A Quick and Advantageous Synthesis of 2H-1-Benzopyran-2-ones Unsubstituted on the Pyranic Nucleus

The synthesis of 2H-1-benzopyran-2-ones (coumarins) unsubstituted on the pyranic nucleus was realized by condensation of malic acid and phenols under mild conditions. A short reaction time, improved yields, good purity of the products, and an easy clean experimental protocol are the advantages of this procedure.