Cross-coupling Reactions In Water Research Articles

Stabilized Palladium Nanoparticles from Bis-(N-benzoylthiourea) Derived-PdII Complexes as Efficient Catalysts for Sustainable Cross-Coupling Reactions in Water.

Stable palladium (II) complexes, incorporating a double (N-benzoylthiourea) arrangement bonded to a complex heterocyclic scaffold, are used as precursors of catalytic species able to promote Suzuki-Miyaura, Mizoroki-Heck, Hiyama, Buchwald-Hartwig, Hirao and Sonogashira-Hagihara cross-coupling transformations in water. These sustainable processes are chemoselective and very versatile. The nanoparticles responsible for these catalytic reactions were analyzed and studied. Their usefulness is demonstrated after several tests and analyses. The heterogeneous character of this species in water was also confirmed.

Synthesis of naphthalimide-type chemsensor and its application in quality evaluation for polygonatum sibiricum Red.

The premise and key of ensuring the safety and effectiveness of traditional Chinese medicine (TCM) is to construct appropriate quality evaluation system of TCM. This study aimed to establish a pre-column derivatization HPLC method for achieving the quality control of Polygonatum sibiricum by reacting synthesized 4-hydrazino-1,8-naphthalimide (HAN) with diverse monosaccharides from the hydrolytic product of P. sibiricum polysaccharides (PSPs), followed by HPLC separation. The HAN was synthesized based on a CuI-catalyzed cross-coupling reaction in water, and then employed as a novel chemosensor that reacts with reducing sugars. Good separation was achieved at a detection wavelength of 448 nm using an ZORBAX SB-C8 column under a gradient elution at a flow rate of 0.5 ml/min within 12 min. The monosaccharide compositions of PSP mainly include two hexoses [glucose (Glc), galactose (Gal)] and two hexuronic acids [glucuronic acid (GlcA) and galacturonic acid (GalA)], and the molar ratio of Glc, Gal, GlcA and GalA is 16.67:52.94:10.58:19.81. The verified HPLC method, possessing excellent precision and good accuracy, successfully achieved rapid qualitative and quantitative determination for PSP. Additionally, the HAN displayed fluorescence enhancement through “push–pull” mode, and fluorescence decreased through “pull–pull” mode after binding to monosaccharides, which is a potential for fluorescence determination of different monosaccharides.

Pyrene Functionalized Highly Reduced Graphene Oxide-palladium Nanocomposite: A Novel Catalyst for the Mizoroki-Heck Reaction in Water.

The formation of a C-C bond through Mizoroki-Heck cross-coupling reactions in water with efficient heterogeneous catalysts is a challenging task. In this current study, a highly reduced graphene oxide (HRG) immobilized palladium (Pd) nanoparticle based catalyst (HRG-Py-Pd) is used to catalyze Mizoroki-Heck cross-coupling reactions in water. During the preparation of the catalyst, amino pyrene is used as a smart functionalizing ligand, which offered chemically specific binding sites for the effective and homogeneous nucleation of Pd NPs on the surface of HRG, which significantly enhanced the physical stability and dispersibility of the resulting catalyst in an aqueous medium. Microscopic analysis of the catalyst revealed a uniform distribution of ultrafine Pd NPs on a solid support. The catalytic properties of HRG-Py-Pd are tested towards the Mizoroki-Heck cross-coupling reactions of various aryl halides with acrylic acid in an aqueous medium. Furthermore, the catalytic efficacy of HRG-Py-Pd is also compared with its non-functionalized counterparts such as HRG-Pd and pristine Pd NPs (Pd-NPs). Using the HRG-Py-Pd nanocatalyst, the highest conversion of 99% is achieved in the coupling reaction of 4-bromoanisol and acrylic acid in an aqueous solution in a relatively short period of time (3 h), with less quantity of catalyst (3 mg). Comparatively, pristine Pd NPs delivered lower conversion (∼92%) for the same reaction required a long reaction time and a large amount of catalyst (5.3 mg). Indeed, the conversion of the reaction further decreased to just 40% when 3 mg of Pd-NPs was used which was sufficient to produce 99% conversion in the case of HRG-Py-Pd. On the other hand, HRG-Pd did not deliver any conversion and was ineffective even after using a high amount of catalyst and a longer reaction time. The inability of the HRG-Pd to promote coupling reactions can be attributed to the agglomeration of Pd NPs which reduced the dispersion quality of the catalyst in water. Therefore, the high aqueous stability of HRG-Py-Pd due to smart functionalization can be utilized to perform other organic transformations in water which was otherwise not possible.

Minimalistic β-sitosterol based designer surfactants for efficient cross-coupling in water

In this contribution, we report about the synthesis, the aggregation properties and their application in cross-coupling catalysis of two new designer surfactants comprising a rigid hydrophobic portion based on β-sitosterol directly linked by an etheric bond to methyl polyoxoethylene chains. The proposed amphiphilic compounds represent a minimalistic approach with respect to the Lipshutz's third generation designer surfactant Nok. The amphiphiles displayed improved chemical stability, shorter synthesis, and good properties in Pd-catalyzed cross-coupling reactions in water under mild conditions, as compared with other neutral commercially available surfactants.

Facile synthesis of Fe3O4@GlcA@Ni-MOF composites as environmentally green catalyst in organic reactions

The design and use of green catalysts and catalytic systems to achieve the dual goals of environmental protection and economic benefits is an important task, and is necessary for the sustainability of the chemical industry. In this study, we reported a facile synthesis and characterization of a novel type of MOF-based porous catalyst, namely, Fe 3 O 4 @GlcA@Ni-MOF nanocomposite. Catalytic activity of Fe 3 O 4 @GlcA@Ni-MOF nanocomposite considered in the C–C cross-coupling reaction in water as green solvent. In addition, the scope of the prepared Fe 3 O 4 @GlcA@Ni-MOF studied in the synthesis of symmetric diaryl sulfides using 2-thioxo-4-thiazolidinone (Rhodanine) as a green sulfur source. • Fe 3 O 4 @GlcA@Ni-MOF was synthesized by the encapsulation of Fe 3 O 4 @GlcA nanoparticles into Ni-MOF. • These Superparamagnetic nanocomposites offers novel properties such as large surface area, and thermal stability. • Rhodanin was used as a novel sulfur transfer agent. • The structure of obtained nanoparticles characterized by FT-IR, FE-SEM, TEM, XRD, EDS, VSM, TGA, and BET.

Magnetic silica surface functionalized palladium catalyst: A modular approach for C-C cross-coupling reactions in water

A novel Pd immobilized catalyst has been prepared via surface modification of magnetic silica and characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), UV–Vis spectroscopy, X-ray diffractometer (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and transmission electron microscopy (TEM) and inductively coupled plasma-optical emission spectrometry (ICP-OES) analysis. The prepared composite material found to be highly efficient and recyclable heterogeneous catalyst for the Suzuki coupling reaction in aqueous medium with high turnover number (TON) of 1138 and turnover frequency (TOF) of 2276 h−1. The Pd content of the catalyst was 0.09 mol% and afforded excellent to good yield of biaryls from a wide variety of aryl halides, including electron- withdrawing and releasing groups. The catalyst was reused up to six cycles with 97% efficiency for the Suzuki coupling reaction.

Mizoroki-Heck carbon-carbon cross-coupling reactions by water-soluble palladium (II) complexes in neat water

Water-soluble palladium complexes were synthesized, characterized, tested as (pre)catalyst for Mizoroki-Heck carbon-carbon cross-coupling reactions in water. Cross-coupling of aryl iodides and bromides with methyl and ethyl acrylates was achieved at 140 °C. When styrene was employed as the substrate excellent conversion to trans-stilbene was observed using 5 mol% catalyst loading in the presence of TBAB. The catalysts are versatile and can couple various substrates in a non-toxic and benign solvent. After extraction of the organic product the catalyst containing aqueous layer could be recycled twice with a significant drop in the aryl halide conversion after the third recycle. No catalyst poisoning was observed in the mercury poisoning experiments with both catalysts and this proves that both catalytic systems function as molecular homogeneous catalysts.

Copper nanoparticles loaded polymer vesicles as environmentally amicable nanoreactors: A sustainable approach for cascading synthesis of benzimidazole

This paper reports the synthesis and characterization of Cu nanoparticle loaded, surfactant free metallovesicles (CuNPs@vesicles) as nanoreactors to produce benzimidazoles via cascade reaction. The vesicles exhibited uniform size distribution, spherical morphology, excellent stability and efficient Cu loading. This strategy is unique for the fact that, environmental contaminants like nitroaniline have been utilized as precursor and converted into fine chemicals of commercial significance via non-toxic intermediates. CuNPs@vesicles reduces 2-nitroaniline to o-phenylenediamine which further acts as precursor for benzimidazole synthesis. Thus the reaction occurs via two step cascade pathway comprising reduction and CN cross coupling reactions in water. The preliminary studies suggest encouraging results for performing dehydrogenative coupling under relatively mild conditions using CuNPs@vesicles as a catalyst. All the products are obtained in good to excellent yield with facile catalyst regeneration and recyclability upto 5 cascading cycles.

A new PEPPSI type N-heterocyclic carbene palladium(II) complexes and its efficiency as a catalyst for Mizoroki-Heck cross-coupling reactions in water : Synthesis, Characterization and their antimicrobial and Cytotoxic activities

A series of novel benzimidazolium salts 2 and their new air and moisture stable PEPPSI type N-heterocyclic carbene palladium(II) complexes (PEPPSI: pyridine-enhanced pre-catalyst preparation, stabilisation, and initiation), were synthesized and characterized by means of 1H and 13C{1H} NMR, FTIR spectroscopic methods and elemental analysis was employed to catalyze the Mizoroki-Heck cross-coupling reactions of aryl bromides with styrene in water. To the best of our knowledge, this is the first report where a Pd-PEPPSI catalyst was successfully employed in aqueous-phase Mizoroki-Heck reaction. Good to excellent yields of cross-coupling products were obtained with a range of representative aryl bromides under relatively mild conditions. Moreever the antimicrobial activity of the PEPPSI type N-heterocyclic carbene palladium(II) complexes 3a-e varies with the nature of the ligands. Also, the IC50 values of both, complexes (3a-e) have been determined. In addition, the new PEPPSI type N-heterocyclic carbene palladium(II) complexes were screened for their cytotoxic activities. Complex 3b exhibited the highest antitumor effect with IC50 values 0.63 μg/mL and against MCF-7.

Introduction of a Recyclable Basic Ionic Solvent with Bis-(NHC) Ligand Property and The Possibility of Immobilization on Magnetite for Ligand- and Base-Free Pd-Catalyzed Heck, Suzuki and Sonogashira Cross-Coupling Reactions in Water

A new versatile and recyclable NHC ligand precursor has been developed with ligand, base, and solvent functionalities for the efficient Pd-catalyzed Heck, Suzuki and Sonogashira cross-coupling reactions under mild conditions. Furthermore, NHC ligand precursor was immobilized on magnetite and its catalytic activity was also evaluated towards the coupling reactions as a heterogeneous catalyst. The NHC ligand precursor was prepared with imidazolium functionalization of TCT followed by a simple ion exchange by hydroxide ions. However, the results revealed an excellent catalytic activity for the both homogeneous and heterogeneous catalytic systems. 1.52 g.cm−3 and 1194 cP was obtained for the density and viscosity of the NHC ligand precursor respectively. On the other hand, the heterogeneous type could be readily recovered from the reaction mixture and reused for several times while preserving its properties. Heterogeneous nature of the magnetic catalyst was studied by hot filtration, mercury poisoning, and three-phase tests. High to excellent yields were obtained for all entries for the both homogeneous and heterogeneous catalysts, which reflects the high consistency of the catalyst.

Environmentally benign approach towards C-S cross-coupling reaction by organo-copper(II) complex.

C-S cross-coupling reaction in water giving an excellent yield of the desired C-S coupled product by using a newly developed Bis[2-(4,5-diphenyl-1H-imidazol-2-yl)-4-nitrophenolato] copper(II) dehydrate complex as catalyst. Although it was the first report of the synthesis of such a novel organo-copper complex from our laboratory, its potential catalytic application was not tested so far. Keeping this in mind and based on our anticipation, we developed a greener route for the C-S coupling reaction. The result is very interesting and comprises the subject matter of this report.

Structural features influencing the activity of bis-biguanide ligands in the Suzuki–Miyaura cross-coupling reaction in neat water

Catalytic reactions play an integral role in the development of green chemistry. Herein, we report new bis-biguanide compounds containing alkyl and aryl spacers as ligands for the Suzuki–Miyaura cross-coupling reaction in water. These ligands show similar catalytic activity to metformin independently of the nature of the spacer between the two biguanide units.

Immobilized Pd on Eggshell Membrane: A powerful and recyclable catalyst for Suzuki and Heck cross-coupling reactions in water

A stable heterogeneous palladium catalysts, the waste eggshell membrane (ESM) anchored Pd complex, was synthesized by a simple and green technique. The catalyst obtained can display an outstanding catalytic activity for Suzuki and Heck coupling reactions in water media. The reactions of various aryl halides with aryl boronic acids and terminal alkenes provided the corresponding products in moderate to excellent yields. More importantly, this novel and efficient catalyst with high stability can be easily reused for at least twelve times with no decrease of the catalytic activity, performing an endurable and wide tolerance of the substrates. Facile synthesis, high catalytic activity, and recyclability make these catalysts interesting for further studies.

Synthesis of glucoside-based imidazolium salts for Pd-catalyzed cross-coupling reaction in water

Sugar-based imidazolium salts (IMSs) represent an outstanding type of material making them eye-catching for a wide variety of applications. Herein, a series of glucoside-based IMSs (Glu-IMSs) combining glucoside and imidazolium head groups with different substituents were synthesized. The catalytic activities of these Glu-IMSs were evaluated by Pd-catalyzed Heck–Mizoroki and Suzuki–Miyaura reactions in water. Among them, the Glu-IMSs contain both –OH and NHCs coordination sites was found to be the most efficient ancillary ligand in comparison with other Glu-IMSs with just single NHCs coordination site. The HR-TEM analysis showed that the palladium nanoparticles stabilized by the Glu-IMSs with an average size of ~4.0 nm was formed in the reaction system, which may be act as an efficient real catalytic species. Under the optimized reaction conditions, a series of novel fluorine-cored organic small molecule functional materials were synthesized with favorable yields.

Evaluation of Nitrogen-Based Polymeric Heterogeneous Catalysts for the Suzuki–Miyaura Cross-Coupling Reaction in Water

As environmental issues continuously increase, the development of effective and eco-friendly catalytic systems in organic chemistry is of great importance. To achieve this goal, two representative ...

Bio-surfactant: a green and environmentally benign reaction medium for ligand-free Pd-catalyzed Mizoroki–Heck cross-coupling reaction in water

A simple and efficient protocol for the ligand-free Mizoroki–Heck coupling reaction of various aryl bromides with different olefins has been reported by using in situ generated PdNPs of size 5–10 nm in aqueous solution of bio-surfactant. The bio-surfactant used in this study is a saponin extract of the seeds of pericarps (pods) of the Acacia concinna plant. The in situ generated PdNPs have been characterized by various techniques such as HRTEM, EDS and XPS. The influence of various parameters such as the nature and amount of bases, the nature of Pd precatalysts as well as the effect of temperature has been investigated on Mizoroki–Heck coupling reaction. The generated PdNPs significantly coupled the various aryl bromides with different olefins in aqueous extract of the seeds of pericarps (pods) of the Acacia concinna plant at 100 °C.

A Self-Assembling NHC-Pd-Loaded Calixarene as a Potent Catalyst for the Suzuki-Miyaura Cross-Coupling Reaction in Water.

Nanoformulated calix[8]arenes functionalized with N-heterocyclic carbene (NHC)-palladium complexes were found to be efficient nano-reactors for Suzuki-Miyaura cross-coupling reactions of water soluble iodo- and bromoaryl compounds with cyclic triol arylborates at low temperature in water without any organic co-solvent. Combined with an improved one-step synthesis of triol arylborates from boronic acid, this remarkably efficient new tool provided a variety of 4′-arylated phenylalanines and tyrosines in good yields at low catalyst loading with a wide functional group tolerance.

A new PEPPSI type N-heterocyclic carbene palladium(II) complex and its efficiency as a catalyst for Mizoroki-Heck cross-coupling reactions in water

A new air and moisture stable PEPPSI (PEPPSI: pyridine-enhanced pre-catalyst preparation, stabilisation, and initiation) themed palladium N-heterocyclic carbene (NHC) complex [Pd(L)Br2(Py)] (1) [L: 2-flurobenzyl)-1-(4-methoxyphenyl)-1H-imidazolline-2-ylidene] was synthesized and characterized. The structure of complex 1 was determined by X-ray single-crystal analysis. The palladium center in 1 adopted a square planar geometry with carbene and pyridine ligands occupying the mutual trans position. The complex 1 was employed to catalyze the Mizoroki-Heck cross-coupling reactions of aryl bromides/iodides with styrene in water. To the best of our knowledge, this is the first report where a Pd-PEPPSI catalyst was successfully employed in aqueous-phase Mizoroki-Heck reaction. Good to excellent yields of cross-coupling products were obtained with a range of representative aryl bromides/iodides under relatively mild conditions (100 °C, 1 mol% of 1). A new palladium PEPPSI complex was synthesized, characterized and evaluated as catalyst for the Mizoroki-Heck reaction in aqueous medium. Both electron-donating and electron-withdrawing aryl halides (bromides and iodides) reacted with styrene to give corresponding coupling products in moderate to excellent yields.

A hydrophilic heterogeneous cobalt catalyst for fluoride-free Hiyama, Suzuki, Heck and Hirao cross-coupling reactions in water

A hydrophilic chitosan-cobalt-Schiff base catalyst denoted as mTEG-CS-Co-Schiff-base was prepared for C–C and C–P cross coupling reactions in water.

A Co-Cu bimetallic magnetic nanocatalyst with synergistic and bifunctional performance for the base-free Suzuki, Sonogashira, and C-N cross-coupling reactions in water.

A novel magnetically recyclable bimetallic catalyst was prepared by anchoring imidazolium moiety and PEG chains on Fe3O4 NPs and named as Fe3O4@PEG/Cu-Co. It was found to be a powerful catalyst for the Sonogashira, Suzuki, and C-N cross-coupling reactions in water as a green solvent without the need for any external base. Fe3O4@PEG/Cu-Co was well characterized with FT-IR, FE-SEM, TEM, VSM, EDX, ICP, UV-visible, CV, and XPS analyses. Optimum ranges of parameters such as time, temperature, and amount of catalyst were investigated by Design-Expert 10.0.7 software for C-C Suzuki, Sonogashira, and C-N cross-coupling reactions to find the optimum conditions. The catalyst was compatible with a variety of aryl halides and N-arenes and gave favorable coupling products with good to high yields for all of them. Hot filtration and Hg poisoning tests involving the nanocatalyst revealed the stability, low metal leaching, and heterogeneous nature of the catalyst. Reaction mechanisms were proposed by study of the UV-visible spectra in situ as well as hydroquinone tests during the progress of reactions. In situ XPS analysis was also used to study the reaction mechanism. To prove the synergistic performance of Co and Cu in the catalyst, its various homologues were synthesized and applied to a model reaction separately, and then their catalytic activities were investigated. Finally, the catalyst could be recovered from the reaction mixture simply, and reused for several cycles with a minimum loss in catalytic activity and performance.