Search

An extremely efficient green protocol for palladium acetate-catalysed ligand-free Suzuki–Miyaura cross-coupling reactions of aryl/heteroaryl bromides with aryl/substitute aryl boronic acids in neat 'Water Extract of Leaf Ash of Neem' (WELAN)' was developed. This method offers a simple, mild, efficient and highly cost-effective alternative to the existing protocols since the reaction proceeds in natural feedstock WELAN at room temperature in air at very short reaction times (5–60 min) under ligand/external base/promoter/organic medium free conditions. Here WELAN has been found to be the effective base and reaction medium for this cross-coupling reaction with high turnover number (TON). This manuscript also theoretically depicts the probable mechanism of WELAN catalysed cross-coupling reaction. [ABSTRACT FROM AUTHOR]

This work reports the synthesis and characterization of Nanosized-Ni doped montmorillonite heterocatalyst and its application for Suzuki Miyaura cross coupling of aryl iodides with aryl boronic acids. The catalyst is highly selective and did not give any other byproducts. The reaction was complete within 24 h with > 98% yield. Nickel was uniformly dispersed on the catalyst with approximately 4.0 ± 2 nm clusters of Ni. The solvent, base, catalyst loading, and catalyst precursors were varied to obtain optimum reaction conditions for highest yield. The catalyst was recovered and reused for reactions demonstrating excellent recyclability with high yield. Ni doped montmorillonite catalyst is very effective for Suzuki Miyaura cross coupling reactions and can be used to replace expensive Pd-based catalysts with earth abundant and inexpensive Ni-based catalysts. [ABSTRACT FROM AUTHOR]

This document contains abstracts from the 21st European Symposium on Radiopharmacy and Radiopharmaceuticals. The abstracts cover a range of topics related to the development and evaluation of radiopharmaceuticals for various applications, including cancer imaging and therapy. The studies demonstrate promising results and potential for improving diagnosis and treatment in different types of cancer. The research is supported by grants and funding sources, indicating the importance and interest in this field of study. [Extracted from the article]

To prepare very-long-chain fatty acids and alkenes (VLCFAs and VLC alkenes) that are known pollinator attractants for sexually deceptive orchids, and biosynthetic precursors thereof, we applied a methodology allowing us to prepare monounsaturated VLCFAs with chain lengths up to 28 carbons and VLC alkenes up to 31 carbons. We implemented a coupling reaction between commercially available terminal alkynes and bromoalkanoic acids to prepare VLCFAs, allowing the products to be formed in two steps. For VLC alkenes, with many alkyltriphenylphosphonium bromides commercially available, we applied a Wittig reaction approach to prepare (Z)-configured monoenes in a single step. Using practical methods not requiring special reagents or equipment, we obtained 11 VLCFAs in > 90% isomeric purity, and 17 VLC alkenes in > 97% isomeric purity. Such general and accessible synthetic methods are essential for chemical ecology and biochemistry research to aid researchers in unambiguously identifying isolated semiochemicals and their precursors. [ABSTRACT FROM AUTHOR]

A highly sensitive dual-recognition fluorescence amplification method is presented for lipopolysaccharide (LPS) detection based on boronic functionalized aptamer macroarrays with dual-recognition and isothermal amplification. The surface of the polystyrene microplate was firstly carboxylated, and then, 3-aminophenylboronic acid was conjugated to the carboxyl groups through EDC/NHS reaction, creating boronic acid groups as the capture moiety for LPS. A recognition DNA aptamer labeled with the fluorescent dye 6-FAM, which exhibits specificity towards LPS, was selected as the signal reporting moiety. By introducing primers and Klenow enzyme, the fluorescent-labeled aptamers are released from the microplate bottom, and double-stranded structures were formed via isothermal amplification. The addition of SYBR Green I, which strongly fluoresces upon binding to the double-stranded structures, enables signal amplification and detection. This detection method exhibits a linear range of 1–10,000 ng/mL and has a detection limit as low as 401.93 pg/mL. This analytical approach shows high selectivity and sensitivity and may serve as a universal platform in lipopolysaccharide detection. [ABSTRACT FROM AUTHOR]

Transferrin (TRF), recognized as a glycoprotein clinical biomarker and therapeutic target, has its concentration applicable for disease diagnosis and treatment monitoring. Consequently, this study developed boronic acid affinity magnetic surface molecularly imprinted polymers (B-MMIPs) with pH-responsitivity as the "capture probe" for TRF, which have high affinity similar to antibodies, with a dissociation constant of (3.82 ± 0.24) × 10−8 M, showing 7 times of reusability. The self-copolymerized imprinted layer synthesized with dopamine (DA) and 3-Aminophenylboronic acid (APBA) as double monomers avoided nonspecific binding sites and produced excellent adsorption properties. Taking the gold nanostar (AuNS) with a branch tip "hot spot" structure as the core, the silver-coated AuNS functionalized with the biorecognition element 4-mercaptophenylboronic acid (MPBA) was employed as a surface-enhanced Raman scattering (SERS) nanotag (AuNS@Ag-MPBA) to label TRF, thereby constructing a double boronic acid affinity "sandwich" SERS biosensor (B-MMIPs-TRF-SERS nanotag) for the highly sensitive detection of TRF. The SERS biosensor exhibited a detection limit for TRF of 0.004 ng/mL, and its application to spiked serum samples confirmed its reliability and feasibility, demonstrating significant potential for clinical TRF detection. Moreover, the SERS biosensor designed in this study offers advantages in stability, detection speed (40 min), and cost efficiency. The portable Raman instrument for SERS detection fulfills the requirements for point-of-care testing. [ABSTRACT FROM AUTHOR]

A variety of 3-hydroxy-isoindolin-1-one derivatives were synthesized using the photodecarboxylative addition of carboxylates to phthalimide derivatives in aqueous media. Subsequent acid-catalyzed dehydration furnished 3-(alkyl and aryl)methyleneisoindolin-1-ones with variable E-diastereoselectivity in good to excellent overall yields. Noteworthy, the parent 3-phenylmethyleneisoindolin-1-one underwent isomerization and oxidative decomposition when exposed to light and air. Selected 3-hydroxy-isoindolin-1-one and 3-(alkyl and aryl)methyleneisoindolin-1-one derivatives showed moderate antibacterial activity that justifies future elaboration and study of these important bioactive scaffolds. [ABSTRACT FROM AUTHOR]

This study investigates quercetin complexes as potential synergistic agents against the important respiratory pathogen Streptococcus pneumoniae. Six quercetin complexes (QCX1–6) were synthesized by reacting quercetin with various metal salts and boronic acids and characterized using FTIR spectroscopy. Their antibacterial activity alone and in synergism with antibiotics was evaluated against S. pneumoniae ATCC 49619 using disc diffusion screening, broth microdilution MIC determination, and checkerboard assays. Complexes QCX-3 and QCX-4 demonstrated synergy when combined with levofloxacin via fractional inhibitory concentration indices ≤ 0.5 as confirmed by time-kill kinetics. Molecular docking elucidated interactions of these combinations with virulence enzymes sortase A and sialidase. A biofilm inhibition assay found the synergistic combinations more potently reduced biofilm formation versus monotherapy. Additionally, gene–gene interaction networks, biological activity predictions and in-silico toxicity profiling provided insights into potential mechanisms of action and safety. [ABSTRACT FROM AUTHOR]

A new method has been proposed for the green and efficient synthesis of xanthenediones and their corresponding open-chain analogs aryl-methylene bis(3-hydroxy-5,5'-dimethyl-2-cyclohexene-1-ones) using natural acid, Lemon juice, as the catalyst. This method involves the use of lemon juice as a surfactant-type bronsted acid, which makes it non-polluting and produces a high-purity product with excellent yield. Additionally, the work-up procedure is clean and straightforward. Dimedone and aldehydes are the starting materials for this process. [ABSTRACT FROM AUTHOR]

For early diabetes identification and management, the progression of an uncomplicated and exceedingly responsive glucose testing technology is crucial. In this study, we present a new sensor incorporating a composite of metal organic framework (MOF) based on cobalt, coated with boronic acid to facilitate selective glucose binding. Additionally, we successfully employed a highly sensitive electro-optical immunosensor for the detection of subtle changes in concentration of the diabetes biomarker glycated haemoglobin (HbA1c), using zeolitic imidazolate framework-67 (ZIF-67) coated with polydopamine which further modified with boronic acid. Utilizing the polymerization characteristics of dopamine and the NH2 groups, a bonding structure is formed between ZIF-67 and 4-carboxyphenylboronic acid. ZIF-67 composite served as an effective substrate for immobilising 4-carboxyphenylboronic acid binding agent, ensuring precise and highly selective glucose identification. The sensing response was evaluated through both electrochemical and optical methods, confirming its efficacy. Under optimized experimental condition, the ZIF-67 based sensor demonstrated a broad detection range of 50–500 mg dL−1, a low limit of detection (LOD) of 9.87 mg dL−1 and a high correlation coefficient of 0.98. Furthermore, the 4-carboxyphenylboronic acid-conjugated ZIF-67-based sensor platform exhibited remarkable sensitivity and selectivity in optical-based detection for glycated haemoglobin within the clinical range of 4.7–11.3%, achieving a LOD of 3.7%. These findings highlight the potential of the 4-carboxyphenylboronic acid-conjugated ZIF-67-based electro-optical sensor as a highly sensitive platform for diabetes detection. [ABSTRACT FROM AUTHOR]

The development of facile, sensitive, and robust methods for the detection of metal ions is fascinating for chemists because traditional strategies for their detection usually involve complicated instrumentation and critical sample preparation procedures. In this work, bicinchoninic acid was used in a specific reaction with Cu(I) for the spectrophotometric determination of various metal ions. The optimization of experimental parameters led to the establishment of a simple, fast, and accurate analytical method. Mn(II), Co(II), and Fe(II) can be detected at submicromolar levels using this method. Calibration graphs for Mn(II), Co(II), and Fe(II) are rectilinear within the range of 8–40, 15–150, and 15–150 μM, respectively. The detection limit for Mn(II), Co(II), and Fe(II) were 0.83, 1.4, and 1.9 mg/L, respectively, and the relative standard deviation did not exceed 2.5% for five replicates. The bathocuproine reaction demonstrated that Cu(II) can be reduced to Cu(I) by Mn(II). Then bicinchoninic acid can bind to Cu(I), creating a purple-colored product at 562 nm. The method has been successfully applied to evaluate the reaction process and stability of metal-organic frameworks. Moreover, the results were found to be in satisfactory agreement with those acquired by using the inductively coupled plasma mass spectrometry technique, which will open up a new avenue for using the proposed strategy as a conventional method to detect metal ions in scientific research. [ABSTRACT FROM AUTHOR]

A comparative analysis of molecularly imprinted polymers based on different synthesis techniques was performed for the recognition of molnupiravir (MOL). The polymerizations were performed with 3-thienyl boronic acid (3-TBA) as a functional monomer by electropolymerization (EP) and with guanine methacrylate (GuaM) as a functional monomer by photopolymerization (PP). Morphological and electrochemical characterizations of the developed sensors were investigated to verify the constructed sensors. Moreover, quantum chemical calculations were used to evaluate changes on the electrode surface at the molecular and electronic levels. The dynamic linear range of both designed sensors under optimized experimental conditions was found to be 7.5 × 10−12–2.5 × 10−10 M and 7.5 × 10−13–2.5 × 10−11 M for EP and PP, respectively. The effect of various interfering agents on MOL peak current was assessed for the selectivity of the study. In the presence of 100 times more interfering agents, the RSD and recovery values were determined. The RSD values of GuaM/MOL@MIP/GCE and poly(Py-co-3-PBA)/MOL@MIP/GCE sensors were found to be 1.99% and 1.72%, respectively. Furthermore, the recovery values of the MIP-based sensors were 98.18–102.69% and 98.05–103.72%, respectively. In addition, the relative selectivity coefficient (k′) of the proposed sensor was evaluated, and it exhibited good selectivity for MOL with respect to the NIP sensor. The prepared sensor was successfully applied to determine MOL in commercial serum samples and capsule form. In conclusion, the developed sensors provided excellent reproducibility, repeatability, high sensitivity, and selectivity against the MOL molecule. [ABSTRACT FROM AUTHOR]

Molecules containing sulfonamide groups possess significant bioactivity in medicinal and pharmaceutical chemistry, showcasing valuable anti-bacterial and anti-parasitic properties. In recent years, the immobilization of metallic catalysts, including copper, palladium, nickel, and zinc, onto the surface of Fe3O4 nanoparticles modified with ligands, has emerged as an effective and captivating catalytic strategy for enhancing chemical reactions. In this study, we successfully fabricated a novel and highly efficient magnetically recoverable nanocatalyst [Fe3O4@Dopamine-PO-CuBr2] by immobilizing CuBr2 on magnetic Fe3O4 nanoparticles coated with dopamine. This nanocatalyst was utilized for the synthesis of N-aryl sulfonamides via a convenient one-pot three-component reaction involving aryl boronic acids, aryl amines, and DABSO as the SO2 source. The spectroscopic techniques employed thoroughly validated the successful preparation of the [Fe3O4@Dopamine-PO-CuBr2] nanocomposite.Notably, our research adds significant scientific value by presenting a well-designed nanocatalyst that efficiently promotes the synthesis of N-aryl sulfonamides. The ease of recovery and reusability of the [Fe3O4@Dopamine-PO-CuBr2] nanocatalyst, which maintained its catalytic efficiency for up to 8 cycles without any substantial loss, further emphasizes its practicality and sustainability.This study introduces a promising and eco-friendly approach to produce bioactive N-aryl sulfonamides using a magnetically recoverable nanocatalyst. The reported findings hold great potential in the field of medicinal and pharmaceutical chemistry, demonstrating a significant step forward in the development of innovative catalytic strategies. [ABSTRACT FROM AUTHOR]

Owing to their improved catalytic stability and ability to undergo repeated cycles, solid-supported catalysts show great potential for various catalytic reactions. In this study, we synthesized a catalyst comprising a palladium-2,2-bipyridine complex supported on TiO2 nanoparticles (TiO2@BDP-PdCl2) fully characterised and investigated its efficacy in Suzuki–Miyaura cross coupling reactions involving phenyl boronic acid with various aryl halides under mild reaction conditions. The 2,2′- bipyridine (bp) has shown excellent complexation properties for Pd (II) and it could be easily anchored onto functionalized TiO2 support by the bridging carboxylate ions. The composition and structure of the as-prepared catalyst was characterized by powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), Transmission Electron Microscope (TEM), X-ray photoelectron spectroscopy (XPS), and UV–Vis spectroscopy. The catalyst easily demonstrated separability, enhancing its practicality in catalytic processes. Subsequent utilization showed a consistent activity level, suggesting the stabilization of the aggregated catalyst species. This research sheds light on the importance of catalyst stability and maintenance during consecutive reaction cycles. [ABSTRACT FROM AUTHOR]

In this study, novel boron-containing salen ligands (1 and 2) and their tetra-coordinated boron-based polymers (1a-b and 2a-b) containing N → B coordination bonds were synthesized under suitable conditions. In the first step, the synthesis of boron-containing salen ligands (1 and 2) was carried out as a result of the reaction of 4-formyl phenylboronic acid with different primary amines. Then, the obtained boron-containing salen ligands (1 and 2) were reacted with pentaerythritol and different N-donor ligands, respectively, to synthesize tetra-coordinated polymers (1a-b and 2a-b) containing N → B coordination bonds. Synthesized boron-containing salen ligands and corresponding tetra-coordinated polymers containing (N → B) coordination bonds were characterized by melting point, elemental analysis, LC–MS/MS spectrometer, FT-IR, UV–Vis and NMR (1H, 13C, and 11B) spectroscopy for illuminate of their structures. The use of synthesized boron-containing salen ligands (1 and 2) and their polymers (1a-b and 2a-b) containing N → B coordination bonds as novel organocatalysts were tested for the transfer hydrogenation of various aromatic ketones under suitable conditions. Considering all the catalytic results, it was seen that salen ligands (1 and 2) and tetra-coordinated boron-based polymers (1a-b and 2a-b) containing N → B coordination bonds to be suitable organocatalysts in the future for transfer hydrogenation with other boron compounds. [ABSTRACT FROM AUTHOR]

Sulfamic acid functionalized polyvinyl chloride catalysts (PVC-N-SO3H, N = EDA, DTA, TTA, TPA, PHA) were prepared as efficient heterogeneous solid acid catalysts via two-step treatment processes. The prepared catalysts were characterized by X-ray diffraction analysis (XRD), TG thermograms/derivative thermogravimetric (TG/DTG), transmission electron microscope (TEM), elemental mappings and energy-dispersive spectroscopy analyses (STEM-EDS), and FTIR measurements (FTIR) as well as acid–base back-titration. The acetalization of aldehydes (ketones) and alcohols to acetal (ketal) was selected to evaluate the acid catalytic performance of PVC-N-SO3H. The results showed that PVC-EDA-SO3H exhibit excellent activity and reusability due to its highly exposed sulfonic acid sites, high surface acid density (2.28 mmol g−1) for the conversion of aldehydes (ketones) to acetal (ketal). This new solid acid has obvious advantages in reusability and catalytic activity over traditional homogeneous concentrated sulfuric acid and heterogeneous sulfonated resin catalysts. Furthermore, PVC-EDA-SO3H exhibited an excellent catalytic performance in the synthesis of 12 acetals (ketals) as well as a good compatibility in the hydroxyalkylation of phenol with formaldehyde to bisphenol F (BPF) and the esterification reaction of oleic acid and methanol to biodiesel. More importantly, it could also be recovered easily and used repeatedly at least nine times without an obvious decrease in the activity. [ABSTRACT FROM AUTHOR]

In this paper, a cellulose-based hydrogel with the ability to lower glucose levels, scavenge reactive oxygen species (ROS), and colorimetrically monitor early lesions was synthesized to address the issue of glucose and H2O2 overexpression on the wound surface. Briefly, boronic acid pinacol ester containing phenolphthalein (BAPE-PPH) was employed as a crosslinker to react with hydroxypropyl methylcellulose (HPMC) to afford hydrogels (HPMC@PPH-Hs) with good biocompatibility. Because glucose has higher affinity for the phenylboronic ester group than cellulose derivatives, the HPMC@PPH-Hs showed excellent glucose-lowering performance. The presence of B-C bonds in the network endows the as-obtained hydrogel with H2O2 sensitivity, and cleavage of the B-C bonds forces the transformation of BAPE-PPH moieties into PPH, giving rise to colorimetric behaviour. Thus, the obtained HPMC@PPH-Hs provide information to enrich the family of smart hydrogels, and its potential application in diabetic wound healing may be desirable. [ABSTRACT FROM AUTHOR]

In this work, the mesoporous magnetic heterogeneous catalyst was synthesized by anchoring copper (II) onto the nitrogen-rich poly (melamine) Schiff base networks magnetic nanocomposite. First, MNP (Fe3O4@SiO2) was functionalized with chlorosilane (CPTS). Then, the chlorine of these functionalized magnetic nanoparticles could react with the –NH2 groups of the melamine through a nucleophilic substitution reaction. Simultaneously, the condensation polymerization of melamine and benzene-1, 3, 5-tricarbaldehyde was carried out in the presence of surface-modified magnetic nanoparticles. Later, Fourier-transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), scanning electron microscopy (SEM), atomic absorption spectroscopy (AAS), Brunauer–Emmett–Teller surface analysis (BET), and energy dispersive analysis were deployed to characterize the catalyst. The results of the AAS measurement showed that the copper ion loading on the mesoporous nitrogen-rich supported catalyst was about 0.82 mmol g−1. The synthesized nanocomposite was used as a catalyst and shows excellent activity in the three-component coupling reaction of amines, carbon disulfide, and boronic acids. In the presence of 70 mg of the catalyst, a wide range of functionalized dithiocarbamates were synthesized leading to excellent yields. Moreover, this MNP@SNWMe@Cu catalyst was easily recovered and reused seven times without significant loss of its activity. The results of this research exhibited that the synthesized catalyst functioned with high catalytic activity in this reaction. [ABSTRACT FROM AUTHOR]

Boronic acids and their conjugate esters have been employed in a variety of biomedical applications. This work reports structural, bonding, and thermochemical calculations for the boronic acids, RB(OH)2 (R = H, methyl, phenyl, and ortho-methyl-phenyl) and the corresponding ethylene glycol diesters, RB(−OCH2CH2O−), in the presence of explicit NH3 and/or H2O molecules. Calculations were performed in vacuo and in polarizable continuum model (PCM) aqueous media using density functional theory (DFT) and second-order Moller-Plesset perturbation theory (MP2) with the Dunning-Woon aug-cc-pVTZ basis set. These results quantify the relative stability of N→B dative-bonded, water-inserted Owater→B (Ow→B) dative-bonded, Zwitterionic, and hydrogen-bonded conformers on the model RB(OH)2⋅NH3⋅H2O and RB(−OCH2CH2O−)⋅NH3⋅H2O potential energy surfaces (PESs). In the PCM aqueous media model, conformers containing an H3N→B dative bond and a water molecule bridging the NH3 and acid/ester moieties were found consistently to be lower in energy than arrangements with either a H3N⋯H(H)Ow→B linkage or Zwitterionic forms, [H4N]+[HOw−BR(OH)2]− or [H4N]+[HOw−BR(−OCH2CH2O−)]−. For the acids, however, conformers with a H3N⋯HOwH moiety hydrogen bonded to the boronate hydroxyl group(s) proved to be lowest in energy. [ABSTRACT FROM AUTHOR]

The Diels—Alder reaction of 16-(3-trimethylsilyloxybutadienyl)furanolabdanoids with 5-methylene(arylidene)-3,3-dimethyl-2,4-dioxane-1,5-diones or 5-methylene(arylidene)-1,3-dimethylpyrimidine-2,4,6(1H,3H,5H)-triones in the presence of l-proline proceeded regioselectively and led to 7-furanoterpenyl-substituted 3,3-dimethyl-2,4-dioxaspiro[5.5]-undecane-1,5,9-triones or 2,4-dimethyl-2,4-diazaspiro[5.5]undecane-1,3,5,9-tetraones, respectively. The conditions for the one-pot synthesis of terpenyl-substituted dioxaspiro-[5.5]undecane-1,5,9-triones by the l-proline catalyzed three-component Knoevenagel—Diels—Alder reaction of diterpenoid enone, aldehyde, and the Meldrum's acid were proposed. A diterpenoid analog of anticancer agents with an 11-(biphenyl-4-yl)-2,4-di-oxaspiro[5.5]undecanone substituent was synthesized by the Suzuki reaction of the obtained bromophenyl-substituted spirocyclic ketone with 3,4,5-(trimethoxyphenyl)boronic acid. [ABSTRACT FROM AUTHOR]

Invertase, an industrially significant glycoenzyme, was purified from baker's yeast using poly (2-Hydroxyethyl methacrylate) [PHema-Pba] cryogels functionalized with boronic acid. At subzero temperatures, PHema-Pba cryogels were synthesized and characterized using swelling tests, scanning electron microscopy, and Fourier-transform infrared spectroscopy. The surface area of the PHema-Pba cryogels was 14 m2/g with a swelling ratio of 88.3% and macroporosity of 72%. The interconnected macropores of PHema-Pba cryogels were shown via scanning electron microscopy. Invertase binding capacity of PHema-Pba cryogel was evaluated by binding studies in different pH, temperature, and interaction time conditions and the maximum Invertase binding of PHema-Pba cryogel was found as 15.2 mg/g. and 23.7 fold Invertase purification was achieved from baker's yeast using PHema-Pba cryogels. The results show that PHema-Pba cryogels have high Invertase binding capacity and may be used as an alternative method for enzyme purification via boronate affinity systems. [ABSTRACT FROM AUTHOR]

Various boron-containing isocyanides have been efficiently synthesized from the corresponding enantiopure β-substituted β-amino boronic acid pinacol esters, without need for protecting group interconversion, through a two-step, purification-free procedure. They were employed in a variety of isocyanide-based multicomponent reactions, proving to be reliable components for all of them and allowing the efficient synthesis of unprecedented, boron-containing peptidomimetics and heteroatom-rich small molecules, including biologically relevant cyclic boronates. Jointing together the β-amido boronic acid moiety, deriving from the isocyanide component, with prominent pharmacophoric rings emerging from the multicomponent process, a successful application of the molecular hybridization concept could be realized. [ABSTRACT FROM AUTHOR]

In the history of catalysis and organic synthesis, boric chemistry has been developed into one of the most varied and practical disciplines. Several useful Suzuki–Miyaura cross-coupling (SMC) reactions as well as hydroborylation reactions are regarded the essential tools inside the chemical synthesis toolkit accompanied by researchers of the industry or the academia. Novel synthesis of the less electrically and sterically ongoing carbon–boron synthetic reagents is carried out to ensure a unique coupling reaction utilizing metals along with these reagents which draws considerable interest in accelerating the discovery of creative uses for otherwise difficult organic adducts in many disciplines. This article details the noteworthy advancements in the use of traditional metal-catalyzed carbon–carbon coupling processes with cutting-edge coupling partners such as carbon–boron reagents often the beta-alkyl Suzuki–Miyaura coupling since 2001. The current review covers alkylboranes, organotrifluoroborates, 9-BBN, alkylboronic acids and boronic esters as useful reagents in SMCs that will help synthetic chemists in developing new compounds. [ABSTRACT FROM AUTHOR]

The HILIC enrichment is a greatly compatible strategy for the extraction of glycopeptides in proteomics. Herein, a boric acid and fructose-1,6-diphosphate (FDP) dual-functionalized Zr-based metal–organic framework material UIO-PBA&FDP (UIO is the abbreviation for the University of Oslo, and PBA is the abbreviation for carboxy phenylboronic acid) was synthesized, characterized with the desirable excellent hydrophilicity and thus was explored for the enrichment of N-linked glycopeptides utilizing the HILIC interaction between the glycopeptides and the hydrophilic UIO-PBA&FDP at a high level of ACN concentration. A total of 359 N-linked glycopeptides corresponding to 104 glycoproteins were identified from only 1 μL of digested human serum by the enrichment of UIO-PBA&FDP, which showed a superiorly high coverage of the identified glycopeptides. The dual hydrophilic functionalized UIO-PBA&FDP could be an efficient HILIC material for the enrichment of N-linked glycopeptides from complex biological samples. [ABSTRACT FROM AUTHOR]

Synthesis of amino acids with isolated saturated (hetero)carbocyclic scaffold was disclosed. The method relied on Suzuki cross-coupling reaction of heteroacycloalkene triflates and N-Boc-tetrahydropyridine boron pinacolates followed by catalytic hydrogenation of the conjugated dienes thus obtained, which proceeded with good diastereoselectivity for scaffolds with two six-membered cycles and low diastereoselectivity for a five-membered analog. Several amino acid derivatives have also been obtained, i.e. amino esters, NH- and N-Boc-substituted amino acids – promising building blocks for medicinal and synthetic chemistry. [ABSTRACT FROM AUTHOR]

The affinity interactions between boronic acids and sugars have been successfully exploited in many fields, such as the sensing of saccharides, selective enrichment of glycoconjugates, and drug delivery. However, despite multiple techniques having been adopted to investigate the reaction of boronate affinity, the pathway of boronate esters formation under aqueous conditions remains controversial. We report a MALDI-MS approach to investigate the interactions between phenylboronic acid and monosaccharides in neutral aqueous solution by using polylevodopa as an innovative substrate instead of conventional matrix. A series of unusual tri-benzeneboronic esters were then revealed. The mass spectrometry data indicate that they bear a dibenzenepyroboronate cyclic ester moiety with seven-membered ring or eight-membered ring. With the aid of theoretical computations, their most likely geometrical structures are elucidated, and these tri-benzeneboronic esters are proposed to be formed via a boroxine binding monosaccharide pathway. This work provides more insight into the mechanism of boronate affinity interaction between boronic acid and sugars and proves the developed MALDI-MS approach is promising for studying interactions between small molecules. [ABSTRACT FROM AUTHOR]

The porous organic framework has been receiving significant attention for the past few years because of its various applications, including heterogeneous catalysis. The catalytic activity of the parent porous organic framework is often increased by incorporating or doping metal ions in the framework. In this context, copper has been loaded in a melamine–terephthaldehyde based porous organic framework (MTPOF), and its catalytical activity is successfully examined for the C–S coupling reaction of 2-mercaptobenzimidazole with aryl halides and 2-halobenzoic acids. The MTPOF is synthesized by reacting melamine with terephthaldehyde, and then the copper acetate is integrated in the framework. The MTPOF and Cu@MTPOF have been characterized by FTIR, SEM, EDS, solid-state NMR, BET, TGA-DTG, and XPS analysis. It has been found that Cu@MTPOF is quite effective in catalyzing C–S coupling reaction with Cu@MTPOF, which is effortlessly recuperated and reused multiple times without much change in catalytic activity. [ABSTRACT FROM AUTHOR]

Synthesis methods, properties, and application fields of various boron-containing coumarin derivatives are summarized. Particular attention is paid to derivatives with various polyhedral boron clusters as substituents, such as carboranes, metallacarboranes, and the closo-dodecaborate anion. Derivatives of coumarin with simple organoboron compounds, boronic acids and their esters, are also considered. [ABSTRACT FROM AUTHOR]

Small molecule drugs that covalently bind irreversibly to their target proteins have several advantages over conventional reversible inhibitors. They include increased duration of action, less-frequent drug dosing, reduced pharmacokinetic sensitivity, and the potential to target intractable shallow binding sites. Despite these advantages, the key challenges of irreversible covalent drugs are their potential for off-target toxicities and immunogenicity risks. Incorporating reversibility into covalent drugs would lead to less off-target toxicity by forming reversible adducts with off-target proteins and thus reducing the risk of idiosyncratic toxicities caused by the permanent modification of proteins, which leads to higher levels of potential haptens. Herein, we systematically review electrophilic warheads employed during the development of reversible covalent drugs. We hope the structural insights of electrophilic warheads would provide helpful information to medicinal chemists and aid in designing covalent drugs with better on-target selectivity and improved safety. [ABSTRACT FROM AUTHOR]

In this study, we developed a new synthetic strategy to convert secoiridoid glucosides into unique dialdehydic compounds using solid acid catalysts. Specifically, we succeeded in the direct synthesis of oleacein, a rare component of extra-virgin olive oil, from oleuropein, which is abundant in olive leaves. Whereas the conventional total synthesis of oleacein from lyxose requires more than 10 steps, these solid acid catalysts enabled the one-step synthesis of oleacein from oleuropein. A key step in this synthesis was the selective hydrolysis of methyl ester. Density functional theory calculations at the B3LYP/631+G (d) level of theory revealed the formation of a tetrahedral intermediate bonded to one H2O molecule. These solid acid catalysts were easily recovered and reused at least five times by simple cleaning. Importantly, this synthetic procedure was not only applicable to other secoiridoid glucosides, but could also be employed for the corresponding scale-up reaction using oleuropein extracted from olive leaves as the starting material. [ABSTRACT FROM AUTHOR]

An efficient and high-yielding method was developed for the synthesis of N-(benzo[d]thiazol-2-yl)-6-methoxy-5-(4-methyl-1H-imidazol-1-yl)pyridine-2-carboxamide derivatives by reacting benzo[d]thiazol-2-amine/1H-benzo[d]imidazol-2-amine with 5-bromo-6-methoxypicolinic acid in the presence of HBTU/Et3N in DMSO followed by coupling with 4-methyl-1H-imidazole in the presence of K2CO3/CuI in trans-1,2-diaminocyclohexane.The mild reaction conditions and easy operations allow introducing a wide range of functionalities, as well as a high reaction efficiency. The synthesized compounds were tested for their anticancer potential against MCF-7 and DU145 human cancer cell lines. N-(5-Fluoro-1H-benzo[d]imidazol-2-yl)- and N-(4-fluorobenzo[d]thiazol-2-yl)-6-methoxy-5-(4-methyl-1H-imidazol-1-yl)pyridine-2-carboxamides exhibited the highest activity among the test compounds against both the cell lines, with IC50 values ranging from 8.9 to 10.8 µM. Docking analysis revealed the potential inhibitory activity of the former compound against VEGFR-2 kinase, with the binding energy of 7.9 kcal/mol. [ABSTRACT FROM AUTHOR]

Despite great therapeutic effect of Abraxane®, complex preparation technology and unfavorable pharmacokinetics still restricted the clinical application of albumin-based paclitaxel (PTX) nanoparticles (NPs). Herein, we reported that an albumin-binding prodrug, phenylboronic acid-conjugated PTX (P-PTX), can form the uniform NPs with the diameters around 100 nm with the help of albumin via simple one-step nano-precipitation method. The albumin-based nanomedicines were stabilized by the integration of a single boronic acid with PTX due to the increased affinity based on multiple intermolecular interactions. We found that albumin-based P-PTX NPs exhibited superior colloidal stability over albumin-based PTX NPs through one-step nanoprecipitation approach, achieving longer in vivo circulation time and higher concentration in tumor than those of the marketed Abraxane®. Furthermore, the albumin-based P-PTX NPs with great stability and enhanced intratumoral enrichment, increased the maximum tolerated dose of PTX, remarkably suppressed the growth of breast tumor and lung metastasis, and prolonged survival of melanoma tumors-bearing mice. Such a convenient and effective system gains an insight into the impact of phenylboronic acid group on the albumin-based PTX NPs, and provides potent strategy for the rational design of albumin-based antitumor nanomedicines. [ABSTRACT FROM AUTHOR]

The application of natural and synthetic boron-containing compounds (BCC) in biomedical field is expanding. BCC have effects in the metabolism of living organisms. Some boron-enriched supplements are marketed as they exert effects in the bone and skeletal muscle; but also, BCC are being reported as acting on the enzymes and transporters of membrane suggesting they could modify the carbohydrate metabolism linked to some pathologies of high global burden, as an example is diabetes mellitus. Also, some recent findings are showing effects of BCC on lipid metabolism. In this review, information regarding the effects and interaction of these compounds was compiled, as well as the potential application for treating human metabolic disorders is suggested. [ABSTRACT FROM AUTHOR]

Aptamer-based molecular switches that undergo a binding-induced conformational change have proven valuable for a wide range of applications, such as imaging metabolites in cells, targeted drug delivery, and real-time detection of biomolecules. Since conventional aptamer selection methods do not typically produce aptamers with inherent structure-switching functionality, the aptamers must be converted to molecular switches in a post-selection process. Efforts to engineer such aptamer switches often use rational design approaches based on in silico secondary structure predictions. Unfortunately, existing software cannot accurately model three-dimensional oligonucleotide structures or non-canonical base-pairing, limiting the ability to identify appropriate sequence elements for targeted modification. Here, we describe a massively parallel screening-based strategy that enables the conversion of virtually any aptamer into a molecular switch without requiring any prior knowledge of aptamer structure. Using this approach, we generate multiple switches from a previously published ATP aptamer as well as a newly-selected boronic acid base-modified aptamer for glucose, which respectively undergo signal-on and signal-off switching upon binding their molecular targets with second-scale kinetics. Notably, our glucose-responsive switch achieves ~30-fold greater sensitivity than a previously-reported natural DNA-based switch. We believe our approach could offer a generalizable strategy for producing target-specific switches from a wide range of aptamers. Efforts to convert aptamers into molecular switches using rational design are often unsuccessful. Here the authors describe a massively parallel screening-based strategy whereby millions of potential aptamer switches are synthesised, sequenced and screened directly on a flow-cell. [ABSTRACT FROM AUTHOR]

C–N bond cross-couplings are fundamental in the field of organic chemistry. Herein, silylboronate-mediated selective defluorinative cross-coupling of organic fluorides with secondary amines via a transition-metal-free strategy is disclosed. The cooperation of silylboronate and potassium tert-butoxide enables the room-temperature cross-coupling of C–F and N–H bonds, effectively avoiding the high barriers associated with thermally induced SN2 or SN1 amination. The significant advantage of this transformation is the selective activation of the C–F bond of the organic fluoride by silylboronate without affecting potentially cleavable C–O, C–Cl, heteroaryl C–H, or C–N bonds and CF3 groups. Tertiary amines with aromatic, heteroaromatic, and/or aliphatic groups were efficiently synthesized in a single step using electronically and sterically varying organic fluorides and N-alkylanilines or secondary amines. The protocol is extended to the late-stage syntheses of drug candidates, including their deuterium-labeled analogs. C–N bond cross-coupling is fundamental in organic chemistry, but the readily available organic fluorides are unsuitable as coupling substrates. Here, we realize defluorinative cross-coupling with amines via a silylboronate-mediated strategy. [ABSTRACT FROM AUTHOR]

Polystyrene anchored palladium (II) complex of 2-acetylbenzimidazole was synthesized and characterized by elemental analysis, FT-IR, UV–Vis/DRS spectroscopic and thermogravimetric analysis. Based on the analytical studies, square planar geometry was assigned to Pd (II) ion in the polymer supported palladium complex. The novel polymer supported palladium complex exhibited excellent catalytic activity towards Suzuki–Miyaura cross-coupling reaction of 4-bromoanisole with differently substituted boronic acids in H2O/EtOH solvent system, to obtain coupled products in excellent yields. Supported complex exhibited better activity and recyclability as compared to unsupported palladium complex. Based on the results obtained, a plausible mechanism for the Suzuki–Miyaura cross-coupling reaction has been proposed. Under the optimized reaction conditions, the complex showed recycling ability up to six runs without any metal leaching and not much loss in its catalytic activity. [ABSTRACT FROM AUTHOR]

Thermally stimulated processes in mixtures of boric acid (BA) with aluminum after plastic deformation under a pressure of 0.5–4.0 GPa were studied by differential scanning calorimetry (DSC) and thermogravimetry. In the original BC, in the range of 20–200°C, splitting of water occurs, accompanied by an endothermic effect. In deformed mixtures BC–Al = 50–50, the endoprocess was recorded on DSC thermograms in the range of 20–200°С, an exoprocess in the range of 200–550°С, an aluminum-oxidation exoprocess at 620°С, and an aluminum melting endoprocess at 656°С. The baric dependences of the parameters of thermal processes in deformed mixtures exhibited extrema at pressures of 1.0 and 2.5 GPa, which were associated with changes in the electronic structure of aluminum caused by high pressure. Such changes can be retained in deformed mixtures after completion of pressure treatment and manifest themselves upon heating due to the formation of electrical double layers in mixture samples. [ABSTRACT FROM AUTHOR]

The chemoselective borylation of bromoiodoarenes under continuous flow conditions is described. Bromoarylboronic acids were synthesized in high yields using iPrMgCl•LiCl as the halogen-metal exchange reagent, with 5.7–86 s residence time at room temperature. The process is compatible with a variety of functional groups, including carbanion-reactive moieties, enabling post-product functionalization. A gram-scale reaction, including a continuous-flow work-up, afforded the desired product in a highly efficient manner. Successful telescoping with a Suzuki coupling has also been performed, converting 1-bromo-3-iodobenzene to 3-bromo-1,1′-biphenyl on a gram-scale in a good yield. Highlights: • Bromoarylboronic acids were synthesized in high yields using iPrMgCl•LiCl. • The reactions were performed at room temperature in commercial PFA tubing. • The short residence time enables a high degree of functional group compatibility. • Telescoped synthesis of the corresponding bromobiaryl compound was performed by coupling the boronic acid formation reaction to a Suzuki coupling. Graphical abstract [ABSTRACT FROM AUTHOR]

Cu@Phen@MGO catalyst was synthesized by the functionalization of magnetic graphene oxide (MGO) with phenanthroline type ligand. The catalyst was characterized by several characterization methods and used as an effective magnetic heterogeneous nanocatalyst for the N-arylation of 2-amino-N-phenylbenzamide. Cu@Phen@MGO catalyst showed very good efficiency in base-free Chan–Evans–Lam coupling of arylboronic acid with 2-amino-N-phenylbenzamide at room temperature. The products were obtained in high isolated yields. Easy recoverability of the catalyst by an external magnet, reusability up to six runs without significant loss of activity, and its well stability during the reaction are among the other highlights of this catalyst. [ABSTRACT FROM AUTHOR]

Access to carbocyclic C-nucleosides (CC-Ns) is currently restricted. The few methods available to make CC-Ns suffer from long syntheses and poor modularity, hindering the examination of potentially important chemical space. Here we report an approach to CC-Ns which uses an asymmetric Suzuki-Miyaura type reaction as the key C-C bond forming step. After coupling the densely functionalized racemic bicyclic allyl chloride and heterocyclic boronic acids, the trisubstituted cyclopentenyl core is elaborated to RNA analogues via a hydroborylation-homologation-oxidation sequence. We demonstrate that the approach can be used to produce a variety of enantiomerically enriched CC-Ns, including a carbocyclic derivative of Showdomycin. Carbocyclic nucleosides show a broad spectrum of antiviral activity with enhanced flexibility, lipophilicity and metabolic stability, however, synthetic access to carbocyclic C-nucleosides (CC-Ns) remains very challenging. Here, the authors use an asymmetric Suzuki-Miyaura coupling reaction as the key C-C bond forming step to produce a variety of enantiomerically enriched CC-Ns, including antiviral showdomycin. [ABSTRACT FROM AUTHOR]

The preparation of high value-added boronic acids from cheap and plentiful carboxylic acids is desirable. To date, the decarboxylative borylation of carboxylic acids is generally realized through the extra step synthesized redox-active ester intermediate or in situ generated carboxylic acid covalent derivatives above 150 °C reaction temperature. Here, we report a direct decarboxylative borylation method of carboxylic acids enabled by visible-light catalysis and that does not require any extra stoichiometric additives or synthesis steps. This operationally simple process produces CO2 and proceeds under mild reaction conditions, in terms of high step economy and good functional group compatibility. A guanidine-based biomimetic active decarboxylative mechanism is proposed and rationalized by mechanistic studies. The methodology reported herein should see broad application extending beyond borylation. Boronic acids are useful reagents in organic synthesis and thus methods to prepare these compounds under mild conditions are desirable. Here, the authors synthesize boronic acids via photocatalytic decarboxylation of benzoic acids followed by borylation; guanidine-type additives are used to assist the process. [ABSTRACT FROM AUTHOR]

The transition metal-catalyzed hydrofunctionalization of alkenes offers an efficient solution for the rapid construction of complex functional molecules, and significant progress has been made during last decades. However, the hydrofunctionalization of internal alkenes remains a significant challenge due to low reactivity and the difficulties of controlling the regioselectivity. Here, we report the hydroarylation and hydroalkenylation of internal alkenes lacking a directing group with aryl and alkenyl boronic acids in the presence of a nickel catalyst, featuring a broad substrate scope and wide functional group tolerance under redox-neutral conditions. The key to achieving this reaction is the identification of a bulky 1-adamantyl β-diketone ligand, which is capable of overcoming the low reactivity of internal 1,2-disubstituted alkenes. Preliminary mechanistic studies unveiled that this reaction undergoes an Ar-Ni(II)-H initiated hydroarylation process, which is generated by the oxidative addition of alcoholic solvent with Ni(0) species and sequential transmetalation. In addition, the oxidative addition of the alcoholic solvent proves to be the turnover-limiting step. The hydrocarbofunctionalization of alkenes represents one of the most efficient methods for generating complex products from simple starting materials. Here, the authors report a bulky β-diketone-ligand-enabled hydroarylation and hydroalkenylation of internal alkenes. [ABSTRACT FROM AUTHOR]

A novel boron-containing monomer, (4-(3,4-dicyanophenoxy)phenyl)boronic acid (BPhPN) was synthesized and used to promote the curing process of phthalonitrile monomer 1,3-bis(3,4-dicyanophenoxy)benzene (MPN). Differential scanning calorimetry and rheological analysis were used to study the curing behaviors of BPhPN/MPN (namely B-MPN), and results suggested that B-MPN systems have better processibility. FTIR spectra and solid-state 13C-NMR exhibited triazine and isoindoline have been formed in the curing process. Boron-containing Lewis acid curing mechanism was preliminarily speculated and verified by two model compounds with different boron chemical environments. The thermogravimetric analysis and dynamic mechanical analysis demonstrated that the cured B-MPN polymers showed excellent thermal stability and heat resistance, which were comparable with conventional catalytic systems for phthalonitrile resins. This study not only presented a novel curing system for phthalonitrile resins, but also shed light on future design of high temperature thermosets. [ABSTRACT FROM AUTHOR]

A palladium-catalyzed Suzuki cross-coupling of benzyl ammonium triflates via activation of a Csp3–N bond to construct a Csp3–Csp2 bond is described. Various boronic acids can be coupled with a range of benzylamine-derived quaternary ammonium salts in 1:1 molar ratio by the bench-stable N-heterocyclic carbene palladium complex, SIPr-PdCl2-Py to afford diarylmethane derivatives. This reaction exhibits a wide substrate scope and functional group tolerance. Direct arylation of benzylamine in a one-pot process and the gram-scale reaction can be performed successfully. [ABSTRACT FROM AUTHOR]

Succinimide derivatives were synthesized by direct fusion of alkenyl-substituted succinic anhydride with amino acids such as glycine, alanine, aminobutyric, aminopentanoic, and aminohexanoic acids. Their further transformations afforded new allenoates and chloro- and bromomethyl ketones containing a succinimide fragment, which were involved in [3+2]- and [2+1]-cycloaddition reactions with fullerene C60 to produce new cyclopenta- and cyclopropafullerenes. It was found that the Bingel reaction with chloromethyl ketones is easier to occur. The phosphine-catalyzed cycloaddition of allenoates to the fullerene sphere was shown to be preferred for the synthesis of monosubstituted C60 derivatives. The obtained fullerene adducts are readily soluble in organic solvents, which extends the scopes of their further transformations and application in organic photovoltaics. [ABSTRACT FROM AUTHOR]

Transition metal-catalyzed C-H alkylation has appeared as a well-built tool for the step-economical transformations of inert C-H bonds. Keeping in view the growing importance of these reactions, an outline of the application of transition metal catalysis in C-H functionalization/late-stage diversification processes has been demonstrated. In this review, we have focused on metals such as palladium, gold, scandium, silver, rhenium and manganese playing role as catalysts in C-H alkylation. Various alkylating agents, e.g., alcohols, alkyl halides, alkenes, diazo compounds and boronic acids, etc., have been used to get the products in good yields. [ABSTRACT FROM AUTHOR]

As a unique organofluorine fragment, gem-difluoromethylated motifs have received widespread attention. Here, a convenient and efficient synthesis of aryldifluoromethyl aryl ethers (ArCF2OAr') was established via Nickel-catalyzed aryloxydifluoromethylation with arylboronic acids. This approach features easily accessible starting materials, good tolerance of functionalities, and mild reaction conditions. Diverse late-stage difluoromethylation of many pharmaceuticals and natural products were readily realized. Notably, a new difluoromethylated PD-1/PD-L1 immune checkpoint inhibitor was conveniently synthesized and showed both improved metabolic stability and enhanced antitumor efficacy. Preliminary mechanistic studies suggested the involvement of a Ni(I/III) catalytic cycle. Aryldifluoromethyl aryl ethers (ArCF2OAr') are powerful structural motifs to improve druggability, however, their targeted synthesis remains challenging. Here, the authors report the efficient synthesis of ArCF2OAr' motifs via nickel-catalyzed aryloxydifluoromethylation with arylboronic acids, and their application in the total synthesis of a difluoromethylated PD-1/PD-L1 immune checkpoint inhibitor with enhanced antitumor efficacy over the non-fluoro congener. [ABSTRACT FROM AUTHOR]

N-functionalized aziridines, which are both useful intermediates and important synthetic targets, can be envisioned as arising from the addition of nitrenes (i.e., NR fragments) to olefinic substrates. The exceptional reactivity of most nitrenes, in particular with respect to unimolecular decomposition, prevents general application of nitrene-transfer to the synthesis of N-functionalized aziridines. Here we demonstrate N-aryl aziridine synthesis via 1) olefin aziridination with N-aminopyridinium reagents to afford N-pyridinium aziridines followed by 2) Ni-catalyzed C–N cross-coupling of the N-pyridinium aziridines with aryl boronic acids. The N-pyridinium aziridine intermediates also participate in ring-opening chemistry with a variety of nucleophiles to afford 1,2-aminofunctionalization products. Mechanistic investigations indicate aziridine cross-coupling proceeds via a noncanonical mechanism involving initial aziridine opening promoted by the bromide counterion of the Ni catalyst, C–N cross-coupling, and finally aziridine reclosure. Together, these results provide new opportunities to achieve selective incorporation of generic aryl nitrene equivalents in organic molecules. Aziridines are useful intermediates, present in important synthetic targets. Here, the authors show a strategy for the synthesis of N-aryl aziridines based on N-aminopyridinium reagents followed by Ni-catalyzed C–N cross-coupling of N-pyridinium aziridines with aryl boronic acids. [ABSTRACT FROM AUTHOR]

MPO-derived oxidants including HOCl contribute to tissue damage and the initiation and propagation of inflammatory diseases. The search for small molecule inhibitors of myeloperoxidase, as molecular tools and potential drugs, requires the application of high throughput screening assays based on monitoring the activity of myeloperoxidase. In this study, we have compared three classes of fluorescent probes for monitoring myeloperoxidase-derived hypochlorous acid, including boronate-, aminophenyl- and thiol-based fluorogenic probes and we show that all three classes of probes are suitable for this purpose. However, probes based on the coumarin fluorophore turned out to be not reliable indicators of the inhibitors' potency. We have also determined the rate constants of the reaction between HOCl and the probes and they are equal to 1.8 × 104 M−1s−1 for coumarin boronic acid (CBA), 1.1 × 104 M−1s−1 for fluorescein based boronic acid (FLBA), 3.1 × 104 M−1s−1 for 7-(p-aminophenyl)-coumarin (APC), 1.6 × 104 M−1s−1 for 3'-(p-aminophenyl)-fluorescein (APF), and 1 × 107 M−1s−1 for 4-thiomorpholino-7-nitrobenz-2-oxa-1,3-diazole (NBD-TM). The high reaction rate constant of NBD-TM with HOCl makes this probe the most reliable tool to monitor HOCl formation in the presence of compounds showing HOCl-scavenging activity. [ABSTRACT FROM AUTHOR]

Here we reported the synthesis of N-substituted imidazole derivatives (VIa–o) that involves Suzuki coupling reaction between 1-(2-((4-bromobenzyl)oxy)-2-(2,4-dichlorophenyl)ethyl)-1H-imidazole (V) and various aryl boronic acids using Pd(dppf)Cl2 with DCM as the catalyst in 1,4-dioxane/H2O (2 : 1) solvent and using potassium carbonate as base. All the newly synthesized compounds were characterized by 1H NMR, 13C NMR and mass spectral data. They were screened for their antibacterial activity against gram-positive bacterial strains, Bacillus subtilis and Staphylococcus aureus where the compounds 4-(4-((1-(2,4-dichlorophenyl)-2-(1H-imidazol-1-yl)ethoxy)methyl)phenyl)pyridine (VIc), 1-(2-(2,4-dichlorophenyl)-2-((3'-fluoro-4'-methoxy-[1,1'-biphenyl]-4-yl)methoxy)ethyl)-1H-imidazole (VIe), 4'-((1-(2,4-dichlorophenyl)-2-(1H-imidazol-1-yl)ethoxy)methyl)-[1,1'-biphenyl]-3-carbonitrile (VIi), 1-(2-(2,4-dichlorophenyl)-2-((3'-fluoro-[1,1'-biphenyl]-4-yl)methoxy)ethyl)-1H-imidazole (VIj), 1-(2-(2,4-dichlorophenyl)-2-((4'-fluoro-3'-methyl-[1,1'-biphenyl]-4-yl)methoxy)ethyl)-1H-imidazole (VIn) and 4-(4-((1-(2,4-dichlorophenyl)-2-(1H-imidazol-1-yl)ethoxy)methyl)phenyl)-1H-pyrazole (VIo) exhibited remarkable activity compared to the reference streptomycin. [ABSTRACT FROM AUTHOR]