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Updated: Jun 29, 2025

A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species
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A Two-Step Protocol for Umpolung Functionalization of Ketones Via Enolonium Species

Published on: August 16, 2018

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乙醇中间体在分子内斯特特反应中的催化作用:一个计算视角

Gou-Tao Huang1, Jen-Shiang K Yu1,2,3

  • 1Department of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsinchu City 300, Taiwan. jsyu@mail.nctu.edu.tw.

Physical chemistry chemical physics : PCCP
|April 3, 2024
PubMed
概括

这项研究使用DFT计算揭示了分子内斯特特反应机制. 形成乙醇中间体的氧-迈克尔反应是限制速度的阶段,控制了整体反应性.

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Development of Heterogeneous Enantioselective Catalysts using Chiral Metal-Organic Frameworks MOFs08:25

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Reactivity of Enols01:18

Reactivity of Enols

Enols are a class of compounds where a hydroxyl group is attached to a carbon–carbon double bond, which implies that it is a vinyl alcohol. A carbonyl compound with an α hydrogen undergoes keto–enol tautomerism and remains in equilibrium with its tautomer, the enol form. Usually, the keto tautomer is present in a higher concentration than the enol tautomer due to the higher bond energy of C=O compared to C=C. Moreover, the direction of the keto–enol equilibrium is...
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Regioselective Formation of Enolates

As depicted in the figure below, the unsymmetrical ketones can form two possible enolates:  less substituted or more substituted enolates. Usually, the thermodynamic enolates are formed from the more substituted α-carbon atom, while the kinetic enolates are formed faster by deprotonation from the less substituted position. The thermodynamic enolates have lower energy, so they are  more stable. But the energy required to form kinetic enolates is less.
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α-Substituted ketones or aldehydes can be synthesized from enamines by the Stork enamine reaction, named after its pioneer Gilbert Stork. Enamines are useful synthetic intermediates where the lone pair on nitrogen is in conjugation with the C=C bond. They resemble enolate ions, as the resonance forms of both species have a nucleophilic α carbon.
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Intramolecular aldol reaction occurs in dicarbonyl compounds such as dialdehydes, diketones, and keto-aldehydes. The dicarbonyl compounds possess more than one nucleophilic ⍺ carbon for the base to deprotonate and form the enolates. For example, in symmetrical diketones, there are four ⍺ carbons. Hence, four types of enolates are possible when treated with a base. However, since the molecule is symmetrical, the enolates formed on either side of one carbonyl group are equivalent to those...
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