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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 chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking ...
of diester
In chemistry, an ester is a compound derived from an oxoacid (organic or inorganic) in which at least one hydroxyl group () is replaced by an alkoxy group (), as in the substitution reaction of a carboxylic acid and an alcohol. Glycerides are ...
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 Muni ...
(1869–1925). The equivalent intermolecular 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, resulting in a β-keto ester or a β-diketone. It is named after Ra ...
.
:
Reaction mechanism
Deprotonation of an ester at the α-position generates anenolate ion
In organic chemistry, alkenols (shortened to enols) are a type of reactive structure or intermediate in organic chemistry that is represented as an alkene (olefin) with a hydroxyl group attached to one end of the alkene double bond (). The ter ...
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, resulting in a β-keto ester or a β-diketone. It is named after Ra ...
* Gabriel-Colman rearrangement
* Thorpe–Ziegler reaction
References
{{Organic reactions Intramolecular condensation reactions Name reactions