Mixed Claisen condensation reaction

Predicting the Product of a Mixed Claisen Condensation Reaction... 

Ethyl benzoate, mixed Claisen condensation reaction of, 890-891... 

Microwaves, electromagnetic spectrum and. 419 Mincralocorticoid, 1083 Minor groove (DNA), 1104-1105 Mitomycin C, structure of, 970 Mixed aldol reaction, 885-886 requirements for. 885-886 Mixed Claisen condensation reaction, 890-891... 

As with ketone enolate anions (see 16-34), the use of amide bases under kinetic control conditions (strong base with a weak conjugate acid, aprotic solvents, low temperatures), allows the mixed Claisen condensation to proceed. Self-condensation of the lithium enolate with the parent ester is a problem when LDA is used as a base, ° but this is minimized with LICA (lithium isopropylcyclohexyl amide).Note that solvent-free Claisen condensation reactions have been reported. ° ... 

The use of preformed enolates continues to provide a valuable route for performing mixed Claisen condensations. Reaction of a 2-indolylacetic ester with 2 mol of LDA and treatment of the product with an a-trisubstituted acid chloride gave the corresponding keto ester as a diastereomeric mixture in 74% yield (equation 1) ... 

The Claisen condensation reaction is a carbonyl condensation that occurs between two ester components and gives a /3-keto ester product. Mixed Claisen condensations between two different esters are successful only when one of the two partners has no acidic a hydrogens (ethyl benzoate and ethyl formate, for instance) and thus can function only as the acceptor partner. Intramolecular Claisen condensations, called Dieckmann cyclization reactions, yield five-and six-membered cyclic j8-keto esters starting from 1,6- and 1,7-diesters. 

Claisen-Schmidt reaction. Aromatic aldehydes condense with aliphatic or mixed alkyl-aryl ketones in the presence of aqueous alkali to form ap-unsaturated ketones ... 

In a reaction related to the mixed Claisen condensation nonenolizable esters are used as acylatmg agents for ketone enolates Ketones (via their enolates) are converted to p keto esters by reaction with diethyl carbonate... 

Claisen-Schmidt reaction (Section 18.10) A mixed aldol condensation in which an aromatic aldehyde reacts with an enolizable aldehyde or ketone. 

The mixed Claisen condensation of two different esters is similar to the mixed aldol condensation of two different aldehydes or ketones (Section 23.5). Mixed Claisen reactions are successful only when one of the two ester components has no a hydrogens and thus can t form an enolate ion. For example, ethyl benzoate and ethyl formate can t form enolate ions and thus can t serve as donors. They can, however, act as the electrophilic acceptor components in reactions with other ester anions to give mixed /3-keto ester products. 

Mixed Claisen-like reactions can also be carried out between an ester and a ketone, resulting in the synthesis of a jS-diketone. The reaction works best when the ester component has no a hydrogens and thus can t act as the nucleophilic donor. For example, ethyl formate gives high yields in mixed Claisen condensations with ketones. 

The Claisen reaction is a carbonyl condensation that occurs between two ester molecules and gives a /3-keto ester product. Mixed Claisen condensations... 

Claisen condensations can be carried out between two different esters but, because there are four possible products, mixtures often result. Less difficulty is encountered if one of the esters has no a hydrogen and reacts readily with a carbanion according to Equations 18-11 and 18-12. The reaction then has considerable resemblance to the mixed aldol additions discussed in Section 17-3C. Among the useful esters without a hydrogens, and with the requisite electrophilic reactivity, are those of benzenecarboxyiic, methanoic, ethanedioic, and carbonic acids. Several practical examples of mixed Claisen condensations are shown in Equations 18-14 through 18-16 (all of the products exist to the extent of 10% or so as the enol forms) ... 

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