Arylboronic Acids In Water Research Articles

Elucidating the Synergistic Promotional Mechanism of Water and Oxygen in the Aerobic C-C Homocoupling Reaction Catalyzed by Visible-Light-Derived Core-Shell Pd@A-CQDs Nanostructures.

Rational design and precise synthesis of biogenic noble-metal-based catalysts possessing distinctive structure and composition play a crucial role in the chemical industry, enabling sustainable construction of an inclusive range of chemical resources. In this study, we have effectively fabricated Pd@A-CQDs through a straightforward one-pot aqueous protocol assisted by visible light employing renewable biomass-derived amine-rich carbon quantum dots (A-CQDs). The remarkable visible light harnessing capability (bandgap, ca. 2.81 eV), high density (35.7 × 1018 cm-3), and long lifetime (25 ps) of photocharge carriers and amine-rich surface in A-CQDs make them ideal candidates as both reducing and stabilizing agents, thereby facilitating the in situ construction of metallic Pd(0) nanoparticles. Comprehensive physicochemical characterizations have provided compelling evidence for the spherical morphology of Pd@A-CQDs core-shell nanostructures, with ultrathin A-CQDs shells of ca. 1.9 nm and an average diameter of 14 ± 1 nm. The effectiveness of the synthesized Pd@A-CQDs catalysts was assessed in the ligand- and base-free homocoupling reaction of arylboronic acids in water at ambient temperature. The catalytic tests demonstrated the selective production of the homocoupled compound over protodeboronation products with excellent yield and high catalyst recyclability under ambient conditions. The protocol employed exhibited a high TOF (1.05 × 10-2 mol g-1 min-1) and a low E-factor, with a remarkably low palladium loading. XPS analysis confirmed the retention of the metallic nature of the palladium core within the catalysts during the reaction. The catalytic function of the palladium core in conjunction with the A-CQDs shell, along with the promotional effects provided by water and oxygen for the formation of nucleophilic tetravalent boron, was conclusively recognized by 11B NMR and O2-TPD measurements. The obtained experimental results deliver valuable insights into the probable reaction pathway for the homocoupling reaction catalyzed by the Pd@A-CQDs catalysts. Through a comprehensive and sustainable evaluation, the current methodology exhibits superior performance compared to previously documented techniques in relation to estimated circularity and adherence to good manufacturing practices (GMP).

Pd nanoparticles supported in PDMAEMA-b-PLMA micelles: A superb catalytic platform for Suzuki-Miyaura cross-coupling in water

Pd nanoparticles (NPs) supported by micelles formed with poly(2-(dimethylamino)ethyl methacrylate)-b-poly(lauryl methacrylate) (Pd/PDMAEMA-b-PLMA) were prepared and employed as catalyst in the Suzuki-Miyaura cross-coupling reaction of aryl bromides with arylboronic acids in water. Most reactions proceeded with high efficiency at room temperature with only 0.05 mol% Pd loading in the absence of ligands, which afforded the desired functionalized biaryls in 73–98 % yields after 24 h. After reaction, Pd/PDMAEMA-b-PLMA retained in the aqueous phase was easily separated from the insoluble biaryl product and could be further reused two times without significant loss in catalytic efficiency. Characterization of the catalyst disclosed that sub-2 nm Pd NPs were embedded in the hydrophilic corona of polymeric micelles that served as nanoreactors in water.

Synthesis of a Water‐Soluble Pd‐Based Catalyst with a Thymine‐Modified β‐Cyclodextrin Ligand for Suzuki Coupling Reactions

AbstractHerein, the synthesis and crystal structure identification of thymine‐modified β‐cyclodextrin (mono‐(6‐Thymine‐6‐deoxy)‐β‐CD, Thy‐CD) are reported. The catalyst system (Pd@Thy‐CD) was prepared by using the thymine‐modified β‐cyclodextrin as ligand and palladium acetate (Pd(OAc)2) as palladium source. The as‐obtained Pd@Thy‐CD catalyst was characterized by NMR, IR, SEM, and XPS analysis. The catalyst can efficiently catalyze the aqueous phase Suzuki coupling reaction in situ. Under mild reaction conditions, the catalyst system provides excellent yields for the Suzuki coupling reaction of aryl halides, including with aryl chlorides and aryl boronic acids in water. The major advantages of this technique are the ease of preparation of the palladium catalyst, the aqueous phase coupling reaction, the broad functional group tolerance, and the easy recyclability.

Sulfonylation of aryl boronic acids by sulfonyl fluorides in water under visible-light irradiation

Sulfonyl fluoride was used as a stable and modifiable sulfonyl radical source under visible-light irradiation to react with diverse aryl boronic acids in water, affording various complex sulfones under mild and environmentally benign conditions.

A Green and Base‐Free Arylation of Thiomethylated 2‐pyranones and Ketene Dithioacetals via Liebeskind‐Srogl Coupling in Water

AbstractA green and base‐free desulfitative coupling of different thioethers with aryl boronic acids in water. Various thiomethylated 2H‐pyran‐2‐ones, 2‐oxobenzo[h[chromones and α‐aroyl ketene‐dithioacetals were used as substrate to obtained arylated product in very good to excellent yield. Further utility of reaction was carried out by a one‐pot arylation followed by amination of α‐aroyl ketene dithioacetals for the synthesis of 3‐amino chalcones and diarylazoles. The structure of isolated product 4 a and 6 c were ascertained by spectroscopic and single crystal X‐ray diffraction analyses.

Selective Palladium‐Catalyzed α,β‐Homodiarylation of Vinyl Esters in Aqueous Medium

AbstractA palladium‐catalyzed 1,2‐diarylation of vinyl esters with arylboronic acids in water has been developed. This newly elaborated protocol features a good functional group tolerance and provides one‐step access to 1,2‐diarylethanol derivatives under mild reaction conditions. The presented reaction can be carried out in the water at ambient temperature without the addition of any ligands, what makes this procedure environmentally benign. The transformation occurs within a single catalytic cycle and is feasible due to the modification of transition metal catalytic activity through the influence of π‐acceptor olefin (benzoquinone) as well as water as a medium. Moreover, this protocol allows to generate entire compound libraries (highly profitable in medicinal chemistry) and utilizes sustainable arylboronic acids as coupling partners under mild conditions. It is also noted that the structure of boron moiety has a great impact on the reaction selectivity, the usage of sterically hindered esters of arylboronic acids influence the reaction course towards stilbenes.

Investigation on the reactivity of nucleophilic radiohalogens with arylboronic acids in water: access to an efficient single-step method for the radioiodination and astatination of antibodies.

Easy access to radioiodinated and 211At-labelled bio(macro)molecules is essential to develop new strategies in nuclear imaging and targeted radionuclide therapy of cancers. Yet, the labelling of complex molecules with heavy radiohalogens is often poorly effective due to the multiple steps and intermediate purifications needed. Herein, we investigate the potential of arylboron chemistry as an alternative approach for the late stage labelling of antibodies. The reactivity of a model precursor, 4-chlorobenzeneboronic acid (1) with nucleophilic iodine-125 and astatine-211 was at first investigated in aqueous conditions. In the presence of a copper(ii) catalyst and 1,10-phenanthroline, quantitative radiochemical yields (RCYs) were achieved within 30 minutes at room temperature. The optimum conditions were then applied to a CD138 targeting monoclonal antibody (mAb) that has previously been validated for imaging and therapy in a preclinical model of multiple myeloma. RCYs remained high (>80% for 125I-labelling and >95% for 211At-labelling), and the whole procedure led to increased specific activities within less time in comparison with previously reported methods. Biodistribution study in mice indicated that targeting properties of the radiolabelled mAb were well preserved, leading to a high tumour uptake in a CD138 expressing tumour model. The possibility of divergent synthesis from a common modified carrier protein demonstrated herein opens facilitated perspectives in radiotheranostic applications with the radioiodine/211At pairs. Overall, the possibility to develop radiolabelling kits offered by this procedure should facilitate its translation to clinical applications.

Pd-Catalyzed Approach for Assembling 9-Arylacridines via a Cascade Tandem Reaction of 2-(Arylamino)benzonitrile with Arylboronic Acids in Water.

A novel palladium-catalyzed protocol for the synthesis of 9-arylacridines via tandem reaction of 2-(arylamino)benzonitrile with arylboronic acids in water has been developed with good functional group tolerance. The present synthetic route could be readily scaled up to gram quantity without difficulty. This methodology was further extended to the synthesis of a 4'-OH derivative, which showed estrogenic biological activity. Preliminary mechanistic experiments showed that this transformation involves a nucleophilic addition of aryl palladium species to the nitrile to generate an aryl ketone intermediate followed by an intramolecular Friedel-Crafts acylation and dehydration to acridines.

Glucopyranoside-substituted imidazolium-based chiral ionic liquids for Pd-catalyzed homo-coupling of arylboronic acids in water

Chiral ionic liquids (CILs) are widely used solvents and materials with prominent properties. Carbohydrate-derived imidazolium-based CILs represent a distinctive type of CILs possessing multiple chiral centers from natural chiral pool. Herein, a series of glucopyranoside-substituted imidazolium-based CILs (Glu-imi-CILs) were synthesized and evaluated as ligands for Pd-catalyzed homo-coupling reactions of arylboronic acids in water. The glucopyranoside substituent was instrumental for improving the catalytic activity of the resulting catalysts. Moreover, a Glu-imi-CIL with a free hydroxyl group for additional coordination was found to be the most efficient ligand. A series of symmetric biaryl compounds (13 examples) were synthesized from arylboronic acids by this method in high isolated yields (85−99%).

Visible-light-promoted aerobic oxidative hydroxylation of arylboronic acids in water by hydrophilic organic semiconductor

A green and sustainable catalytic system was developed based on perylenediimide (PDI) organic semiconductor for the aerobic oxidative hydroxylation of arylboronic acids in aqueous solution with visible light. By using PDI-SN, a hydrophilic organic semiconductor, which can activate oxygen to produce superoxide radicals in aqueous solution, this reaction proceeds under ambient conditions: water as the solvent and air as the oxidant, giving various phenols as products with high yields. In contrast to methods using organic solvents, this novel process has the potential of green industrial application.

Recyclable Cu@C3N4-Catalyzed Hydroxylation of Aryl Boronic Acids in Water under Visible Light: Synthesis of Phenols under Ambient Conditions and Room Temperature

A heterogeneous photocatalyst based on copper-doped g-C3N4 was developed for the oxidative hydroxylation of aryl boronic acids into phenols at room temperature under the irradiation of blue light (...

Green Synthesis of Aryl Thioethers through Cu-catalysed C-S Coupling of Thiols and Aryl Boronic Acids in Water

An efficient, practical, highly selective and environmentally benign method is reported for the synthesis of aryl thioethers via the coupling of thiols with aryl boronic acids in the presence of NaOH and a catalytic amount of CuSO4 at 130 °C using water as a green solvent. The products were obtained in moderate to excellent yields; more importantly, the use of toxic ligands and solvents was avoided. A broad range of aryl boronic acids and scalable processes make this methodology valuable and versatile for the synthesis of a broad range of aryl sulfides.

Chemically Modified Chitosan as a Biopolymer Support in Copper‐catalyzedipso‐Hydroxylation of Arylboronic Acids in Water

Figure S1. IR spectra of Chitosan (CTS), CTS-Py (L1), and CTS-Th (L2). Figure S2. TGA Thermograms of (a) L1 and (b) L2. Figure S3. SEM images of (a) L1 before use, (b) L1 after use, (c) L2 before use, and (d) L2 after use. Figure S4. IR spectra of L1 (before and after). Table S1. Optimization of reaction conditions. Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Visible‐Light‐Enhanced Suzuki–Miyaura Reactions of Aryl Chlorides in Water with Pd NPs Supported on a Conjugated Nanoporous Polycarbazole

The visible-light-enhanced catalytic activation of aryl chlorides for Suzuki-Miyaura cross-coupling (SMC) reactions is highly challenging because of the strength of the C-Cl bond. In this work, palladium nanoparticles (Pd NPs) were grown on a conjugated nanoporous polycarbazole (CNP), named Pd/CNP. The hybrid material Pd/CNP could catalyze the SMC reactions of aryl chlorides with arylboronic acids in water under blue LED irradiation at room temperature with high efficiency. This protocol exhibited good functional group tolerance and the catalyst could be recycled without significant loss of its catalytic activity. CNP not only provided photogenerated electrons to enrich the electron density of the Pd NPs but also generated holes for the activation of the arylboronic acids.

1,2,3-Triazolylidene palladium complex with triazole ligand: Synthesis, characterization and application in Suzuki–Miyaura coupling reaction in water

Palladium complex containing 1,2,3-triazolylidene and a labile triazole moiety has been prepared and characterized. Simple azide alkyne click reaction using three fold excess of dibromoethane afforded 1-(2-bromoethyl)-4-phenyl-1H-1,2,3-triazole. The latter on dehydrobromination yields N-vinyl triazole (Ntzl) which is subsequently used for preparing its triazolium salt. Further, Ntzl–Pd–Ntzl complex was prepared from triazole by simple palladation which underwent a ligand substitution reaction when treated with in situ generated triazolylidene to form Ctzl–Pd–Ntzl type complex. This mixed palladium complex was found to be highly effective in catalyzing Suzuki–Miyaura coupling reaction between aryl halides and aryl boronic acids in water at room temperature with very low catalyst loading.

Copper-catalyzed cross-coupling of chloramine salts and arylboronic acids in water: A green and practical route to N-arylsulfonamides

A green and practical method for the synthesis of N-arylsulfonamides from chloramine salts and arylboronic acids is herein developed. The reaction proceeds readily in the presence of 5 mol% of CuI and 2.5 equiv. K2CO3 in water at room temperature, generating a variety of N-arylsulfonamides in moderate to good yields with good functional group tolerance.

Picolinamide modified β-cyclodextrin/Pd (II) complex: Asupramolecular catalyst for Suzuki-Miyaura coupling of aryl, benzyl and allyl halides with arylboronic acids in water

Novel supramolecular catalysts for Suzuki-Miyaura coupling were prepared and characterized by NMR, FT-IR, TEM, XRD, TGA, and XPS. The resulting picolinamide-modified β-cyclodextrin/Pd(II) complex (Pd(II)@PCA-β-CD) showed very efficient catalytic activity for Suzuki-Miyaura coupling of aryl, benzyl, and allyl halides with arylboronic acids in an environmentally benign aqueous solution. Various organic halides including chlorides can produce good to excellent yields with phenyl-boronic acid and a catalytic amount of Pd(II)@PCA-β-CD. This hydro-soluble catalyst was capable of being reused for at least eight runs with only a slight loss of catalytic activity. A putative mechanism of the Pd(II)/Pd(IV) catalytic cycle was also explored and calculated by ab initio QM/MM methods.

PEPPSI-type complexes with small NHC ligands obtained according to the new method efficiently catalyzed Suzuki-Miyaura reaction

A series of 13 new PEPPSI-type complexes with small NHC ligands and differently substituted imidazoles were prepared using as substrates [Pd(μ-X)X(bmim-y)]2 dimer or imidazole complexes PdCl2(imidazole)2. Improvement of the synthetic method allowed simplification of the purification step. The obtained complexes efficiently catalyzed the Suzuki-Miyaura cross-coupling of substituted bromobenzenes and arylboronic acids in water and in iPrOH/water mixture. The observed catalytic activity was significantly better than that of Pd(OAc)2 and similar to that of Pd(IPr)Cl2(3-Cl-py) in the same conditions. TEM analysis of the post-reaction mixture evidenced formation of Pd NPs of diameter ca. 3 nm, participating in the catalytic process.

Palladium‐Catalyzed Direct β‐C−H Arylation of Ketones with Arylboronic Acids in Water

AbstractA palladium‐catalyzed direct β‐C−H arylation of ketones was developed under mild conditions in water, featuring commercially available arylboronic acids as nucleophilic aryl sources and o‐iodoxybenzoic acid as the oxidant. The method provides a concise route to access β‐arylated ketones. Preliminary studies indicated that direct asymmetric β‐C−H arylation of ketones could be achieved by this strategy.magnified image

Inside Cover: Arylation of N‐Methyl‐2‐oxindole with Arylboronic Acids in Water Catalyzed by Palladium(II) Pincer Complexes with a Low Catalyst Loading (ChemCatChem 6/2017)

Inside Cover: Arylation of <i>N</i>‐Methyl‐2‐oxindole with Arylboronic Acids in Water Catalyzed by Palladium(II) Pincer Complexes with a Low Catalyst Loading (ChemCatChem 6/2017)