Advances in Magnetic Nanoparticles-Supported Palladium Complexes for Coupling Reactions

Phosphonated Polyethylenimine Maghemite Nanoparticles: A Convenient Support of Palladium for Cross-Coupling Reactions

Phosphonated polyethylenimine grafted on iron oxide nanoparticles was used as a magnetic support for loading palladium. This cheap and accessible heterogeneous catalyst demonstrated good efficiency in Suzuki-Miyaura, Mizoroki-Heck, and Tsuji-Trost couplings. The nanocomposite is resistant to harsh conditions and can therefore be recycled up to 10 cycles with high catalyst efficiency.

Rapid one-pot synthesis of magnetically separable Fe3O4-Pd nanocatalysts: a highly reusable catalyst for the Suzuki-Miyaura coupling reaction

Heterogeneous catalysts comprising noble metals and magnetic materials allow a straightforward separation from a reaction using an external magnet and are recovered easily. In this study, we synthesized magnetic Fe₃O₄-Pd_n hybrid heterogeneous catalysts via a rapid one-pot aqueous-phase method. The synthesized Fe₃O₄-Pd NPs dispersed well with small size (∼50 nm), maintaining high magnetic responsiveness, and showed high reactivity and reusability for the Suzuki-Miyaura coupling reaction between aryl halides and phenylboronic acid. The synthesized Fe₃O₄-Pd₅₀ catalyst could be recycled at least ten times with no significant loss of catalytic activity by external magnet separation.

Supported Metal Catalysts for the Synthesis of N-Heterocycles

Nitrogen-containing heterocycles are important scaffolds for a large number of compounds with biological, pharmaceutical, industrial and optoelectronic applications. A wide range of different methodologies for the preparation of N-heterocycles are based on metal-catalyzed cyclization of suitable substrates. Due to the growing interest in Green Chemistry criteria over the past two decades, the use of supported metal catalysts in the preparation of N-heterocycles has become a central topic in Organic Chemistry. Here we will give a critical overview of all the solid supported metal catalysts applied in the synthesis of N-heterocycles, following a systematic approach as a function of the type of support: (i) metal catalysts supported on inorganic matrices; (ii) metal catalysts supported on organic matrices; (iii) metal catalysts supported on hybrid inorganic-organic matrices. In particular, we will try to emphasize the effective heterogeneity and recyclability of the described metal catalysts, specifying which studies were carried out in order to evaluate these aspects.

Recent progress in application of nanocatalysts for carbonylative Suzuki cross-coupling reactions

In the past few decades, cross-coupling of aryl halides and arylboronic acids in the presence of carbon monoxide (CO), also called carbonylative Suzuki coupling, to form two new carbon-carbon bonds in the production of synthetically and biologically important biaryl ketones, has been widely studied. Consequently, various catalytic systems have been extensively investigated in order to maximize the efficiency of this appealing area of biaryl ketone synthesis. As evidenced in the literature, nanometal-based systems are among the most powerful catalysts for this transformation as their large surface area to volume ratio and reactive morphologies allow faster reaction rates under milder CO pressure even at very low catalyst loadings. This review aims to provide an overview of the recent advances and achievements in the application of nano-sized metal catalysts for carbonylative Suzuki cross-coupling reactions, which may serve as an inspiration to researchers in their future work.

Synthesis of nano magnetic supported NHC-palladium and investigation of its applications as a catalyst in the Mizoroki-Heck cross-coupling reaction in H2O

The unique properties of N-heterocyclic carbenes (NHCs) as an effective ligand for palladium catalytic centers have recently found much attention. In this work, Fe₃O₄ nanoparticle supported palladium(II)-N-heterocyclic carbene catalyst was successfully designed, synthesized and characterized by various methods. The activity of the catalyst was evaluated in the Mizoroki-Heck cross-coupling reaction in which the desired products were obtained in high yield in H₂O as a green solvent. The reaction was carried out in short reaction times using low amounts of the catalyst. Moreover, the catalyst was easily separated from the reaction media and reused for 5 cycles.

Chitosan modified Ti-PILC supported PdOx catalysts for coupling reactions of aryl halides with terminal alkynes

Biopolymer of chitosan (CS) and titanium pillared clays (Ti-PILCs) have been combined in a hybrid as advanced supports for immobilization of PdOx=0,1 species to prepare novel PdOx=0,1@Ti-PILC/CS nano-composite catalysts. The Ti-PILC materials showed high specific surface areas and abundant meso-porous structure with many irregular pore channels caused by collapses of layered structure of clay during Ti pillaring process. Both CS chains and sub-nano sized PdOx particles were successfully incorporated into the pore channels of Ti-PILC, resulting in a decrease in both the specific surface areas and uniform distribution of pore size. Besides conventional methods characterizations, the strong interactions between PdOx species and Ti-PILC/CS support were further evidenced with positron annihilation lifetime spectroscopy studies. The resultant PdOx@Ti-PILC/CS catalyst was highly active for the coupling reactions of aryl halides with phenyl acetylenes. It was recyclable and gave excellent yield up to 13 runs with low leaching of Pd species.

A facile synthesis of mesoporous graphitic carbon nitride supported palladium nanoparticles as highly effective and reusable catalysts for Stille coupling reactions under mild conditions

This paper reports a facile one-pot synthesis of mesoporous graphitic carbon nitride (mpg-CN) supported Pd NPs, denoted as mpg-CN/Pd, as highly efficient catalysts for Stille C–C coupling reactions under mild conditions.