Organic Chemistry Portal
Reactions >> Name Reactions

Further Information
Literature

Related Reactions
Michael Addition
Synthesis of coumarins

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, Synthesis, 2005, 1231-1233.


Coumarin syntheses via Pechmann condensation in Lewis acidic chloroaluminate ionic liquid
M. K. Potdar, S. S. Mohile, M. M. Salunkhe, Tetrahedron Lett., 2001, 42, 9285-9287.