Palladium Nanoparticles Supported on Poly(N-vinylpyrrolidone)-Grafted Silica as an Efficient Catalyst for Copper-Free Sonogashira and Suzuki Cross-Coupling Reactions

Bahman Tamami,Fatemeh Farjadian,Motahareh Mirzadeh,Soheila Ghasemi,Hamed Allahyari

doi:10.5935/0103-5053.20150129

Bahman Tamami, Fatemeh Farjadian + Show 3 more

Open Access

https://doi.org/10.5935/0103-5053.20150129

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Abstract

Palladium catalyst based on polyvinylpyrrolidone-silica hybrid support was prepared and exhibited excellent activity and stability in copper, amine and phosphine-free Sonogashira-Hagihara and Suzuki-Miyaura cross-coupling reactions. The polymeric catalyst was applied efficiently in the coupling reactions of chloro (as well as iodo) and bromoarenes. Elemental analysis of Pd by inductively coupled plasma (ICP) and hot filtration test revealed low leaching of the metal into solution from the supported system. The catalyst could be reused many times in repeated cycles without significant decline in its activity.

Highlights

Palladium-catalyzed cross coupling reactions are among the most employed organic transformations for the generation of C−C bonds in academic as well as industrial communities.[1,2,3] These reactions should be fully developed for their industrialization potential in all aspects such as: the use of benign solvents,[4,5,6] recovery and recycling of the expensive catalysts and their complete removal from the products.[7]
Various kinds of cross coupling reactions have been taken into account, among them Sonogashira-Hagihara, which consist of aryl halides coupling with terminal alkynes, as an efficient way for constructing substituted arylated alkyne compounds
In consequence of our recent reports on synthesis of heterogeneous Pd catalyst either based on polymeric support[34,35] or polymer-grafted silica,[36,37] and our successful synthesis and characterization of Pd nanoparticles supported on poly(N-vinylpyrrolidone)-grafted silica (Si‐PVP-Pd) as a new heterogeneous catalyst in Heck cross‐coupling reactions[38] we report new application of Si-PVP-Pd catalyst for copper, amine and phosphine-free Sonogashira and Suzuki coupling reactions

Summary

Introduction

Palladium-catalyzed cross coupling reactions are among the most employed organic transformations for the generation of C−C bonds in academic as well as industrial communities.[1,2,3] These reactions should be fully developed for their industrialization potential in all aspects such as: the use of benign solvents,[4,5,6] recovery and recycling of the expensive catalysts and their complete removal from the products.[7]. Arylated alkyne compounds are important intermediates in organic synthesis including natural compounds, pharmaceutical, molecular electronics, dendrimeric, oligomeric and polymeric materials.[14,15,16,17] Traditionally, Pd-catalayzed reactions are mostly catalyzed by homogenous Pd complexes in the presence of phosphine ligands, catalytic amount of copper salt as a cocatalyst and a large scale of amine as a solvent.[18] To overcome shortcoming of traditional methods, several modified methods have been reported by different concepts including: phosphine-free reaction condition,[19,20,21] copper and amine-free medium,[22,23,24] utilization of Ni instead of Pd,[25,26] and solid supported catalyst.[27,28] Another efficient method in C−C coupling reaction is Suzuki-Miyaura; the reaction of organo boron compounds with aryl halides or pseudohalides.[29,30,31] This reaction. This resultant was utilized in the reaction cycle without any pre-treatment with a new portion of reagents

Results and Discussion

Conclusions

H Si-P4VPy-Pd0