Scope and Mechanism in Palladium-Catalyzed Isomerizations of Highly Substituted Allylic, Homoallylic, and Alkenyl Alcohols

Larionov, Evgeny; Lin, Luqing; Guénée, Laure; Mazet, Clément

doi:10.1021/ja508736u

Cited by 184 publications

(75 citation statements)

References 82 publications

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“…For this reaction, Mazet et al have computed an energy span of 20.0 kcal/mol for cationic bis(ditert-butylphosphino)ethane palladium hydride. 50 For Pd1 Br , we found an energy span of only 11.9 kcal/mol. Figure 4), we initially came across excessive energetic barriers.…”

Section: Resultsmentioning

confidence: 76%

Dinuclear Pd^I Catalysts in Equilibrium Isomerizations: Mechanistic Understanding, in Silico Casting, and Catalyst Development

Sivendran

Maity

et al. 2020

ACS Catal.

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The unique reactivity profile of the dinuclear Pd I complex [Pd I (µ-Br) t Bu 3 P] 2 as an isomerization co-catalyst has enabled orthogonal tandem processes ranging from styrene syntheses to biodiesel refining. We have now elucidated the mechanistic basis of its distinct catalytic profile by DFT calculations and experimental studies. Activation of the catalyst proceeds intramolecularly, giving rise to a dinuclear complex composed of a reactive palladium hydride and an inert palladacycle. This complex mediates double-bond migrations with an energy span of 9.5 kcal/mol, which is well below those calculated for known catalysts. Its dissociation leads to an even more active monophosphinopalladium hydride catalyst and an inert dinuclear bispalladacycle. In the main deactivation pathway, two mononuclear Pd species react with each other, liberating a hydrogenation product and regenerating the catalyst precursor [Pd I (µ-Br) t Bu 3 P] 2. The experimentally observed build-up of dinuclear palladacycles during the catalysis is, thus, the result of a conversion of binuclear into mononuclear Pd-H catalyst. Phosphines, which would deactivate metathesis cocatalysts, are not liberated at any stage. This explains the unique suitability of [Pd I (µ-Br) t Bu 3 P] 2 for isomerizing metatheses. The mechanistic insights were used for the in silico casting of a catalyst generation, targeting complexes with a reduced barrier towards the formation of dinuclear Pd-H species, a low energy span of the catalytic cycles, and increased barriers either towards deactivation or, alternatively, towards dissociation to short-lived mononuclear complexes. Complexes with bisadamantyl-n-butylphosphine ligands were identified as lead structures. Experimental studies with model catalysts confirmed the validity of the predicted structureactivity relationship. SUPPORTING INFORMATION The Supporting Information is available free of charge on the ACS Publications website at DOI: xx.xxxx/jacs.xxxxxxx. Further mechanistic routes and energy profiles Full experimental and computational details

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Section: Resultsmentioning

confidence: 76%

Dinuclear Pd^I Catalysts in Equilibrium Isomerizations: Mechanistic Understanding, in Silico Casting, and Catalyst Development

Sivendran

Maity

et al. 2020

ACS Catal.

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“…Recently, metal-mediated chain walking has been emerging as a useful tool for remote functionalization of organic molecules [37][38][39][40][41][42][43][44][45][46][47][48][49][50][51][52][53][54] . The directions for chain walking can be controlled by catalysts or directing groups in organic substrates.…”

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confidence: 99%

Versatile cobalt-catalyzed regioselective chain-walking double hydroboration of 1,n-dienes to access gem-bis(boryl)alkanes

2020

Nat Commun

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Double hydroboration of dienes is the addition of a hydrogen and a boryl group to the two double bonds of a diene molecule and represents a straightforward and effective protocol to prepare synthetically versatile bis(boryl)alkanes, provided that this reaction occurs selectively. However, this reaction can potentially yield several isomeric organoboron products, and it still remains a challenge to control the regioselectivity of this reaction, which allows the selective production of a single organoboron product, in particular, for a broad scope of dienes. By employing a readily available cobalt catalyst, here we show that this double hydroboration yields synthetically useful gem-bis(boryl)alkanes with excellent regioselectivity. In addition, the scope of dienes for this reaction is broad and encompasses a wide range of conjugated and non-conjugated dienes. Furthermore, mechanistic studies indicate that this cobalt-catalyzed double hydroboration occurs through boryl-directed chain-walking hydroboration of alkenylboronates generated from anti-Markovnikov 1,2-hydroboration of 1,n-diene.

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“…Despitet he prior developmento fs everal protocols, [4][5][6][7][8][9][10][11] ag enerala nd simple catalytic system able to isomerize selectively and efficientlyb oth primary and sec-allylic alcohols under mild conditions has remained ac hallenge. The scope is commonly limitedt om olecules with few substituents, in particular for sec-allylic alcohols.…”

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confidence: 99%

General, Simple, and Chemoselective Catalysts for the Isomerization of Allylic Alcohols: The Importance of the Halide Ligand

Erbing

Vázquez-Romero

Gómez

et al. 2016

Chemistry A European J

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Scope and Mechanism in Palladium-Catalyzed Isomerizations of Highly Substituted Allylic, Homoallylic, and Alkenyl Alcohols

Cited by 184 publications

References 82 publications

Dinuclear Pd^I Catalysts in Equilibrium Isomerizations: Mechanistic Understanding, in Silico Casting, and Catalyst Development

Dinuclear Pd^I Catalysts in Equilibrium Isomerizations: Mechanistic Understanding, in Silico Casting, and Catalyst Development

Versatile cobalt-catalyzed regioselective chain-walking double hydroboration of 1,n-dienes to access gem-bis(boryl)alkanes

General, Simple, and Chemoselective Catalysts for the Isomerization of Allylic Alcohols: The Importance of the Halide Ligand

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Scope and Mechanism in Palladium-Catalyzed Isomerizations of Highly Substituted Allylic, Homoallylic, and Alkenyl Alcohols

Cited by 184 publications

References 82 publications

Dinuclear PdI Catalysts in Equilibrium Isomerizations: Mechanistic Understanding, in Silico Casting, and Catalyst Development

Dinuclear PdI Catalysts in Equilibrium Isomerizations: Mechanistic Understanding, in Silico Casting, and Catalyst Development

Versatile cobalt-catalyzed regioselective chain-walking double hydroboration of 1,n-dienes to access gem-bis(boryl)alkanes

General, Simple, and Chemoselective Catalysts for the Isomerization of Allylic Alcohols: The Importance of the Halide Ligand

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Dinuclear Pd^I Catalysts in Equilibrium Isomerizations: Mechanistic Understanding, in Silico Casting, and Catalyst Development

Dinuclear Pd^I Catalysts in Equilibrium Isomerizations: Mechanistic Understanding, in Silico Casting, and Catalyst Development