Efficient synthesis of biscoumarins using zinc acetate as a catalyst in aqueous media

Bis-(4-hydroxycoumarin)methanes derivatives (1-9) were synthesized via one pot condensation reaction of various aromatic aldehyde and 4-hydroxycoumarin using zinc acetate as a catalyst in presence of water as a solvent. This mediated reaction of various aromatic and hetero-aromatic aldehydes using catalytic amounts of zinc acetate avoids the use of expensive, corrosive reagents, toxic solvents and provides operational simplicity