The Role of Bent Acyclic Allene Gold Complexes in Axis‐to‐Center Chirality Transfers

Gandon, Vincent; Lemière, Gilles; Hours, Alexandra; Fensterbank, Louis; Malacrìa, Max

doi:10.1002/anie.200802332

Cited by 124 publications

(89 citation statements)

References 57 publications

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“…However, computational studies have predicted the barrier for exchange between the two diastereomeric faces of a simple disubstituted alkyl allene to be very low15. In addition, the energy difference between the two π-complexes that could form is calculated to be only 1.0 kcal/mol.…”

Section: Resultsmentioning

confidence: 99%

“…Though the methyl carbazate is included in calculations, the nucleophile itself is not associated with TS1 or 6 . Malacria and co-workers reported15 that the steric hindrance at the allylic positions determines the energies and stabilities of the possible isomeric forms of the planar, cationic gold(I) complex. In agreement with their analysis, we find that only intermediate 6 is stable.…”

Section: Mechanistic Discussionmentioning

confidence: 99%

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Mechanistic Study of Gold(I)-Catalyzed Intermolecular Hydroamination of Allenes

et al. 2010

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The intermolecular hydroamination of allenes occurs readily with hydrazide nucleophiles, in the presence of 3-12% Ph 3 PAuNTf 2 . Mechanistic studies have been conducted to establish the resting state of the gold catalyst, the kinetic order of the reaction, the effect of ligand electronics on the overall rate, and the reversibility of the last steps in the catalytic cycle. We have found the overall reaction to be first order in gold and allene and zero order in nucleophile. Our studies suggest that the rate-limiting transition state for the reaction does not involve the nucleophile and that the active catalyst is monomeric in gold(I). Computational studies support an "outersphere" mechanism and predicts that a two-step, no intermediate mechanism may be operative. In accord with this mechanistic proposal, the reaction can be accelerated with the use of more electron deficient phosphine ligands on the gold(I) catalyst.

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Section: Resultsmentioning

confidence: 99%

Section: Mechanistic Discussionmentioning

confidence: 99%

Mechanistic Study of Gold(I)-Catalyzed Intermolecular Hydroamination of Allenes

et al. 2010

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“…The structures are very dependent on the nature of the allene substituents as well as on the properties of the particular gold complex employed. 117 …”

Section: ■ Models and Computational Methodsmentioning

confidence: 99%

Hydroamination of C–C Multiple Bonds with Hydrazine Catalyzed by N-Heterocyclic Carbene–Gold(I) Complexes: Substrate and Ligand Effects

et al. 2015

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In this work, we computationally address, from DFT calculations, mechanistic issues of the recently described hydroamination reactions catalyzed by (carbene) gold(I) complexes that use hydrazine as N-nucleophile. We have explored the hydrohydrazination of alkynes, alkenes, and allenes using three gold− carbene catalysts reported by Bertrand's and Hashmi's groups. Aspects such as the associative or dissociative nature of the ligand exchange between hydrazine and the substrate, the generation of the catalytically active π-complex, the inner-or outer-sphere mechanism for the nucleophilic attack, the nitrogen to carbon proton transfer or the relative importance of the ligand substitution, the nucleophile addition, and the proton transfer barriers in the catalytic cycle are analyzed in light of the DFT results, taking into account the nature of the carbene ligand and the substrate. The study can provide background for the design of further hydroamination reactions using simple small N-nucleophiles.

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“…Different structures have been proposed to represent these gold-activated allene complexes, including η 2 -complexes ( B , B’ and B’’ ), planar σ-allylic cations C , zwitterionic carbenes C’ or η 1 -bent allenes C’’ (Fig. 2) [48]. In some cases, experimental and theoretical evidence supports the participation of one of those structures, but in many other cases the precise nature of these species remains unknown.…”

Section: Reviewmentioning

confidence: 99%

Gold(I)-catalyzed enantioselective cycloaddition reactions

López

Mascareñas

2013

Beilstein J. Org. Chem.

109

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In recent years there have been extraordinary developments of gold(I)-catalyzed enantioselective processes. This includes progress in the area of cycloaddition reactions, which are of particular interest due to their potential for the rapid construction of optically active cyclic products. In this article we will summarize some of the most remarkable examples, emphasizing reaction mechanisms and key intermediates involved in the processes. 2250

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The Role of Bent Acyclic Allene Gold Complexes in Axis‐to‐Center Chirality Transfers

Abstract: Activation of allenes toward nucleophilic attack by gold complexes ([Au], see scheme) often proceeds with axis‐to‐center chirality transfer. The stereochemical information is shown to be maintained in not only η2 allene complexes, but also in bent η1 allene complexes.

Cited by 124 publications

References 57 publications

Mechanistic Study of Gold(I)-Catalyzed Intermolecular Hydroamination of Allenes

Mechanistic Study of Gold(I)-Catalyzed Intermolecular Hydroamination of Allenes

Hydroamination of C–C Multiple Bonds with Hydrazine Catalyzed by N-Heterocyclic Carbene–Gold(I) Complexes: Substrate and Ligand Effects

Gold(I)-catalyzed enantioselective cycloaddition reactions

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