Catalytic application of two novel sandwich-type polyoxometalates in synthesis of 14-substituted-14H-dibenzo[a, j]xanthenes

Abstract

Two sandwich-type polyoxometalates K12[As2W 18Cu3O68]·30H2O and K 12[As2W18U3O74] ·21H2O were found to be as novel efficient catalysts for one-pot synthesis of various 14-aryl or alkyl-14H-dibenzo[a, j]xanthenes. Three-component condensation reactions of β-naphthol with aromatic or aliphatic aldehydes in the presence of these catalysts were investigated. These reactions were studied under different conditions such as solvent-free media using both conventional heating and microwave irradiation and also several solvents. Results showed that the optimum reaction time and the yield were obtained when reactions were carried out under solvent-free conditions. Furthermore, the catalysts could be recovered conveniently and reused efficiently. © 2013 Indian Academy of Sciences.