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Bromination by N-bromosuccinimide of the β-carboline alkaloid 8-acetylharmine in CH2Cl2 smoothly formed 8-acetyl-6-bromoharmine. Cross coupling of 8-acetyl-6-bromoharmine with arylboronic acids in aqueous toluene in the presence of Pd(PPh3)4 as a catalyst, Na2CO3 as a base, and ammonium salt Bu4N+Br- as an additive synthesized the corresponding 6-aryl-8-acetylharmine derivatives. The new aryl-substituted 8-acetylharmine derivatives possessed moderate cytotoxicity and antidepressant activity in the Porsolt test. [ABSTRACT FROM AUTHOR]

Investigations of bromination of naphtho[2,3-c][1,2,5]thiadiazole-4,9-dione revealed that the reaction proceeded most efficiently with N-bromosuccinimide in sulfuric acid and depending on the reaction conditions, can give mono-, di-, tri- and tetrabromo derivatives of naphtho[2,3-c][1,2,5]thiadiazole-4,9-dione. A series of the major isomers was isolated, and their structure was proven using heteronuclear multiple bond correlation NMR spectroscopy and high-resolution mass spectrometry. [ABSTRACT FROM AUTHOR]

The influence of the 7-O-acetyl group of acetylhaplophyllidine (2) on the bromination process was studied. Acetylhaplophyllidine in bromination by molecular Br2 and N-bromosuccinimide under various conditions formed multicomponent mixtures consisting of bromination products of intramolecular annelation (3, 4, and 6) and bromo-derivatives of 4-oxofuranoquinolines (5 and 7). [ABSTRACT FROM AUTHOR]

An unexpected and selective synthetic technique was devised for 3-bromo-2-arylimidazo[1,2-a]pyridine and 3-formyl-2-arylimidazo[1,2-a]pyridine derivatives synthesis, utilizing DMSO and copper(II) bromide under time-controlled settings. Initially, the imidazopyridines underwent bromination, followed by the subsequent conversion of the brominated imidazopyridines into formylated imidazopyridines. This innovative technique has various advantages over previous ones, such as sequential synthesis of brominated and formylated imidazo[1,2-a]pyridines and, for the first time, utilizing CuBr2 and DMSO as dual active agents simultaneously. This practical process can moreover produce two widely used products in the medical and pharmaceutical realm which increases its efficiency and adaptability. [ABSTRACT FROM AUTHOR]

The bromination of benzo[1,2-c:3,4-c']bis([1,2,5]thiadiazole) was studied. An efficient method has been developed for the synthesis of 4,5-dibromobenzo[1,2-c:3,4-c']bis([1,2,5]thiadiazole), an important intermediate for the preparation of highly efficient photochromic diarylethenes for photosensitive and mechanoreactive materials that can be useful in a number of applications, including stress perception and information storage. [ABSTRACT FROM AUTHOR]

Context: This study delves into hole-electron transport and distribution properties inherent in mono-brominated dibenzofuran (DBF) and dibenzothiophene (DBT) isomers. As determined by frontier molecular orbitals, all brominated structures have narrower bandgaps than their primary structures. The TD-DFT calculation showed that 2BDBT had the highest absorption wavelength of all molecules at 315.35 nm. Notably, the study unveils remarkably low electron and hole reorganization energies due to bromine substitution in DBF and DBT molecules. Specifically, the 4BDBF has the lowest hole reorganization energy of all DBF configurations, 0.229 eV. In addition, 3BDBF has 0.226 eV less electron reorganization energy than all other molecules. Compared to DBT, 3BDBT has the lowest electron reorganization energy of 0.254 eV. Overall, this research sheds significant light on the fundamental electronic and hole transport characteristics of bromine-substituted DBF and DBT isomers, highlighting their promising role in polymer design as donors/acceptors for advanced organic electronic applications. Methods: Molecular structures were optimized using Density Functional Theory (DFT) B3LYP/6-311 + + G (d, p) level of theory, and the study further elucidates these molecules' energy levels and absorption spectra through Time-Dependent Density Functional Theory TD-DFT; these calculations were performed using Gaussian 09W software package. The key parameters such as reorganization energies, Electron Localization Function map, Laplacian Bond Order, and NCI-RDG were meticulously examined for the molecules with the results of DFT calculations were analyzed and displayed by utilizing the software packages VMD 1.9.4 and Multiwfn 3.8, aiming to comprehend their charge transport and distribution properties. [ABSTRACT FROM AUTHOR]

2,6-Di-tert-butyl-4-methylphenol reacted with an equimolar amount of benzyltrimethylammonium tribromide to give 4-bromomethyl derivative but not 4-hydroxymethyl derivative as was reported earlier. The present work is devoted to the synthesis of 4-bromomethylphenols with bulky tert-butyl and/or isobornyl moieties at positions 2 and 6. [ABSTRACT FROM AUTHOR]

The kinetics and mechanism of osmium(VIII)-catalyzed oxidation of paracetamol (PAM) with N-bromosuccinimide (NBS) in acidic medium have been studied at a constant ionic strength of 0.50 M. The reaction is characterized by 1:1 stoichiometry. The main products were identified by spot test and IR and UV-visible spectroscopy. The activation parameters of the rate-determining step were computed and discussed, and the thermodynamic parameters were also calculated. First-order kinetics with respect to Os(VIII) was observed for the oxidation of paracetamol. The reaction rate decreased with increase in the acidity and NBS concentration. Variation of the ionic strength had no significant effect on the reaction rate. A plausible mechanism has been proposed on the basis of the kinetic studies, reaction stoichiometry, and product analysis. Quantum chemical study of the oxidation of paracetamol with NBS was performed in the framework of the density functional theory (DFT) using B3LYP/6-31G(d,p) basis set. The DFT studies included computation of various structural parameters, viz. electrostatic potential, electrophilicity, chemical potential, chemical hardness, thermodynamic properties at various temperatures, nonlinear optical (NLO) properties, Mulliken charges, electric dipole moments, polarizability, and first static hyperpolarizability, as well as natural bond orbital (NBO) and atom in molecule (AIM) analysis. [ABSTRACT FROM AUTHOR]

A low-cost 3D printed standardized flow-photochemistry setup has been designed and developed for use with a pressure-driven flow system using photochemistry lamps available in most laboratories. In this research, photochemical reactors were 3D printed from polypropylene which facilitated rapid optimization of both reactor geometry and experimental setup of the lamp housing system. To exemplify the rapidity of this approach to optimization, a Kessil LED lamp was used in the bromination of a range of toluenes in the 3D printed reactors in good yields with residence times as low as 27 s. The reaction compared favorably with the batch photochemical procedure and was able to be scaled up to a productivity of 75 mmol h−1. Highlights: • We demonstrate the rapid optimization of 3D printed polypropylene reactors for flow photochemistry. • We show that the reactors can be used with a standardized 3D printed Kessil lamp set up. • We show how the system can be used in an exemplary photochemistry reaction for the bromination of a range of toluenes and that it can be easily scaled. [ABSTRACT FROM AUTHOR]

Celecoxib are COX2 inhibitors approved to reduce the COX2 level. Celecoxib and its major metabolites labeled with deuteriums are applied for drug metabolism studies. [2H4] celecoxib was prepared from [2H4] 4-acetamidobenzenesolfonyl through amination, hydrosis, diazotization, reduction and cyclization. After bromination and hydrolysis reaction, [2H4] hydroxy celecoxib was obtained and further oxidized by tetrabutylammonium permanganate to afford [2H4] celecoxib carboxylic acid. The title compounds showed remarkable chemical purity and isotope abundance which can be utilized in pharmacokinetic research. [ABSTRACT FROM AUTHOR]

Hexabromobenzene (HBB), pentabromotoluene (PBT), and pentabromoethylbenzene (PBEB) are current-use brominated flame retardants (cuBFRs) which have been repeatedly detected in environmental samples. Since information on hydroxylated transformation products (OH-TPs) was scarcely available, the three polybrominated compounds were UV irradiated for 10 min in benzotrifluoride. Fractionation on silica gel enabled the separate collection and identification of OH-TPs. For more insights, aliquots of the separated OH-TPs were UV irradiated for another 50 min (60 min total UV irradiation time). The present investigation of polar UV irradiation products of HBB, PBT, and PBEB was successful in each case. Altogether, eight bromophenols were detected in the case of HBB (three Br3-, four Br4-, and one Br5-isomer), and nine OH-TPs were observed in the case of PBT/PBEB (six Br3- and three Br4-congeners). In either case, Br➔OH exchange was more relevant than H➔OH exchange. Also, such exchange was most relevant in meta- and ortho-positions. As a further point, and in agreement with other studies, the transformation rate decreased with decreasing degree of bromination. UV irradiation of HBB additionally resulted in the formation of tri- and tetrabrominated dihydroxylated compounds (brominated diphenols) that were subsequently identified. These dihydroxylated transformation products were found to be more stable than OH-TPs. [ABSTRACT FROM AUTHOR]

By means of the Hurd–Mori reaction, 2-(1,2,3-thiadiazol-4-yl)-5-methyl-thiophene was synthesized. Its bromination with N-bromosuccinimide under conditions of radical initiation leads to a labile 2-bromomethyl derivative which, in the presence of proton donors or when heated, rearranges to 2-(1,2,3-thiadiazol-4-yl)-4-bromo-5-methylthiophene. The possibility of rearrangement was confirmed by quantum chemical calculations. Chlorination of 2-(1,2,3-thiadiazol-4-yl)-5-methylthiophene with sulfuryl chloride both in the presence of AIBN and without it leads to 2-(1,2,3-thiadiazol-4-yl)-3,4-dichloro-5-methylthiophene. Intermediate products that form in the course of both processes are established and schemes of their formation are offered. Bromination of 2-(1,2,3-thiadiazol-4-yl)-4-bromo- and -3,4-dichloro-5-methylthiophenes with N-bromosuccinimide proceeds at the methyl group. Obtained bromomethyl derivatives undergo nucleophilic substitution reactions in the usual manner. [ABSTRACT FROM AUTHOR]

An effective method was developed for the synthesis of (2E)-5-arylpent-2-ene-4-ynoates based on the olefination-dehydrobromination of (2Z)-2-bromo-3-arylprop-2-enals obtained by bromination of commercially available cinnamaldehyde and its derivatives. [ABSTRACT FROM AUTHOR]

Ethylene ketal of the Michael adduct of levoglucosenone and 2-(ethoxycarbonyl)cyclo-dodecanone brominated with the system Br2—CCl4 in CHCl3 gave three types of products, namely, mono- and dibromo derivatives, as well as deprotected bromo diketone. The bromination occurred in the levoglucosenone moiety and in the cyclododecanone fragment, with the ketal protection being partially removed. Reductive debromination of difficult-to-separate di- and monobromo derivatives under the action of Zn—Bu4NI in EtOAc—EtOH and ultrasound led to the opening of the protective group dioxolane ring to give the corresponding enol ether. Treatment of the mixture of di- and monobromo derivatives with the system NaOH—EtOH or NaHCO3—DMSO triggered a stereoselective intramolecular cyclization to result in the cyclopropane and tetrahydrofuran derivatives, respectively. [ABSTRACT FROM AUTHOR]

A convenient and catalyst-free method for the α-bromination of acetophenones using NaBr and CHCl3 in biphasic electrolysis with H2SO4 as a supporting electrolyte at room temperature has been introduced. This approach results in an excellent yield of α-bromo acetophenones with high selectivity in a beaker-type cell equipped with C/SS electrodes. To achieve good yield with high current efficiency, various optimization studies are carried out and reported. [ABSTRACT FROM AUTHOR]

The reactivity of 2,4-diphenylfuran has been studied and its promising potential as a substrate for oxidative homocoupling, lithiation followed by modification, bromination, and subsequent cross-coupling reactions has been demonstrated. [ABSTRACT FROM AUTHOR]

The thermal stability of carbon sorbents modified by ammonium bromide is investigated. The sorbent is produced from D coal by alkaline activation at 800°C with 1 h holding, when the coal/KOH mass ratio is 1.0. This sorbent is microporous, with a high specific surface (1340 m2/g). The sorbent is modified by steeping with ammonium bromide solution of different concentrations (1, 2, and 4%). Such modification changes all the textural characteristics of the sorbent. The specific surface SBET and total pore volume VΣ decrease. Thermogravimetric analysis establishes the temperature limits on oxidative pyrolysis of the sorbent samples: the ignition temperature and complete combustion temperature. Taking account of the time parameters, the ignition and combustion indices are calculated. It is found that increase in concentration of the ammonium bromide solution is accompanied by increase in the ignition temperature Tig of the samples and also the temperature T1 at which mass loss begins. In addition, the ignition index D and combustion index S increase. The results show that modification of the sorbents with ammonium bromide raises the threshold of oxidative pyrolysis. [ABSTRACT FROM AUTHOR]

We determined optimal conditions to brominate various isobornyl phenols with molecular bromine and N-bromosuccinimide as well as studied oxidative bromination of them with KBr–Oxone®. For obtained brominated derivatives, as isobornylphenols, an assessment of erythrotoxicity, membrane-protective and antioxidant activity was performed using in vitro models. Halogen derivatives of isobornylphenols containing a bromine atom in the para-position and an alkyl fragment in the ortho-position relative to the phenolic hydroxyl group showed high antioxidant activity in the model of oxidative hemolysis of erythrocytes. [ABSTRACT FROM AUTHOR]

New derivatives of 3-methylcytisine with 9-aromatic substituents bonded to the pyridone core of the starting alkaloid through spacers of various natures, e.g., aminomethyl, amide, thio- and carboxamide, ethenyl, and ethyl, were synthesized from 9-amino- and 9-bromo-2-oxomethylcytisine. [ABSTRACT FROM AUTHOR]

2,3-Dihydro-1H-imidazo[1,2-a]benzimidazole in acetic acid, and its N1-Me derivative in CHCl3, are brominated at position 6 with bromine. Less nucleophilic N9-R derivatives do not enter into the reaction under these conditions, but, like their N1-R isomers, they are quite effectively brominated by the KBrO3–HBr system, but at position 7, probably due to the transition of the reaction to the mode of bromination of protonated forms of substrates. N1- and N9-alkyl-6(7)-Br-2,3-dihydroimidazo[1,2-a]benzimidazoles can also be obtained by N-alkylation of 6(7)-Br-2,3-dihydroimidazo[1,2-a]benzimidazoles under neutral or basic conditions. [ABSTRACT FROM AUTHOR]

The nitration and halogenation reactions of 2-(pentafluorosulfanyl)- and 2-(trifluoromethyl)-1,3-benzothiazoles were studied. Methods for the preparation of previously undescribed mononitro-substituted 1,3-benzothiazoles (4-nitro-2-(pentafluorosulfanyl)-1,3-benzothiazole, 4-nitro-2-(trifluoromethyl)-1,3-benzothiazole, and 6-nitro-2-(pentafluorosulfanyl)-1,3-benzothiazole) as well as a new method for the synthesis of the previously known 6-nitro-2-(trifluoromethyl)-1,3-benzothiazole were developed. The procedure involved the reaction of 2-(trifluoromethyl)-1,3-benzothiazole with NH4NO3 in TFAA at room temperature. An efficient method for the preparation of 2-substituted 4,5,6,7-tetrabromo-1,3-benzothiazoles based on the reaction of 2-substituted 1,3-benzothiazoles with NBS in TFA–H2SO4 at room temperature was proposed. [ABSTRACT FROM AUTHOR]

Bromination of N-acyl-2,2,4-trimethyl-1,2-dihydroquinolines with N-bromosuccinimide (NBS) in CCl4 in the presence of Bz2O2 proceeded at the 4-positioned methyl group. In a DMF solution, the direction of the reaction was determined by the nature of substituent at the nitrogen atom: the reaction with one equivalent of NBS can proceed either as described above, or at position 3 with the allylic rearrangement-type migration of the multiple bond. The use of two equimoles of NBS in DMF led to 3-bromo-4-bromometh-ylene-2,2-dimethyl-3,4-dihydroquinolines. The N- and S-alkylation reactions of 3- and 4-brominated isomers resulted in the same 4-N- and 4-S-methyl derivatives. [ABSTRACT FROM AUTHOR]

Alkaline hydrolysis of 6-tert-butyl 8-ethyl 7-amino-3-tert-butyl-2-oxo-1,2-dihydropyrrolo[1,2-b][1,2,4]triazine-6,8-dicarboxylate gave the corresponding 8-carboxylic acid, and treatment of the latter with butyl bromide or N-bromosuccinimide in the presence of triethylamine resulted in decarboxylation with simultaneous alkylation at N1, or C2–O or bromination at the 8-position, respectively. Diazotization of 7-amino-3-tert-butyl-8-R1-2-R2O-pyrrolo[1,2-b][1,2,4]triazine-6-carboxylates afforded 7-azido (R1 = Br, CO2Et; R1 = H, Bu) and 7-unsubstituted (R1 = Br, CN; R2 = Bu, CH2CO2Et, CH2Boc) derivatives, and 1,3-dipolar cycloaddition of the 7-azido derivative and diethyl acetylenedicarboxylate produced 7-(1H-1,2,3-triazol-1-yl)pyrrolo[1,2-b]-[1,2,4]triazine-6,8-dicarboxylate. The structure of the synthesized compounds was confirmed by spectroscopic and X-ray diffraction data, and their antimicrobial activity was evaluated. [ABSTRACT FROM AUTHOR]

The (2E,2′E)-2,2′-(1,2,4-thiadiazole-3,5-diyl)bis[3-aryl(hetaryl)-2-cyanoprop-2-entioamides] were obtained by treating (E)-3-aryl(hetaryl)-2-cyanoprop-2-entioamides or their [4 + 2] dimerization products, 6-amino-2,4-diaryl-3,5-dicyano-3,4-dihydro-2H-thiopyran-3-carbothioamides, with bromine or iodine in DMF. The scope and limitations of the reaction are discussed. Partial ring bromination of starting thioamide was observed only in the case of (E)-2-cyano-3-(4-hydroxy-3-methoxyphenyl)prop-2-enethioamide. When treated with bromine in DMF, 2-cyano-2-cyclopentylideneethanthioamide gives 2,2′-(1,2,4-thiadiazole-3,5-diyl)bis[2-cyclopentylideneacetonitrile] in 69% yield. When 2-imino-7-methoxy-2H-chromene-3-carbothioamide was brominated, 3a,4-dibromo-7-methoxy-3a,4-dihydro-3H-chromeno[2,3-c]isothiazol-3-iminium bromide was isolated instead of the expected 3,3′-(1,2,4-thiadiazole-3,5-diyl)bis(7-methoxy-4a,8a-dihydro-2H-chromene-2-one). The structure of (2E,2′E)-2,2′-(1,2,4-thiadiazole-3,5-diyl)bis{3-[2-(trifluoromethyl)phenyl]acrylonitrile} was confirmed by X-ray studies. Molecular docking was performed in order to find possible protein targets for the prepared new 1,2,4-thiadiazoles. One of the compound, ((2E,2′E)-2,2′-(1,2,4-thiadiazole-3,5-diyl)bis(3-(4-chlorophenyl)acrylonitrile), showed good herbicide safening effect in the experiments with sunflower seedlings. [ABSTRACT FROM AUTHOR]

Cis-[MoVIO2(CH3-hptb)(MeOH)] (1) has been synthesized by the reaction of [MoVIO2(acac)2] and deferasirox [ICL670: 4-[3,5-bis(2-hydroxyphenyl)-1H-1,2,4-triazol-1-yl]benzoic acid, H3hptb, I] in 1:1 molar ratio in MeOH. Complex 1 has been characterized successfully by several spectral techniques, viz. FT-IR, UV–Vis, 1H and 13C NMR, elemental (CHN) and thermogravimetric analysis. The esterification of the carboxylic group of ligand was observed during the complexation process with molybdenum. The analogous heterogeneous complex [MoVIO2(hptb)(MeOH)]@APTMS-TiO2 (2) has been synthesized by immobilizing I on amine-functionalized TiO2, {[H2hptb]@APTMS-TiO2 (II)} and then reacting it with [MoVIO2(acac)2] in MeOH. Characterization of the immobilized complex was achieved through FT-IR, DRS, P-XRD, TEM, thermogravimetric analysis and MP-AES. Both the complexes have been utilized in synthesizing organobromine compounds through oxidative bromination of styrene in the presence of KBr, oxidant (30% aq. H2O2) and 70% aq. HClO4 at room temperature. With the formation of 2-bromo-1-phenylethane-1-ol and 1-phenylethane-1,2-diol under the optimized reaction conditions, 72 and 100% conversion of styrene was achieved in the presence of catalysts 1 and 2, respectively. The oxidative bromination of thymol with catalyst 2 provides 2-bromothymol (52%) and 2,4-dibromothymol (48%) with 100% conversion. Dioxidomolybdenum(VI) complex of ICL670 immobilized on amine-functionalized titania has been synthesized and used as a functional model of haloperoxidases for the oxidative bromination of thymol and styrene. [ABSTRACT FROM AUTHOR]

The corresponding amides and hydrazides were obtained by the reaction of 1-hydroxy-1H-imidazole-2-carboxylates with amines and hydrazine. In the reaction of an ester of 1-methoxy-4-methyl-5-(thiophen-2-yl)-1H-imidazole-2-carboxylic acid with NBS, bromination occurred at the thiophene ring, whereas in the reaction with 1,3-dibromo-5,5-dimethylhydantoin it took place at both the methyl group and the thiophene ring; its nitration led to mononitro- or dinitrothiophene derivatives. The reaction of 1-hydroxy-1H-imidazole-2-carboxylates with chloroacetone in Me2CO in the presence of Et3N resulted in the formation of reduced compounds. [ABSTRACT FROM AUTHOR]

Electrochemical methods have been widely applied in the treatment of phenol wastewater for the past few years. However, conventional electrochemical advanced oxidation processes (EAOPs) generally encounter the problem of electrode passivation and the energy consumption required for mineralization is high. In this work, we reported the treatment of phenol wastewater by electrochemical bromination method in a flow electrolysis cell. The Ti/Sb-SnO2/PbO2 electrode was prepared and used as anode. The experiments were carried out under different initial pH, KBr concentrations, current densities, and volumetric flow rates. The generated 2,4,6-tribromophenol (TBP) could be easily separated from the electrode surface and electrolyte. The brominated intermediates were identified by GC/MS. The removal efficiencies for phenol and COD were 100% and 82.7%, respectively, under the best operational conditions (current density of 40 mA cm−2, KBr concentration of 0.074 mol L−1, initial pH of 1.0, and volumetric flow rate of 114 mL min−1). Furthermore, our electrochemical bromination method offered a high apparent current efficiency (ACE) of 276.6% and a low energy consumption (EC) of 4.54 × 10−3 kWh gCOD−1 after 40 min of electrolysis time, indicating that this process was suitable for phenol wastewater treatment. [ABSTRACT FROM AUTHOR]

Benzalkonium salts are widely used in the composition of antimicrobial preparations in industry and everyday life and as algaecides to treat pool water. The disinfection of tap or waste water with active chlorine in the presence of natural or anthropogenic bromide anions or using bromine as a pool water disinfectant creates conditions for the interaction of benzalkonium cations with active bromine to form disinfection by-products. This study presents the results of a model benzalkonium bromination with the identification of the resulting products by high-performance liquid and gas chromatography combined with high-resolution mass spectrometry. The primary transformation products are monobromo derivatives formed by the radical substitution of hydrogen atoms of the alkyl chain with bromine. Their further transformations yield dibromo-, hydroxy-, and hydroxybromo derivatives. The final products of the deep degradation of benzalkonium are bromoform, bromoacetonitrile, and several brominated hydrocarbons. [ABSTRACT FROM AUTHOR]

The purity of drinking water is an important issue of the human life quality. Water disinfection has saved millions people from the diseases spread with water. However, that procedure has a certain drawback due to formation of toxic organic disinfection products. Establishing the structures of these products and the mechanisms of their formation and diminishing their levels in drinking water represent an important task for chemistry and medicine, while mass spectrometry is the most efficient tool for the corresponding studies. The current review throws light upon natural and anthropogenic sources of the formation of disinfection by-products (DBPs) and the mechanisms of their formation related to the structural peculiarities and the presence of functional groups. In addition to chlorination, bromination is discussed since it is used quite often as an alternative method of disinfection, particularly, for the purification of swimming pool water. The benefits of the contemporary GC/MS and LC/MS methods for the elucidation of DBP structures and study of the mechanisms of their formation are discussed. The reactions characteristic for various functional groups and directions of transformation of certain classes of organic compounds in conditions of aqueous chlorination/bromination are also covered in the review. [ABSTRACT FROM AUTHOR]

Trimethyl or triethyl phosphite in the Arbuzov reaction with 6-bromomethyl-3,4-dihydropyrimidin-2(1H)-one or analogous 6-bromomethyl-3,4-dihydropyridin-2(1H)-one provided the respective 6-alkylphosphonates in excellent yields. The heterocyclic alkylphosphonates are useful synthons in the Horner–Wadsworth–Emmons reaction for introducing a styryl moiety. Bromination of 6-methyl-4-phenyl-3,4-dihydropyridin-2(1H)-one with NBS in methanol resulted in an unexpected compound, while bromination in chloroform with bromine yielded the expected 6-bromomethyl-3,4-dihydropyridin-2(1H)-one, which undergoes facile nucleophilic substitutions. The intermediates and products are validated by single crystal X-ray diffraction. [ABSTRACT FROM AUTHOR]

A metal-free C(sp3)-H bromination methodology has been developed for aromatic ketones and some substituted toluenes under ambient conditions. The reaction for the toluenes is mediated by PhI(OAc)2 (iodobenzene diacetate) in presence of KBr, while the bromination in aromatic ketones requires additional assistance of p-TsOH.H2O and BF3.Et2O. Synopsis: Synthesis of phenacyl bromides has been achieved under transition metal-free conditions. Some observations on substituted toluene systems have also been reported. In both cases, C(sp3)-H bromination has taken place at room temperature in the presence of phenyliodine diacetate (PIDA). [ABSTRACT FROM AUTHOR]

Bromination of the furanoquinoline alkaloid haplophyllidine by molecular bromine and N-bromosuccinimide was accompanied by intramolecular cyclization to form mixtures of new compounds containing additional penta-, hexa-, and spirocyclic rings incorporating the prenyl group of haplophyllidine. The structures and absolute configurations of the chiral centers of all four bromo-derivatives were elucidated using a combination of NMR spectroscopic methods and X-ray crystal structure analyses. [ABSTRACT FROM AUTHOR]

The synthesis of mesocentroquinone, a metabolite of the sea urchins Mesocentrotus nudus and Strongylocentrotus intermedius, is described. The procedure includes bromination of 2-hydroxy-6,7-dimethoxy-3-ethylnaphthazarin, dehydrobromination of the resulting 1′-bromoethyl derivative, and heterodiene condensation of the 2-oxo-3-ethylidene- and 3-vinyl-2-hydroxy-derivatives formed by this. The general nature of the proposed approach to the synthesis of 2-(1,4-naphthoquinon-2-yl)-benzo[g]-2Hbenzochromene-5,10-diones is demonstrated using two examples. [ABSTRACT FROM AUTHOR]

The synthesis of mesocentroquinone, a metabolite of the sea urchins Mesocentrotus nudus and Strongylocentrotus intermedius, is described. The procedure includes bromination of 2-hydroxy-6,7-dimethoxy-3-ethylnaphthazarin, dehydrobromination of the resulting 1′-bromoethyl derivative, and heterodiene condensation of the 2-oxo-3-ethylidene- and 3-vinyl-2-hydroxy-derivatives formed by this. The general nature of the proposed approach to the synthesis of 2-(1,4-naphthoquinon-2-yl)-benzo[g]-2Hbenzochromene-5,10-diones is demonstrated using two examples. [ABSTRACT FROM AUTHOR]

Primary nitramines have been shown to react with a triple bond of methyl propiolate to form 3-(nitramino)acrylates, on the basis of which a number of bromine derivatives have been synthesized. [ABSTRACT FROM AUTHOR]

The bromination reaction of oligoetherdiol derived from allyl glycidyl ether by two procedures has been studied. It has been shown that one procedure provides monohydroxy conpounds and compounds containing no OH groups along with completely brominated oligoetherdiol. Their formation has been supposed to proceed via cyclodehydrobromination reaction due to elimination of one or two hydrogen bromide molecules from oligoetherdiol to form dioxane and dioxepane cyclic fragments. Conditions for complete bromination of oligodiol with retention of OH group functionality have been determined. [ABSTRACT FROM AUTHOR]

A series of new benzamidine derivatives have been synthesized in good yields by involving 1-(1H-benzimidazol-2-yl)-2-bromoethanone, 4-(1H-benzimidazol-2-yl)-1,3-thiazol-2-amine, and N-benzyli-dene-4-(1H-benzimidazol-2-yl)-1,3-thiazol-2-amine as reactive intermediates. The synthesized compounds were characterized by spectral data. Molecular docking study of N-(4-(1H-benzimidazol-2-yl)-1,3-thiazol-2-yl]-1-[(E)-phenyldiazenyl]-1-phenylmethanimine has been carried out as a representative case. [ABSTRACT FROM AUTHOR]

(Z)-2-(5-Amino-1,2,4-thiadiazole-3-yl)-2-(methoxyimino)acetic acid, an important intermediate prod-uct in the synthesis of Ceftobiprole, was prepared from cyanoacetamide via oximation, methylation, dehydration, oxidation, etherification, bromination, and cyclization with an overall yield of 57%. The structures of the target product and intermediates in each step were characterized by mass spectrometry and 1H NMR. [ABSTRACT FROM AUTHOR]

The conditions for bromination of the methyl groups of dimethylglyoxime were found, and the resulting product, a 1,4-dioxane solvate of bis(bromomethyl)glyoxime, was used as a precursor for heterocyclizations involving cyclodehydration or oxidative cyclization of the oxime groups leading to the formation of furazan and furoxan rings, respectively. [ABSTRACT FROM AUTHOR]

In order to obtain perhalogenated metalloporphyrins, exhaustive bromination and chlorination of β-positions of nickel(II) and zinc(II) 5,10,15,20-tetra(2,6-dichlorophenyl)- and 5,10,15,20-tetra(2,6-difluorophenyl)porphyrins with N-bromosuccinimide and N-chlorosuccinimide in dimethylformamide have been carried out. When treating zinc(II) 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetra(2,6-difluorophenyl)porphyrin and zinc(II) 2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetra(2,6-difluorophenyl)porphyrin with trifluoroacetic acid, the corresponding porphyrin ligands have been obtained. The synthesized compounds have been identified by electron absorption, 1H NMR spectroscopy, and mass spectrometry. The structures of halogen-substituted porphyrins and their zinc(II) complexes have been calculated by the DFT method. The introduction of bromine and chlorine atoms into the pyrrole rings of ortho-substituted porphyrins and their metal complexes leads to a distortion of the planar structure of molecules to a saddle-like one. The effect of β-halogenation on the fluorescence quantum yields of the synthesized compounds have been estimated. The quantum yield of β-chlorine-substituted porphyrin decreases by ~7 times as compared to the initial tetra(2,6-difluorophenyl)porphyrin, and that of its zinc porphyrinate decreases by ~15 times as compared to the initial complex. Complete quenching of fluorescence caused by the influence of heavy bromine atoms in the β-positions of the macrocycle is observed for both porphyrins and their metal complexes. Perhalogenated metalloporphyrins have increased n-conductivity and can be used to create new materials exhibiting nonlinear optical and catalytic properties. [ABSTRACT FROM AUTHOR]

A novel, microwave safe and recyclable polymeric reagent was prepared by anchoring bromoderivative of 2-pyrrolidone in the polymer matrix of 3% tetraethyleneglycol diacrylate cross-linked polystyrene. The synthetic utility of the prepared polymeric reagent was demonstrated by the efficient bromination of unsaturated compounds, activated aromatic compounds and also for the α-bromination of ketones under microwave activation. Operational simplicity, moderate to excellent yield of the products, shorter reaction time and dry reaction medium are the foremost attraction of this protocol. Moreover, the synthesized functional polymer was stable under standard laboratory conditions and can be kept for several months without any significant loss of activity. [ABSTRACT FROM AUTHOR]

This paper analyzes the state of production of carbon fiber (CF) materials, including pitch-based CFs. It is shown that in Russia there is a significant potential for industrial production of pitch-based CFs. Considerable attention is paid to possible ways of modifying pitch-based CFs in order to improve their electrical properties. The efficiency of using gaseous bromine to reduce the electrical resistance of pitch-based CFs is shown. Based on the analysis of X-ray and Raman spectroscopy data, it is shown that a 7-fold decrease in electrical resistance during bromination is related to changes in the fiber structure. [ABSTRACT FROM AUTHOR]

A procedure has been developed for the synthesis of highly functionalized tetracyclic diterpenoids from natural ent-kaur-16-en-19-oic acid under modified Prévost–Woodward reaction conditions. The reaction follows an unusual pathway which leads mainly to bromination or rearrangement products. The transforma-tion of ent-kaur-16-en-19-oic acid afforded a mixture of (16ZE)-17-bromo-ent-kaur-16-en-19-oic, (15R,16E)-17-bromo-15-acetoxy-ent-kaur-16-en-19-oic, (16S)-17-bromo-16-acetoxy-ent-kaur-19-oic, (15S)-15-acetoxy-ent-kaur-16-en-19-oic, and (15S)-15-hydroxy-ent-kaur-16-en-19-oic acids, the latter two being reported previously. The newly syn-thesized compounds were evaluated for their cytotoxicity against two cancer cell lines, HeLa and BxPC-3. [ABSTRACT FROM AUTHOR]

Vanadium(IV) oxido complex of 1-Phenyl-1,3-butanedione [VIVO(bzac)2] (1) was prepared, characterized, and heterogenized onto APTMS modified graphene oxide, as well as imidazole modified polystyrene beads. Graphene oxide supported complex GO-APTMS-[VIVO(bzac)2] (2) and polymer anchored complex PS-im-[VIVO(bzac)2] (3) were used for the oxidative bromination of a number of small organic molecules and oxidation of a series of thioethers. Both 2 and 3 evolve as excellent heterogeneous catalysts. The nature of solid support does not impact substrate conversion (%) during the oxidative bromination of salicylaldehyde, phenol, or styrene, whereas it influences the substrate conversion (%) as well as the product selectivity (%) during the oxidation of thioethers. [ABSTRACT FROM AUTHOR]

Oligofurans have attracted great attention in the field of materials over the last decades because of their several advantages, such as strong fluorescence, charge delocalization, and increased solubility. Although unsubstituted or alkyl-substituted oligofurans have been well-established, there is an increasing demand for the development of the aryl decorated oligofuran with structural diversity and unrevealed properties. Here, we report the bottom-up modular construction of chemically and structurally well-defined oligo(arylfuran)s by de novo synthesis of α,β′-bifuran monomers and late-stage bromination, stannylation and subsequent coupling reaction. The preliminary study of the photophysical properties demonstrated that the polarity-sensitive fluorescence emission and high quantum yields in THF solution could be achieved by modulating the aryl groups on the oligo(arylfuran)s. These twisted molecules constitute a new class of oligofuran backbone useful for structure−activities relationship studies. Meanwhile, the experimental studies and calculations showed that tetrafurans have appropriate HOMO energy levels, and could therefore potentially be high-performance p-type semiconductors. Oligofurans have attracted great attention because of their strong fluorescence, charge delocalization, and increased solubility. Here the authors show a bottom-up modular construction of chemically and structurally well-defined oligo(arylfuran)s by de novo synthesis of α,β′-bifuran monomers and late-stage bromination, stannylation and subsequent coupling reaction. [ABSTRACT FROM AUTHOR]

Bromination of 3,4-dihydro-2H-thiopyran derivatives leads to bromo-substituted 3,4-dihydro-2H-thiopyrans or 4H-thiopyrans, depending on the reaction conditions and the structure of the starting heterocycles. [ABSTRACT FROM AUTHOR]

Oxidative halogenation of lappaconitine and N-deacetyllappaconitine HBr or HCl in the presence of H2O2 in MeOH was associated upon bromination by N-20-deethylation and produced the 3′,5′-dibromo derivative of N-20-nordeacetyllappaconitine; upon chlorination, a mixture of 5′-mono- and 3′,5′-dichloro derivatives of N-deacetyllappaconitine with the monochloro-derivative dominating. [ABSTRACT FROM AUTHOR]

The impacts of chlorination on methylparaben (MP) removal, as well as of bromide and ammonia on the MP elimination kinetics, were studied. Bromide and ammonia react with chlorine and are promptly transformed into bromine and chloramines, respectively. Rate constants of chlorine, bromine, and monochloramine with MP were determined under different pH conditions. At pH 8.5, the apparent second-order rate constants of MP reactions with chlorine and bromine were found to be 3.37(±0.50) × 101 and 2.37 (±0.11) × 106 M-1.s-1 for kChlorine/MP and kBromine/MP, respectively, yet there was low reactivity with monochloramine ( k NH 2 Cl / MP = 0.045 M-1.s-1). Regarding chlorination and bromination, in order to gain further insight into the observed pH-dependence of the reaction, the elementary reactions were considered and the corresponding second-order rate constants were calculated. The experimental and modeled values were quite consistent under these conditions. Then, chlorination experiments with different bromide and/or ammonia concentrations were performed to assess the impact of inorganic water content on MP elimination and a kinetic model was designed to assess MP degradation. Under these conditions, MP degradation was found to be enhanced in the presence of bromide whereas it was inhibited in the presence of ammonia, and the overall impact was pH dependent. [ABSTRACT FROM AUTHOR]

Rearrangements of 3-tert-butyl-8-methyl-4-phenylethynyl-1,4-dihydropyrazolo[5,1-c][1,2,4]triazine derivatives by the action of bases led to the formation of aromatic (E)- or (Z)-4-styryl-functionalized compounds. At the same time, 4-styryl-1,4-dihydropyrazolotriazines did not rearrange to form the expected 4-phenylethylpyrazolo[5,1-c][1,2,4]triazine. The latter was obtained via an alternative route by the addition reaction of phenylethynylmagnesium bromide to 3-tert-butyl-8-methylpyrazolo[5,1-c][1,2,4]triazine, as well as by reduction of double bonds in the ring and side chain of the 4-styryl derivative with subsequent selective oxidation by N-bromosuccinimide. The spectral and X-ray structural data as well as the antimicrobial properties of the synthesized compounds are discussed. [ABSTRACT FROM AUTHOR]

The post-functionalization of porphyrins through the bromination in β position of the pyrrolic rings is a relevant transformation because the resulting bromoderivatives are useful synthons to covalently link a variety of chemical architectures to a porphyrin ring. However, single bromination of porphyrins is a challenging reaction for the abundancy of reactive β-pyrrolic positions in the aromatic macrocycle. We herein report a synthetic procedure for the efficient preparation of 2-bromo-5,10,15,20-tetraphenylporphyrin (1) under continuous flow conditions. The use of flow technology allows to reach an accurate control over critical reaction parameters such as temperature and reaction time. Furthermore, by performing the optimization process through a statistical DoE (Design of Experiment) approach, these parameters could be properly adjusted with a limited number of experiments. This process led us to a better understanding of the relevant factors that govern porphyrins monobromination and to obtain compound 1 with an unprecedent 80% yield. [ABSTRACT FROM AUTHOR]