Solution Structures of Lithium Enolates of Cyclopentanone, Cyclohexanone, Acetophenones, and Benzyl Ketones. Triple Ions and Higher Lithiate Complexes

Kolonko, Kristopher J.; Biddle, Margaret; Guzei, Ilia A.; Reich, Hans J.

doi:10.1021/ja903479p

Cited by 41 publications

(22 citation statements)

References 76 publications

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“…While experimental observations indicate that enolates derived from these ketones are oxidized, hydrogen atom abstraction from THF coordinated to the lithium centers of the aggregates becomes a competitive pathway. 16, 17 …”

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confidence: 99%

On the Nature of the Oxidative Heterocoupling of Lithium Enolates

Casey

Flowers

2011

J. Am. Chem. Soc.

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The coupling of enolates through single electron oxidation is one of the most direct routes to generating 1,4-dicarbonyls. Recent work on the intermolecular heterocoupling of equimolar amounts of two different enolates through single electron oxidation has shown that synthetically useful yields beyond those statistically predicted can be obtained. To determine the underlying basis for the selective formation of heterocoupled products, kinetic, 7Li NMR, and synthetic studies were performed. The collection of data obtained from these experiments show that the selective formation of heterocoupled products is a consequence of heteroaggregation of lithium enolates.

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confidence: 99%

On the Nature of the Oxidative Heterocoupling of Lithium Enolates

Casey

Flowers

2011

J. Am. Chem. Soc.

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“…Besides lithiated thioethers and dithianes,, the focus of our collaboration was on Li‐enolates,,, workhorses of organic synthesis, see the ketone ( 1 ), ester ( 2 ), and amide ( 3 ) Li‐enolates and a Li‐dienolate ( 1c ) in Figure . They are all dimeric or tetrameric aggregates in the solid state (and, as shown by others, also in solution) . What have we learned from the Li‐enolate structures?…”

Section: Meeting Of a Synthetic Methodologist With An X‐ray Crystallmentioning

confidence: 82%

What I Have Learned from Jack Dunitz

Seebàch

2016

Israel Journal of Chemistry

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The lessons taught me by Jack Dunitz about the use of X‐ray crystal structure analysis, far beyond just for determining the structure of an isolated product, are described. The direct and indirect influence Jack had on the way various topics of my synthetic group developed at ETH is demonstrated with selected examples from our various research areas: Li‐enolates, the gem‐diaryl effect and TADDOLs, self‐regeneration of stereocenters, poly(hydroxybutanoates) (PHB), β‐peptides, and mechanistic investigations of organocatalytic reactions. Furthermore, the role Jack plays in the Laboratorium of Organic Chemistry at ETH Zürich is described and appreciated.

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“…Even though a lithium enolate can be expressed as ROLi, its composition in a real solution is far more complex. In polar solvents like THF (and in the absence of chelating agents) lithium enolates are cubic tetramers,23 although in some cases dimers can be formed and, in the presence of additives, monomers can also be present 24. A computational study carried out with the lithium enolate derived from acetaldehyde demonstrated that monomeric species is important in the equilibrium due to its high solvation energies,25 although more recent calculations showed that tetramer is the major species in THF, monomeric species being preferred in the presence of chelating agents 26.…”

Section: Resultsmentioning

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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Solution Structures of Lithium Enolates of Cyclopentanone, Cyclohexanone, Acetophenones, and Benzyl Ketones. Triple Ions and Higher Lithiate Complexes

Cited by 41 publications

References 76 publications

On the Nature of the Oxidative Heterocoupling of Lithium Enolates

On the Nature of the Oxidative Heterocoupling of Lithium Enolates

What I Have Learned from Jack Dunitz

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

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