Search

A unique direct asymmetric synthesis of α‐aminoimines is realized, through rapid and exclusive mono‐allylation of chiral bis‐N‐sulfinylimines using allylboronic acids. The highly selective allylation was possible as electrophilic imine functional group in the product α‐aminoimines remained unreactive towards allyl boronic acid nucleophiles. Notably, by varying the geometry and chiral auxiliary, all four isomers of the α‐aminoimines were accessed from readily available precursors. A range of allyl nucleophiles, which are tricky to generate by other means possessing highly reactive functional groups also took part in this reaction, expanding the scope further. The applicability of the products α‐aminoimines were further demonstrated by accessing a range of structurally diverse chiral cyclic and acyclic 1,2‐diamines bearing adjacent stereocenters through addition of a second nucleophile or Prins‐type cyclization by exploiting the nucleophilicity of the tethered alkene moiety. Moreover, the leaving group aptitude of sulfinyl auxiliary attached to imine, was exploited to access valuable chiral α‐aminonitriles under thermal conditions without employing any reagents. Detailed DFT calculation revealed a chair‐like transition state, arising from corresponding allylboroxine species, likely operating for the allylboration reaction across imine. [ABSTRACT FROM AUTHOR]

Herein, a method for the assembly of biologically valuable 3‐selenospiro[4,5]decatrienones through CuBr2‐catalyzed ispo‐cyclization of Se powder, boronic acids, and N‐(p‐methoxyaryl)propiolamides has been established. In this protocol, noble transition metal, prefunctionalized selenylation reagent, and strong chemical oxidant are not employed. This method feature wide substrate scope, good functional group tolerance, easy operation, and employing earth‐abundant metal as catalyst and green air as oxidant. Furthermore, several derivatizations of 3‐selenospiro[4,5]decatrienones are performed to showcase the practicability of our strategy. [ABSTRACT FROM AUTHOR]

Radical‐involved arylative cross‐coupling reactions have recently emerged as an attractive strategy to access valuable aryl‐substituted motifs. However, there still exist several challenges such as limited scope of radical precursors/acceptors, and lack of general asymmetric catalytic systems, especially regarding the multicomponent variants. Herein, we reported a general copper‐Box system for asymmetric three‐component arylative radical cross‐coupling of vinylarenes and 1,3‐enynes, with oxime carbonates and aryl boronic acids. The reactions proceed under practical conditions in the absence or presence of visible‐light irradiation, affording chiral 1,1‐diarylalkanes, benzylic alkynes and allenes with good enantioselectivities. Mechanistic studies imply that the copper/Box complexes play a dual role in both radical generation and ensuing asymmetric cross‐coupling. In the cases of 1,3‐enynes, visible‐light irradiation could improve the activity of copper/Box complex toward the initial radical generation, enabling better efficiency match between radical formation and cross‐coupling. [ABSTRACT FROM AUTHOR]

ABSTRACT Green synthesis of metal nanoparticles using plant sources is one of the most environmentally sound, economically safer, and operationally simple approaches compared with their physiochemical methods. In this work, we have developed the biogenic synthesis of Ag nanoparticles using the aqueous peel extract of Punica granatum L. fruit, which mitigates the requirement for any hazardous reagents or toxic chemicals. The ultraviolet‐visible spectrum confirmed the formation of Ag@PPE NPs with an absorption peak at 420 nm. The X‐ray diffraction analysis confirms that the biosynthesized Ag@PPE NPs are crystalline, with a crystallite size of 9.23 nm. SEM and TEM images revealed the spherical morphology of Ag@PPE NPs, with particle sizes ranging from 2 to 20 nm. The biosynthesized Ag@PPE NPs were explored as antimicrobial agents against both Gram‐positive (CA‐MRSA) and Gram‐negative (Escherichia coli) bacteria as well as Candida albicans (ATCC 14053). The mean zone of inhibition against the CA‐MRSA group was 15.34 ± 2.5 mm, while it was 12.33 ± 1.5 mm against E. coli. In this study, Ag@PPE NPs demonstrated strong antibiofilm activity and antioxidant activity. Moreover, the catalytic applicability of the synthesized Ag@PPE NPs has been investigated for the oxidative hydroxylation of differently substituted aryl boronic acids into phenols at room temperature. The reaction proceeded efficiently in a short reaction time, and the desired products were obtained with high to excellent yields (82%–94%). Notably, the nanocatalyst can be recovered in five consecutive runs without decreasing its catalytic performance. The plausible mechanism of this ipso‐hydroxylation reaction is well presented. [ABSTRACT FROM AUTHOR]

Amides and peptides are ubiquitous functional groups found in several natural and artificial materials, and they are essential for the advancement of life and material sciences. In particular, their relevance in clinical medicine and drug discovery has increased in recent years. Dehydrative condensation of readily available carboxylic acids with amines is the most "direct" method for amide synthesis; however, this methodology generally requires a stoichiometric amount of condensation agent (coupling reagent). Catalytic direct dehydrative amidation has become an "ideal" methodology for synthesizing amides from the perspective of green chemistry, with water as the only byproduct in principle, high atom efficiency, environmentally friendly, energy saving, and safety. Conversely, organoboron compounds, such as boronic acids, which are widely used in various industries as coupling reagents for Suzuki–Miyaura cross-coupling reactions or pharmaceutical structures, are environmentally friendly molecules that have low toxicity and are easy to handle. Based on the chemical properties of organoboron compounds, they have potential Lewis acidity and the ability to form reversible covalent bonds with dehydration, making them attractive as catalysts. This review explores studies on the development of direct dehydrative amide/peptide bond formation reactions from carboxylic acids using organoboron catalysis, classifying them based on chemical bonding and catalysis over approximately 25 years, from the early developmental days to 2023. [ABSTRACT FROM AUTHOR]

Current routes to boronic acids and their corresponding esters to be used in subsequent Suzuki–Miyaura (SM) cross couplings impact the cost, waste, and safety concerns associated with generating these materials. A new method for installing the ethyl pinacol boronic ester, or B(Epin) derivative leads to stable borylated products under near-neat conditions using high concentrations of a green solvent and moderate reaction temperatures, catalyzed by relatively low palladium loadings. Alternatively, the newly fashioned Ar–B(Epin) can be generated in situ and used directly in the same pot for SM reactions leading to aromatic and heteroaromatic residues characteristic of the biaryl products being formed. An array of complex targets, including API-related products, can be generated via this green and environmentally responsible methodology. [ABSTRACT FROM AUTHOR]

Fluorenones are suitable candidates for negolytes in flow batteries, as they demonstrate the ability to store 2 electrons, and can achieve reversibility, solubility, and stability with appropriate molecular design. However, limitations persist such as the use of alkaline media, high redox potentials, and a limited scope for optimization. Herein, azoniafluorenones is reported as a novel class of negolytes. They can be readily accessed in a highly modular fashion from inexpensive commercially available materials (e.g., boronic acids). Variations in the substitution patterns reveal the 3‐substituted N‐alkylated AZON3, which demonstrates excellent solubility at neutral pH (1.64 m) with two low reversible redox potentials (−0.31 and −0.58 V vs Ag/AgCl). AZON3 exhibits high stability when evaluated at high concentration in a neutral supporting electrolyte (1 m in 3 m KCl), paired with BTMAP‐Fc on the positive side. Capacity retentions of 99.95% and 99.91% per cycle (99.35% and 99.21% per day) are achieved when cycling with 1 and 2 electrons, respectively, coupled with high volumetric capacity of 46.4 Ah L−1 (87% of capacity utilization). [ABSTRACT FROM AUTHOR]

In this study, a difluorocarbene‐promoted O−O bond activation of peroxy acids is developed through the insertion of difluorocarbene into O−H bond. This activation strategy in synergy with O−B coordination with boronic acids/ester greatly polarizes the O−O bond for in‐situ generation of carboxylium species that reacts with the nucleophilic part of boronic acids in a concerted way to produce carboxylic esters. Good efficiency and functional group tolerance are demonstrated. Application of this method to the functionalization of a boronic acid drug used as HSL enzyme inhibitor produces smoothly the ester derivative. This difluorocarbene‐mediated O−O bond activation strategy is conceptually different from traditional radical type methods, and is also complementary to conventional esterification methods with a distinct retro‐synthetic disconnection. [ABSTRACT FROM AUTHOR]

Five compounds, [Zn2(bpe)(BPTA)2(H2O)2] ⋅ 2H2O (1); [Zn(bpe)(BPTA)] (2); [Cd(bpe)(BPTA)H2O] (3); [Cd(BPTA) (bpmh)] ⋅ 2H2O (4); and Cu2(BPTA)2(bpmh)3(H2O)2] ⋅ 2H2O (5) were prepared employing 2,5‐bis(prop‐2‐yn‐1‐yloxy)terephthalic acid (2, 5 BPTA) as the primary ligand and 1,2‐di(pyridin‐4‐yl)ethane (4, 4′ bpe) (1–3) and 1,2‐bis(pyridin‐3‐ylmethylene)hydrazine (bpmh) (4–5) as the secondary ligands. Single crystal studies indicated that the compounds 1, 3 and 5 have two‐dimensional layer structures and compounds 2 and 4 three‐dimensional structures. The luminescence behaviour of the compounds 2 and 3 were explored for the sensing of metronidazole in aqueous medium. The studies indicated that the compounds can detect metronidazole in ppm level both in solution as well as simple paper strips. The Cu compound 5 was found to lose the coordinated water molecule at 100 °C without any structural change. The coordinatively unsaturated Cu‐centre were examined towards the Lewis acidic character by carrying out the Ullmann type C−C homocoupling reaction of the aromatic halide compounds. The compounds, 4 and 5, also have the Lewis basic functionality arising out the =N−N=, aza groups. The bifunctional nature of the coordination polymers (CP) was explored towards the Chan‐Lam coupling reaction between phenyl boronic acid and aniline derivatives in the ethanol medium. In both the catalytic reactions, good yields and recyclability were observed. The present studies illustrated the rich diversity that the transition metal containing compounds exhibit in extended framework structures. [ABSTRACT FROM AUTHOR]

Comprehensive Summary Salimabromide, a unique and scarce marine tetracyclic polyketide, was synthesized in both racemic and optically active forms. A novel carboxylic acid‐directed method for tandem oxidative difunctionalization of olefins was developed, whereby the formation of bridged butyrolactone and enone moieties occurs concurrently. Density functional theory (DFT) calculations indicate that this reaction follows a [3+2] process rather than the [2+2] process. In the meantime, the distinctive benzo‐fused [4.3.1] carbon skeleton and highly hindered vicinal quaternary stereocenters were simultaneously constructed through a challenging intramolecular Giese‐Baran radical cyclization. Furthermore, deuterium kinetic isotopic effects were utilized to enhance the efficacy of this pivotal step. This represents a new illustration of the application of kinetic isotope effects in natural product synthesis. Then, the short asymmetric synthesis of (+)‐salimabromide (13 or 15 steps) was accomplished by combing this method with rhodium‐catalyzed enantioselective hydrogenation of a cycloheptenone derivative (97% ee) or conjugate addition of an aryl boronic acid with 2‐cyclohepten‐1‐one (> 99% ee). [ABSTRACT FROM AUTHOR]

Aldehyde decarbonylation is a vital chemical transformation in the synthesis of natural products. Nature accomplishes this process through a family of decarbonylase enzymes, while in the laboratory, harsh transition metals and elevated temperatures are required. Herein, we report a mild aldehyde decarbonylation reaction that exhibits exclusive selectivity for ortho -aldehydes during a tandem nitrile boronic acid cross-coupling reaction. A wide substrate scope is displayed that includes regioselective removal of the ortho -aldehyde from phenyl boronic acids in the presence of meta - or para -aldehydes. A mechanistic investigation of the observed regioselectivity for ortho -aldehydes by density functional theory (DFT) calculations shows that the CO ligand extrusion is energetically more favorable for the ortho position as compared to the para position. [ABSTRACT FROM AUTHOR]

The present article provides a personalized account on CH-arylation reactions employed for the synthesis of heterocycles. The presence of a nitro group allowed for direct and regioselective CH-arylations of pyrazoles, imidazoles, indoles and a variety of purine analogues. Direct CH-arylations without the presence of an activating nitro-group were employed for inter- and intramolecular reactions of purine derivatives, which allowed for the synthesis of a great variety of polycyclic systems. Domino C–N coupling / hydroamination / CH-activation reactions of diarylacetylenes with anilines allowed for the synthesis of polycondensated N -heterocycles. Products include indolo- and azaindolo[1,2- f ]phenanthridines, quinolino[3′,4′:4,5]pyrrolo[1,2- f ]phenanthridines, pyrimido[5′,4′:4,5]pyrrolo[1,2- f ]phenanthridines, and benzothieno[2′,3′:4,5]pyrrolo[1,2- f ]phenanthridines. The reaction of N -heterocycles, such as indoles, with 1,1-difluoroalkenes resulted in a twofold addition-elimination reaction to give 1,1-diaminoalkenes, which were transformed by CH-arylation into various polycondensated heterocycles, such as indoloisoquinolines, thienoindolizines, oxepines and helicenes. Pyridofluoranthenes, diindenopyrene and azadiindenopyrenes were prepared by a combination of Pd-catalyzed cross-coupling reactions with acid-mediated cycloisomerizations and Pd-catalyzed intramolecular CH-arylations. Bis(carbazoles), benzodithiazoles, benzodithiophenes and 2,5-diarylpyrroles were prepared by inter- and intramolecular CH-arylation reactions. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: 2,3‐Allenyl amines have shown wide applicability in biomedical and synthetic applications. Due to their enormous potential for applications, researchers have been dedicated to the development of methods for synthesizing 2,3‐allenyl amines. Herein, a palladium‐catalyzed three‐component reaction of 2‐alkynyl‐1,4‐diol dicarbonates, organoboronic acids, and nitrogen nucleophiles forming 2,3‐allenyl amines with excellent regio‐ and chemo‐selectivity has been developed. Substrate compatibility and synthetic applications have been demonstrated. Control experiments supported a mechanism involving 1,2,3‐triene‐Pd species and methylene‐π‐allyl palladium species. [ABSTRACT FROM AUTHOR]

We demonstrated that the combination of a Pd(0) catalyst and a water‐soluble TPPMS ligand has high activity for the direct arylation of readily available allylic alcohols in the Tsuji–Trost type cross‐coupling. Various organoboron reagents can be applied, enabling rapid access to the corresponding arylated products with a wide range of functional group tolerance. Kinetic studies revealed a first‐order rate dependence for the allylic alcohol, boronic acid, CsF and Pd(0)/TPPMS concentrations. A Hammett study found a slightly positive ρ value of 0.79, suggesting that a partial negative charge is generated on the aromatic ring of the aryl boronate in the rate‐determining transmetalation step. Based on several control experiments, we concluded that the transmetalation employing CsF would proceed via the oxo‐palladium mechanism. [ABSTRACT FROM AUTHOR]

The long-lived room-temperature phosphorescence (RTP) originating from thiophene boronate polyvinyl alcohol (PVA) has enabled the creation of metal-ion-responsive RTP films doped with spirolactam ring-containing rhodamine 6G (1). In this study, RTP-active PVA films, namely, TDB@PVA and ATB@PVA, were prepared through boronate esterification of thiophene-2,5-diboronic acid (TDB) and 5-acetylthiophene-2-boronic acid (ATB) with the diol units of PVA. The delayed emission properties were evaluated, revealing an emission band at 477 nm with a turquoise afterglow for TDB@PVA and at 510 nm with a green afterglow for ATB@PVA after UV light irradiation ceased. The photophysical properties were assessed using TD-DFT and DFT calculations at the B3LYP/cc-pVDZ level. N-(rhodamine-6G)lactam dye with a salicylimine unit (1) was doped into the RTP-based PVA films, producing a multicolored afterglow upon the addition of metal ions. This phenomenon is explained by a triplet-tosinglet Förster-type resonance energy transfer process from the cross-linked thiophene boronate in PVA to the metal-ion-activated colored form of 1. This photophysical feature finds applicability in encryption techniques. Notably, the reversible metal-ligand coordination of 1 in the PVA system enabled a write/erase information process. [ABSTRACT FROM AUTHOR]

ABSTRACT Herein, we have developed palladium‐trifluoroacetate‐catalyzed carbo‐palladation reaction of pyrrole‐2‐carbonitriles and aryl boronic acids leading to functionally diverse pyrrolo[1,2‐α]pyrazines under thoroughly optimized reaction conditions. The reaction proceeded smoothly and allowed the diversity‐oriented synthesis of pyrrolo[1,2‐α]pyrazines with broad substrate scope with respect to pyrrole‐2‐carbonitriles and aryl boronic acids. [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]

ABSTRACT We have described herein a simple and formal two‐step synthesis of 3‐(4,6‐diaryl‐1,3,5‐triazin‐2‐yl)‐2‐aryl quinolines from 2‐chloro‐3‐(4,6‐diaryl‐1,3,5‐triazin‐2‐yl) quinolines and boronic acids under the Suzuki–Miyaura conditions. This protocol provides the C‐2 arylation of 2‐chloro‐3‐(4,6‐diaryl‐1,3,5‐triazin‐2‐yl) quinolines under the mild reaction conditions. These newly formed chemo‐types may be useful in drug discovery programs or in material chemistry. [ABSTRACT FROM AUTHOR]

Rapid distinguishing and detection of Gram-positive and Gram-negative bacteria with high sensitivity is essential for human health worldwide. Herein, an excellent fluorescence biosensing platform for bacterial identification and detection is constructed on the basis of boronic acid functionalized carbon dots (B-CDs). The B-CDs fluorescence probes were tightly attached to the bacterial surface through the interaction of the boronic acid group with glycolipids on the outside of bacterial cells. Our experimental results showed that the B-CDs displayed a stronger binding ability toward Gram-positive bacteria, enabling the specific detection of Gram-positive bacteria. More importantly, Gram-positive bacteria and Gram-negative bacteria differ in terms of their saccharide units on the cell wall, resulting in distinct fluorescence signals, which could be employed for distinguishing Gram-positive and Gram-negative bacteria. Taking S. aureus as a representative of Gram-positive bacteria, the results showed that the linear range of detection was 2.6 × 101–5.2 × 106 CFU mL−1 and the detection limit was 7 CFU mL−1. Our research provides great potential for further development of a novel platform for bacterial determination and identification. [ABSTRACT FROM AUTHOR]

A strategy for transition metal‐free cross‐coupling of alkyl nitroso‐carbamates and boronic acids is reported. The N‐nitroso carbamates are easily prepared from the corresponding amine in two simple steps. This method allows for the synthesis of a wide variety of secondary boronates, benzylic boronates and formal Csp3−Csp2 cross‐coupling products under operationally simple conditions. Functional group tolerance is also demonstrated and applied in the modification of lysine to make non‐canonical amino acids. [ABSTRACT FROM AUTHOR]

In this work, we present a copper‐catalyzed rapid and efficient method for cross‐coupling of N‐hydroxy benzotriazole with boronic acids under microwave irradiation for the synthesis of 1‐aryl benzotriazole 3‐oxides. This protocol tolerates a wide range of substituted boronic acids to provide the corresponding products in good to excellent yields. The features of this strategy include a broad substrate scope, high functional group tolerance, short reaction time, and good to excellent yields. [ABSTRACT FROM AUTHOR]

The general synthesis of boron-containing cyclic compounds (boracycles) necessitates toxic organotin precursors or highly reactive boron halides. Here, we report the synthesis of seven- and five-membered boracycles utilizing arylboronic acid pinacol esters (ArBpins) as stable boron sources. Grignard reagents generated from 2,2′-dibromodibenzyl or 2,2′-dibromobiphenyl reacted with ArBpins, where Ar = 9-anthryl (Anth), 2,4,6-trimethylphenyl (Mes), or 2,4,6-triisopropylphenyl (Tip), to give 10,11-dihydro-5H-dibenzo[b,f]borepins or dibenzoborole derivatives. This Bpin-based method was successfully applied to a one-shot double boracycle formation, providing a dihydrodibenzoborepin–anthracene–dihydrodibenzoborepin triad molecule in a good yield. The dihydrodibenzoborepin bearing the Anth group was directly converted to the unsaturated borepin by NBS/AIBN. All products were characterized by NMR, HRMS, and in some cases, single-crystal X-ray diffraction analysis. Additionally, the photophysical properties of the products are also reported. [ABSTRACT FROM AUTHOR]

Two chelating N‐heterocyclic carbene (NHC) palladium complexes 3a‐b containing N‐(3‐bromopropyl)‐N′‐thioether difunctionalized imidazol‐2‐ylidene were synthesized by direct metalation of the precursor imidazolium salts and characterized by NMR and HR‐MS. The molecular structure of 3a has been further characterized unambiguously by X‐ray single crystal analysis. The subsequent substitution reaction with amine‐functionalized magnetic nanoparticles (MNPs‐NH2) afforded two highly active, stable, and recyclable magnetic nanoparticle supported NHC palladium complexes, MNPs‐NHC‐Pd I‐II, which were characterized by Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), inductively coupled plasma optical emission spectrometry (ICP‐OES), scanning electron microscopy (SEM), and X‐ray photoelectron spectroscopy (XPS). The MNPs‐NHC‐Pd complexes exhibited high catalytic activity in the Suzuki–Miyaura cross‐coupling reaction of aryl bromides with arylboronic acids, as well as in the reduction of toxic 4‐nitrophenol (4‐NP) under mild conditions. The recycling experiment of MNPs‐NHC‐Pd I in the Suzuki–Miyaura cross‐coupling reaction between 4‐bromoanisole and phenylboronic acid showed that the yield of 4‐methoxybiphenyl remained high at 88% within 0.5 h at 60 °C, indicating that the catalytic activity was well maintained for at least 10 cycles. [ABSTRACT FROM AUTHOR]

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]

Complex dynamic systems displaying interdependency between nitroaldol and boronic ester reactions have been demonstrated. Nitroalkane‐1,3‐diols, generated by the nitroaldol reaction, were susceptible to ester formation with different boronic acids in aprotic solvents, whereas hydrolysis of the esters occurred in the presence of water. The boronic ester formation led to significant stabilization of the nitroaldol adducts under basic conditions. The use of bifunctional building blocks was furthermore established, allowing for main chain nitroaldol‐boronate dynamers as well as complex network dynamers with distinct topologies. The shape and rigidity of the resulting dynamers showed an apparent dependency on the configuration of the boronic acids. [ABSTRACT FROM AUTHOR]

We describe a palladium-catalyzed Suzuki-type cross-coupling reaction of 2-pyridyl carbamoyl fluorides with boronic acids, which provides entry to medicinally relevant pyridyl amides. Mechanistic studies, including the synthesis and reactivity of carbamoyl Pd–F complexes, reveal the importance of both the fluoride electrophile and nitrogen directing group for aiding reactivity. [ABSTRACT FROM AUTHOR]

ABSTRACT We have developed a highly efficient, ligand‐free Suzuki–Miyaura cross‐coupling protocol employing our lab‐prepared air and moisture‐stable Pd‐PEPPSI catalysts. The reaction of ethyl 2‐{4‐[(6‐chloroquinoxalin‐2‐yl)oxy]phenoxy}propionate (Assure) with various boronic acids afforded both traditional and decarbonylative coupling products in high yields. The catalyst's steric influence was assessed computationally using %Vbur calculations. The decarbonylative coupling pathway proved more efficient than the traditional Suzuki–Miyaura coupling under these conditions. Additionally, regioselectivity studies have been conducted on a variety of Assure analogues. This method excels in efficiency, requiring minimal catalyst, moderate temperatures, and rapid reaction completion. [ABSTRACT FROM AUTHOR]

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]

Selective detection of reactive oxygen species (ROS) is vital for studying their role in brain diseases. Fluorescence probes can distinguish ONOO− species from other ROS; however, their selectivity toward ONOO− species depends on the ONOO− recognition group. Aryl‐boronic acids and esters, which are common ONOO− recognition groups, are not selective for ONOO− over H2O2. In this study, we developed a diaminonaphthalene (DAN)‐protected boronic acid as a new ONOO− recognition group that selectively reacts with ONOO− over H2O2 and other ROS. Three DAN‐protected boronic acid (DANBA)‐based fluorophores that emit fluorescence over visible to near‐infrared (NIR) regions, Cou‐BN, BVP‐BN, and HDM‐BN, and their aryl‐boronic acid‐based counterparts (Cou‐BO, BVP‐BO, and HDM‐BO), were developed. The DANBA‐based probes exhibited enhanced selectivity toward ONOO− over that of their control group, as well as universality in solution assays and in vitro experiments with PC12 cells. The NIR‐emissive HDM‐BN was optimized to delineate in vivo ONOO− levels in mouse brains with Parkinson's disease. This DAN‐protected boronic acid belongs to a new generation of recognition groups for developing ONOO− probes, and this strategy could be extended to other common hydroxyl‐containing dyes to detect ONOO− levels in complex biological systems and processes. [ABSTRACT FROM AUTHOR]

Saccharides, being one of the fundamental molecules of life, play essential roles in the physiological and pathological functions of cells. However, their intricate structures pose challenges for detection. Nanopore technology, with its high sensitivity and capability for single-molecule-level analysis, has revolutionized the identification and structural analysis of saccharide molecules. This review focuses on recent advancements in nanopore technology for carbohydrate detection, presenting an array of methods that leverage the molecular complexity of saccharides. Biological nanopore techniques utilize specific protein binding or pore modifications to trigger typical resistive pulses, enabling the high-sensitivity detection of monosaccharides and oligosaccharides. In solid-state nanopore sensing, boronic acid modification and pH gating mechanisms are employed for the specific recognition and quantitative analysis of polysaccharides. The integration of artificial intelligence algorithms can further enhance the accuracy and reliability of analyses. Serving as a crucial tool in carbohydrate detection, we foresee significant potential in the application of nanopore technology for the detection of carbohydrate molecules in disease diagnosis, drug screening, and biosensing, fostering innovative progress in related research domains. [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]

Opportunistic bacterial pathogens can evade the immune response by residing and reproducing within host immune cells, including macrophages. These intracellular infections provide reservoirs for pathogens that enhance the progression of infections and inhibit therapeutic strategies. Current sensing strategies for intracellular infections generally use immunosensing of specific biomarkers on the cell surface or polymerase chain reaction (PCR) of the corresponding nucleic acids, making detection difficult, time-consuming, and challenging to generalize. Intracellular infections can induce changes in macrophage glycosylation, providing a potential strategy for signature-based detection of intracellular infections. We report here the detection of bacterial infection in macrophages using a boronic acid (BA)-based pH-responsive polymer sensor array engineered to distinguish mammalian cell phenotypes by their cell surface glycosylation signatures. The sensor was able to discriminate between different infecting bacteria in minutes, providing a promising tool for diagnostic and screening applications. [ABSTRACT FROM AUTHOR]

Currently, there are many uses of metal complexes, especially in the fields of medicinal chemistry and catalysis. Thus, fabrication of new complexes which perform as a catalyst and chemotherapeutic drug is always a beneficial addition to the literature. Herein, we report three heterocyclic thiosemicarbazone-based Pd(II) complexes [Pd(HL1)Cl] (C1), [Pd(L2)(PPh3)] (C2) and [Pd(L3)(PPh3)]Cl (C3) having coligands Cl and PPh3. Thiosemicarbazone ligands (H2L1, H2L2 and HL3) and the complexes (C1–C3) were characterized methodically using several spectroscopic techniques. Single-crystal X-ray diffraction methods reveal that the structural environment around the metal center of C2 is square planar, while for C1 and C3 it is a slighty distorted square plane. The supramolecular network of compounds was built via hydrogen bonds, C–H⋯π and π⋯π interactions. Density functional theory (DFT) study of the structure of the complexes supports experimental findings. The application of these complexes as catalysts toward Suzuki–Miyaura coupling reactions has been examined with various aryl halides and phenyl boronic acid in PEG 400 solvent. The complexes displayed good biomolecular interactions with DNA/protein, with a binding constant value of the order of 105 M−1. C3 showed greater binding efficacy toward these biomolecules than the other complexes, which might be due to the cationic nature of C3. Furthermore, antitumor activity of the complexes was studied against the human triple-negative breast cancer (TNBC) cell line MDA-MB-231. It was found that C3 was more toxic (IC50 = 10 ± 2.90 μM) toward MDA-MB-231 cells than the other complexes. A known chemotherapeutic drug, 5-fluorouracil, was included as positive control. The programmed cell death mechanism of C3 was confirmed. Additionally, complex-induced apoptosis was confirmed and occurred via a mitochondria-dependent (intrinsic) pathway. [ABSTRACT FROM AUTHOR]

The environmentally benign synthesis of indoline boronic esters, especially through a way of arylboration to alkenes, remains a challenge due to the use of transition metals or high-temperature conditions. We described a photoinduced metal-free arylboration of unactivated alkenes for the synthesis of indoline boronic esters and 1,2,3,4-tetrahydroquinoline boronic ester in good yields. This approach showed good compatibility and great efficiency for a range of allylphenylamines as well as alkylamine. Remarkably, this transformation also suggested that the base is not necessary for photosensitizer-free diboron reagent mediated mild generation of aryl radical. Furthermore, compared to previously reported methods, this approach is mild and environmentally benign. [ABSTRACT FROM AUTHOR]

Organoboron compounds have a wide range of applications in numerous research fields, and methods to incorporate them in biomolecules are much sought after. Here, on‐resin chemical syntheses of aliphatic and vinylogous peptide boronic acids are presented by transition metal‐catalyzed late‐stage hydroboration of alkene and alkyne groups in peptides and peptoids, for example on allyl‐ and propargylglycine residues, using readily available chemicals. These methods yield peptide boronic acids with much shorter linkers than previously reported on‐resin methods. Furthermore, the methods are regio‐ and stereoselective, compatible with all canonical amino acid residues and can be applied to short, long, and in part even "difficult" peptide sequences. In a feasibility study, the protected peptide vinylboronic acids are further derivatized by the Petasis reaction using salicylaldehyde derivatives. The ability of the obtained peptide boronic acids to reversibly bind to carbohydrates is demonstrated in a catch‐release model experiment using a fluorescently labeled peptide boronic acid on cross‐linked dextran beads. In summary, this highlights the potential of the target compounds for drug discovery, glycan‐specific target recognition, controlled release, and diagnostics. [ABSTRACT FROM AUTHOR]

Sterically hindered 2,7-diaryl fluorenes have been efficiently synthesized via double Suzuki–Miyaura cross-coupling reactions of challenging 2,7-dichlorofluorene with a broad range of di-ortho-substituted arylboronic acids using the N-heterocyclic carbene Pd catalyst INPd. The efficiency of chloride-directed reactions is superior to that of bromide-directed reactions. Mechanistic studies revealed a tandem process for the double Suzuki–Miyaura cross-coupling reaction. [ABSTRACT FROM AUTHOR]

Organic molecules with light‐modifiable reactivity are important in many fields because they can serve as the "switch" for light to trigger chemical processes. Herein, we disclose a new type of stable non‐twisted amides, the reactivity of which can be turned on by light as acyl transfer reagents. Upon photo‐activation, these amides react with various nucleophiles including amines, phenols, hydroxide, thiols, boronic acids, and alkynes either under metal‐free or metal‐catalysis conditions. This reactivity hinges on the design and synthesis of a photo‐activatable reagent (7‐nitro‐5,6‐dihydrophenanthridine), which undergoes self‐aromatization enabled by an internal oxidant under light. This masked acyl donor group is anticipated to be useful in scenarios where light is preferred to trigger a chemical process. [ABSTRACT FROM AUTHOR]

Novel fluorescent pyrazole-containing boron (III) complexes were synthesized employing a one-pot three-component reaction of 3-hydroxy-1-phenyl-1H-pyrazole-4-carbaldehyde, 2-aminobenzenecarboxylic acids, and boronic acids. The structures of the novel heterocyclic compounds were confirmed using 1H-, 13C-, 15N-, 19F-, and 11B-NMR, IR spectroscopy, HRMS, and single-crystal X-ray diffraction data. The photophysical properties of the obtained iminoboronates were investigated using spectroscopic techniques, such as UV–vis and fluorescence spectroscopies. Compounds display main UV–vis absorption maxima in the blue region, and fluorescence emission maxima are observed in the green region of the visible spectrum. It was revealed that compounds exhibit fluorescence quantum yield up to 4.3% in different solvents and demonstrate an aggregation-induced emission enhancement effect in mixed THF–water solutions. [ABSTRACT FROM AUTHOR]

A visible‐light‐induced method was developed to synthesize selenylated cyclic boronic esters through intermolecular oxyselenenylation. This method can be performed under additive‐free and photocatalyst‐free conditions and generates potentially pharmaceutically useful heterocycles. A plausible reaction mechanism was proposed based on several control experiments and previous reports. [ABSTRACT FROM AUTHOR]

A novel class of crystalline porous materials has been developed utilizing multilevel dynamic linkages, including covalent B−O, dative B←N and hydrogen bonds. Typically, boronic acids undergo in situ condensation to afford B3O3‐based units, which further extend to molecular complexes or chains via B←N bonds. The obtained superstructures are subsequently interconnected via hydrogen bonds and π–π interactions, producing crystalline porous organic frameworks (CPOFs). The CPOFs display excellent solution processability, allowing dissolution and subsequent crystallization to their original structures, independent of recrystallization conditions, possibly due to the diverse bond energies of the involved interactions. Significantly, the CPOFs can be synthesized on a gram‐scale using cost‐effective monomers. In addition, the numerous acidic sites endow the CPOFs with high NH3 capacity, surpassing most porous organic materials and commercial materials. [ABSTRACT FROM AUTHOR]

This study introduces boronic ester-based ROS-responsive amphiphilic copolymers for antioxidant drug delivery. Tuning the hydrophobic/hydrophilic balance optimized the size, curcumin encapsulation, ROS-triggered release, cellular uptake, and intracellular ROS scavenging. The lead P1b formulation self-assembled into stable 10 nm micelles enabling rapid ROS-triggered curcumin release and preferential cellular internalization. P1b eliminated over 90% of pathogenic intracellular ROS within 10 minutes, demonstrating a rapid antioxidant therapy. [ABSTRACT FROM AUTHOR]

Cellulose acetate (CA) has found broad applications for many years. However, the development of mechanically strengthened CA materials without losing the processibility in solution remains quite difficult. In this work, novel CA thermosets are reported that can be readily constructed by employing alkyl diboronic acid as a crosslinking agent, which has allowed convenient reconfiguration of CA networks without demanding catalysts or harsh processing conditions. Various properties including thermal stability, creeping resistance, rheological and mechanical strength have been successfully improved by using small amounts (1–5 wt%) of diboronic acid. The dynamic cross‐linked network based on boron chemistry has facilitated solution processing during three times of recycling. Control experiments have shown that alkyl diboronic acid can deliver superior mechanical strength to CA as compared to aryl diboronic acid or single‐arm alkyl boronic acid. Based on the importance of CA materials, this work should be attractive to the design of reprocessible CA thermosets with high performance. [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]

The given text consists of multiple articles and documents related to the synthesis and characterization of various compounds. These compounds have potential biological activities and are synthesized using different reactions and characterized using spectroscopic techniques. The articles provide detailed information on the synthesis methods, experimental conditions, and characterization data for each compound. The text also includes a graph that visually represents data on a specific topic, which can be helpful for researchers conducting further studies. [Extracted from the article]

The Zweifel olefination is a highly efficient and versatile method for constructing carbon-carbon double bonds in organic synthesis. It avoids the use of transition metals and has been applied in natural product synthesis and drug discovery. Recent progress in the field includes the use of new organometallic species, electrochemical and photocatalyzed reactions, and exploration of milder reaction conditions. However, further research is needed to develop less functional-group-sensitive reagents and investigate new strategies for generating alkenyl boron complexes. [Extracted from the article]

This article discusses the modular synthesis of conjugated aromatic boronate esters through radical xanthate addition. The researchers successfully synthesized xanthates with phenylboronate groups and demonstrated their potential for synthesizing boronate-containing conjugated aromatic compounds. The document provides detailed information about the synthesis and characterization of various compounds, including their chemical structures, spectroscopic data, and yields. It can be useful for researchers studying organic synthesis and compound characterization. [Extracted from the article]

Chemoselective monoborylation of methane in high yield is a grand challenge. We have developed a metal–organic framework confined pyridylimine-iridium hydride catalyst, which is efficient in methane C–H borylation using bis(pinacolato)diboron to afford methyl boronic acid pinacol ester in 98% GC-yield at 130 °C with a TON of 196. Mechanistic investigation suggests the oxidative addition of methane to IrIII(Bpin)2(H) species to form IrV(Bpin)2(CH3)(H)2 as the turnover limiting step. [ABSTRACT FROM AUTHOR]

A one‐pot Pd‐catalyzed tandem process to prepare (2‐arylallyl) aryl sulfones has been developed. This strategy is based on the modular assembly of a boronic acid, a sodium sulfinate and 2‐bromoallyl acetate. The reaction is completely regioselective towards the terminal alkene, yielding (2‐arylallyl) aryl (or alkyl) sulfones with yields ranging from 56 to 93%. Control experiments together with DFT calculations allowed to propose a plausible reaction mechanism of the tandem reaction. The usefulness of this methodology has been demonstrated with the formal synthesis of the marketed drug Apremilast and of several natural products by asymmetric hydrogenation. Using the commercially available UbaPHOX iridium complex, chiral β‐methyl sulfones with up to 98% ee were obtained [ABSTRACT FROM AUTHOR]