Synthesis of the Coumarins via Pechmann Method in the Presence of Environmentally Friendly Y(NO3)3•6H2O

Several substituted coumarins can be prepared in high yield and purity by direct reaction of beta-keto esters and phenol derivatives in the presence of a catalytic amount Y(NO3)(3)center dot 6H(2)O as Lewis acid and at ambient temperature under solvent-free conditions.