Pechmann condensation reaction of 3-hydroxyphenol and ethyl acetoacetate in the presence of 1,10-butylenebispyridinium hydrogen sulfate as an
efficient, green, and recyclable catalyst produces 7-hydroxy-4-methylcoumarin in
good yield under solvent-free conditions at room temperature. This catalyst has
advantages such as the following: good to excellent yields, short reaction times,
simplicity in operation, and easy workup procedure.
