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1.
Domino oxidation-Suzuki–Miyaura cross-coupling of benzyl alcohols with phenylboronic acid and domino reduction-C–N cross-coupling of the nitro compounds with aryl halides were carried out using a strong Ni/Pd bimetallic redox catalyst. The catalyst bearing a copolymer with two Ni/Pd coordinated metals in porphyrin (derived from demetalated chlorophyll b) and salen-type ligands, and pyridine moiety as a base functionality all immobilized on magnetite NPs was synthesised and characterized. The domino oxidation cross-coupling reaction was accomplished under molecular O2 in the absence of any hydride acceptor or/and base. Also, the domino reduction C–N cross-coupling reaction was performed in the presence of NaBH4 without the need for any base and co-reductant. This multifunctional catalyst gave moderate to good yields for both coupling reactions with high chemoselectivity. A wide investigation was conducted to determine its mechanism and chemoselectivity.A new Ni/Pd bimetallic multifunctional catalytic system has been developed for the domino Suzuki–Miyaura cross-coupling of benzyl alcohols with phenyl boronic acid and domino reduction C–N cross-coupling of the nitro compounds with aryl halides. 相似文献
2.
Sinem akr Serdar Batkan Kavukcu Hande Karabyk Senthil Rethinam Hayati Türkmen 《RSC advances》2021,11(60):37684
Application of N-heterocyclic carbene (NHC) palladium complexes has been successful for the modulation of C–C coupling reactions. For this purpose, a series of azolium salts (1a–f) including benzothiazolium, benzimidazolium, and imidazolium, bearing a CN-substituted benzyl moiety, and their (NHC)2PdBr2 (2a–c) and PEPPSI-type palladium (3b–f) complexes have been systematically prepared to catalyse acylative Suzuki–Miyaura coupling reaction of acyl chlorides with arylboronic acids to form benzophenone derivatives in the presence of potassium carbonate as a base and to catalyse the traditional Suzuki–Miyaura coupling reaction of bromobenzene with arylboronic acids to form biaryls. All the synthesized compounds were fully characterized by Fourier Transform Infrared (FTIR), and 1H and 13C NMR spectroscopies. X-ray diffraction studies on single crystals of 3c, 3e and 3f prove the square planar geometry. Scanning Electron Microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), metal mapping analyses and thermal gravimetric analysis (TGA) were performed to get further insights into the mechanism of the Suzuki–Miyaura cross coupling reactions. Mechanistic studies have revealed that the stability and coordination of the complexes by the CN group are achieved by the removal of pyridine from the complex in catalytic cycles. The presence of the CN group in the (NHC)Pd complexes significantly increased the catalytic activities for both reactions.Nitrile-functionalized Pd(ii) complexes have evaluated for the Suzuki–Miyaura cross-coupling reactions. The highest TON value was reached for the acylative Suzuki–Miyaura cross-coupling reaction of acyl chlorides with phenylboronic acids. 相似文献
3.
This study investigates the potential application of an efficient, easily recoverable and reusable magnetically separable Fe3O4/KCC-1/APTPOSS nanoparticle-supported salen/Pd(ii) catalyst for C–C and C–H cross-couplings. The Fe3O4/KCC-1/APTPOSS/salen/Pd(ii) MNPs were thoroughly characterized by using TEM, FE-SEM, TGA, XRD, VSM, FT-IR, ICP-MS, and BET. This observation was exploited in the direct and selective chemical reaction of 2-acetyl-benzaldehyde with cyclopentadiene for the synthesis of pentafulvene. The recycled catalyst has been analyzed by ICP-MS showing only minor changes in the morphology after the reaction, thus confirming the robustness of the catalyst.This study investigates the potential application of an efficient, easily recoverable and reusable magnetically separable Fe3O4/KCC-1/APTPOSS nanoparticle-supported salen/Pd(ii) catalyst for C–C and C–H cross-couplings. 相似文献
4.
Three bimetallic Ir(iii)–Pd(ii) complexes [Ir(ppy)2(bpm)PdCl2](PF6) (ppy = 2-phenylpyridine, 1), [Ir(dfppy)2(bpm)PdCl2](PF6) (dfppy = (4,6-difluorophenyl)pyridine, 2), and [Ir(pq)2(bpm)PdCl2](PF6) (pq = 2-phenylquinoline, 3) were synthesized by using 2,2′-bipyrimidine (bpm) as a bridging ligand. The influences of the cyclometalated ligand at the Ir(iii) center on the photophysical and electrochemical properties as well as photocatalytic activity for the Suzuki–Miyaura coupling reaction under mild conditions were evaluated. The results revealed that complex 3 enables dramatically accelerating the Suzuki–Miyaura coupling reaction under visible light irradiation at room temperature, due to the effective absorption of visible light and appropriate locus of the excited chromophore. Mechanism studies showed that the chromophore [Ir(pq)2(bpm)] fragment absorbs visible light to produce the triplet excited state centering on the bridging ligand which boosts the formation of electron rich Pd(ii) units and facilitates the oxidative addition step of the catalytic cycle. Simultaneously, the excited chromophore undergoes energy transfer efficiently to the Pd(ii) reaction site to form the excited Pd(ii) species, resulting in enhancement of Pd(ii) reduction steps of the Suzuki–Miyaura coupling reaction and increasing the reactivity of the catalyst. This provides a new strategy for designing photocatalysts for coupling reaction through altering the cyclometalated ligand to modulate the photophysical properties and the cooperation between two metal units.A series bimetallic catalysts were synthesized. Relationship between the structure of catalysts and catalytic reactivities were studied and improvement of the catalytic efficiency for Suzuki–Miyaura coupling was accomplished by regulating their chromophores. 相似文献
5.
The Pd catalyst for Suzuki–Miyaura or the other C–C coupling reactions is one of the central tools in organic synthesis related to medicine, agricultural chemicals and advanced materials. However, recycling palladium is a bottleneck for developing the extreme potential of Pd in chemistry. Herein, we established a new heterogeneous Pd catalytic system in which the catalyst is a nanopetal-gathered flower-like microsphere self-assembled from PdCl2 and alkyl-linked bis-theophyllines. The microflowers catalyzed quantitatively the reaction of aryl bromides and phenylboronic acid in aqueous media at room temperature. It was found that the reaction proceeds better in an air atmosphere than in nitrogen gas even though the Pd(ii) species employed was lowered to 0.001 mol% in the substance. Very interestingly, the microflowers could be recycled 20 times without deactivation in the C–C coupling reaction between bromobenzene and phenylboronic acid in the presence of sodium chloride. We found that the sodium chloride added played an important role in maintaining the morphology of microflowers and preventing the formation of metallic Pd particles.Bis-theophylline-palladium complex exhibit high catalytic activity in the C–C coupling reaction with excellent recyclability in the presence of NaCl. 相似文献
6.
Siavash Salek Soltani Reza Taheri-Ledari S. Morteza F. Farnia Ali Maleki Alireza Foroumadi 《RSC advances》2020,10(39):23359
Herein, a novel high-performance heterogeneous catalytic system made of volcanic pumice magnetic particles (VPMP), cellulose (CLS) natural polymeric texture, and palladium nanoparticles (Pd NPs) is presented. The introduced VPMP@CLS-Pd composite has been designed based on the principles of green chemistry, and suitably applied in the Suzuki–Miyaura cross-coupling reactions, as an efficient heterogeneous catalytic system. Concisely, the inherent magnetic property of VPMP (30 emu g−1) provides a great possibility for separation of the catalyst particles from the reaction mixture with great ease. In addition, high heterogeneity and high structural stability are obtained by this composition resulting in remarkable recyclability (ten times successive use). As the main catalytic sites, palladium nanoparticles (Pd NPs) are finely distributed onto the VPMP@CLS structure. To catalyze the Suzuki–Miyaura cross-coupling reactions producing biphenyl pharmaceutical derivatives, the present Pd NPs were reduced from chemical state Pd2+ to Pd0. In this regard, a plausible mechanism is submitted in the context as well. As the main result of the performed analytical methods (including FT-IR, EDX, VSM, TGA, FESEM, TEM, BTE, and XPS), it is shown that the spherical-shaped nanoscale Pd particles have been well distributed onto the surfaces of the porous laminate-shaped VPMP. However, the novel designed VPMP@CLS-Pd catalyst is used for facilitating the synthetic reactions of biphenyls, and high reaction yields (∼98%) are obtained in a short reaction time (10 min) by using a small amount of catalytic system (0.01 g), under mild conditions (room temperature).An efficient natural-based catalyst constructed of volcanic pumice, cellulose polymeric chains, and palladium nanoparticles is presented for Suzuki–Miyaura coupling reaction. 相似文献
7.
We proposed a strategy that a benzothiazole-linked covalent organic framework (TTT-COF) was used as a substrate to prepare metal composite photocatalyst Pd NPs@TTT-COF. Firstly, benzothiazole linked TTT-COF exhibited superior chemical stability and photoresponse. Moreover, a finer particle size (2.01 nm) and more uniform distribution of Pd NPs were observed in Pd NPs@TTT-COF owing to the binding interaction between Pd NPs and S in benzothiazole groups. Pd NPs@TTT-COF exhibited superior efficiency and reusability in photocatalytic C–C cross-coupling reactions. Mechanism study suggested that photogenerated electrons and holes on TTT-COF played important roles in these reactions.Benzothiazole-linked covalent organic framework with characteristic properties loaded Pd nanoparticles for photocatalytic C–C cross-coupling reactions. 相似文献
8.
In the current research work, a new KIT-5-biguanidine-Pd(0) catalyst was prepared and applied to ultrasound-assisted Suzuki–Miyaura cross-coupling reactions using ultrasound waves at ambient temperature. The ultrasound-assisted method is a green and efficient method for C–C coupling. Many parameters of the Suzuki coupling reaction were examined, such as the irradiation time, the types of organic and inorganic bases, the types of aprotic and protic solvents, and the dosage (mol%) of catalyst. Also, the results showed that the yields from the ultrasound-assisted coupling reactions were higher than from non-irradiated reactions. The prepared catalyst was characterized via HR-TEM, SEM-EDX-mapping, FT-IR, ICP-AAS, BET-BJH, and XRD studies. The stability and catalytic performance of the prepared catalyst were good, and it could be reused 6 times without catalytic activity loss for the Suzuki–Miyaura cross-coupling reaction.In the current research work, a new KIT-5-biguanidine-Pd(0) catalyst was prepared and applied to ultrasound-assisted Suzuki–Miyaura cross-coupling reactions using ultrasound waves at ambient temperature. 相似文献
9.
Jairus L. Lamola Paseka T. Moshapo Cedric W. Holzapfel Munaka Christopher Maumela 《RSC advances》2021,11(43):26883
A family of biaryl phosphacyclic ligands derived from phobane and phosphatrioxa-adamantane frameworks is described. The rigid biaryl phosphacycles are efficient for Suzuki–Miyaura cross-coupling of aryl bromides and chlorides. In particular, coupling reactions of the challenging sterically hindered and heterocyclic substrates were viable at room temperature.Efficient palladium catalyst systems consisting of bench-stable biaryl phosphacycles and Pd(OAc)2 are described for Suzuki–Miyaura cross-coupling reactions of a diverse array of aryl halides and arylboronic acids. 相似文献
10.
Fatemeh Mohammadsaleh Maryam Dehdashti Jahromi Abdol Reza Hajipour Seyed Mostafa Hosseini Khodabakhsh Niknam 《RSC advances》2021,11(34):20812
1,2,3-Triazole is an interesting N-heterocyclic framework which can act as both a hydrogen bond donor and metal chelator. In the present study, C–H hydrogen bonding of the 1,2,3-triazole ring was surveyed theoretically and the results showed a good agreement with the experimental observations. The click-modified magnetic nanocatalyst Pd@click-Fe3O4/chitosan was successfully prepared, in which the triazole moiety plays a dual role as both a strong linker and an excellent ligand and immobilizes the palladium species in the catalyst matrix. This nanostructure was well characterized and found to be an efficient catalyst for the CO gas-free formylation of aryl halides using formic acid (HCOOH) as the most convenient, inexpensive and environmentally friendly CO source. Here, the aryl halides are selectively converted to the corresponding aromatic aldehydes under mild reaction conditions and low Pd loading. The activity of this catalyst was also excellent in the Suzuki cross-coupling reaction of various aryl halides with phenylboronic acids in EtOH/H2O (1 : 1) at room temperature. In addition, this catalyst was stable in the reaction media and could be magnetically separated and recovered several times.The C–H hydrogen bonding of a 1,2,3-triazole framework was studied. An Fe3O4–chitosan core–shell incorporating a triazole/Pd complex was investigated as a nanocatalyst in carbonylation and C–C coupling. 相似文献
11.
Herein, a novel magnetic metal–organic framework functionalized (MMOF) with 2-aminothiophenol (2-ATP) was fabricated and employed for separation/preconcentration of trace silver amounts. At first magnetite nanoparticles (Fe3O4 NPs) were synthesized and then coated with SiO2. Thereafter, the Fe3O4@SiO2 nanoparticles were modified with 2-ATP. Finally, the functionalized MMOF was prepared by the fabrication of MIL-101(Cr) in the presence of Fe3O4@SiO2@2-ATP NPs. MIL-101(Cr)/Fe3O4@SiO2@2-ATP nanocomposite was characterized with FT-IR, SEM, elemental analysis, XRD and VSM and then utilized in the separation/determination of silver ions in various real samples. The effects of diverse experimental variables such as pH, uptake time, adsorbent amount, desorption time, eluent concentration and volume were studied comprehensively employing experimental design methodology. After optimization, LOD and linearity were 0.05 ng mL−1 and 0.2–200 ng mL−1, respectively. Repeatability of the new method was determined based on RSD value for 5, 50, 150 ng mL−1 (n = 5) concentrations which was 9.3%, 6.8% and 4.5%, respectively. Ultimately, the outlined method was utilized in the separation/determination of silver ions in various water and wastewater samples satisfactorily.A scheme for the synthesis of MIL-101/Fe3O4@SiO2@2-ATP nanocomposite. 相似文献
12.
Irina N. Denisenko Oleg A. Varzatskii Roman A. Selin Alexander S. Belov Ekaterina G. Lebed Anna V. Vologzhanina Yan V. Zubavichus Yan Z. Voloshin 《RSC advances》2018,8(24):13578
A new approach for performing Suzuki–Miyaura and Sonogashira reactions of iron(ii) dihalogenoclathrochelates, optimizing their reaction conditions (such as temperature, solvent and a palladium-containing catalyst) and the nature of other reagents (such as arylboron components) is elaborated. These palladium-catalyzed reactions are very sensitive to the nature of the macrobicyclic substrates. The reactivity of the leaving halogen atoms correlates with their ability to undergo an oxidative addition, decreasing in the order: I > Br > Cl, and iron(ii) diiodoclathrochelate underwent these C–C cross-couplings under their “classical” conditions. Phenylboronic, 4-carboxyphenylboronic and 6-ethoxy-2-naphthylboronic acids, and the diethyl ether of 4-(ethoxycarbonyl)boronic acid were tested as components of Suzuki–Miyaura reactions in DMF and in THF. The highest yields of the target products were obtained in DMF, while the highest activation was observed with sodium and potassium carbonates. The Suzuki–Miyaura reaction of a diiodoclathrochelate with 6-ethoxy-2-naphthylboronic acid gave the mono- and difunctionalized clathrochelates resulting from the tandem hydrodeiodination – C–C cross-coupling and double C–C cross-coupling reactions, respectively. Its Sonogashira reactions with trimethylsilylacetylene and acetylenecarboxylic acid in THF and in DMF were tested. This palladium-catalyzed reaction with a (CH3)3Si-containing active component gave the target products in a high total yield. The complexes obtained were characterized using elemental analysis, MALDI-TOF, UV-Vis, 1H and 13C{1H} NMR spectroscopy, and by single crystal XRD. Despite the non-equivalence of the ribbed α-dioximate fragments of their molecules, the encapsulated iron(ii) ion is situated almost in the centre of its FeN6-coordination polyhedron, the geometry of which is almost intermediate between a trigonal prism and a trigonal antiprism.A new approach for performing Suzuki and Sonogashira reactions of iron(ii) dihalogenoclathrochelates, optimizing their reaction conditions, is elaborated. 相似文献
13.
An eco-friendly and efficient method has been developed for the synthesis of 2-arylbenzoxazoles via a domino iron-catalyzed C–N/C–O cross-coupling reaction. Some of the issues typically encountered during the synthesis of 2-arylbenzoxazoles in the presence of palladium and copper catalysts, including poor substrate scope and long reaction times have been addressed using this newly developed iron-catalyzed method.The synthesis of benzoxazoles via an iron-catalyzed cascade C–N and C–O coupling is described.2-Arylbenzoxazoles are an important class of structures in natural products, and pharmaceuticals and has shown a wide range of biological activities, such as antitumor, antiviral, and antimicrobial activities.1 In particular, they show a marvellous efficacy in the treatment of duchenne muscular dystrophy (DMD) which is one of the most common of the muscular dystrophies that is caused by a mutation in the gene DMD, located in humans on the X chromosome (Xp21).2 So the synthesis of 2-arylbenzoxazoles has been intensively studied for use in organic and medicinal chemistry over the past few years.Numerous methods have been reported to synthesise this motif, one of the common methods is transition-metal-catalyzed (like Pd,3 Ni,4 Cu,5 Mn6etc.) cross-coupling from pre-existing benzoxazoles with aryl halide or arylboronic acid. And another method is the classic one employing a cyclocondensation approach between an aminophenol and either a carboxylic acid7 or benzaldehyde8 (Scheme 1, path a). In 2004, Frank Glorius'' group reported a domino copper-catalyzed C–N and C–O cross-coupling for the conversion of primary amides into benzoxazoles9 (Scheme 1, path b) which is a new reaction type for the synthesis of benzoxazoles. Bunch et al. apply this domino reaction in the synthesis of planar heterocycles in 2014.10 In addition the cyclization of o-halobenzenamides to benzoxazoles has been reported several times.11,12 Nevertheless, some limitations in the reported methods need to be overcome, such as the use of palladium complexes and narrow substrate range.Open in a separate windowScheme 1Classic method of benzoxazole formation.In the last few years, there has been a significant increase in the number of reports pertaining to the development of iron-catalyzed reactions in organic synthesis, where iron has shown several significant advantages over other metals, such as being more abundant, commercially inexpensive, environmentally friendly and drug safety.13 Compared with palladium and copper, the use of iron is particularly suitable for reactions involving the preparation of therapeutic agents for human consumption. With this in mind, it was envisaged that an new method should be developed for the synthesis of benzoxazoles via an iron-catalyzed domino C–N/C–O cross-coupling reaction.The reaction of benzamide (1a) with 1-bromo-2-iodobenzene was used as model transformation to identify the optimum reaction conditions by screening a variety of different iron salts, bases, ligands and solvents (l-proline provided no product (14 high-purity Fe2O3 (99.999%) and K2CO3 (99.999%) were applied in the reaction ( Entry Iron salt Ligand Base Solvent Y b (%) 1 FeCl3 DMEDA KOtBu PhMe Trace 2 FeCl2·4H2O DMEDA KOtBu PhMe Trace 3 FeSO4·7H2O DMEDA KOtBu PhMe 0 4 Fe(acac)3 DMEDA KOtBu PhMe 0 5 Fe2O3 DMEDA KOtBu PhMe 15 6 Fe3O4 DMEDA KOtBu PhMe 0 7 Fe3O4(nano) DMEDA KOtBu PhMe 10 8 Fe2O3(nano) DMEDA KOtBu PhMe 0 9 Fe2(SO4)3 DMEDA KOtBu PhMe 0 10 Fe(NO3)3·9H2O DMEDA KOtBu PhMe 0 11 Fe2O3 DMEDA LiOtBu PhMe 0 12 Fe2O3 DMEDA Na2CO3 PhMe 0 13 Fe2O3 DMEDA NaOAc PhMe 0 14 Fe2O3 DMEDA KOH PhMe 0 15 Fe2O3 DMEDA K2CO3 (24 h) PhMe 37 16 Fe2O3 DMEDA K2CO3 (48 h) PhMe 87 17 Fe2O3 Phen K2CO3 PhMe Trace 18 Fe2O3 l-Proline K2CO3 PhMe 0 19 Fe2O3 Dpy K2CO3 PhMe 0 20 Fe2O3 DMEDA K2CO3 DMSO 0 21 Fe2O3 DMEDA K2CO3 DMF 0 22 Fe2O3 DMEDA K2CO3 PhMe2 0 23 — DMEDA K2CO3 PhMe 0 24 Fe2O3 DMEDA K2CO3 PhMe 86c 25 Fe2O3 DMEDA K2CO3 PhMe 58d