R.; Kooyman, E. C.

doi:10.1002/recl.19670860204

Cited by 9 publications

(4 citation statements)

References 14 publications

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“…Reactions 11 and 28 thus close a catalytic cycle for the metal catalyzed radical induced decomposition of allyl acetate, most likely related to that observed for pyrolysis (eq 2). , …”

Section: Resultsmentioning

confidence: 99%

“…Thermally induced metal catalyzed decarboxylation reactions have attracted significant recent interest because they exhibit excellent atom economy for the organic substrate, which only produces CO 2 as a byproduct, involve the use of widely available carboxylic acids and their derivatives, and are often more selective than thermolysis in the absence of a metal catalyst. With regards to the latter point, Tunge has developed Pd catalyzed decarboxylative allylation reactions (eq ), , which are more selective than the competing radical fragmentation pathways that occur under pyrolysis of allyl carboxylates (e.g., eqs 2–4 for allyl acetate) …”

Section: Introductionmentioning

confidence: 99%

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Decarboxylative-Coupling of Allyl Acetate Catalyzed by Group 10 Organometallics, [(phen)M(CH₃)]⁺

et al. 2014

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Gas-phase carbon-carbon bond forming reactions, catalyzed by group 10 metal acetate cations [(phen)M(O2CCH3)](+) (where M = Ni, Pd or Pt) formed via electrospray ionization of metal acetate complexes [(phen)M(O2CCH3)2], were examined using an ion trap mass spectrometer and density functional theory (DFT) calculations. In step 1 of the catalytic cycle, collision induced dissociation (CID) of [(phen)M(O2CCH3)](+) yields the organometallic complex, [(phen)M(CH3)](+), via decarboxylation. [(phen)M(CH3)](+) reacts with allyl acetate via three competing reactions, with reactivity orders (% reaction efficiencies) established via kinetic modeling. In step 2a, allylic alkylation occurs to give 1-butene and reform metal acetate, [(phen)M(O2CCH3)](+), with Ni (36%) > Pd (28%) > Pt (2%). Adduct formation, [(phen)M(C6H11O2)](+), occurs with Pt (24%) > Pd (21%) > Ni(11%). The major losses upon CID on the adduct, [(phen)M(C6H11O2)](+), are 1-butene for M = Ni and Pd and methane for Pt. Loss of methane only occurs for Pt (10%) to give [(phen)Pt(C5H7O2)](+). The sequences of steps 1 and 2a close a catalytic cycle for decarboxylative carbon-carbon bond coupling. DFT calculations suggest that carbon-carbon bond formation occurs via alkene insertion as the initial step for all three metals, without involving higher oxidation states for the metal centers.

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“…Reactions 11 and 28 thus close a catalytic cycle for the metal catalyzed radical induced decomposition of allyl acetate, most likely related to that observed for pyrolysis (eq 2). , …”

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Decarboxylative-Coupling of Allyl Acetate Catalyzed by Group 10 Organometallics, [(phen)M(CH₃)]⁺

et al. 2014

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“…(3) Based on the detection of cross-over products from the co-pyrolysis of CH 3 CO 2 CH 2 CH = CH 2 and CD 3 CO 2 CH 2 CH = CH 2 , allyl acetate has been proposed to decompose via a radical chain mechanism involving bond homolysis followed by attack of the methyl radical onto a second allyl acetate to either produce 1-butene (path (a) of Scheme 5c) or acrolein [path (b)] [59,60].…”

Section: Thermolysis Of Esters In the Absence Of A Metal Catalystmentioning

confidence: 99%

“…CuCH 3 ] -[71][72][73][74][75][76][77][78];(2) [CH3 M 1 M 2 ] + (where M 1 and M 2 = Cu or Ag) [79-81]; (3) [RM(phen)] + [82-85] (where R = CH 3 and a c b Scheme 5 Mechanisms for pyrolytic decomposition reactions of esters: (a) cis-elimination[48][49][50][51]; (b) six centered TS for vinyl ester decomposition[51]; (c) radical decompositions in allyl acetates[59,60].…”

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confidence: 99%

Gas-phase studies of metal catalyzed decarboxylative cross-coupling reactions of esters

O’Hair

2015

Pure and Applied Chemistry

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Metal-catalyzed decarboxylative coupling reactions of esters offer new opportunities for formation of C-C bonds with CO 2 as the only coproduct. Here I provide an overview of: key solution phase literature; thermochemical considerations for decarboxylation of esters and thermolysis of esters in the absence of a metal catalyst. Results from my laboratory on the use of multistage ion trap mass spectrometry experiments and DFT calculations to probe the gas-phase metal catalyzed decarboxylative cross-coupling reactions of allyl acetate and related esters are then reviewed. These studies have explored the role of the metal carboxylate complex in the gas phase decarboxylative coupling of allyl acetate proceeding via a simple twostep catalytic cycle. In Step 1, an organometallic ion, [CH 3 ML] +/-(where M is a group 10 or 11 metal and L is an auxillary ligand), is allowed to undergo ion-molecule reactions with allyl acetate to generate 1-butene and the metal acetate ion, [CH 3 CO 2 ML] +/-. In Step 2, the metal acetate ion is subjected to collision-induced dissociation to reform the organometallic ion and thereby close the catalytic cycle. DFT calculations have been used to explore the mechanisms of these reactions. The organometallic ions [CH 3 CuCH 3 ] -, [CH 3 Cu 2 ] + , [CH 3 AgCu] + and [CH 3 M(phen)] + (where M = Ni, Pd and Pt) all undergo C-C bond coupling reactions with allyl acetate (Step 1), although the reaction efficiencies and product branching ratios are highly dependant on the nature of the metal complex. For example, [CH 3 Ag 2 ] + does not undergo C-C bond coupling. Using DFT calculations, a diverse range of mechanisms have been explored for these C-C bond-coupling reactions including: oxidative-addition, followed by reductive elimination; insertion reactions and S N 2-like reactions. Which of these mechanisms operate is dependant on the nature of the metal complex. A wide range of organometallic ions can be formed via decarboxylation (Step 2) although these reactions can be in competition with other fragmentation channels. DFT calculations have located different types of transition states for the formation of [CH 3 CuCH 3 ] -, [CH 3 Cu 2 ] + , [CH 3 AgCu] + and [CH 3 M(phen)] + (where M = Ni, Pd and Pt). Of the catalysts studied to date, [CH 3 Cu 2 ] + and [CH 3 Pd(phen)] + are best at promoting C-C bond formation (Step 1) as well as being regenerated (Step 2). Preliminary results on the reactions of [C 6 H 5 M(phen)] + (M = Ni and Pd) with C 6 H 5 CO 2 CH 2 CH = CH 2 and C 6 H 5 CO 2 CH 2 C 6 H 5 are described.

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Structure‐Reactivity Relationships in Homogeneous Gas‐Phase Reactions: Thermolyses and Rearrangements

Smith¹,

Kelly²

1971

Progress in Physical Organic Chemistry

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Thermolytic reactions of esters. Part II. Structural effects in the radical decomposition of simple allyl esters

Cited by 9 publications

References 14 publications

Decarboxylative-Coupling of Allyl Acetate Catalyzed by Group 10 Organometallics, [(phen)M(CH₃)]⁺

Decarboxylative-Coupling of Allyl Acetate Catalyzed by Group 10 Organometallics, [(phen)M(CH₃)]⁺

Gas-phase studies of metal catalyzed decarboxylative cross-coupling reactions of esters

Structure‐Reactivity Relationships in Homogeneous Gas‐Phase Reactions: Thermolyses and Rearrangements

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Thermolytic reactions of esters. Part II. Structural effects in the radical decomposition of simple allyl esters

Cited by 9 publications

References 14 publications

Decarboxylative-Coupling of Allyl Acetate Catalyzed by Group 10 Organometallics, [(phen)M(CH3)]+

Decarboxylative-Coupling of Allyl Acetate Catalyzed by Group 10 Organometallics, [(phen)M(CH3)]+

Gas-phase studies of metal catalyzed decarboxylative cross-coupling reactions of esters

Structure‐Reactivity Relationships in Homogeneous Gas‐Phase Reactions: Thermolyses and Rearrangements

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Product

Resources

About

Decarboxylative-Coupling of Allyl Acetate Catalyzed by Group 10 Organometallics, [(phen)M(CH₃)]⁺

Decarboxylative-Coupling of Allyl Acetate Catalyzed by Group 10 Organometallics, [(phen)M(CH₃)]⁺