One-pot and chemoselective synthesis of bis(4-hydroxycoumarin) derivatives catalyzed by nano silica chloride

Nano silica chloride (nano SiO 2 Cl) has been found to be an efficient, chemoselective and recyclable catalyst for facile and simple condensation of 4-hydroxycoumarin with aromatic and heteroaromatic aldehydes into bis(4-hydroxycoumarin)methanes in dry CH 2 Cl 2 . The products were obtained in high to excellent yields.