Catalyst-Free Synthesis of alpha,alpha-bis(4-Hydroxycoumarin-3-yl)toluene in Aqueous Media Under Microwave Irradiation

An efficient catalyst-free synthesis of alpha,alpha-bis(4-hydroxycoumarin-3-yl)toluene was performed by the reaction of 4-hydroxycoumarin with aromatic aldehydes in aqueous media under microwave irradiation. The reaction was completed in short reaction time of 8-10 min with high yields of 76-94, was environmental benign, and had easy workup. Their structures were confirmed by IR spectra, H-1 NMR, C-13 NMR, and elemental analysis.