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
Solvent-Free Coumarin Synthesis
T. Sugino, K. Tanaka, Chem. Lett., 2001,
110-111.
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.
