Copper‐ and phosphine‐free Sonogashira coupling reaction catalyzed by silica–(acac)‐supported palladium nanoparticles in water

Abstract

A palladium-based catalyst supported on acac-functionalized silica was used as a heterogeneous catalyst for the Sonogashira cross-coupling reaction of various aryl halides and phenylacetylene under copper-and phosphine-free conditions. This catalytic system serves as an efficient and stable catalyst for this cross-coupling reaction and allows easy separation and recycling of the catalyst. The catalyst could be recycled for five runs without appreciable loss of its catalytic activity. In addition, the reaction was carried out in water as a green solvent.

Silica–acetylacetone‐supported palladium nanoparticles as an efficient and reusable catalyst in the Heck–Mizoroki C–C cross‐coupling reaction

“…In continuation of our recent investigations of the synthesis and application of SiO 2 ‐acac‐PdNPs in carbon–carbon cross‐coupling reactions, we now report the extension of the use of this heterogeneous nano‐catalyst for the cross‐coupling reaction of olefins with various aryl halides (Scheme ).…”

Solid-Supported Palladium Catalysts in Sonogashira Reactions: Recent Developments

“…The catalyst was recovered by centrifugation and reused for three times with some decrease in the yields being observed (from 98% in the first to 80% in the third run) [72]. In addition, the use of acetylacetonate (acac) silica supported particles (SiO2-acacPdNPs) 34 ( Figure 12) allowed to perform the coupling reactions between aryl iodides, bromides and even chlorides with phenylacetylene in refluxing water as solvent, under copper-free conditions [73]. Aryl halides containing electron-withdrawing substituents gave better results than those bearing electrondonating groups, ortho substitution in the aromatic ring leading to lower yields with longer reaction times.…”

Palladium nanoparticles immobilized on cyclodextrin‐decorated halloysite nanotubes: Efficient heterogeneous catalyst for promoting copper‐ and ligand‐free Sonogashira reaction in water–ethanol mixture

“…As the use of copper‐based co‐catalysts can induce the formation of by‐products through promoting homocoupling of alkynes, the development of ligand‐ and copper‐free Sonogashira reactions has received growing attention. In this line, various Pd‐based homogeneous catalytic systems have been developed . However, they suffer from some drawbacks such as tedious recovery of precious catalyst and purification of products.…”