Enols and enolates a substitutions and condensations of ketones and aldehydes
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Enols and Enolates a Substitutions and Condensations of Ketones and Aldehydes PowerPoint PPT Presentation

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Enols and Enolates a Substitutions and Condensations of Ketones and Aldehydes. Tautomerization Accelerated in Acid. a -Halogenation. Reaction Occurs via Enol. Tautomerization Acceleration in Base. Alkylation in Base Reaction with 1 o RX. Using LDA as Base to form Enolate.

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Enols and Enolates a Substitutions and Condensations of Ketones and Aldehydes

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Enols and Enolatesa Substitutions and Condensations of Ketones and Aldehydes

Tautomerization Accelerated in Acid


Reaction Occurs via Enol

Tautomerization Acceleration in Base

Alkylation in BaseReaction with 1o RX

Using LDA as Base to form Enolate

Alkylation a to C=OC-alkylation preferred

Alkylation Occurs on Less Hindered Side of C=O

Malonic Ester Synthesis of Carboxylic Acids

H’s are unusually acidic

Decarboxylation (loss of CO2)

2 Acidic a H’s, 2 Alkylations; Determine the Product of the Synthesis

All b-keto acids are unstable and Decarboxylate

Enamines can be Alkylated

Alkylation of an Enaminea Position is Activated

Complements LDA Reaction

LDA vs. Enamine Reaction

a-Selenation: Formation of a,b-Unsaturated Ketones



Aldol Condensation

Enolate Undergoes Nucleophilic Addition

Aldol CondensationDimerization of 3-Pentanone

Crossed Aldol Between 2 Different C=O Compounds

Four Possible Condensation Products

Crossed Aldol Condensation

Dehydration of Aldol Products

Predicting Aldol Dehydration Products

Intramolecular Aldol

Predict the Product

Conjugate Addition

1,2 - vs. 1,4 - Addition

Michael AdditionConjugate Addition of Enolate to a,b-Unsaturated Ketone

Robinson Annulation:Michael Addition followed by Aldol Consensation

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