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Pechmann Condensation Coumarin Synthesis

Lianyungang Klinechem Co.,Ltd | Updated: Dec 17, 2018

Pechmann Condensation
Coumarin Synthesis

The Pechmann Condensation allows the synthesis of coumarins by reaction of phenols with β-keto esters.

Mechanism of the Pechmann Condensation

The reaction is conducted with a strong Brønstedt acid such as methanesulfonic acid or a Lewis acid such as AlCl3. The acid catalyses transesterification as well as keto-enol tautomerisation:

A Michael Addition leads to the formation of the coumarin skeleton. This addition is followed by rearomatisation:

Subsequent acid-induced elimination of water gives the product:

Recent Literature

An Efficient and Practical Procedure for the Synthesis of 4-Substituted Coumarins
S. K. De, R. A. Gibbs, Synthesis2005, 1231-1233.

Coumarin syntheses via Pechmann condensation in Lewis acidic chloroaluminate ionic liquid
M. K. Potdar, S. S. Mohile, M. M. Salunkhe, Tetrahedron Lett., 200142, 9285-9287.

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