The malonic acid mono phenol ester was synthesized by Meldrum’s acid and phenol under a solvent-free condition in 90.6% yield, then cyclized by Eaton’s reagent (phosphoric anhydride and methylsulfonic acid) in mild conditions to give 4-hydroxycoumarin in 78.8% yield. This methodology was then extended to prepare 4-hydroxycoumarin and 4-hydroxythiocoumarin derivatives. The fluorescent properties of some 4-hydroxycoumarin derivatives were studied.

Key words: 4-hydroxycoumarin, Meldrum’s acid, 4-hydroxythiocoumarin, PPA, Eaton’s reagent