Definition: What is Dieckmann Condensation?

The Dieckmann condensation is an organic reaction which is used to form a carbon-carbon bond between two tethered ester groups using an alkoxide base in alcohol. The resulting product is a cyclic β-ketoester. This reaction is an intermolecular form of Claisen condensation ^[1-3].

The history of Dieckmann condensation goes back to 1894 when German chemist Walter Dieckmann first reported it in a journal.

Examples of Dieckmann Condensation

Examples of Dieckmann condensation include conversion of diethyl adipate into ethyl 2-oxocyclopentanecarboxylate and diethyl heptanedioate (pimelate) into 2-propanoylcyclohexanone ^[4-5].

Mechanism of Dieckmann Condensation

The mechanism is similar to that of Claisen condensation. A strong base removes the alpha proton resulting in an enolate. The enolate then attacks the carbonyl carbon of another ester molecule, resulting in a cyclic β-ketoester and regenerating the conjugate base. The base then deprotonates the cyclic compounds, and an acid workup is required to produce the final cyclic β-ketoester ^[6-8].

Applications of Dieckmann Condensation

Dieckmann condensation is used in the preparation of cyclic indole. There has been a report of preparing five-membered pyrroles through this condensation method ^[9].