Gold‐ vs. Platinum‐Catalyzed Polycyclizations by <i>O</i>‐Acyl Migration. Solvent‐Free Reactions

Moreau, Xavier; Goddard, Jean‐Philippe; Bernard, Matthieu; Lemière, Gilles; López‐Romero, Juan Manuel; Mainetti, Emily; Marion, Nicolas; Mouriès, Virginie; Thorimbert, Serge; Fensterbank, Louis; Malacrìa, Max

doi:10.1002/adsc.200700356

Cited by 96 publications

(39 citation statements)

References 59 publications

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“…The results presented here show the viability of ester migration onto the allene moiety in the context of intramolecular cyclization. As observed previously in the cyclization of the corresponding propargylic acetate, [49] the reaction produced only one diastereomer. In an attempt to extend the scope of this reaction, formation of tricyclic derivative 18 was envisioned.…”

Section: Reversibility Of Acetate Migrationmentioning

confidence: 52%

“…Flash chromatography was performed on silica gel 60 (230-400 mesh, Silicycle were synthesized according to literature procedures. Compounds 2, [11a] 7, [12] 10, [12] 15, [49] 17, [49] 19, [49] 20, [49] and 23 [49] were synthesized according to literature procedures, and their spectroscopic data found to be in good agreement with previously reported characteristic data. Characterization of cyclized compounds 3, [11a] 4, [12] 5, [12] 9, [12] 16, [49] 21, [49] and 24 [49] was based on previous reports, and their spectroscopic data were in good agreement with previously reported characteristic data.…”

Section: Methodsmentioning

confidence: 63%

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Gold‐ and Platinum‐Catalyzed Cycloisomerization of Enynyl Esters versus Allenenyl Esters: An Experimental and Theoretical Study

Marion

Lemière

Correa

et al. 2009

Chemistry A European J

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130

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Ester-way to heaven: Unexpected formation of bicyclo[3.1.0]hexene 4 was the main focus of combined experimental and theoretical studies on the Au-catalyzed cycloisomerization of branched dienyne 1 (see scheme), which provided better understanding of the mechanistic details governing the cyclization of enynes bearing a propargylic ester group.Experimental and theoretical studies on Au- and Pt-catalyzed cycloisomerization of a branched dienyne with an acetate group at the propargylic position are presented. The peculiar architecture of the dienyne precursor, which has both a 1,6- and a 1,5-enyne skeleton, leads, in the presence of alkynophilic gold catalysts, to mixtures of bicyclic compounds 3, 4, and 5. Formation of unprecedented bicyclo[3.1.0]hexene 5 is the main focus of this study. The effect of the ancillary ligand on the gold center was examined and found to be crucial for formation of 5. Further mechanistic studies, involving cyclization of an enantioenriched dienyne precursor, (18)O-labeling experiments, and DFT calculations, allowed an unprecedented reaction pathway to be proposed. We show that bicyclo[3.1.0]hexene 5 is likely formed by a 1,3-OAc shift/allene-ene cyclization/1,2-OAc shift sequence, as calculated by DFT and supported by Au-catalyzed cyclization of isolated allenenyl acetate 7, which leads to improved selectivity in the formation of 5. Additionally, the possibility of OAc migration from allenyl acetates was supported by a trapping experiment with styrene that afforded the corresponding cyclopropane derivative. This unprecedented generation of a vinyl metal carbene from an allenyl ester supports a facile enynyl ester/allenenyl ester equilibrium. Further examination of the difference in reactivity between enynyl acetates and their corresponding [3,3]-rearranged allenenyl acetates toward Au- and Pt-catalyzed cycloisomerization is also presented.

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Section: Reversibility Of Acetate Migrationmentioning

confidence: 52%

Section: Methodsmentioning

confidence: 63%

Gold‐ and Platinum‐Catalyzed Cycloisomerization of Enynyl Esters versus Allenenyl Esters: An Experimental and Theoretical Study

Marion

Lemière

Correa

et al. 2009

Chemistry A European J

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130

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“…[16] Formation of allene: The transformation of propargylic esters into allenyl esters is a common reaction than can be mediated by late transition metals. [18,[27][28][29] Moreover, these catalysts can further activate the allene formed for subsequent reactivity; this gives rise to a wide diversity of products. [13b, 30] Hence, this [3,3]-sigmatropic rearrangement competes with the formation of the vinyl carbenoid intermediate through another intramolecular mechanism that involves similar entropic effects.…”

Section: Insights Into the Stereochemistrymentioning

confidence: 99%

New Insights on the Mechanism of the Transition‐Metal Stereoselective Olefin Cyclopropanation

Soriano

Marco‐Contelles

2008

Chemistry A European J

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We have carried out a theoretical analysis of the intermolecular cyclopropanation of propargylic esters with alkenes. DFT calculations allow us to propose a reaction mechanism, and provide explanations for the reasons behind the difference between the inter‐ and intramolecular versions of this process. The results strongly suggest that the entropic effects could modulate the operative mechanism and account for the mechanistic discrepancy. The calculated model also justifies the experimental stereoselectivity on the basis of intra‐ and intermolecular interactions. In addition, we have taken into account other transformations of propargylic carboxylates catalyzed by late transition metals, and the results rationalize the accumulated experimental observations.

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“…[4] These cyclopropanation reactions, [5] which lead selectively to complex polycyclic compounds, are generally catalyzed by platinum [6] or gold. [7] During further studies on enynols of type A, we discovered that a cyclization-fragmentation pathway (Scheme 1, A!D) could compete with the cyclopropanation, and that [Cu(CH 3 CN) 4 ]BF 4 was the reagent of choice for promoting this rearrangement, as opposed to Ag, [8] Au, [7b] or Pt catalysts.…”

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confidence: 99%

Enantioselective Synthesis of (−)‐β‐Santalol by a Copper‐Catalyzed Enynol Cyclization–Fragmentation Reaction

et al. 2009

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Der Katalysator bestimmt den Duft: Die enantioselektive Synthese des Duftstoffs (−)‐β‐Santalol macht sich als Schlüsselschritt eine hoch selektive kupferkatalysierte Cyclisierung und Fragmentierung eines Eninols zunutze (siehe Schema). Wurde die Cyclisierung durch einen Platinkatalysator eingeleitet, so blieb die gewünschte Fragmentierung aus – stattdessen wurde vollständig selektiv ein Produkt mit Cyclopropanring gebildet.

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Gold‐ vs. Platinum‐Catalyzed Polycyclizations by O‐Acyl Migration. Solvent‐Free Reactions

Cited by 96 publications

References 59 publications

Gold‐ and Platinum‐Catalyzed Cycloisomerization of Enynyl Esters versus Allenenyl Esters: An Experimental and Theoretical Study

Gold‐ and Platinum‐Catalyzed Cycloisomerization of Enynyl Esters versus Allenenyl Esters: An Experimental and Theoretical Study

New Insights on the Mechanism of the Transition‐Metal Stereoselective Olefin Cyclopropanation

Enantioselective Synthesis of (−)‐β‐Santalol by a Copper‐Catalyzed Enynol Cyclization–Fragmentation Reaction

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