The base-catalyzed intramolecular condensation of a diester. The Dieckmann Condensation works well to produce 5- or 6-membered cyclic ß-keto esters, and is usually effected with sodium alkoxide in alcoholic solvent.
The yields are good if the product has an enolizable proton; otherwise, the reverse reaction (cleavage with ring scission) can compete. See the Claisen Condensation.
Mechanism of the Dieckmann Condensation
The mechanism is similar to the Claisen Condensation.
Aluminum Chloride-Mediated Dieckmann Cyclization for the Synthesis of Cyclic 2-Alkyl-1,3-alkanediones: One-Step Synthesis of the Chiloglottones
A. M. Armaly, S. Bar, C. S. Schindler, Org. Lett., 2017, 19, 3958-3961.
An Efficient and Scalable One-Pot Double Michael Addition-Dieckmann Condensation for the Synthesis of 4,4-Disubstituted Cyclohexane β-Keto Esters
M. R. DeGraffenreid, S. Bennett, S. Caille, F. Gonzalez-Lopez de Turiso, R. W. Hungate, L. D. Julian, J. A. Kaizerman, D. L. McMinn, D. Sun, X. Yan, J. P. Powers, J. Org. Chem., 2007, 72, 7455-7458.