The Aldol Condensation and Enone Disconnections

The Aldol Condensation and Enone Disconnections - The Aldol...

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The Aldol Condensation and Enone Disconnections The aldol condensation is a versatile method for making carbon-carbon bonds. It is a carbonyl addition reaction in which the nucleophile is an aldehyde or ketone enolate. This question asks you to start with the enone product and visualize the precursors you would need to synthesize it. Aldol Equilibria Equilibrium constants for condensation of aldehydes are favorable, K eq = 400 M -1 for the condensation of ethanal (below). In contrast, simple ketones give low equilibrium concentrations of aldol product. K eq = 0.039 for the condensation of 2-propanone (below). Organic chemists have devised effective strategies for carrying out ketone condensations. Dehydration of the aldol product to an enone can drive even ketone condensations to completion when it forms extended conjugated systems. Reaction Mechanism The key step of a base-catalyzed aldol condensation is donation of an electron pair from an enolate nucleophile to an aldehyde or ketone carbonyl carbon to form a new carbon- carbon bond. The product is a beta-hydroxy aldehyde or ketone, otherwise known as an aldol.
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The Aldol Condensation and Enone Disconnections - The Aldol...

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