�ber Condensationsproducte der Aldehyde

Brauchbar, Max; Kohn, Leopold

doi:10.1007/bf01517394

Cited by 8 publications

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“…The aldol-Tishchenko reaction is a powerful means for construction of 1,3-diols through the stereoselective reaction of an enolate with 2 equiv of aldehyde. While this type of reaction has been known for over 100 years, it was only in the 1990s that a mechanistic understanding of the transformation was developed . In subsequent years, the use of chiral ligands, such as BINOLs and cinchona alkaloids, made asymmetric variants possible …”

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Mechanism and Origins of Stereoselectivity of the Aldol-Tishchenko Reaction of Sulfinimines

et al. 2021

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Density functional theory computations have elucidated the mechanism and origins of stereoselectivity in McGlacken’s aldol-Tishchenko reaction for the diastereoselective synthesis of 1,3-amino alcohols using Ellman’s t -butylsulfinimines as chiral auxiliaries. Variations of stereochemical outcome are dependent on the nature of the ketone starting materials used, and the aspects leading to these differences have been rationalized. The intramolecular hydride transfer step is the rate- and stereochemistry-determining step, and all prior steps are reversible.

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Mechanism and Origins of Stereoselectivity of the Aldol-Tishchenko Reaction of Sulfinimines

et al. 2021

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The Aldol Condensation

Nielsen

Houlihan²

2011

Organic Reactions

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The aldol condensation takes its name from aldol (3‐hydroxybutanal) a name introduced by Wurtz who first prepared the beta‐hydroxy aldehyde from acetaldehdye in 1872. The aldol condensation includes reactions producing beta‐hydroxy aldehydes or beta‐hydroxy ketones by self condensations or mixed condensations of aldehydes and ketones as well as reactions leading to alpha, beta‐unsaturated aldehydes or alpha,beta‐unsaturated ketones formed by dehydration of intermediate beta‐aldols or beta‐ketals. The Claisen‐Schmidt condensation is most often taken to be the condensation of an aromatic aldehyde or ketone usually in the presence of a basic catalyst. The term aldol condensation has also been applied to many other condensations involving the reaction of an aldehyde or ketone. These condenations are discussed. The present review includes examples that are solely condensation reactions of aldehydes and ketones.

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The Tishchenko Reaction

Koskinen

Kataja

2015

Organic Reactions

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Aldehydes may be dimerized to symmetric esters via the Tishchenko reaction. This process is traditionally catalyzed by aluminum alkoxides, but a wide variety of different metal catalysts has been explored and implemented, ranging from simple alkali metal compounds to actinoid complexes. The mechanistic key step is a hydride transfer from a hemiacetal intermediate to an aldehyde, both participants being coordinated to the metal catalyst in the transition state. Recent research on the Tishchenko reaction has especially focused on the controlled synthesis of unsymmetrical esters. In the aldol‐Tishchenko variant, an aldol reaction takes place first between two aldehydes, or a ketone and an aldehyde. In the subsequent Tishchenko step, another aldehyde molecule coordinates to the aldol product, forming a hemiacetal intermediate. An intramolecular hydrogen transfer from the hemiacetal to the carbonyl group takes place, giving a 1,3‐diol monoester product. With ‐hydroxy ketone substrates, the reaction is highly diastereoselective towards 1,3‐ anti ‐diols due to a highly organized six‐membered transition state promoted by coordination of a metal catalyst to both the hemiacetal and carbonyl groups. Thus, recent research has strongly focused on the development of direct catalytic asymmetric aldol‐Tishchenko reactions. The Evans‐Tishchenko reaction is a further variant of the aldol‐Tishchenko reaction, being used to reduce preformed ‐hydroxy ketones to anti ‐1,3‐diols under relatively mild conditions. This method is applied to various total syntheses of natural products. Samarium iodide is commonly used as the catalyst, and nearly any aldehyde is suitable as the reducing agent. The reaction has also been exploited in a reverse fashion to oxidize complex aldehydes to carboxylic acids using a simple sacrificial ‐hydroxy ketone as the oxidant. This review covers the literature from the discovery of the Tishchenko reaction in 1887 up to early 2014. Different catalyst systems for both Tishchenko and aldol‐Tishchenko reactions are discussed and compared in the “Scope and Limitations” section, and the state of the art in substrate complexity for the reaction is presented in the “Tabular Survey”.

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�ber Condensationsproducte der Aldehyde

Cited by 8 publications

References 0 publications

Mechanism and Origins of Stereoselectivity of the Aldol-Tishchenko Reaction of Sulfinimines

Mechanism and Origins of Stereoselectivity of the Aldol-Tishchenko Reaction of Sulfinimines

The Aldol Condensation

The Tishchenko Reaction

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