Catalytic performance of a Keplerate-type, giant-ball nanoporous isopolyoxomolybdate as a highly efficient recyclable catalyst for the synthesis of biscoumarins

Abstract

Abstract In continuation of our previous works on the application of (NH4)42[MoVI 72MoV 60O372(CH3COO)30(H2O)72], a Keplerate-type giant-ball nanoporous isopolyoxomolybdate, as a catalyst for a series of organic transformations, in this paper, we discovered that this new attractive catalyst has high catalytic activity in the synthesis of biscoumarins prepared by the reaction of 4-hydroxycoumarin and aromatic or aliphatic aldehydes in refluxing ethanol. The catalyst was prepared according to a previously published literature procedure using inexpensive and readily available starting materials. Furthermore, the catalyst could be recovered conveniently and reused efficiently such that a considerable catalytic activity still could be achieved after fifth run. Other beneficial features of this new synthetic approach include short reaction time, high yields, clean reaction profiles, and a simple work-up procedure.