10.1021/acs.joc.9b00270
The study presents a novel Lewis acid-catalyzed approach for the synthesis of benzofurans and 4,5,6,7-tetrahydrobenzofurans from acrolein dimer and 1,3-dicarbonyl compounds. The method employs N-bromosuccinimide (NBS) as an oxidizing agent and utilizes a combination of Lewis acid catalysts to achieve high yields of 2,3-disubstituted benzofurans. The researchers successfully synthesized two commercial drug molecules, benzbromarone and amiodarone, using this method. The study also explores the substrate scope and optimizes the reaction conditions. Additionally, the authors propose a mechanism involving NBS-assisted auto-tandem catalysis and provide evidence by isolating an intermediate that can be further converted to tetrahydrobenzofurans. This work offers an efficient and practical route to synthesize benzofuran derivatives with potential applications in pharmaceutical chemistry.
10.1016/j.molstruc.2020.128560
The research focuses on the synthesis, structural characterization, and biological evaluation of a series of brominated plastoquinone analogs (BrPQ1-13). Two different synthetic routes were employed: dibromination followed by oxidation and amination, and oxidation followed by amination and bromination. It was dibrominated and then oxidized to form the corresponding dibrominated 1,4-benzoquinones. Dimethyl hydroquinone was the starting material for the synthesis of the brominated plastoquinone analogs. N-bromosuccinimide (NBS) was employed as a brominating agent in the second synthetic route to brominate the aminoquinones (AQs) that were previously synthesized. The structures of the analogs were determined using spectral data from FTIR, 1H NMR, 13C NMR, and HRMS, with single-crystal X-ray structural characterization for two analogs (BrPQ2 and BrPQ3). The synthesized compounds were evaluated for their in vitro antibacterial and antifungal activities against a panel of ATCC? strains, including seven bacterial strains (three Gram-positive and four Gram-negative) and three fungi, using the broth microdilution method. The study revealed that the presence of an electron-withdrawing group, particularly the trifluoromethyl group, on the phenyl ring positively impacted antibacterial activity, suggesting potential for the development of new antibacterial agents against S. aureus and S. epidermidis.
10.1016/S0022-328X(00)00181-9
This study focused on the synthesis of acylsilanes, a class of compounds with unique chemical properties that are widely used in various synthetic methods. The researchers used an oxidative hydrolysis method to generate acylsilanes in high yields in a short reaction time using N-bromosuccinimide (NBS) as a medium for the hydrolysis of 2-silyl-1,3-dithianes. This study aimed to find an alternative to the traditional mercuric chloride hydrolysis method, which is time-consuming and toxic. The chemicals used in the study included aldehydes, 1,3-propanedithiol, BF3·OEt2, n-BuLi, trimethylsilyl chloride, and various bases such as Et3N, Ba(OH)2, and imidazole. These chemicals were used to convert aldehydes into 1,3-dithianes, which were then converted into 2-silyl-1,3-dithianes, and finally hydrolyzed to generate acylsilanes. The use of NBS was intended to improve the efficiency and safety of the hydrolysis process and avoid the formation of undesirable byproducts such as carboxylic acids due to the oxidation of aromatic acylsilanes.
10.1007/BF00473862
The research focuses on the synthesis and reactivity of polyfunctional stable nitrile oxides of the thiophene series in 1,3-dipolar cycloaddition with styrene. The purpose of the study was to understand how various functional groups in the 4 and 5 positions of the thiophene ring affect the stability and reactivity of these nitrile oxides. The researchers synthesized a series of 2-alkylthio- and 2-alkylsulfonylthiophene-3-carbonitrile oxides with different substituents such as bromine, methoxy, methylthio, and methylsulfonyl groups. They found that the introduction of electron-acceptor substituents accelerated the cycloaddition reaction with styrene, and the reactivities were influenced by both electronic and steric factors of the substituents. The study concluded that electron-acceptor groups significantly increase the reactivity of nitrile oxides in the reaction with styrene, and the effect of substituents in the ortho positions relative to the nitrile oxide group is determined by a combination of electronic and steric factors. Key chemicals used in the process included N-bromosuccinimide (NBS) for the synthesis of bromo aldehydes, and various substituted alkylmercapto-, methoxy-, or alkyl-sulfonyl-substituted aldehydes as starting materials for the nitrile oxides.
10.1021/jo00822a019
The research explores the conversion of 1,3-dithiane derivatives to carbonyl compounds through oxidative hydrolysis using N-halosuccinimide reagents. The study aims to develop specific and effective procedures for this conversion, which is significant in the synthesis and interconversion of monocarbonyl and 1,3-dicarbonyl compounds. The researchers found that mercury(II)-promoted hydrolysis is effective for 2,2-dialkyl derivatives but less so for 2-monoalkyl and 2-acyl derivatives. To address this, they devised three N-halosuccinimide reagents—N-bromosuccinimide alone, N-bromosuccinimide with silver ion, and N-chlorosuccinimide with silver ion—which efficiently hydrolyze 2-acyl-1,3-dithianes to 1,2-dicarbonyl compounds, significantly extending the synthetic utility of the lithiodithiane method. The study concludes that these reagents, particularly N-chlorosuccinimide with silver ion, are advantageous for unsaturated dithianes as they do not affect olefinic linkages, and they can be buffered with 2,6-lutidine or 2,4,6-collidine for acid-sensitive substrates, yielding aldehydes and ketones in high percentages (70-100%).
10.1246/bcsj.64.1037
This study aims to develop a convenient method for preparing 3,5-disubstituted 1,2,4-selenadiazoles from primary selenoamides using N-bromosuccinimide (NBS) as the oxidizing agent. The study investigates various conditions and reagents to optimize the yield and stability of the synthesized selenadiazoles. Key chemicals involved include primary selenoamides as starting materials, which are treated with NBS in solvents like CHCl3. The research concludes that NBS is effective for synthesizing 1,2,4-selenadiazoles with aromatic substituents, yielding good to moderate results. However, aliphatic and heteroatom analogues are obtained in lower yields due to the decomposition of selenoamides to nitriles. The synthesized selenadiazoles are expected to promote further chemical conversions, and the study highlights the potential for introducing various functionalities to the 3- and 5-positions of the nucleus, paving the way for the development of novel heterocyclic ring systems.
10.1021/jo102060j
The study presents an efficient method for synthesizing iodoisoquinoline-fused benzimidazole derivatives, which are significant for their potential biological activities such as anti-HIV-1, anticancer, antimicrobial, and antifungal properties. The researchers developed a tandem cyclization strategy using CuI/I2 to promote the electrophilic tandem cyclization of 2-ethynylbenzaldehydes with ortho-benzenediamines. This approach led to the formation of the desired iodoisoquinoline-fused benzimidazoles in moderate to good yields. The study also explored the scope of the reaction with various substrates and demonstrated the potential of the synthesized products for further functionalization through cross-coupling reactions, highlighting the importance of this method for drug discovery and the development of heterocyclic compounds with diverse biological activities.
10.1039/c2nj40194k
The research focuses on the synthesis, characterization, and investigation of a series of poly(p-phenylenevinylene) (PPV) based polymers, specifically MEH-OXD-PPVs, which are functionalized with Y-shaped double 1,3,4-oxadiazole-containing side chains. The polymers were synthesized through a modified Gilch reaction and were found to be soluble in common organic solvents. The chemical structures were confirmed using 1H NMR, GPC, and elemental analysis. The polymers exhibited good thermal stability with decomposition temperatures ranging from 312°C to 326°C as determined by thermogravimetric analysis. The optical properties, including absorption and fluorescence emission, were analyzed and showed a blue-shift with the increase of oxadiazole-containing moieties. Electrochemical investigation revealed that the HOMO energy levels varied with the content of oxadiazole-containing moieties. The PL quantum efficiencies were significantly enhanced by introducing more OXD-PV units during copolymerization. The experiments utilized various reactants such as N-bromosuccinimide, potassium tert-butoxide, and different monomers, while analyses included 1H NMR for structural confirmation, GPC for molecular weight determination, and cyclic voltammetry for electrochemical properties.
10.1002/jhet.5570380512
The study focuses on the synthesis and isolation of bromo-β-carbolines, which are derivatives of β-carboline alkaloids. The researchers used N-bromosuccinimide (NBS) as the brominating agent to induce electrophilic aromatic substitution in various β-carbolines, including nor-harmane, harmane, harmine, harmol, and 7-acetylharmol. The purpose of using these chemicals was to explore the behavior of substituted β-carbolines, prepare nitro-β-carbolines and bromo-β-carbolines, and investigate their potential use as matrices (photosensitizers) in matrix-assisted ultraviolet laser desorption/ionization time-of-flight mass spectrometry (uv-maldi-tof ms). The study also aimed to understand the effects of substituents on the acid-base properties and electronic excited states of these molecules. The researchers compared the use of NBS in solution and in solid state, and employed semiempirical AM1 and PM3 calculations to predict reactivity in terms of molecular orbital energies and charge density. The results provided insights into the regioselectivity of bromination and the influence of the β-carboline/NBS molar ratio and reaction time on product selectivity.
10.1021/ol047402m
The study investigates the NBS-catalyzed hydroamination and hydroalkoxylation of activated styrenes. NBS (N-bromosuccinimide) acts as an efficient catalyst, while tosylamides, carbamates, and alcohols serve as nucleophiles to produce amino and ether derivatives, respectively. The reactions proceed with good to excellent yields and 100% regioselectivity in a Markovnikov fashion. The researchers found that NBS outperformed other catalysts like pyridinium bromide perbromide and N-bromoacetamide in terms of yield. The study also explored the scope of the hydroamination process with various electron-rich styrenes and nucleophiles, and extended the methodology to hydroalkoxylation using alcohols as nucleophiles. The proposed mechanism involves the formation of TsNHBr (from TsNH2 and NBS), protonation of the styrenic double bond in a Markovnikov fashion, and regeneration of TsNHBr. Further work is underway to develop an asymmetric version of this catalytic process.
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