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Graft polymerization of polymethyl methacrylate-block-polystyrene (PMMA-b-PSt) has been carried out from the surface of multi-walled carbon nanotubes (MWCNTs) using living radical polymerization methods. For this purpose, the first surfaces of MWCNTs were functionalized by acid treatment and then acylated by thionyl chloride (SOCl2). After that, the toluene unit was successfully grafted onto MWCNTs side walls by Friedel craft acylation reaction in the presence of ZnO as a catalyst. The obtained nanotube-toluene was brominated by N-bromosuccinimide (NBS). This brominated nanotube-toluene was used as a macroinitiator for atom transfer radical polymerization (ATRP) of methyl methacrylate (MMA) in the presence of the CuBr/2, 2 -bipyridine (bpy) catalyst system to obtain MWCNTs-graft-polymethyl methacrylate (MWCNTs-g-PMMA). Then 1-hydroxy-2, 2, 6, 6-tetramethyl-piperidine (TEMPO-OH) obtained by reduction of 2, 2, 6, 6-tetramethyl-piperidinyl-1-oxy (TEMPO) with sodium ascorbate. The bromine groups at the end of PMMA have converted to nitroxide mediated groups by coupling with TEMPO-OH to yield MWCNTs terminated with a TEMPO unit (MWCNTs-PMMA-TEMPO). At last, the resulting macroinitiator was employed for 'living' free-radical polymerization of styrene (St) by nitroxide-mediated radical polymerization (NMRP) to form MWCNTs-g-(PMMA-b-PS). Fourier transform infrared (FT-IR) spectroscopy, transmission electron microscopy (TEM), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and thermogravimetric analysis (TGA) show the effective grafting of MMA and styrene onto the MWCNTs. [ABSTRACT FROM AUTHOR]

The study assesses the relative reactivity of the regio isomers of methyl indole in bromination reactions on a quantitative scaffold. The kinetic and thermodynamic data have been obtained for the bromination reactions with the regio isomers of methyl indole by N-Bromo succinimide in the aqueous medium using hydrodynamic voltammetry technique. These reactions follow second order kinetics and are found to be very rapid and the rapidity of the reactions compels the use of the special technique employed herein. The variation in reaction rates with temperature was studied. The specific reaction rates, energies of activation, entropy change and the pre-exponential factor in the reactions were evaluated. The specific reaction rates at 306 K for 1-methyl indole, 2-methyl indole and 3-methyl indole are 2800, 4955 and 1558 M-1s-1 respectively. The data has been analyzed to quantitatively ascertain the steric constraints in the dynamics of these reactions. [ABSTRACT FROM AUTHOR]

Background: Analytical tests were conducted to investigate the use of N-bromosuccinimide (NBS) as an important, safe analytical reagent for the spectrophotometric detection of therapeutically significant dihydropyridine-based calcium antagonists (DHP), namely nifedipine (NIF) and amlodipine (AML), which have been demonstrated to possess antioxidant activity in vivo and to reduce the intracellular production of reactive oxygen species (ROS). Following the reaction of DHP and NBS in acidic media, the excess NBS was evaluated for the first time by its interaction with P-aminophenol (PAP), which produced a violet-colored product that was detected at 556 nm., Objective: The analytical method was performed and validated since different variables disturbing the reaction (concentration of reagent, type and concentration of the selected acid, reaction time and the diluting solvents) were carefully studied and optimized., Methods: The stoichiometry of the applied reaction was determined by Job's method of continuous variation. Monitoring of these drug dosage forms' content uniformity is a first tool or evidence for their efficacy and safety after their administration., Results: Beer's law was obeyed in the concentration range 1.25-11.0 µg/mL for NIF and 1.25-10.0 µg/mL for AML. The calculated limit of detection (LODs) and limit of quantification (LOQs) for NIF and AML were 0.220, 0.155 µg/mL and 0.519, 0.735 µg/mL, respectively. The precision of the applied method was satisfactory; the RSDs did not exceed 2%. Two greenness assessment tools, the Green Analytical Procedure Index (GAPI) and Analytical Greenness Metric for Sample Preparation (AGREEprep) were used for measuring the environmental friendliness of the recommended method., Conclusion: The micro-determinations of content uniformity for NIF and AML in their pharmaceutical dosage forms were extremely comparable with those from official and validated procedures., Highlights: A validated indirect spectrophotometric method for accurate quantification of some 1,4-dihydropyridine drugs using NBS with the aid of PAP. Monitoring of NIF and AML dosage forms' content uniformity as a first tool or evidence for their efficacy and safety after their administration. Greenness evaluation tools, GAPI and AGREEprep, for measuring the environmental friendliness of the recommended method., (© The Author(s) 2023. Published by Oxford University Press on behalf of AOAC INTERNATIONAL. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

An efficient and unprecedented green protocol has been developed for the synthesis of N,S-heterocycles from styrenes and alkyl dithiocarbamates with high to excellent yields. The reaction of primary or secondary amines, CS2 , and styrenes was carried out in water in the presence of a catalytic amount of an inorganic base. All products were made by using an N -bromosuccinimide–H2 O combination as a green and inexpensive reagent. [ABSTRACT FROM AUTHOR]

After an initial report from our laboratory describing metal-free decarboxylative halogenation of various azaheteroarenes, we set out to investigate the possible mechanism by which this chemistry occurs. Evidence from this mechanistic investigation suggests that this chemistry occurs via a radical pathway, with1 H NMR studies suggesting that the acidic substrates activate NBS. [ABSTRACT FROM AUTHOR]

The oxidation of glycine using N-bromosuccinimide (NBrS) has been studied for different pH’s values. With respect to both substrate and oxidant, the reaction presents a consecutive-first order reaction. It is noted that the rate of reaction increases with increasing the manganese ion concentration. Addition of reaction product (succunumide) slightly affects the oxidation reaction rate. The protonated Br+ or NBrS and NBrS are used to be the reactive species of the N-bromosuccinimide. Furthermore, intermediate compounds are noticed through the reaction. Finally, a mechanism for the oxidation reaction is suggested in this work. [ABSTRACT FROM AUTHOR]

A new, direct, efficient, and transition-metal-free method is reported for the synthesis of β-bromostyrenes from styrenes by using N -bromosuccinimide as the brominating reagent and sodium persulfate (Na2 S2 O8) as the oxidant. This convenient and concise reaction is practical, operationally simple, and can be adapted for large-scale syntheses. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Education & Science is the property of Republic of Iraq Ministry of Higher Education & Scientific Research (MOHESR) and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Abstract Experimental design approach was used to optimize the experimental factors in developing a spectrophotometric method for quantification of acetazolamide using N -bromosuccinimide (NBS) as a reagent. In this method, a known excess of NBS was mixed with acetazolamide in acid medium and the unreacted NBS was treated with methyl orange which was monitored at 513 nm. The effects of critical factors such as volumes of 5.60 × 10−4 mol L−1 NBS, 0.5 mol L−1 HCl, 4.2 × 10−2 mol L−1 KBr and 1.53 × 10−4 mol L−1 methyl orange on the absorbance were analysed and these factors were optimized using Box-Behnken design (BBD) and desirability function. The calibration curve was linear in the range of 6–18 μg mL−1 with a correlation coefficient of 0.9999. The detection limit was 0.023 μg mL−1. The method was used to quantify the acetazolamide content in commercial tablets and urine samples. The percentage recoveries of acetazolamide in urine samples were found to vary from 96.22–96.39%. Graphical abstract Unlabelled Image Highlights • Method is based on bromination of acetazolamide by N -bromosuccinimide. • Box-Behnken design is used to optimize the experimental factors. • Method is applicable in the concentration range of 6–18 μg mL−1. • Acetazolamide, WADA banned drug, is determined in urine samples. [ABSTRACT FROM AUTHOR]

A novel acidic α‐galactosidase (EC 3.2.1.22) designated as Leucopaxillus tricolor α‐galactosidase (LTG) has been purified to homogeneity from the fruiting bodies of L. tricolor to 855‐fold with a specific activity of 956 U mg−1 by the application of chromatography and gel filtration. The molecular mass of LTG was estimated to be 60 kDa as determined by both SDS–PAGE and by gel filtration. The purified enzyme was identified by LC‐MS/MS and four inner amino acid sequences were obtained. When 4‐nitrophenyl α‐D‐glucopyranoside (pNPGal) was used as substrate, the optimal pH and optimal temperature of LTG were pH 5.0 and 50 °C, respectively. The enzyme activity was strongly inhibited by Hg2+, Fe3, Cu2+, Cd2+, and Mn2+ ions. The chemical modification agent N‐bromosuccinimide (NBS) completely inhibited the enzyme activity of LTG, indicating the paramount importance of tryptophan residue(s) to its enzymatic activity. Besides, LTG displayed wide substrate diversity with activity toward a variety of substrates such as stachyose, raffinose, melibiose, locust bean gum, and guar gum. Given the good ability of degrading the non‐digestible and flatulence‐causing oligosaccharides, this fungus may become a useful source of α‐galactosidase for multiple applications. [ABSTRACT FROM AUTHOR]

Oligonucleotides (ODNs) find applications as diagnostic and therapeutic tools due to their unique ability to interact, thanks to Watson-Crick base pairing, with a specific DNA or RNA target strand. Although most of the tools available today rely on mere hydrogen bond formation, chemical modifications to enable covalent interstrand-crosslinking (ICL) have been reported, and are gaining a place under the spotlight as they potentially offer a series of advantages over the state of the art, including a higher potency and selectivity. This methodological paper focuses on the use of a pro-reactive furan moiety and its subsequent oxidation for applications in ODN targeting. The design of effective capture and targeting probes to ensure high ICL yields is discussed and the mechanisms underlying the (photo)chemical oxidation of furan are explained. Furthermore, examples of furan-containing DNAs designed for different applications, including DNA-DNA or DNA-RNA ICL and DNA-peptide/protein targeting, are provided. The paper highlights the advantages of using different oxidative chemical triggers, such as N-bromosuccinimide or singlet oxygen, to offer additional selectivity control over the ICL reaction., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

The versatility of the trityl cation (TrBF4) as a highly efficient Lewis acid organocatalyst is demonstrated in a light induced benzylic brominaion of alkyl‐arenes under mild conditions. The reaction was conducted at ambient temperature under common hood light (55 W fluorescent light) with catalyst loadings down to 2.0 mol% using N‐bromosuccinimide (NBS) as the brominating agent. The protocol is applicable to an extensive number of substrates to give benzyl bromides in good to excellent yields. In contrast to most previously reported strategies, this protocol does not require any radical initiator or extensive heating. For electron‐rich alkyl‐arenes, the trityl ion catalyzed bromination could be easily switched between benzylic sp3 C−H functionalization and arene sp2 C−H functionalization by simply alternating the solvent. This chemoselective switch allows for high substrate control and easy preparation of benzyl bromides and bromoarenes, respectively. The chemoselective switch was also applied in a one‐pot reaction of 1‐methylnaphthalene for direct introduction of both sp3 C−Br and sp2 C−Br functionality. [ABSTRACT FROM AUTHOR]

The reaction of bromosuccinimide with esters of 3-substituted 2,2'-bithiophene-5-carboxylic acids was used to obtain their 5'-bromo derivatives, which were further converted to esters of 3,3'''-disubstituted 2,2':5',2'':5'',2'''-quaterthiophene-5,5'''-dicarboxylic acids by heating in DMF with catalytic amounts of Pd(PPh3)4. Ester of 3-decyl-2,2'-bithiophene-5-carboxylic acid was acylated at the С-5' position with lauroyl chloride in the presence of SnCl4, producing the respective ketone that was used in Vilsmeier-Haack reaction (DMF, POCl3). The 3-chloroacrylaldehyde derivative that was thus obtained was further used in reaction with ethyl thioglycolate in the presence of sodium ethoxide, giving ester of 3,3''-decyl-2,2':5',2''-terthiophene-5,5''-dicarboxylic acid. Alkaline hydrolysis of the obtained esters led to the corresponding 2,2':5',2'':5'',2'''-quaterthiophene-5,5'''- and 2,2':5',2''-terthiophene-5,5''-dicarboxylic acids. [ABSTRACT FROM AUTHOR]

The mechanism of N‐Bromosuccinimide (NBS) promoted synthesis of imidazo[1,2‐a]pyridine in water as well as the effective activation modes of NBS was investigated by Density Functional Theory (DFT) calculations. Two main mechanisms that differ in the reaction sequence of substrate were explored: styrene with NBS then followed by 2‐aminopyridine (M1) or simultaneously with NBS and 2‐aminopyridine (M2), and water‐assisted M2 is the more favored one. We found that the adding sequence of 2‐aminopyridine affects profoundly on the title reaction. Moreover, upon the assistance of water and NBS, the preferential mechanistic scenario involves three major processes: nucleophilic addition, stepwise H‐shift and intramolecular cyclization, three‐step deprotonation, rather than a classical bromonium ion species. Specifically, the cooperative interaction of NBS and water plays a critical role in the title reaction. Water acts as solvent, reactant, anchoring, stabilizer, and catalyst. NBS promotes the above three processes by the effective forms of Br+/Br−, succinimide, and its ethanol isomer. Furthermore, noncovalent interactions between catalysts and substrates are responsible for the different reactive activities of M1 and M2. Our results indicate that simultaneous adding of all reactants is recommended toward economical synthesis. © 2018 Wiley Periodicals, Inc. DFT calculations disclosed a H2O‐NBS cooperated preferential synthesis strategy of imidazo[1,2‐a]pyridine differ in the reaction sequence of substrates. [ABSTRACT FROM AUTHOR]

Abstract A N -bromosuccinimide (NBS) mediated decarboxylative sulfonylation of β -keto acids with sodium sulfinates is developed. The transformation exhibits a broad substrate scope and good functional group tolerance. Preliminary mechanistic studies showed that this reaction is likely to proceed through a nucleophilic substitution of β -keto acid with sulfonyl bromide pathway. All synthesized β -keto sulfones were evaluated the inhibitory effect against human carboxylesterase 1 (CES1). This investigation offers an expedient strategy for efficient synthesis of β -keto sulfones that are widely present in biologically active natural products and pharmaceutical agents. Graphical abstract Image 1 [ABSTRACT FROM AUTHOR]

Abstract: Metal‐free halogen(I) catalysts were used for the selective oxidation of aryl(heteroaryl)methanes [C(sp3)−H] to ketones [C(sp2)=O] or esters [C(sp3)−O]. The synthesis of ketones was performed with a catalytic amount of NBS in DMSO solvent. Experimental studies and density functional theory (DFT) calculations supported the formation of halogen bonding (XB) between the heteroarene and N‐bromosuccinimide, which enabled imine–enamine tautomerism of the substrates. No additional activator was required for this crucial step. Isotope‐labeling and other supporting experiments suggested that a Kornblum‐type oxidation with DMSO and aerobic oxygenation with molecular oxygen took place simultaneously. A background XB‐assisted electron transfer between the heteroarenes and halogen(I) catalysts was responsible for the formation of heterobenzylic radicals and, thus, the aerobic oxygenation. For selective acyloxylation (ester formation), a catalytic amount of iodine was employed with tert‐butyl hydroperoxide in aliphatic carboxylic acid solvent. Several control reactions, spectroscopic studies, and Time‐Dependent Density Functional Theory (TD–DFT) calculations established the presence of acetyl hypoiodite as an active halogen(I) species in the acetoxylation process. With the help of a selectivity study, for the first time we report that the strength of the XB interaction and the frontier orbital mixing between the substrates and acyl hypoiodites determined the extent of the background electron‐transfer process and, thus, the selectivity of the reaction. [ABSTRACT FROM AUTHOR]

Abstract: The chiral, triangular‐shape hexaimine macrocycles (trianglimines), bearing bulky alkynyl or aryl substituents were synthesized and studied by means of experimental and theoretical methods. The macrocyclization reactions are driven by the extraordinary stability of the trianglimine ring and provided products with high yields. Electrostatic repulsion between imine nitrogen atoms and the substituents forced an anti conformation of the aromatic linkers. Although the DFT‐optimized structure of 7 is D3 symmetrical, in the crystal, the macrocycle adopts a bowl‐like molecular shape. The macrocycle self‐assembles into tail‐to‐tail dimers by mutual interdigitation of aromatic moieties. In contrast, macrocycle 8 adopts a rigid pillararene‐like conformation. The nature of the substituent significantly affects the electronic properties of the linker. As a result, unexpectedly high exciton Cotton effects are observed in the electronic circular dichroism (ECD) spectra. The origin of these effects was subject of an in‐depth study. [ABSTRACT FROM AUTHOR]

N-halosuccinimides (NXSs) are well-known to be convenient, easily manipulable and low-priced halogenation reagents in organic synthesis. In the present work, N-bromosuccinimide (NBS) has been promoted as the most efficient and selective catalyst among the NXSs in the reaction of direct esterification of aryl and alkyl carboxylic acids. Comprehensive esterification of substituted benzoic acids, mono-, di- and tri-carboxy alkyl derivatives has been performed under neat reaction conditions. The method is metal-free, air- and moisture-tolerant, allowing for a simple synthetic and isolation procedure as well as the large-scale synthesis of aromatic and alkyl esters with yields up to 100%. Protocol for the recycling of the catalyst has been proposed. [ABSTRACT FROM AUTHOR]

CuBr2-catalysed bromoamination of maleimides has been achieved in THF with alkylamines and N-bromosuccinimide as nitrogen and bromine sources respectively. The reaction conditions were optimised. A series of bromoamination products such as 3-amino-4-bromomaleimides was synthesised with satisfactory yields. Furthermore, a plausible mechanism of the bromoamination of maleimides was discussed. [ABSTRACT FROM AUTHOR]

An N-bromosuccinimide (NBS)-initiated vic-diphosphination of styrenes with diphosphines proceeds under visible-light-promoted Ir(ppy)3 photoredox catalysis to deliver the corresponding 1,2-diphosphinoethane derivatives in good yields. The NBS is a bromine cation source and generates a bromophosphine, which undergoes a singleelectron reduction by the excited iridium species to form phosphinyl radicals of key species in the diphoshination reaction. The newly developed photoredox catalysis demonstrates better reaction efficiency, functional group compatibility, and scalability than the previous photocatalysis using N-fluorobenzenesulfonimide (NFSI) and silylphosphine. [ABSTRACT FROM AUTHOR]

Reaction of cyclohexane-1,3-diones with TsCl/Et 3 N and treatment of the resulting 3-(tosyloxy)cyclohex-2-en-1-ones with aryl- or alkyl thiols and K 2 CO 3 in MeCN gives 3-(arylsulfanyl)cyclohex-2-en-1-ones or 3-(alkylsulfanyl)cyclohex-2-en-1-ones, respectively. These compounds are easily brominated at C-2 by using NBS in MeCN; exposure to DBU in MeCN at room temperature then causes aromatization to afford meta -arylsulfanyl- and meta -(alkylsulfanyl)phenols. [ABSTRACT FROM AUTHOR]

An expedient one-pot synthesis of aromatic amides has been reported from styrenes in the presence of N -bromosuccinimide and iodine by using aqueous ammonia in water. The reaction proceeds through the formation of α-bromoketone as an intermediate in the presence of NBS and water. α-Bromoketone on reaction with iodine forms bromodiiodoketone which on nucleophilic substitution with aqueous ammonia gives aromatic amide. Substituted aromatic amides were obtained in good yields with wide functional group compatibility. [ABSTRACT FROM AUTHOR]

(2,3-Dihydrobenzo[b][1,4]oxathiin-3-yl)methanols were synthesized via reactions of aryloxymethylthiiranes and N-bromosuccinimide (NBS) in DMSO under microwave irradiation. The reaction mechanism was proposed as an intramolecular aromatic electrophilic substitution of 1-bromo-2-(aryloxymethyl)thiiran-1-iums, generated from aryloxymethylthiiranes and NBS, and the subsequent DMSO nucleophilic ring opening reaction of thiiran-1-iums followed by the water displacement. The current method provides a direct and simple strategy in the efficient preparation of (2,3-dihydrobenzo[b][1,4]oxathiin-3-yl)methanols from readily available aryloxymethylthiiranes. [ABSTRACT FROM AUTHOR]

A sequence of microwave-assisted Suzuki cross-coupling reaction and bromination with N-bromosuccinimide was used for the synthesis of 3,3'-(5,5'-{5-[5-(9-ethyl-9H-carbazol-3-yl)-3-hexylthiophen-2-yl]pyrimidine-4,6-diyl}bis(thiophene-5,2-diyl))bis(9-ethyl-9H-carbazole). The obtained compound was characterized with regard to its optical properties, as well as possible applications in sensors for nitroaromatic compounds in acetonitrile solutions and in vapor phase. [ABSTRACT FROM AUTHOR]

Transformation of a methylene group of the pillar[5]arene scaffold into a ketone has been achieved by treatment with N‐bromosuccinimide followed by hydrolysis of the bromide intermediate and oxidation of the resulting secondary benzylic alcohol with BaMnO4. Condensation of the resulting macrocycle including a ketone function with p‐toluenesulfonyl hydrazide followed by reaction of the corresponding tosylhydrazone with C60 under modified Bamford–Stevens conditions gave a fulleropillar[5]arene derivative. This building block has been used to prepare a rotaxane. The resulting molecule combining the fullerene‐functionalized macrocycle with an axle bearing a porphyrin stopper is a photoactive molecular device in which the porphyrin emission is efficiently quenched by the fullerene moiety. [ABSTRACT FROM AUTHOR]

2-Alkylidene-5-methylidene-1,3-thiazolidin-2-ylidenes react with N-bromosuccinimide to form 2-alkylidene-5-(bromomethyl)-2,3-dihydro-1,3-thiazoles, the reaction of which with S,O,N-nucleophiles is used for the selective synthesis of the corresponding 5-methylfunctionalized derivatives. [ABSTRACT FROM AUTHOR]

Abstract: A metal‐free, one‐pot synthesis of 1,2‐naphthoquinone was accomplished from 2‐naphthol by utilizing economically cheap NBS under open air conditions. Initial formation of 1,1‐dibromonaphthalen‐2‐one and subsequent transformation afforded the 1,2‐naphthoquinone. This oxidation was completed within 30 min and had broad substrate scope. Moreover, this system tolerated heterocyclic systems and was also applicable to 1,3‐dicarbonyl systems. This practical approach with short reaction times, a simple workup, and insensitivity to moisture could override the usage of expensive and hazardous oxidizing and metal reagents. [ABSTRACT FROM AUTHOR]

A mild and efficient vicinal dibromination of olefins has been developed by using saturated aqueous ammonium fluoride solution as the promoter. Inexpensive and commercially available N-bromosuccinimide (NBS) was used as the brominating reagent. The corresponding vicinal dibromoalkanes could be obtained in good to excellent yields. [ABSTRACT FROM AUTHOR]

An efficient dual stereocontrol in iridium‐catalyzed hydrogenation of 1‐substituted 3,4‐dihydroisoquinolines was realized by tuning the amount of N‐bromosuccinimide using chiral ligand of single configuration, providing both enantiomers of 1‐substituted 1,2,3,4‐tetrahydroisoquinolines with up to 89% ee (S) and 98% ee (R), respectively. Dual activation role of N‐bromosuccinimide is proposed to be responsible for the reversal of enantioselectivity under two hydrogenation conditions. [ABSTRACT FROM AUTHOR]

The syntheses, physico-chemical characterization and cytotoxicity toward three human cell lines (standard and resistant sarcoma cells, and fibroblast) of a new copper(II) complex [Cu(HBPA)(L1)Cl]·3H 2 O 2 are reported. Complex 2 was obtained through the reaction between the ligand stilbene-quinone ( HL1 ) and Cu[HBPA]Cl 2 1 , where HBPA = 2-hydroxybenzyl-2pyridylmethylamine. The synthesis of HL1 was performed in high yield through Heck reaction on PEG-400. X-ray diffraction and solution studies (UV–Vis, EPR, ESI(+)−MS and ESI(+)−MS/MS) were performed for complex 2 , in which the copper(II) center is coordinated to the quinone in its deprotonated form, to the ligand HBPA and to a chloro ligand. Similar reaction employing CuCl 2 ·2H 2 O, instead of Cu[HBPA]Cl 2 1 and HL1 , has resulted in the obtainment of a furano- o -naphtoquinone (L2) with 99% selectivity, suggesting a new methodology to cyclize the ligand HL1 . In order to obtain the analogous para- isomer (L3), and to evaluate the isomerism influence on cytotoxicity activity, a cyclization reaction of HL1 with NBS ( N -bromosuccinimide) was also performed, which resulted in the obtainment of L2 (8%) and L3 (13%). X-ray diffraction studies were performed for L2 and complex 2 , and the description of their structure elucidated. Results from MTT assay revealed that complex 2 is more active against sarcoma cell lines (MES-SA/Dx5 and MES-SA) than both the free ligand HL1 and complex 1 , reducing cell viability to less than 50 μmol L −1 . L2 was the most active in the series, presenting cytotoxicity against resistant MES-SA/Dx5 and its standard MES-SA cell line, respectively, three and ten times higher than the current drug doxorubicin. [ABSTRACT FROM AUTHOR]

The oxidation kinetics of a ternary chromium(III) complex involving dipicolinic acid and oxalic acid by N-bromosuccinamide (NBS) was carried out in aqueous medium. The effect of pH, temperature and ionic strength on the reaction rate was investigated. The condition of reaction was studied under pseudo-first order. The reaction rate increases with the increase in pH and temperature. The derived rate law was compared with experimental rate law and obeyed the following equation: d[CrVI]/dt = k4K2[NBS ][CrIII]T/(([H+]/K1) + 1 + K2[NBS]), where K1 is the equilibrium constant for dissociation of [CrIII(DPA)(OX)(H2O)]- to [CrIII(DPA)(OX)(OH)]2-, K2 - the pre-equilibrium formation constant and k4 - the rate constant of electron transfer process. The reaction takes please via one or two electrons. The entropy and enthalpy of activation are calculated. The electron transfer occurs through an inner sphere mechanism. [ABSTRACT FROM AUTHOR]

An easily performed fully automated and miniaturized flow injection chemiluminescence (CL) method for determination of phenols in smoked food samples has been proposed. This method includes the ultrasound assisted solid-liquid extraction coupled with gas-diffusion separation of phenols from smoked food sample and analytes absorption into a NaOH solution in a specially designed gas-diffusion cell. The flow system was designed to focus on automation and miniaturization with minimal sample and reagent consumption by inexpensive instrumentation. The luminol – N -bromosuccinimide system in an alkaline medium was used for the CL determination of phenols. The limit of detection of the proposed procedure was 3·10 −8 ·mol L −1 (0.01 mg kg −1 ) in terms of phenol. The presented method demonstrated to be a good tool for easy, rapid and cost-effective point-of-need screening phenols in smoked food samples. [ABSTRACT FROM AUTHOR]

N-bromosuccinimide (NBS)-mediated one-pot, green, efficient and practical synthesis of substituted imidazoles and quinoxalines has been achieved by the reaction of styrenes with N-arylbenzamidines and o-phenylenediamines, respectively, in a water:1,4-dioxane mixture. The reaction involves formation of an α-bromo ketone as an intermediate in the presence of NBS and water, followed by condensation with the N-arylbenzamidine and o-phenylenediamine. Use of an inexpensive NBS as a bromine source as well as an oxidant, water as a solvent and readily available starting materials makes this protocol environmentally benign and economically viable. Substituted imidazoles and quinoxalines were obtained in good to excellent yields with wide functional group compatibility. [ABSTRACT FROM AUTHOR]

An N-bromosuccinimide-catalyzed intermolecular annulation of acetyl indoles with alkynes was developed, allowing for regioselective formation of valuable carbazoles through direct C-H bond functionalization. The readily available catalyst, wide substrate scope, gram scale synthesis, and mild conditions make this method practical. Mechanistic investigations indicate that the bromination of acetyl indole takes place to generate a bromide intermediate, followed by coupling with an alkyne and intramolecular cycloaromatization to furnish carbazole products. [ABSTRACT FROM AUTHOR]

Regioselective monobromination of various aromatics was achieved at room temperature using N -bromosuccinimide and 5 mol% of thioamides in acetonitrile. With thiourea as catalyst, activated aromatics, such as anisole, acetanilide, benzamide and phenol analogues containing electron donating or withdrawing groups, were brominated with high regioselectivity. Room temperature brominations of weakly activated aromatics and deactivated 9-fluorenone were accomplished by 5 mol% thioacetamide, higher substrates concentrations and longer reaction times. A backbonding of the bromine lone pairs with the π*of C S group and a halogen bond between the halogen bond donor bromine and the halogen bond acceptor sulfur of the thioamide are thought to be the principal interactions and cause of N -bromosuccinimide activation. [ABSTRACT FROM AUTHOR]

A new synthetic method for triazatruxenes from indoles is developed using N -bromosuccinimide (NBS) as a user-friendly reagent. Major reaction parameters including the amount of NBS, substrate concentration, temperature, addition rate and addition method are investigated. Additional experiments are also conducted in order to gain access toward the reaction mechanism. Compared to the use of Br 2 in the conventional method, this reaction requires less reaction time, provides better yields, and displays excellent reproducibility. The reaction can be conveniently performed at 10 g scale and it is also applicable to several substituted indoles, benzoindole, and N -alkyl indoles. [ABSTRACT FROM AUTHOR]

A facile and environmental friendly protocol for the synthesis of N -bridged fused bicyclic compounds such as imidazo[1,2- a ]pyridines, imidazo[1,2- a ]pyrimidines, and imidazo[2,1- b ]thiazole, from commercially available starting materials has been developed. The reaction proceeds via NBS mediated in situ formation of α -brominated intermediate of corresponding aromatic ketones, 1,3-diketones, β -keto esters, followed by trapping with suitable nucleophiles to provide these versatile imidazole fused bicyclic heterocycles in good yields under metal-free conditions. [ABSTRACT FROM AUTHOR]

Sn(OTf)2-catalyzed 1,3-aminobromination of donor-acceptor cyclopropanes with various sulfonyl amides or electron-poor anilines and N-bromosuccinimide is reported. These experimentally straightforward reactions occurred with complete regio- and stereospecificity (for anilines) to give γ-aminated α-brominated malonic diesters in good to excellent yields (up to 98 %). These compounds served as valuable substrates for subsequent reactions to provide substituted azetidines and γ-lactams in high yields. [ABSTRACT FROM AUTHOR]

The enantiospecific coupling of secondary and tertiary boronic esters to aromatics has been investigated. Using p-lithiated phenylacetylenes and a range of boronic esters coupling has been achieved by the addition of N-bromosuccinimide (NBS). The alkyne functionality of the intermediate boronate complex reacts with NBS triggering the 1,2-migration of the group on boron to carbon giving a dearomatized bromoallene intermediate. At this point elimination and rearomatization occurs with neopentyl boronic esters, giving the coupled products. However, using pinacol boronic esters, the boron moiety migrates to the adjacent carbon resulting in formation of ortho boron-incorporated coupled products. The synthetic utility of the boron incorporated product has been demonstrated by orthogonal transformation of both the alkyne and boronic ester functionalities. [ABSTRACT FROM AUTHOR]

A ultrasound-assisted oxidative cyclization of semicarbazones using N-bromosuccinimide in the presence of sodium acetate was established providing efficient and rapid access to a variety of 2-amino-1,3,4-oxadiazoles. Moreover, the new synthetic protocol provides a simple procedure utilizing a safer oxidizing system that affords the target products in high regioselectivity, satisfactory yields, and elevated purities. [ABSTRACT FROM AUTHOR]

Bromination of (5,10,15,20-tetraphenylporphyrinato)palladium(II) and [5,10,15,20-tetrakis(4-methoxyphenyl)porphyrinato]palladium(II) with N-bromosuccinimide in chloroform-dimethylformamide and chloroform afforded mono-, tetra-, and octabromo derivatives substituted at the pyrrole rings. The products were identified by electronic absorption, H NMR, and mass spectra and elemental analyses. [ABSTRACT FROM AUTHOR]

A simple aluminium(III) chloride-catalyzed synthesis of tri-substituted furans from aliphatic aldehydes and 1,3-dicarbonyl compounds was developed by using N-bromosuccinimide (NBS) as an oxidant. This method was effective for the synthesis of various furan derivatives. Some of the products were not accessible with the previously reported methods. Mechanically, this reaction involved an auto-tandem catalysis based on a newly reported acid-acid-catalyzed tandem reaction to ensure that furans were successfully synthesized. [ABSTRACT FROM AUTHOR]

A neighbouring ester group-participated diketonization of o-alkynylbenzoate is described here for the synthesis of benzil-o-carboxylate. Application of the resulting benzil- o-carboxylate in the synthesis of quinoxalines is also reached from o-alkynylbenzoate in an one-pot fashion. This diketonization proceeds smoothly with a high regioselectivity under mild conditions. Importantly, neighbouring group plays an important role in diketonization. A plausible mechanism suggests that a bromo-incoporated isocoumarin cation is described as an intermediate, and the whole process is constituted by NBS-mediated electrophilic 6- endo annulation and oxygen transfer reaction through NBS-mediated oxidative ring-opening. Water serves as a nucleophile of ring-opening. [ABSTRACT FROM AUTHOR]