General and Theoretical Aspects of the Metal Enolates

Domingo, Luís R.; Andrés, Juán

doi:10.1002/9780470682531.pat0417

Cited by 3 publications

(3 citation statements)

References 222 publications

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“…9,10 By contrast, few experimental probes of mechanism have been carried out with either simple boron enolates 11 or oxazolidinone-based variants. 6,12–15 On the heels of investigations of lithium-based aldol additions of Evans enolates, 12 we undertook structural and mechanistic studies of the boron variant in Scheme 1.…”

Section: Introductionmentioning

confidence: 99%

“…Boron enolates, including several derived from oxazolidinones, have been examined crystallographically, spectroscopically, , and computationally. , By contrast, few experimental probes of mechanism have been carried out with either simple boron enolates or oxazolidinone-based variants. ,− On the heels of investigations of lithium-based aldol additions of Evans enolates, we undertook structural and mechanistic studies of the boron variant in Scheme…”

Section: Introductionmentioning

confidence: 99%

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Evans Enolates: Structures and Mechanisms Underlying the Aldol Addition of Oxazolidinone-Derived Boron Enolates

Zhang

Collum

2017

J. Org. Chem.

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The soft enolization of an acylated oxazolidinone using di-n-butylboron triflate (n-Bu2BOTf) and trialkylamines and subsequent aldol addition was probed structurally and mechanistically using a combination of IR and NMR spectroscopies. None of the species along the reaction coordinate shows a penchant for aggregating. Complexation of the acylated oxazolidinone by n-Bu2BOTf was too rapid to monitor, as was the subsequent enolization with Et3N (triethylamine). The pre-formed n-Bu2BOTf·Et3N complex displaying muted Lewis acidity and affiliated tractable rates reveals a rate-limiting complexation via a transition structure with a complicated counterion. n-Bu2BOTf·i-Bu3N bearing a hindered amine shifts the rate-limiting step to proton transfer. Rate studies show that the aldol addition with isobutyraldehyde occurs as proffered by others.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Evans Enolates: Structures and Mechanisms Underlying the Aldol Addition of Oxazolidinone-Derived Boron Enolates

Zhang

Collum

2017

J. Org. Chem.

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“…Despite the apparent similarity between lithium enolates derived from aldehydes, ketones and esters all these species are rather different if we consider their electronic properties,22 which are crucial for the stability of postulated intermediates. In order to shed some light on the preferred pathways (concerted or stepwise) it is necessary a full theoretical study considering in detail all the possible paths.…”

Section: Introductionmentioning

confidence: 99%

Mechanism Switch in Mannich‐Type Reactions: ELF and NCI Topological Analyses of the Reaction between Nitrones and Lithium Enolates

et al. 2015

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The mechanism of the addition of lithium enolates derived from esters, ketones and aldehydes to nitrones (Mannich‐type reaction) has been studied using DFT methods. While the reactions with α‐methoxy and α‐methyl enolates takes place through a stepwise mechanism, consisting of an initial nucleophilic attack of the enolate to the nitrone carbon followed by a second nucleophilic attack of the nitrone oxygen to the formed carbonyl group, the reaction with α‐unsusbtituted enolates takes place through a one‐step mechanism. The IRC analysis shows the presence of a hidden intermediate in agreement with one kinetic step two stages process. The topological analysis of the electronic localization function (ELF) confirms that only when the first C–C bond is formed, does the C–O bond formation begin. The NCI analyses, are also in agreement with the formation of intermediates for α‐methoxy and α‐methyl enolates and a highly asynchronous one‐step process in the case of α‐unsusbtituted enolates.

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Stereoselective alkylation of chiral pyrrolidin-2-ones leading to novel conformationally restricted analogues of 3-methylaspartic acid: a computational investigation

et al. 2012

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General and Theoretical Aspects of the Metal Enolates

Abstract: General Aspects Structure of the Metal Enolates Spectroscopy of the Metal Enolates Reactivity of the Metal Enolates Acknowledgments

Cited by 3 publications

References 222 publications

Evans Enolates: Structures and Mechanisms Underlying the Aldol Addition of Oxazolidinone-Derived Boron Enolates

Evans Enolates: Structures and Mechanisms Underlying the Aldol Addition of Oxazolidinone-Derived Boron Enolates

Mechanism Switch in Mannich‐Type Reactions: ELF and NCI Topological Analyses of the Reaction between Nitrones and Lithium Enolates

Stereoselective alkylation of chiral pyrrolidin-2-ones leading to novel conformationally restricted analogues of 3-methylaspartic acid: a computational investigation

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