Academic literature on the topic 'Synthesis of benzoxazoles'

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Journal articles on the topic "Synthesis of benzoxazoles"

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Özil, Musa, and Emre Menteşe. "Microwave-assisted Synthesis of Benzoxazoles Derivatives." Current Microwave Chemistry 7, no. 3 (December 30, 2020): 183–95. http://dx.doi.org/10.2174/2213335607999200518094114.

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Background: Benzoxazole, containing a 1,3-oxazole system fused with a benzene ring, has a profound effect on medicinal chemistry research owing to its important pharmacological activities. On the other hand, the benzoxazole derivative has exhibited important properties in material science. Especially in recent years, microwave-assisted synthesis is a technique that can be used to increase diversity and quick research in modern chemistry. The utilization of microwave irradiation is beneficial for the synthesis of benzoxazole in recent years. In this focused review, we provide a metaanalysis of studies on benzoxazole in different reaction conditions, catalysts, and starting materials by microwave technique so far, which is different from conventional heating. Methods: Synthesis of different kind of benzoxazole derivatives have been carried out by microwave irradiation. The most used method to obtain benzoxazoles is the condensation of 2-aminophenol or its derivatives with aldehydes, carboxylic acids, nitriles, isocyanates, and aliphatic amines. Results: Benzoxazole system and its derivatives have exhibited a broad range of pharmacological properties. Thus, many scientists have remarked on the importance of the synthesis of different benzoxazole derivatives. Conventional heating is a relatively inefficient and slow method to convey energy in orientation to the reaction medium. However, the microwave-assisted heating technique is a more effective interior heating by straight coupling of microwave energy with the molecules. Conclusion: In this review, different studies were presented on the recent details accessible in the microwave- assisted techniques on the synthesis of the benzoxazole ring. It presents all examples of such compounds that have been reported from 1996 to the present. Benzoxazoles showed an extensive class of chemical substances not only in pharmaceutical chemistry but also in dyestuff, polymer industries, agrochemical, and optical brighteners. Thus the development of fast and efficient achievement of benzoxazoles with a diversity of substituents in high yield is getting more noteworthy. As shown in this review, microwave-assisted synthesis of benzoxazoles is a very effective and useful technique.
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Kumar, Dinesh, Santosh Rudrawar, and Asit K. Chakraborti. "One-Pot Synthesis of 2-Substituted Benzoxazoles Directly from Carboxylic Acids." Australian Journal of Chemistry 61, no. 11 (2008): 881. http://dx.doi.org/10.1071/ch08193.

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Methanesulfonic acid has been found to be a highly effective catalyst for a convenient and one-pot synthesis of 2-substituted benzoxazoles by the reaction of 2-aminophenol with acid chlorides, generated in situ from carboxylic acids. Aryl, heteroaryl, and arylalkyl carboxylic acids provided excellent yields of the corresponding benzoxazoles. The reaction conditions were compatible with various substituents such as chloro, bromo, nitro, methoxy, cyclopentyloxy, phenoxy, thiophenoxy, and conjugated double bonds. Benzoxazole formation was found to be general with respect to substituted 2-aminophenols.
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Staniszewska, Monika, Łukasz Kuryk, Aleksander Gryciuk, Joanna Kawalec, Marta Rogalska, Joanna Baran, Edyta Łukowska-Chojnacka, and Anna Kowalkowska. "In Vitro Anti-Candida Activity and Action Mode of Benzoxazole Derivatives." Molecules 26, no. 16 (August 18, 2021): 5008. http://dx.doi.org/10.3390/molecules26165008.

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A newly synthetized series of N-phenacyl derivatives of 2-mercaptobenzoxazole, including analogues of 5-bromo- and 5,7-dibromobenzoxazole, were screened against Candida strains and the action mechanism was evaluated. 2-(1,3-benzoxazol-2-ylsulfanyl)-1-(4-bromophenyl)ethanone (5d), 2-(1,3-benzoxazol-2-ylsulfanyl)-1-(2,3,4-trichloro-phenyl)ethanone (5i), 2-(1,3-benzoxazol-2-ylsulfanyl)-1-(2,4,6-trichlorophenyl)ethanone (5k) and 2-[(5-bromo-1,3-benzoxazol-2-yl)sulfanyl]-1-phenylethanone (6a) showed anti-C. albicans SC5314 activity, where 5d displayed MICT = 16 µg/mL (%R = 100) and a weak anti-proliferative activity against the clinical strains: C. albicans resistant to azoles (Itr and Flu) and C. glabrata. Derivatives 5k and 6a displayed MICP = 16 µg/mL and %R = 64.2 ± 10.6, %R = 88.0 ± 9.7, respectively, against the C. albicans isolate. Derivative 5i was the most active against C. glabrata (%R = 53.0 ± 3.5 at 16 µg/mL). Benzoxazoles displayed no MIC against C. glabrata. Benzoxazoles showed a pleiotropic action mode: (1) the total sterols content was perturbed; (2) 2-(1,3-benzoxazol-2-ylsulfanyl)-1-(3,4-dichlorophenyl)ethanol and 2-(1,3-benzoxazol-2-ylsulfanyl)-1-(2,3,4-trichlorophenyl)ethanol (8h–i) at the lowest fungistatic conc. inhibited the efflux of the Rho123 tracker during the membrane transport process; (3) mitochondrial respiration was affected/inhibited by the benzoxazoles: 2-(1,3-benzoxazol-2-ylsulfanyl)-1-(4-chlorophenyl)ethanol and 2-(1,3-benzoxazol-2-ylsulfanyl)-1-(4-bromophenyl)ethanol 8c–d and 8i. Benzoxazoles showed comparable activity to commercially available azoles due to (1) the interaction with exogenous ergosterol, (2) endogenous ergosterol synthesis blocking as well as (3) membrane permeabilizing properties typical of AmB. Benzoxazoles display a broad spectrum of anti-Candida activity and action mode towards the membrane without cross-resistance with AmB; furthermore, they are safe to mammals.
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Arisoy, Mustafa, Ozlem Temiz-Arpaci, Fatma Kaynak-Onurdag, and Selda Ozgen. "Synthesis and Antimicrobial Evaluation of 2-(p-Substituted Phenyl)-5-[(4-substituted piperazin-1-yl)acetamido]-benzoxazoles." Zeitschrift für Naturforschung C 69, no. 9-10 (October 1, 2014): 368–74. http://dx.doi.org/10.5560/znc.2014-0024.

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Abstract series of 2-(p-substituted phenyl)-5-(2-{4-[(p-chloro-fluorophenyl)=phenyl] piperazin-1-yl}- acetamido)-benzoxazoles were synthesized and tested for their antimicrobial activities. The structures of the new derivatives were elucidated by spectral techniques. The minimum inhibitory concentrations (MIC) of the new benzoxazoles, along with those of previously synthesized analogues, were determined against standard bacterial and fungal strains and drug-resistant isolates, and compared with those of several reference drugs. The new benzoxazole derivatives were found to possess a broad spectrum of antimicrobial activity with MIC values of 32 - 1024 μg/ml. Although the standard drugs were more active against the tested pathogens, the activities of the new benzoxazoles and the reference drugs were largely similar against the drug-resistant isolates.
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Glamočlija, Una, Subhash Padhye, Selma Špirtović-Halilović, Amar Osmanović, Elma Veljović, Sunčica Roca, Irena Novaković, et al. "Synthesis, Biological Evaluation and Docking Studies of Benzoxazoles Derived from Thymoquinone." Molecules 23, no. 12 (December 12, 2018): 3297. http://dx.doi.org/10.3390/molecules23123297.

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Thymoquinone (TQ), a natural compound with antimicrobial and antitumor activity, was used as the starting molecule for the preparation of 3-aminothymoquinone (ATQ) from which ten novel benzoxazole derivatives were prepared and characterized by elemental analysis, IR spectroscopy, mass spectrometry and NMR (1H, 13C) spectroscopy in solution. The crystal structure of 4-methyl-2-phenyl-7-isopropyl-1,3-benzoxazole-5-ol (1a) has been determined by X-ray diffraction. All compounds were tested for their antibacterial, antifungal and antitumor activities. TQ and ATQ showed better antibacterial activity against tested Gram-positive and Gram-negative bacterial strains than benzoxazoles. ATQ had the most potent antifungal effect against Candida albicans, Saccharomyces cerevisiae and Aspergillus brasiliensis. Three benzoxazole derivatives and ATQ showed the highest antitumor activities. The most potent was 2-(4-fluorophenyl)-4-methyl-7-isopropyl-1,3-benzoxazole-5-ol (1f). Western blot analyses have shown that this compound inhibited phosphorylation of protein kinase B (Akt) and Insulin-like Growth Factor-1 Receptor (IGF1R β) in HeLa and HepG2 cells. The least toxic compound against normal fibroblast cells, which maintains similar antitumor activities as TQ, was 2-(4-chlorophenyl)-4-methyl-7-isopropyl-1,3-benzoxazole-5-ol (1e). Docking studies indicated that 1e and 1f have significant effects against selected receptors playing important roles in tumour survival.
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Aruna, G., Ravindra Kulkarni, Baswaraj Machaa, Malathi Jojula, Shravan Gunda, and G. Achaiah. "Design, Synthesis and Evaluation of Aryloxybenzylidene Hydrazinyl-Benzoxazoles/Benzothiazoles Analogs as Antimycobacterial Agents." Asian Journal of Organic & Medicinal Chemistry 5, no. 3 (2020): 185–91. http://dx.doi.org/10.14233/ajomc.2020.ajomc-p272.

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Substituted 2-(2-(4-aryloxybenzylidene)hydrazinyl)benzothiazole/benzoxazoles series were designed through molecular hybridization and synthesized in condensation reaction of hydrazinylbenzothiazole/ benzoxazole with substituted aryloxy benzaldehydes. All the synthesized compounds were assigned structure based on spectral data and were evaluated for antimycobacterial activity. Among both benzothiazole and benzoxazole derivatives, the compounds 8f and 9e were found to show most potent antitubercular activity with MIC value of 0.89 and 0.92 μM which are on a par with those of standard antitubercular drugs. In order to know the binding interactions of all the compounds were docked within the mycobacterial pantothenate synthetase, which showed interactions with Asp88, Arg200, Ser196, Asn199, Met 195 and Lys 160 of pantothenate synthetase.
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Imramovsky, Ales, Jan Kozic, Matus Pesko, Jirina Stolarikova, Jarmila Vinsova, Katarina Kralova, and Josef Jampilek. "Synthesis and Antimycobacterial and Photosynthesis-Inhibiting Evaluation of 2-[(E)-2-Substituted-ethenyl]-1,3-benzoxazoles." Scientific World Journal 2014 (2014): 1–11. http://dx.doi.org/10.1155/2014/705973.

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A series of twelve 2-[(E)-2-substituted-ethenyl]-1,3-benzoxazoles was designed. All the synthesized compounds were tested against three mycobacterial strains. The compounds were also evaluated for their ability to inhibit photosynthetic electron transport (PET) in spinach (Spinacia oleraceaL.) chloroplasts. 2-[(E)-2-(4-Methoxyphenyl)ethenyl]-1,3-benzoxazole, 2-[(E)-2-(2,3-dihydro-1-benzofuran-5-yl)ethenyl]-1,3-benzoxazole and 2-{(E)-2-[4-(methylsulfanyl)phenyl]ethenyl}-1,3-benzoxazole showed the highest activity againstM. tuberculosis,M. kansasii,andM. avium, and they demonstrated significantly higher activity againstM. aviumandM. kansasiithan isoniazid. The PET-inhibiting activity of the most activeortho-substituted compound 2-[(E)-2-(2-methoxyphenyl)ethenyl]-1,3-benzoxazole was IC50= 76.3 μmol/L, while the PET-inhibiting activity ofpara-substituted compounds was significantly lower. The site of inhibitory action of tested compounds is situated on the donor side of photosystem II. The structure-activity relationships are discussed.
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Malakar, Chandi, Nagaraju Vodnala, Raghuram Gujjarappa, Arup Kabi, Mohan Kumar, and Uwe Beifuss. "Facile Protocols towards C2-Arylated Benzoxazoles using Fe(III)-Catalyzed C(sp 2-H) Functionalization and Metal-Free Domino Approach." Synlett 29, no. 11 (May 16, 2018): 1469–78. http://dx.doi.org/10.1055/s-0037-1609718.

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Considering their growing attention in the field of medicinal chemistry and drug-discovery research, the facile and convenient approaches towards the preparation of 2-aryl benzoxazole derivatives have been described. The transformation is accomplished by using Fe(III)-catalyzed C–H activation of benzoxazoles with boronic acids to obtain a wide range of C2-arylated benzoxazoles in high yields. The developed method excludes the formation of self-coupling compounds as side products. On the other hand, the synthesis of the products is also achieved via a metal-free domino protocol by the reaction between 1-nitroso-2-naphthol and acetophenones using catalytic amounts of CBr4 in the presence of Cs2CO3 as base. The devised tandem method avoids the use of pre-activated α-haloketones as substrates. Due to their immense impact in marketed drugs and molecules under clinical trial, the described method can be a powerful tool for their synthesis which ­restricts the use of precious metals as catalyst.
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M, Jyothi, and Ramchander Merugu. "AN UPDATE ON THE SYNTHESIS OF BENZOXAZOLES." Asian Journal of Pharmaceutical and Clinical Research 10, no. 10 (September 1, 2017): 48. http://dx.doi.org/10.22159/ajpcr.2017.v10i10.19457.

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Benzoxazoles being structurally similar to bases adenine and guanine interact with biomolecules present in living systems. These compounds possess antimicrobial, central nervous system activities, antihyperglycemic potentiating activity, analgesic, and anti-inflammatory activity. It can also be used as starting material for other bioactive molecules. Modifications in structure and the biological profiles of new generations of benzoxazoles were found to be more potent with enhanced biological activity. Considering all these, we have prepared this review and discussed the synthesis and biological activities of benzoxazoles.
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Kale, Dolly, Gajanan Rashinkar, Audumbar Patil, Arjun Kumbhar, and Rajashri Salunkhe. "Facile Access to 2-Substituted Benzoxazoles Using Sawdust Supported N-Heterocyclic Carbene-Ni Complex via C-H Activation." Letters in Organic Chemistry 17, no. 6 (May 20, 2020): 479–89. http://dx.doi.org/10.2174/1570178616666190705153927.

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Sawdust supported N-heterocyclic carbene-nickel complex has been prepared by covalent grafting of 1-methyl imidazole in the matrix of chloropropyl modified sawdust followed by reaction with nickel acetate. The resultant NHC-Ni complex was employed as a heterogeneous catalyst for the synthesis of 2-substituted benzoxazoles from benzoxazole and aryl boronic acids following C-H activation strategy. The recycling experiments showed that the complex could be reused for five consecutive runs without significant loss in the yield of products.
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Dissertations / Theses on the topic "Synthesis of benzoxazoles"

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Hutson, Leslie K. "Synthesis of Benzoxazoles Containing Allyl Crosslinking Sites via Claisen Rearrangements." Wright State University / OhioLINK, 1999. http://rave.ohiolink.edu/etdc/view?acc_num=wright974400715.

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Kleinhans, Dewald Johannes. "Studies in the synthesis of benzoxazole compounds." Thesis, Stellenbosch : Stellenbosch University, 2015. http://hdl.handle.net/10019.1/97900.

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Thesis (PhD)--Stellenbosch University, 2015.
ENGLISH ABSTRACT: Benzoxazoles are an important class of π-electron-excessive, benzene-fused heterocyclic compounds found in natural products and display a wide range of pharmacological applications. It is therefore a widely used starting scaffold for drug and agrochemical discovery programs. Other applications include: chiral auxiliaries in asymmetric reactions, chiral receptors for the resolution of racemic mixtures, fluorescent whitening dyes, various photochromic materials and as ligands for a wide range of catalytic reactions. Due to our interests in resorcinarenes, we came across 4-hydroxybenzoxazoles, a structural motif that has not been explored as potential asymmetric ligands. In this thesis it was attempted to investigate the synthesis, functionalisation and coordination chemistry of these compound class and finally look at a method of synthesising chiral 4-hydroxybenzoxazoles from amino acids. A small library of achiral 4-hydroxybenzoxazoles were synthesised in good yields. These compounds were then reacted with various transition metals, of which only the Pd-salts proved to return any usable compounds. The first structural evidence of the bonding of 4- hydroxybenzoxazoles was recorded from single crystal X-ray diffraction analysis of the coordination compounds that formed. Different coordination modes were recorded, depending on the ligand and the Pd-salt used. The PdCl2 compounds were also tested for catalytic activity with a Heck reaction, showing good conversions for the reaction between iodobenzene and styrene to form stilbene. Further examination pointed to the ligands playing an insignificant role in the reaction and the products possibly due to only the PdCl2’s reactivity. During this period it was also attempted to functionalise the phenol group with P(III) groups and repeat the coordination and catalytic studies. Efforts to synthesise these compounds were not successful, with oxidation of the P(III) to P(V) groups or degradation of these compounds. Efforts to synthesise these via phosphorous protection, utilising BH3 or the in situ trapping of the compounds with transition metals, were also not successful. During the trapping experiments the phosphinite and Pd-salt formed a re-arranged product that is a known and useful catalyst on its own. Finally a small library of chiral benzoxazoles and 4-hydroxybenzoxazoles were synthesised, starting from amino acids and utilising a Mitsunobu reaction to perform the ring closing. Antimicrobial tests with these compounds did not return any appreciable results.
AFRIKAANSE OPSOMMING: Bensoksasool is 'n belangrike klas van π-elektron-ryk, benseen-saamgesmelte heterosikliese verbindings wat in natuurlike produkte voorkom en 'n wye verskeidenheid van farmakologiese funksies vertoon. Dit is dus 'n baie algemene basis struktuur vir dwelm- en landbouchemiese ontdekkings programme. Ander gebruike sluit in: chirale ligande in asimmetriese reaksies, chirale reseptore vir die resolusie van rasemiese mengsels, fluoresserende verwittings kleurstowwe, verskeie fotochromiese materiaal en as ligande vir 'n wye verskeidenheid van katalitiese reaksies. As gevolg van ons belangstelling in resorsinarene, het ons op 'n strukturele motief afgekom wat nog nie ondersoek is as potensiële asimmetriese ligande nie, die 4- hidroksiebensoksasole. In hierdie tesis is gepoog om die sintese, funksionalisering en koördinasie chemie van hierdie klas verbindings te ondersoek en uiteindelik 'n metode te ontwikkel om die sintese van chirale 4-hidroksiebensoksasole vanaf aminosure te bewerkstellig. 'n Klein biblioteek van achirale 4-hidroksiebensoksasole was gesintetiseer in goeie opbrengste. Hierdie verbindings was toe behandel met verskeie oorgangsmetale, waarvan slegs die Pdsoute enige bruikbare verbindings gevorm het. Die eerste strukturele bewyse van die binding van die 4-hidroksiebensoksasole is aangeteken met behulp van enkelkristal X-straaldiffraksie ontleding van die koördinasieverbindings wat gevorm is. Verskillende koördinasie mode is aangeteken, afhangende van die ligand en die Pd-sout wat gebruik was. Die PdCl2 verbindings is ook vir katalitiese aktiwiteit met 'n Heck reaksie getoets. Die reaksie het baie goeie omskakeling gewys vir die reaksie tussen iodobenseen en stireen na stilbeen. Verdere ondersoeke het getoon dat die ligande nie ‘n beduidende rol in die reaksie speel nie en die produkte moontlik slegs as gevolg van die PdCl2 se reaktiwiteit is. Gedurende hierdie tydperk was daar ook probeer om die fenol groep met P(III) groepe te funksionaliseer. Met die uitgangstowwe sou die koördinering en katalitiese studies herhaal word. Pogings om hierdie verbindings te sintetiseer was nie suksesvol nie, met oksidasie van die P(III) na P(V) groepe of afbreking van hierdie verbindings. Pogings om dit te sintetiseer via fosfor beskermingstegnieke, deur gebruik te maak van BH3 of die in situ vasvang van die verbindings met oorgangsmetale, was ook nie suksesvol nie. Gedurende die vasvang eksperimente het die fosfien en PdCl2 ‘n herrangskikkings-produk gevorm wat op sy eie ‘n bekende en nuttige katalisator is. Ten slotte was 'n klein biblioteek van chirale bensoksasole en 4-hidroksiebensoksasole gesintetiseer, vanaf aminosure. Om die ringsluiting te bewerkstellig was ‘n Mitsunobu reaksie gebruik. Antimikrobiese toetse met hierdie verbindings het nie enige noemenswaardige resultate opgelewer nie.
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Park, Joonwon. "Synthesis and molecular control of star-like poly-2,4-benzoxazole." Thesis, Georgia Institute of Technology, 1992. http://hdl.handle.net/1853/8656.

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Avant, Lavern Marshall. "Synthesis and characterization of a cross-digitated poly (2,5-Benzoxazole) (ABPBO)." Thesis, Georgia Institute of Technology, 1995. http://hdl.handle.net/1853/8464.

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Bi, Xiaoman bi. "Synthesis and Characterization of Novel Fluorescent Sensors Based on Terpyridine, Benzoxazole and Benzothiazole Chromophores." University of Akron / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=akron1512743963248758.

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Njaria, Paul Magutu. "Antimycobacterial 2-aminoquinazolinones and benzoxazole-based oximes: synthesis, biological evaluation, physicochemical profiling and supramolecular derivatization." Doctoral thesis, University of Cape Town, 2017. http://hdl.handle.net/11427/26954.

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Tuberculosis (TB) is a life-threatening infectious disease caused by Mycobacterium tuberculosis (Mtb). Globally, TB is a major public health burden with an estimated 10.4 million new cases and 1.8 million deaths reported in 2015. Although TB is curable, the treatment options currently available are beset by numerous shortcomings such as lengthy and complex treatment regimens, drug-drug interactions, drug toxicities, as well as emergence of widespread multi-drug resistance. Therefore, there is an urgent and compelling need to develop new, more effective, safer drugs with novel mechanisms of action, and which are capable of shortening treatment duration. This study focused on hit-to-lead optimization of two new classes of compounds with potential anti-TB properties: 2-aminoquinazolinones (AQZs) and benzoxazole-based oximes (BZOs). A hit compound for each of these classes with low micromolar antimycobacterial activity had previously been identified through phenotypic whole-cell in vitro screening.
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Luo, Guo-Wei, and 羅國瑋. "Synthesis and Properties of Poly(benzoxazole-imide)Copolymer/Clay Nanocomposites." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/76168487506357286813.

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碩士
國立成功大學
材料科學及工程學系碩博士班
92
Poly(benzoxazole-imide) (PBO-PI) copolymer/clay nanocomposites have been prepared from a PBO-PI precursor-poly(hydroxyamide-amic acid) (PHA-PAA) and two different organoclays. The PBO-PI precursor was made by a polycondensation reaction between 2,2-bis(3-amino-4-hydroxyphenol) hexafluoropropane (BisAPAF), 4,4-oxydiphthalic anhydride (ODPA) and isophthaloyl dichloride (IC). The organoclays were formed by a cation exchange reaction between a Na+-montmorillonite clay and an ammonium salt of dodecylamine (DOA) or 4-phenoxyaniline (POA). The glass transition temperature (Tg) of PBO-PI copolymer is 331℃. Both X-ray diffraction (XRD) and transmission electron microscope (TEM) analyses showed that the organoclays were dispersed in PBO-PI copolymer matrix in a nanoscale. The in-plane coefficient of thermal expansion (CTE) of PBO-PI copolymer/clay film was decreased with the increasing amount of organoclay. The CTE of PBO-PI copolymer/clay film which contained 7 wt % DOA-clay was decreased 35% compared to the pure PBO-PI film and the CTE of PBO-PI copolymer/clay film which contained 7 wt % POA-clay was decreased 33%. The thermal decomposition temperatures of PBO-PI copolymer/clay films increased with the increasing amount of organoclay. The tensile modulus of PBO-PI copolymer/clay films increased with the increasing amount of organoclay. The tensile modulus of PBO-PI copolymer/clay film which contained 7 wt % DOA-clay was increased 95% compared to the pure PBO-PI copolymer film and the tensile modulus of PBO-PI copolymer/clay film which contained 7 wt % POA-clay was increased 68%. The water absorption of PBO-PI copolymer/clay film was decreased with the increasing amount of organoclay. From UV-Vis spectra, the PBO-PI copolymer/POA-clay film showed a better transparency than the PBO-PI copolymer/DOA-clay film. That could be due to the fact that POA has a higher thermal stability than DOA.
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Chang, Ying-Ching, and 張孆璟. "Synthesis of Anticacer Bis (benzimidazoles) Library and Benzimidazolyl benzoxazole Related to UK-1." Thesis, 2015. http://ndltd.ncl.edu.tw/handle/8s3bfm.

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Chen, Tai-an, and 陳泰安. "Synthesis and Characterization of New Polyimides Containing Pendent Benzimidazoles Groups and Polybenzimidazoles Containing Pendent Benzoxazole Groups." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/93346838677936173720.

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碩士
國立臺灣科技大學
化學工程系
102
Part 1 A series of new polyimides (PIs) with pendant benzimidazole had been synthesized. They had inherent viscosities in the range of 0.96~1.20 dLg-1, and they could form tough and flexible films. The PIs exhibited high thermal stability with 10% decomposition temperature more than 500℃ in nitrogen, and their and soft temperature around 300℃. These films exhibited good mechanical properties with tensile stress exceeded 132 MPa.However,the mechanical properties of phosphoric acid doped PI significantly decreased. The mechanical properties of crosslinked polyimides (C-PI) were improved via crosslinking reaction of methyl group. The proton conductivity of phosphoric acid doped PBI was dependent on doping PA level and temperatures. The proton conductivity of BPBI8mBI1F0.5DMB0.5 and C5-BPBI8mBI1F0.5DMB0.5 were 75.4 and 78.4 mS/cm at 160℃,respectively.The proton conductivity of PI and C-PI were significantly higher than m-PBI (52.0 mS/cm).Thus, these polyimides (PIs) with pendant benzimidazole membranes could be the promising materials alternative to m-PBI membrane for medium-temperature fuel cells applications because they had high proton conductivity,and good thermal stability. Part 2 A series of new polybenzimidazoles (PBIs) with pendant benzoxazole had been synthesized. They had inherent viscosities in the range of 0.85~2.4 dLg-1, and they could form tough and flexible films. , The PBIs exhibited high thermal stability with 10% decomposition temperature more than 470 ℃ in nitrogen, and their glass transition temperature and soft temperature around 300℃. These films also exhibited good mechanical properties with tensile stress exceeded 70 MPa. However, the mechanical properties of phosphoric acid doped PBI significantly decreased. This is the study that improved mechanical properties of proton exchange membranes via crosslinking reaction of methyl groups.The tensile strength of cross-linked PBI was a approximately twice as strong as uncross-linked PBI. The proton conductivity of phosphoric acid doped PBI was dependent on doping PA level and temperatures. The proton conductivity of PBI-3-3 was 60.2 mS/cm at 160 ℃.The proton conductivity of PBI-3-3 was higher than m-PBI (52.0 S/cm). The proton conductivity of C-PBI-3-3 was 51.7 mS/cm at 160℃,the tensile strength of crosslinked C-PBI-3-3 was about double.Thus, these polybenzimidazoles (PBIs) with pendant benzoxazole membranes could be the promising materials alternative to m-PBI membrane for medium-temperature fuel cells applications because they had high proton conductivity,and good thermal stability.
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Chen, Szu-Yuan, and 陳思源. "Synthesis and Characterization of New Polybenzimidazoles Containing Pendent Benzoxazole Groups for Proton Exchange Membrane Fuel Cell at Intermediate Temperature." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/19376040315169121072.

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碩士
國立臺灣科技大學
化學工程系
101
A series of new polybenzimidazoles (PBIs) with pendant heterocyclic ring have been synthesized. The resulting polymers showed good solubility in aprotic solvents. They had inherent viscosities in the range of 0.92~1.9 dLg-1, and they could form tough and flexible films. They exhibited high thermal stability with initial decomposition temperature ranging from 653 to 705 in nitrogen, and their glass transition temperature around 300℃. These films exhibited good mechanical properties with tensile stress exceeded 94.5 MPa. Phosphoric acid (PA) doped PBI was swollen result in the volume of PBI showed a larger volume swelling. The mechanical properties of phosphoric acid doped PBI significantly decreased. This is the first study that improved mechanical properties of proton exchange membranes using crosslinking in methyl pendent PBIs. Mechanical strength of cross-linked PBI is twice as strong as noncross-linked PBI. The proton conductivity of phosphoric acid doped PBI was dependent on doping PA level and temperatures. The proton conductivity of PBI-1-10 was approximately 61.6 mS/cm at 200 ℃, compared with 57.8 mS/cm of m-PBI membrane. The proton conductivity of C5-PBI-1-10 was approximately 67.7 mS/cm at 200 ℃. Thus, these polybenzimidazoles (PBIs) with pendant heterocyclic ring membranes could be the promising materials alternative to Nafion membrane for medium-temperature fuel cells applications because they had high phosphoric acid doped, good thermal stability, and higher proton conductivity.
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Book chapters on the topic "Synthesis of benzoxazoles"

1

Wang, Fengjiang, and James R. Hauske. "Solid-Phase Synthesis of Benzoxazoles via Mitsunobu Reaction." In Solid-Phase Organic Syntheses, 73–84. New York, USA: John Wiley & Sons, Inc., 2001. http://dx.doi.org/10.1002/0471220434.ch7.

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2

Neelima, G., K. Lakshmi, and K. Sesha Maheswaramma. "In Silico Studies of Benzoxazole Derivatives Using Ferrite-L-cysteine Magnetic Nanoparticles: Green Synthesis." In Special Publications, 288–301. Cambridge: Royal Society of Chemistry, 2019. http://dx.doi.org/10.1039/9781839160783-00288.

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3

Unger, Thomas A. "Benzoxazoles benzoxazolines benzoxazolinones benzoxazolones." In Pesticide Synthesis Handbook, 430. Elsevier, 1996. http://dx.doi.org/10.1016/b978-081551401-5.50339-7.

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4

Block, E. "Synthesis from 2-[(3-Hydroxyalkyl)selanyl]benzoxazoles." In Sulfur, Selenium, and Tellurium, 1. Georg Thieme Verlag KG, 2008. http://dx.doi.org/10.1055/sos-sd-039-01367.

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5

DeRosa, Thomas F. "Benzoxazoles." In Advances in Synthetic Organic Chemistry and Methods Reported in US Patents, 182–85. Elsevier, 2006. http://dx.doi.org/10.1016/b978-008044474-1/50019-0.

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6

Kantlehner, W. "Synthesis from Benzoxazole-2-thiones." In Three Carbon-Heteroatom Bonds: Ketenes and Derivatives, 1. Georg Thieme Verlag KG, 2006. http://dx.doi.org/10.1055/sos-sd-024-00421.

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List, B., C. Chandler, R. R. Torres, and A. Erkkilä. "Synthesis from 2-(Methylsulfanyl)benzoxazole." In X-Ene-X (X=F, Cl, Br, I, O, S, Se, Te, N, P), Ene-Hal, and Ene-O Compounds, 1. Georg Thieme Verlag KG, 2008. http://dx.doi.org/10.1055/sos-sd-032-00279.

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8

Schnrch, M., J. Hmmerle, and P. Stanetty. "Synthesis of Benzoxazole-2(3)-thiones." In Science of Synthesis Knowledge Updates KU 2011/1, 1. Georg Thieme Verlag KG, 2010. http://dx.doi.org/10.1055/sos-sd-111-00428.

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9

"Chapter 8 Oxazoles and benzoxazoles." In Palladium in heterocyclic chemistry - A guide for the synthetic chemist, 321–34. Elsevier, 2000. http://dx.doi.org/10.1016/s1460-1567(00)80012-4.

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10

Balasubramanian, Marudai. "Chapter 8 Oxazoles and benzoxazoles." In Palladium in Heterocyclic Chemistry - A Guide for the Synthetic Chemist, 379–406. Elsevier, 2007. http://dx.doi.org/10.1016/s1460-1567(07)80057-2.

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Conference papers on the topic "Synthesis of benzoxazoles"

1

Jampilek, Josef, Jarmila Vinsova, Tatjana Grafnetterova, and Jiri Dohnal. "Synthesis and Hydrophobic Properties of Benzoxazoles." In The 9th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2005. http://dx.doi.org/10.3390/ecsoc-9-01466.

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Seijas, Julio, M. Vázquez-Tato, M. Carballido-Reboredo, and José Crecente-Campo. "P2S5 Mediated Synthesis of Benzoxazoles and Benzothiazoles by Microwave Irradiation." In The 9th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2005. http://dx.doi.org/10.3390/ecsoc-9-01642.

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Vinšová, Jarmila, Václav Horák, Vladimír Buchta, and Jarmila Kaustová. "Highly Lipophilic Benzoxazoles with Potential Antibacterial Activity." In The 8th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2004. http://dx.doi.org/10.3390/ecsoc-8-01977.

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4

Affeldt, Ricardo F., Dennis Russowsky, and Fabiano S. Rodembusch. "Novel Photoactive N-Heterocycles Bearing a Benzoxazole Moiety: Synthesis and Photophysical study." In 14th Brazilian Meeting on Organic Synthesis. São Paulo: Editora Edgard Blücher, 2013. http://dx.doi.org/10.5151/chempro-14bmos-r0156-1.

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5

Ha, Sie-Tiong, and Kok-Leei Foo. "New thermotropic liquid crystals with benzoxazole core." In The 15th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2011. http://dx.doi.org/10.3390/ecsoc-15-00747.

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Soares, Ana, Susana Costa, and M. Sameiro Gonçalves. "Benzoxazole Derivatives as Phototriggers for the Release of Butyric Acid." In The 18th International Electronic Conference on Synthetic Organic Chemistry. Basel, Switzerland: MDPI, 2014. http://dx.doi.org/10.3390/ecsoc-18-a034.

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