One-pot synthesis of E-chalcones using a multifunctional catalyst comprised of ruthenium nanoparticles and palladium N-heterocyclic carbene complexes immobilized on silica

Abstract

The integrated one-pot synthesis of valuable E-chalcones from aryl iodides, phenylacetylenes, CO and H₂ is achieved using a single catalyst material. The multifunctional catalytic system is composed of a silica support on which ruthenium nanoparticles and covalently functionalized palladium N-heterocyclic carbene (NHC) complexes are jointly assembled. The resulting Ru@SiO₂-[Pd–NHC] catalyst was characterized by a variety of techniques including N₂ physisorption, solid-state nuclear magnetic resonance, electron microscopy, and X-ray photoelectron spectroscopy to collect information on its textural, structural, morphological, and electronic properties. Ru@SiO₂-[Pd–NHC] was found to be active and selective for the one-pot synthesis of a wide variety of E-chalcones, valuable products with widespread applications in the fine chemical, agrochemical, and pharmaceutical industries. The heterogenized Pd–NHC complex catalyzed the carbonylative Sonogashira coupling step, while CO-covered Ru NPs were found to be responsible for the highly selective hydrogenation of the ynones intermediates to E-chalcones. This study outlines the potential of hybrid multifunctional catalytic systems combining molecular and nanoparticle sites to open up new and more sustainable complex reaction sequences toward valuable compounds.