Palladium(II) oxide impregnated on magnetite as a catalyst for the synthesis of 4-arylcoumarins via a Heck-arylation/cyclization process

Heck-arylation/cyclization was achieved using heterogeneous palladium(II) oxide impregnated on magnetite catalyst (2.5 mol%) with a lower catalyst loading than that reported for similar processes. Ethanol was used as a non-toxic and bio-renewable solvent. Good yields were afforded using a broad range of substrates (40–98%). The catalyst could be partially recycled, and analyses confirmed the almost total reduction of palladium(II) oxide to palladium(0) as well as the iodine poissoning effect, which is the main barrier to complete recyclability.

The authors thank the Spanish Ministerio de Economía y Competitividad (MICINN; CTQ2011-24151), University of Alicante, Irish Research Council (RC) and Science Foundation Ireland (SFI/12/IP/1315 and SFI/12/RC/2275). J. M. P. thanks the MICINN (FPI program) for her fellowship.