Intercalation of copper salt to montmorillonite K-10 and its application as a reusable catalyst for Chan–Lam cross-coupling reaction

A simple and efficient catalytic system has been developed by adsorption of copper salt in the interlayers of montmorillonite K-10. The catalytic system impressively exercises the green chemistry perspective leading to effortless recovery and recyclability for the cross-coupling of arylboronic acids and N-nucleophiles. The effect of catalytic activity was studied for electronically diverse arylboronic acids and imidazoles relying on various optimizations under optimum thermal condition. The catalytic system was characterized and the morphology was determined.     

Facile and convenient synthesis of aryl hydrazines via copper-catalyzed C–N cross-coupling of aryl halides and hydrazine hydrate

An efficient and convenient method for the synthesis of aryl hydrazines has been developed via copper-catalyzed cross-coupling of aryl bromides and hydrazine with a readily accessible ligand and water as a solvent. The multigram scale procedure is applicable to aryl bromides bearing both moderately electron-donating and electron-withdrawing substituents in the aromatic nucleus. No column chromatography is required to obtain aryl hydrazine hydrochlorides in good yields.     

CO cross-coupling of activated aryl and heteroaryl halides with aliphatic alcohols

A robust and general catalyst system facilitates the alkoxylation of activated heteroaryl halides with primary, secondary, and select tertiary alcohols without the need for an excess of either coupling partner. This catalyst system displays broad functional-group tolerance and excellent regioselectivity, and is insensitive to the order of reagent addition.     

Facile and efficient protocols for C–C and C–N bond formation reactions using a superparamagnetic palladium complex as reusable catalyst

Research on Chemical Intermediates - Facile and efficient protocols for some multicomponent coupling reactions such as the Suzuki reaction and synthesis of polyhydroquinoline and...     

Porous organic polymer immobilized copper nanoparticles as heterogeneous catalyst for efficient benzylic C–H bond oxidation

A facile and practical heterogeneous copper nanoparticles catalyst (Cu@AEPOP) was prepared by the incorporation of Cu(OAc)₂ to amide and ether functionalized porous organic polymers (AEPOP) that were efficiently prepared by condensation of 4,4′-diaminodiphenyl ether with 1,3,5-benzenetricarbonyl chloride. The prepared AEPOP and Cu@AEPOP were characterized by SEM, BET, TEM, ICP, FT-IR and XRD. With TBHP (70 wt% in water) as oxidant and solvent, Cu@AEPOP showed excellent catalytic activity for the selective oxidation of benzylic C–H bonds. Among the oxidation of alkyl benzenes to ketones, secondary alcohols to ketones, and primary alcohols to acids, the copper catalyst exhibited remarkable selectivity and reactivity for a broad range of substrates in excellent yields. Furthermore, the experimental operation was very facile and the heterogeneous catalyst could be easily recovered by filtration separation.     

Pd nanoparticles supported on reduced graphene oxide as an effective and reusable heterogeneous catalyst for the Mizoroki–Heck coupling reaction

A general method for the synthesis of palladium nanoparticles loaded on reduced graphene oxide functionalized with diethylenetriamine (PdNPs/rGO-NH₂) using a sonochemical procedure is described. The heterogeneous nanocomposite was characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy, energy dispersive X-ray, thermogravimetric analysis, high-angle annular dark field scanning transmission electron microscopy, X-ray photoelectron spectroscopy, UV–visible absorption, and inductively coupled plasma optical emission spectrometry. The PdNPs/rGO-NH₂ was very effective for the Mizoroki–Heck coupling reaction of several aryl iodide compounds with different alkenes in the presence of triethylamine. The reaction provides the coupling products in good to excellent yields (59–100%). Additionally, the PdNPs/rGO-NH₂ catalyst can be reutilized for six successive runs without any apparent diminution of its catalytic reactivity.     

Palladium tetrazole–supported complex as an efficient catalyst for the Heck reaction

Abstract  

A tetrazole-supported polymeric ligand has been synthesized. The palladium complex derived from the polymeric material has been evaluated as a catalyst for the Heck reaction of aryl iodides and bromides with styrene to provide the corresponding products in high yields. The reaction proceeded smoothly in the presence of 1 mol% with respect to Pd of catalyst in DMF at 125 or 140 °C within 1–3 h. Recycling studies showed that the catalyst can be readily recovered and reused for several times without significant loss of catalytic activity.     

An in situ generated CuI/metformin complex as a novel and efficient catalyst for C–N and C–O cross-coupling reactions

An in situ generated complex of copper(I) and a biguanide, namely metformin, was found to be a highly efficient homogeneous catalyst in N/O-arylation reactions. The O-arylation of substituted phenols with various aryl iodides and bromides was also achieved using this copper catalyst to afford diaryl ethers in good to excellent yields in DMF. This heterogeneous copper catalyst also promotes the N-arylation of imidazole with a variety of aryl halides (Cl, Br, I) in acetonitrile.     

Suzuki–Miyaura cross-coupling reaction of aryl and heteroaryl pinacol boronates for the synthesis of 2-substituted pyrimidines

Suzuki–Miyaura cross-coupling reaction with 2-heteroarylboronic acids is generally challenging due to these acids easy decomposition. To overcome this problem, we developed a coupling method that uses 2-heteroaryl pinacol boronates in the presence of 1.0 mol % Pd(OAc)₂ and 2.0 mol % S-Phos with 4 equiv amount of LiOH in dioxane and H₂O at 80 °C for 30 min. This developed method allowed for the synthesis of a wide variety of 2-heteroaryl pyrimidines from 2-chloropyrimidyl derivatives in high yields, and is also useful in the preparation of various biaryl derivatives from heteroaryl chlorides.     

A highly efficient memantine-modified palladium catalyst for Suzuki–Miyaura cross-coupling reaction

A new simple Pd(memantine)₂Cl₂ complex was synthesized and characterized by ¹H NMR, ¹³C NMR and X-ray single crystal structure determination. The Suzuki–Miyaura reaction of aryl bromides catalyzed by Pd(memantine)₂Cl₂ complex was investigated in air with different temperature. The high turnover numbers of 650,000 have been obtained in the reaction of 4-bromonitrobenzene with phenylboronic acid at 80 °C. At room temperature, the complex also showed high activity for Suzuki–Miyaura cross-coupling reaction of aryl bromides with a wide range of functional groups under air, and the turnover number of up to 99,000 was achieved. The catalytic system also gives good yields toward the reaction of several heteroaryl bromides with thiophenylboronic acid.     

New ligands for copper-catalyzed C–N coupling reactions with aryl halides

2-Carbomethoxy-3-hydroxyquinoxaline-di-N-oxide was identified as an efficient novel ligand for the copper-catalyzed coupling reactions of aryl iodides, bromides, and chlorides with aliphatic amines and N-containing heterocycles under mild conditions. The catalytic system showed great functional-group tolerance and excellent chemoselectivity.     

Monodentate phosphorus-coordinated palladium(Ⅱ)complexes as new catalyst for Mizoroki-Heck reaction of aryl halides with electron-deficient olefins

Four novel monodentate phosphorus-coordinated palladium(Ⅱ) complexes derived from 3,5-disubstituted-1H-1,2,4-diazaphospholes were developed as efficient catalyst for Mizoroki-Heck reactions of aryl halides with electron-deficient olefins. The role of these monophosphine ligands in catalysis was illustrated by control experiments using Pd salt and ligands as combined catalyst.     

Palladium-catalyzed Suzuki–Miyaura cross-coupling reaction of potassium 2-pyridyl trifluoroborate with aryl (heteroaryl) halides

Palladium-catalyzed Suzuki–Miyaura cross-coupling reaction of potassium pyridine-2-trifluoroborates and various aryl (heteroaryl) halides can generate the corresponding desired coupling products with moderate to good yields. It can be carried out under the conditions with ethanol as solvent, Pd(OAc)₂ and SPhos as catalyst system and Na₂CO₃ as a base.     

Pd(0)-Schiff-base@MCM-41 as high-efficient and reusable catalyst for C–C coupling reactions

A Pd-Schiff-base grafted on functionalized mesoporous MCM-41 (Pd(0)-Schiff-base@MCM-41) was prepared using a post-grafting procedure and used as a highly efficient and reusable nanostructural catalyst for the carbon–carbon cross-coupling reactions of various aryl halides (including aryl iodide, bromide and chloride) with sodium tetraphenyl borate, phenylboronic acid and butyl acrylate. This catalyst exhibits interesting reactivity through Heck and Suzuki reactions.     

Ligand-free C–N bond formation in aqueous medium using a reusable Cu–Mn bimetallic catalyst

A general ligand-free protocol has been described for the recyclable and reusable Cu–Mn catalyzed C–N bond forming cross coupling reaction of arylboronic acids with various amines to form N-arylated amine products in aqueous medium affording excellent yields under ambient conditions, in 3–4 h.     

P–C bond formation: synthesis of phosphino amino acids by palladium-catalysed cross-coupling

(4-Diethylphosphanyl)- and (4-diphenylphosphanyl)-derivatives of d- and l-phenylalanine have been synthesised using a palladium-catalysed cross-coupling giving the desired products in very high yields and without racemisation.     

Diphenylphosphorylated PEG (DPPPEG) as a new support for generation of nano-Pd(0) as catalyst for carbon–carbon bond formation via copper-free Sonogashira and homocoupling reactions of aryl halides in PEG

In this study, synthesis and application of diphenylphosphorylated PEG₂₀₀ (DPPPEG₂₀₀) are described. Herein, we report a very simple procedure for the preparation of DPPPEG₂₀₀ as a stable solid through the reaction of PEG₂₀₀ with ClPPh₂. This compound was used as a very suitable ligand for the in situ generation of nano-Pd(0) particles through its reaction with PdCl₂ as a pre-catalyst. Isolation of this catalyst is very simple through addition of diethyl ether to the reaction mixture and centrifugations. Full characterization of the nano-Pd(0)/DPPPEG200 was performed by XRD spectra, UV–Vis spectra, and also by TEM image. This nano-complex was used as an efficient catalyst for copper-free Sonogashira and homocoupling reactions of aryl halides. The sonogashira reaction of aryl halides was conducted at 80 °C in PEG. However, the homocoupling reaction was performed at 100 °C for aryl iodides and activated aryl bromides and at 130 °C for deactivated aryl bromides and aryl chlorides in PEG. The catalyst was recovered and recycled for four consecutive runs.     

Pd–Co bimetallic nanoparticles supported on graphene as a highly active catalyst for Suzuki–Miyaura and Sonogashira cross-coupling reactions

Graphene (G) supported Pd–Co bimetallic nanoparticles (NPs) as a highly active catalyst was prepared by a chemical reduction method and used for coupling reactions. With the characterization of X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, and Raman spectrum, the composition of resulting Pd–Co material was identified to be alloy structural. The Pd–Co (1:1)/G exhibited the highest catalytic activity for the Sonogashira-type coupling reactions and also exerted satisfied catalytic activity and recycle stability for Suzuki–Miyaura cross-coupling reactions. This Pd–Co/G material also possessed other advantages such as low-cost, easy recycled from reaction system by a magnet for their magnetic property, and easy experimental handling.     

Copper-catalyzed intramolecular C–N coupling reaction of aryl halide with amide

An efficient and concise method for the ligand-free copper-catalyzed intramolecular C–N bond coupling was developed, which afforded various (NH)-phenanthridinones in good to excellent yields with tolerance of various substrates.