Dieckmann condensation

The Dieckmann condensation is the intramolecular chemical reaction of diesters with base to give β-keto esters.[1] It is named after the German chemist Walter Dieckmann (1869–1925).[2][3] The equivalent intermolecular reaction is the Claisen condensation.

The Dieckmann condensation
Dieckmann condensation
Named after Walter Dieckmann
Reaction type Ring forming reaction
Identifiers
Organic Chemistry Portal dieckmann-condensation
RSC ontology ID RXNO:0000065

Reaction 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.[4]

Dieckmann Condensation reaction mechanism for the example given.

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.[5]

Animation of the reaction mechanism

Further reading
  • Dieckmann, W. Ber. 1894, 27, 102 & 965
  • Dieckmann, W. Chemische Berichte|Ber. 1900, 33, 595 & 2670
  • Dieckmann, W. Ann. 1901, 317, 51 & 93
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See also

References
  1. Davis, B. R.; Garrett, P. J. Compr. Org. Synth. 1991, 2, 806-829. (Review)
  2. Kwart, Harold; King, Kenneth (1969). "Rearrangement and cyclization reactions of carboxylic acids and esters". In S. Patai (ed.). PATAI'S Chemistry of Functional Groups: Carboxylic Acids and Esters (1969). pp. 341–373. doi:10.1002/9780470771099.ch8. ISBN 9780470771099.
  3. Schaefer, J. P.; Bloomfield, J. J. (1967). "The Dieckmann Condensation (Including the Thorpe-Ziegler Condensation)". Organic Reactions. 15: 1–203. doi:10.1002/0471264180.or015.01.
  4. Janice Gorzynski Smith (2007). Organic Chemistry (2nd ed.). pp. 932–933. ISBN 978-0073327495.
  5. "Dieckmann Condensation". Organic Chemistry Portal.
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