Nanocrystalline magnesium oxide stabilized palladium(0): An efficient heterogeneous catalyst for Heck and Sonogashira coupling of aryl halides

Nanocrystalline magnesium oxide supported palladium(0) catalyst [NAP-Mg-Pd(0)], prepared by the counter-ion stabilization of PdCl42- followed by reduction with hydrazine hydrate, was effectively used in the Heck olefination of haloarenes (chloro, bromo, and iodo) to afford good to excellent yields of substituted olefins. This ligand-free heterogeneous NAP-Mg-Pd(0) catalyst was quantitatively recovered from the reaction by a simple filtration and reused for a number of cycles with almost no loss of activity. Moreover, NAP-Mg-Pd(0) efficiently catalyzed the Sonogashira coupling of haloarenes with terminal alkynes without any copper co-catalyst under milder conditions to afford excellent yields of substituted alkynes.