Dieckmann condensation
Chemical reaction of diesters
The Dieckmann condensation is the intramolecular chemical reaction of diesters with base to give β-keto esters. It is named after the German chemist Walter Dieckmann (1869-1925). The equivalent intermolecular reaction is the Claisen condensation. Dieckmann condensations are highly effective routes to 5-, 6-, and 7-member rings, but poor for larger rings.
01Reaction mechanism
Deprotonation of an ester at the α-position generates an enolate ion which then undergoes a 5-exo-trig nucleophilic attack to give a cyclic enol. Protonation with a Brønsted-Lowry acid (H3O+ for example) re-forms the β-keto ester.
Due to the steric stability of five- and six-membered rings, these structures will preferentially be formed. 1,6 diesters will form five-membered cyclic β-keto esters, while 1,7 diesters will form six-membered β-keto esters.
| Animation of the reaction mechanism |
Sources and credits
This article is adapted from the Wikipedia article “Dieckmann condensation”, written by its contributors and licensed under CC BY-SA 4.0. Fathomly has changed the layout, removed citation markers, navigation and maintenance notices, and adjusted punctuation. This adapted version is shared under the same license. For references, see the original article.
Images, from Wikimedia Commons:
- DieckmannCondensation.png by Choij, Public domain
- DieckmannCondensationMechanism.png by Choij, Public domain
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