Uncatalyzed, One-pot Synthesis of 3,3 '-(Benzylene)-bis(4-hydroxy-2H-chromen-2-one) Derivatives under Thermal Solvent-free Conditions

A series of 3,3'-(benzylene)bis(4-hydroxy-2H-chromen-2-one) derivatives have been synthesized from condensation reactions of 4-hydroxycoumarin with benzaldehydes under thermal solvent-free conditions. This environmentally friendly synthesis is uncatalyzed and affords the desired products in excellent yields.