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The Dieckmann condensation is the intramolecular chemical reaction of diesters with base to give β-keto esters.[1][2][3][4][5] It is named after the German chemist Walter Dieckmann (1869–1925). The equivalent intermolecular reaction is the Claisen condensation.

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

Reaction mechanismEdit

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.[6]

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.[7]

 
Animation of the reaction mechanism

See alsoEdit

ReferencesEdit

  1. ^ Dieckmann, W. Ber. 1894, 27, 102 & 965
  2. ^ Dieckmann, W. Ber. 1900, 33, 595 & 2670
  3. ^ Dieckmann, W. Ann. 1901, 317, 51 & 93
  4. ^ 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.
  5. ^ Davis, B. R.; Garrett, P. J. Compr. Org. Synth. 1991, 2, 806-829. (Review)
  6. ^ Janice Gorzynski Smith (2007). Organic Chemistry (2nd ed.). pp. 932–933. ISBN 978-0073327495.
  7. ^ "Dieckmann Condensation". Organic Chemistry Portal.