Impregnated palladium on magnetite as catalyst for direct arylation of heterocycles

Abstract

Palladium impregnated on magnetite is an efficient, cheap and easy to prepare catalyst for the direct arylation of heterocycles. Good yields are afforded under relatively mild conditions and a broad substrate scope is evident. The catalyst is regioselective in many cases, affording arylated products, at the C2- or C3-position (depending of the heterocycle used). The methodology can be extended to prepare chromenes through an intramolecular direct arylation reaction. Some evidence is provided for two catalyst deactivation pathways, which prevents efficient recycling.The authors thank the Irish Research Council (RC), Science Foundation Ireland (SFI/12/IP/1315 and SFI/12/RC/2275), Spanish Ministerio de Economía y Competitividad (MICINN; CTQ2011-24151, University of Alicante and MICINN FPI program (JMP)