Dieckmann condensation


Dieckmann condensation

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

The Dieckmann condensation

Reaction Mechanism

The acidic hydrogen between the two carbonyl groups is deprotonated in step four. Protonation with a Brønsted-Lowry acid (H3O+ for example) re-forms the β-keto ester. [6] This deprotonation step is the driving force for this reaction.

Dieckmann Condensation reaction mechanism for the example given.


Owing to the steric stability of five- and six-membered ring structures, these will preferentially be formed. 1,4- and 1,6 diesters will form five-membered cyclic β-keto esters, while 1,5- and 1,7 diesters will form six-membered β-keto esters. [7]

See also

References

  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. Org. React. 1967, 15, 1-203. (Review)
  5. ^ Davis, B. R.; Garrett, P. J. Comp. Org. Syn. 1991, 2, 806-829. (Review)
  6. ^ Janice Gorzynski Smith. Organic Chemistry: Second Ed. 2008. pp 932-933.
  7. ^ Organic-Chemistry.org. Dieckmann Condensation. http://www.organic-chemistry.org/namedreactions/dieckmann-condensation.shtm

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