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The Dieckmann condensation is the intramolecular 
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.
chemical reaction
A chemical reaction is a process that leads to the chemistry, chemical transformation of one set of chemical substances to another. When chemical reactions occur, the atoms are rearranged and the reaction is accompanied by an Gibbs free energy, ...
of diester
In chemistry, an ester is a compound derived from an acid (either organic or inorganic) in which the hydrogen atom (H) of at least one acidic hydroxyl group () of that acid is replaced by an organyl group (R). These compounds contain a distinc ...
s with base to give β-keto esters. It is named after the German chemist Walter Dieckmann
Walter Dieckmann (8 October 1869 – 12 January 1925) was a German chemist. He is the namesake of the Dieckmann condensation, the intramolecular reaction of diesters with base to give β-keto esters.
Dieckmann studied at the University of Mun ...
(1869–1925). The equivalent intermolecular
An intermolecular force (IMF; also secondary force) is the force that mediates interaction between molecules, including the electromagnetic forces of attraction
or repulsion which act between atoms and other types of neighbouring particles (e.g. ...
reaction is the Claisen condensation
The Claisen condensation is a carbon–carbon bond forming reaction that occurs between two esters or one ester and another carbonyl compound in the presence of a strong base. The reaction produces a β-keto ester or a β- diketone. It is named ...
. Dieckmann condensations are highly effective routes to 5-, 6-, and 7-member rings, but poor for larger rings.
:
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. :
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.
Further reading
*Dieckmann, W. '' Ber.'' 1894, ''27'', 102 & 965 *Dieckmann, W. ''Ber.'' 1900, ''33'', 595 & 2670 *Dieckmann, W. ''Ann.'' 1901, ''317'', 51 & 93See also
*Claisen condensation
The Claisen condensation is a carbon–carbon bond forming reaction that occurs between two esters or one ester and another carbonyl compound in the presence of a strong base. The reaction produces a β-keto ester or a β- diketone. It is named ...
* Gabriel–Colman rearrangement
The Gabriel–Colman rearrangement is the chemical reaction of a saccharin or phthalimido ester with a strong Base (chemistry), base, such as an alkoxide, to form substituted isoquinolines. First described in 1900 by chemists Siegmund Gabriel and J ...
* Thorpe reaction
References
{{Organic reactions Intramolecular condensation reactions Name reactions