Ru(II) complexes bearing tertiary phosphine ligands: a novel and efficient homogeneous catalyst for one-pot synthesis of dihydropyrano[3,2-c]chromene and tetrahydrobenzo[b]pyran derivatives

A number of ruthenium complexes were prepared and their catalytic activities in three-component one-pot condensation of aldehydes, malononitrile and 4-hydroxycoumarin or dimedone was considered to afford dihydropyrano[3,2-c]chromenes and tetrahydrobenzo[b]pyran derivatives under optimum reaction conditions. We found that a catalytic amount of RuBr2(PPh3)4 efficiently promotes the reaction in a short time (315 min) and with high yield (7588%). Copyright (C) 2012 John Wiley & Sons, Ltd.