On the Palladium(II)‐Catalysed Oxidative Rearrangement of Propargylic Acetates

Bartels, A.; Mahrwald, Rainer; Müller, Kurt

doi:10.1002/adsc.200303200

Cited by 17 publications

(3 citation statements)

References 19 publications

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“…While a previous Pd catalysis [43] could also accomplish this transformation, the demonstrated scope is much limited, and the catalyst loading is 20%. With this oxidative gold catalysis, the propargyl esters, except those derived from tertiary alcohols, can be reliably converted into α-acyloxy α,β-unsaturated ketones/aldehydes.…”

Section: Resultsmentioning

confidence: 99%

Gold-catalyzed regioselective oxidation of propargylic carboxylates: a reliable access to α-carboxy-α,β-unsaturated ketones/aldehydes

Ji¹,

Nelson²,

Zhang³

2013

Beilstein J. Org. Chem.

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SummaryGold-catalyzed intermolecular oxidation of carboxylates of primary or secondary propargylic alcohols are realized with excellent regioselectivity, which is ascribed to inductive polarization of the C–C triple bond by the electron-withdrawing carboxy group. The gold carbene intermediates thus generated undergo selective 1,2-acyloxy migration over a 1,2-C–H insertion, and the selectivities could be dramatically improved by the use of a P,S-bidentate ligand, which is proposed to enable the formation of tris-coordinated and hence less electrophilic gold carbene species. α-Carboxy α,β-unsaturated ketones/aldehydes can be obtained with fair to excellent yields.

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Section: Resultsmentioning

confidence: 99%

Gold-catalyzed regioselective oxidation of propargylic carboxylates: a reliable access to α-carboxy-α,β-unsaturated ketones/aldehydes

Ji¹,

Nelson²,

Zhang³

2013

Beilstein J. Org. Chem.

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“…The α-acyloxyenone moieties in 1 and 2 can be introduced via a palladium-catalyzed rearrangement reaction from the corresponding propargylic esters 4 . Such Pd-catalyzed oxidative rearrangements are well established for the transformation of propargylic esters to α-acetoxyenones, − but to our knowledge, the generality of the transformation for the installation of various α-acyloxyenones, such as that present in 1 , has not been investigated. Propargylic ester 4 is in turn derived from the esterification of propargylic alcohol 5 , which can be accessed via a Sonogashira coupling reaction of iodo coumarin 6 and 2-methylbut-3-yn-2-ol.…”

Section: Resultsmentioning

confidence: 99%

Syntheses of Minutuminolate and Related Coumarin Natural Products and Evaluation of Their TNF-α Inhibitory Activities

Choo,

Khaw,

Chai

2023

ACS Omega

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The concise syntheses of the coumarin natural product, minutuminolate (1), and its related natural products, 7methoxy-8-(2-acetoxy-3-methyl-1-oxobut-2-enyl) coumarin (2) and muralatin I (3), were accomplished for the first time in 4−5 steps from the commercially available umbelliferone. The key step involves a palladium-catalyzed oxidative rearrangement reaction to assemble the α-acyloxyenone moiety in 1 and 2. The incorporation of this functionality enables the successful synthesis of coumarin 3 through an acidic hydrolysis reaction. The anti-inflammatory activities of the compounds were also evaluated against tumor necrosis factor-alpha production in lipopolysaccharides-stimulated RAW264.7 cells. Our developed synthetic route will facilitate the development of analogues and derivatives of 1−3 with potent antiinflammatory activities.

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“…However,w ef ound that the treatment of alkynes with catalytic amounts of Pd(OAc) 2 and (diacetoxyiodo)benzene (PIDA) in DMSO afforded (Z)a-acetoxylated enones with high selectivity (Scheme 1c). [11] To the best of our knowledge, a-acetoxylated enones were previously only accessible from prefunctionalized starting materials,f or example,t hrough the isomerization of propargylic acetates [12] or acylation of 1,2-diketone compounds. [13] Theuse of simple alkynes to directly generate such functionality-rich structures is unprecedented.…”

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confidence: 99%

Palladium‐Catalyzed Oxidative Synthesis of α‐Acetoxylated Enones from Alkynes

Jiang

Zhu

et al. 2016

Angewandte Chemie

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We report apalladium-catalyzed oxidative functionalization of alkynes to generate a-acetoxylated enones in one step.Arange of functional groups are well-tolerated in this reaction. Mechanistic studies,i ncluding the use of 18 O-labeled DMSO,r evealed that the ketone oxygen atom in the product originates from DMSO. AngewandteChemie Communications Scheme 3. Acetoxylation of substrates with different aryl substituents. Reactionsw ere carried out on a0 .3 mmol scale. Yields are for the isolated product. [a] Reaction time:4 0h.Scheme 4. Reactions of 1a with PhI(OPiv) 2 or [ 18 O]DMSO. Scheme 5. Isotope-labeling experiments. Angewandte Chemie Communications 5826 www.angewandte.org Scheme 7. Asymmetric hydrogenation of a-acetoxylated enones. tAmOH = 2-methyl-2-butanol, cod = 1,5-cyclooctadiene. Scheme 6. Proposed reaction mechanism. Angewandte Chemie Communications

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On the Palladium(II)‐Catalysed Oxidative Rearrangement of Propargylic Acetates

Abstract: The catalytic transformation of propargylic acetates into the corresponding a-acetoxyenones in the presence of palladium(II) chloride is described. Water is a necessary component in this unusual oxidative rearrangement.

Cited by 17 publications

References 19 publications

Gold-catalyzed regioselective oxidation of propargylic carboxylates: a reliable access to α-carboxy-α,β-unsaturated ketones/aldehydes

Gold-catalyzed regioselective oxidation of propargylic carboxylates: a reliable access to α-carboxy-α,β-unsaturated ketones/aldehydes

Syntheses of Minutuminolate and Related Coumarin Natural Products and Evaluation of Their TNF-α Inhibitory Activities

Palladium‐Catalyzed Oxidative Synthesis of α‐Acetoxylated Enones from Alkynes

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