Polystyrene-Supported Palladium(II) Ethylenediamine Complex: A Highly Active and Recyclable Catalyst for the Synthesis of 2-Benzylimidazo[2,1-b]pyridines Through Heteroannulation of Acetylenic Compounds

摘要

The polymer-supported palladium(II) ethylenediamine [PS-en-Pd(II)] complex is a highly active cata_lyst for the heterocyclization that takes place during the Sonogashira reaction between an aryl iodide and 2-amino-l-(2-propynyl)pyridinium bromide. This heterogeneous palladium catalyst can readily be recovered from the reaction medium by simple filtration and reused without a significant loss in its activity.