- Quantum mechanical and spectroscopic (FT-IR, FT-Raman, 1H NMR and UV) investigations of 5-nitro-2-phenylbenzoxazole
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The optimized molecular structure, vibrational wavenumbers, corresponding vibrational assignments of 5-nitro-2-phenylbenzoxazole have been investigated experimentally and theoretically. The energy and oscillator strength calculated by Time Dependent Density Functional Theory results almost compliments with experimental findings. Gauge-including atomic orbital 1H-NMR chemical shifts calculations were carried out and compared with experimental data. The HOMO and LUMO analysis is used to determine the charge transfer with in the molecule. The stability of the molecule arising from hyper-conjugative interaction and charge delocalization has been analyzed using NBO analysis. molecular electrostatic potential was performed by the DFT method and the infrared intensities and Raman activities are also been reported. Fist hyperpolarizability is calculated in order to find its role in nonlinear optics. Antimicrobial properties indicated that the title compound possessed a broad spectrum activity against the tested Gram-positive, Gram-negative bacteria.
- Bhagyasree,Varghese, Hema Tresa,Panicker, C. Yohannan,Samuel, Jadu,Van Alsenoy, Christian,Ertan-Bolelli, Tugba,Yildiz, Ilkay
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Read Online
- Cu-Catalyzed Synthesis of Benzoxazole with Phenol and Cyclic Oxime
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A Cu-catalyzed straightforward synthesis of benzoxazoles from free phenols and cyclic oxime esters is reported. The mild reaction conditions tolerate various electron-withdrawing and electron-donating functional groups on both substrates, affording benzoxazoles in moderate to good yields. With this protocol, large-scale syntheses of Ezutromid and Flunoxaprofe in one or two steps are demonstrated. A catalytic mechanism, which includes Cu-catalyzed amination via inner-sphere electron transfer and consequent annulation, is proposed.
- Wang, Zheng-Hai,Wang, Dong-Hui
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supporting information
p. 782 - 785
(2022/01/20)
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- Pd/Cu-Catalyzed C-H/C-H Cross Coupling of (Hetero)Arenes with Azoles through Arylsulfonium Intermediates
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A highly efficient method for the selective formal C-H/C-H cross-coupling of azoles and (hetero)arenes was established through arylsulfonium intermediates under transition-metal catalysis, which produced a variety of 2-(hetero)aryl azoles in good to excellent yields. Advantages of the reaction included mildness, a good functional group tolerance, a wide range of substrates, a high regio- and chemoselectivity, one-pot procedures, and the late-stage functionalization of complex molecules without the use of oxidants, offering a promising strategy for the transition-metal-catalyzed C-H arylation of azoles.
- Lin, Zeng-Hui,Tian, Ze-Yu,Zhang, Cheng-Pan
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supporting information
p. 4400 - 4405
(2021/06/27)
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- Acid-promoted cleavage of the C–C double bond of N-(2-Hydroxylphenyl)enaminones for the synthesis of benzoxazoles
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An acid-mediated selective cleavage of C–C double bond of N-(2-hydroxylphenyl)enaminones with formation a new C–O bond for the synthesis of 2-substituted benzoxazoles has been developed. This protocol proceeds under transition metal- and oxidant-free conditions with broad functional group tolerance. The oxidative cleavage of C–C double bond of N-(2-hydroxylphenyl)enaminone is also realized using NCS or NFSI as oxidants with release of 2,2-dihalogen-acetophenone fragments.
- Ge, Bailu,Peng, Yanling,Liu, Jing,Wen, Si,Peng, Cheng,Cheng, Guolin
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- Iridium-catalyzed intramolecular C–N and C–O/S cross-coupling reactions: Preparation of benzoazole derivatives
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The irdium-catalyzed intramolecular arylcarbon-hetero cross-coupling reactions with o-haloarylamides or o-haloarylamidine have been effectively achieved using KOAc and just 1 mol% catalyst. The [Ir(cod)Cl]2 was proved to be more potential for smoothly assembling functional structures benzimidazoles, benzoxazoles and benzothiazoles, which was superior to Cu- and Pd-catalyzed systems. Simultaneously, a concise and efficient synthesis of tafamidis was developed in 5-g scale.
- Shi, Yajie,Zhou, Qifan,Du, Fangyu,Fu, Yang,Du, Yang,Fang, Ting,Chen, Guoliang
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- A 2 - substituted benzoxazole derivative of the preparation method
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The invention discloses a 2 - substituted benzoxazole derivative of the preparation method, its reaction as follows: . The present invention can be 2 - substituted pyrrole derivatives, acetophenone derivatives can be obtained and at the same time 2, 2 - dihalo acetophenone derivatives; and through the C (sp2 ) - C (sp2 ) At the same time selectively fracture of the aromatization. The method of the invention the resulting raw materials are easy, high yield, mild reaction conditions, the reaction time is short, wide substrate range, reaction specificity is strong, easy post treatment and green environmental protection.
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Paragraph 0050-0053
(2019/07/04)
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- Method used for rapid preparation of benzo-heterocycle compound with physical grinding under solvent-free room temperature conditions
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The invention discloses a method used for rapid preparation of benzo-heterocycle compound with physical grinding under solvent-free room temperature conditions. According to the method, glacial aceticacid is taken as a catalyst; at solvent-free room temperature conditions, physical grinding is adopted, reaction of 2-substituted arylamines (2-mercapto arylamine, 2-aminophenol, and o-phenylenediamine) and aromatic aldehydes is carried out using physical grinding. The method is friendly to the environment, is simple in operation, is safe, is low in cost, and is high in efficiency. Compared withthe prior art, the advantages are that: the method is suitable for a large amount of functional groups, yield is high, less by-product is generated, operation is simple, the method is safe, cost is low, and the method is friendly to the environment.
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Paragraph 0062; 0100
(2019/01/21)
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- Phosphonium acidic ionic liquid: An efficient and recyclable homogeneous catalyst for the synthesis of 2-Arylbenzoxazoles, 2-Arylbenzimidazoles, and 2-Arylbenzothiazoles
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A highly efficient and green strategy for the synthesis of 2-Arylbenzoxazoles, 2-Arylbenzimidazoles, and 2-Arylbenzothiazoles catalyzed by phosphonium acidic ionic liquid has been developed via the condensation of o-Aminophenol, o-phenylenediamines, and o-Aminothiophenol, respectively, with aldehydes. The reaction has a good yield, the broad substrate scope, and mild condition. Triphenyl(butyl-3-sulphonyl)phosphonium toluenesulfonate catalyst was easily obtained from cheap and available starting materials through a one-pot synthesis. Its structure was identified by 1H NMR, 13C NMR, 31P NMR, and FT-IR techniques. Other properties including thermal stability and acidity were determined by TGA and Hammett acidity function method. Interestingly, the catalyst can maintain its constantly outstanding performance till the fourth recovery.
- Nguyen, Quang The,Thi Hang, Anh-Hung,Ho Nguyen, Thuy-Linh,Nguyen Chau, Duy-Khiem,Tran, Phuong Hoang
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p. 11834 - 11842
(2018/04/05)
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- N-Heterocyclic Carbene (NHC)-Catalyzed One-Pot Aerobic Oxidative Synthesis of 2-Substituted Benzo[ d ]oxazoles, Benzo[ d ]thiazoles and 1,2-Disubstituted Benzo[ d ]imidazoles
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N-Heterocyclic carbene (NHC), generated in situ from easily available N-heterocyclic imidazolium salt with air as terminal oxidant, has successfully been utilized as a cheap and efficient catalyst for one-pot aerobic oxidative synthesis of 2-arylbenzo[ d ]oxazoles, 2-substituted benzo[ d ]thiazoles, and 1,2-disubstituted benzo[ d ]imidazoles.
- Zhou, Quan,Liu, Shu,Ma, Ming,Cui, He-Zhen,Hong, Xi,Huang, Shuang,Zhang, Jing-Fan,Hou, Xiu-Feng
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supporting information
p. 1315 - 1322
(2018/03/10)
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- Deep eutectic solvent-catalyzed arylation of benzoxazoles with aromatic aldehydes
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A novel and efficient methodology for the arylation of benzoxazoles with aromatic aldehydes catalyzed by deep eutectic solvent has been developed. The reaction smoothly proceeded with a wide range of substrates to give the desired products in high yields within short reaction time. Deep eutectic solvents are easily recovered and reused without significant loss of catalytic activity.
- Tran, Phuong Hoang,Thi Hang, Anh-Hung
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p. 11127 - 11133
(2018/03/26)
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- A new superacid hafnium-based metal-organic framework as a highly active heterogeneous catalyst for the synthesis of benzoxazoles under solvent-free conditions
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A new crystalline porous superacid material was prepared by sulfation of a Hf-MOF constructed from a 6-connected Hf node and 1,3,5-benzenetricarboxylate. The new superacid MOF with the presence of sulfate groups coordinated to a Hf-oxo cluster as superacid sites was found to be an effective heterogeneous catalyst for solvent-free heterocyclization for benzoxazole synthesis.
- Nguyen, Linh H.T.,Nguyen, The T.,Nguyen, Ha L.,Doan, Tan L.H.,Tran, Phuong Hoang
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p. 4346 - 4350
(2017/10/13)
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- Enantioselective 2-alkylation of 3-substituted indoles with dual chiral lewis acid/hydrogen-bond-mediated catalyst
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A chiral-at-metal bis-cyclometalated iridium complex combines electrophile activation via metal coordination with nucleophile activation through hydrogen bond formation. This new bifunctional chiral Lewis acid/hydrogenbond-mediated catalyst permits the challenging enantioselective 2-alkylation of 3-substituted indoles with α, β-unsaturated 2-acyl imidazoles in up to 99% yield and with up to 98% enantiomeric excess at a catalyst loading of 2 mol %. As an application, the straightforward synthesis of a chiral pyrrolo- [1, 2-a]indole is demonstrated.
- Zhou, Zijun,Li, Yanjun,Gong, Lei,Meggers, Eric
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supporting information
p. 222 - 225
(2017/11/27)
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- Preparation method of 2-aryl benzoxazole and 2-aryl benzothiazole compounds
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The invention belongs to the technical field of organic synthesis, and in particular relates to a preparation method of 2-aryl benzoxazole and 2-aryl benzothiazole compounds. According to the invention, 2-aminophenol(2-aminothiophenol) and aromatic aldehydes are stirred at the temperature of 100 to 130 DEG C, imidazolium salt of which the molar equivalent amount is 10% to 20% and K2CO3 of which the molar equivalent amount is 25% to 50% are added, air is used as an oxidant, and then 2-aryl benzoxazole and 2-aryl benzothiazole compounds are synthesized by a reaction. According to the invention, the cheap and easily prepared imidazolium salt is taken as a catalyst and the cheap air is taken as the oxidant to synthesize target products in a high yield, so that the preparation method of the 2-aryl benzoxazole and 2-aryl benzothiazole compounds is greatly lowered in production cost and capable of adapting to the industrial application to a greater extent.
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Paragraph 0020; 0021
(2017/08/29)
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- Environmental benign synthesis of novel double layered nano catalyst and their catalytic activity in synthesis of 2-substituted benzoxazoles
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Synthesis of Cu-Al hydrotalcite by co precipitation method is being described. Synthesized nano catalyst has been characterized by powder X-ray diffraction, scanning electron microscopy, FT-IR and thermogravimetric analyses which confirm hydrotalcite-like structure. Effect of molar concentration, catalyst loading, reaction time and catalytic activity have been investigated in the synthesis of benzoxazoles under solvent free conditions using 2-amino phenol and benzoyl chloride. The influence of the hydrotalcite and their different amounts on reactivity was studied. Catalyst can be recycle and used for further reaction without losing its activity.
- Gupta, Ruchi,Sahu, Pramod K.,Sahu, Praveen K.,Srivastava,Agarwal
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p. 119 - 123
(2017/01/25)
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- p-Toluenesulfonic acid-catalyzed metal-free formal [4?+?1] heteroannulation via N[sbnd]H/O[sbnd]H/S[sbnd]H functionalization: One-pot access to 2-aryl/hetaryl/alkyl benzazole derivatives
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A concise and direct one-pot [4?+?1] synthetic strategy for the construction of 2-substituted benzazoles such as benzoxazoles and benzothiazoles has been disclosed in high yields (80–98%) by cascade coupling reaction of 2-amino(thio)phenols with β-oxodithioesters. The current approach enables N[sbnd]H/O[sbnd]H/S[sbnd]H functionalization in one-pot under solventless condition leading to diverse benzazoles without use of any external metal. A wide range of 2-amino(thio)phenols and β-oxodithioesters are compatible toward this transformation with excellent functional group tolerance. Furthermore, we preempt the wider implications of this novel strategy by demonstrating its compatibility toward versatile diversification of DNA Topoisomerase-II inhibitors.
- Srivastava, Abhijeet,Shukla, Gaurav,Singh, Maya Shankar
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p. 879 - 887
(2017/01/25)
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- Optically operated second order optical effects in some substituted 4-(5-nitro-1,3-benzoxazol-2-yl)aniline chromophores
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In this work, we report on second order nonlinear optical (NLO) susceptibilities of some substituted 4-(5-nitro-1,3-benzoxazol-2-yl)aniline chromophores that were embedded into photopolymer matrices. Depending on the photo-induced nitrogen laser (waveleng
- Szlachcic,Fedorchuk,Danel,Jarosz,El Naggar,Albassam,Wojciechowski,Gondek,Uchacz,Stadnicka,Lakshminarayana,Kityk
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p. 333 - 341
(2017/03/08)
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- An iron and copper system catalyzed C-H arylation of azoles with arylboronic acids
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An efficient, environmentally friendly, and economical new method for arylation reactions of azoles with arylboronic acids via copper-iron-catalyzed C-H and C-B bond activation has been developed. The protocol tolerates a series of functional groups, such as methoxy, nitro, cyano, chloro, and trifluoromethyl groups.
- Hu, Wei-Ye,Wang, Pei-Pei,Zhang, Song-Lin
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supporting information
p. 42 - 48
(2015/02/02)
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- Synthesis of benzoxazoles from 2-aminophenols and β-diketones using a combined catalyst of br?nsted acid and copper iodide
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Cyclization reactions of 2-aminophenols with β-diketones catalyzed by a combination of Br?nsted acid and CuI are presented. Various 2-substituted benzoxazoles were obtained through these reactions. Different substituents such as methyl, chloro, bromo, nitro, and methoxy on 2-aminophenol are tolerated under the optimized reaction conditions.
- Mayo, Muhammad Shareef,Yu, Xiaoqiang,Zhou, Xiaoyu,Feng, Xiujuan,Yamamoto, Yoshinori,Bao, Ming
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p. 6310 - 6314
(2014/07/21)
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- Application of nano SnO2 as a green and recyclable catalyst for the synthesis of 2-aryl or alkylbenzoxazole derivatives under ambient temperature
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Application of nano SnO2 as an efficient and benign catalyst has been explored for the synthesis of 2-aryl or alkylbenzoxazole derivatives via condensation reaction of aldehyde with 2-aminophenol. The reactions proceed under heterogeneous and mild conditions in ethanol at room temperature to provide 2-aryl or alkylbenzoxazoles in high yields.
- Vahdat, Seyed Mohammad,Raz, Shima Ghafouri,Baghery, Saeed
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p. 579 - 585
(2014/07/07)
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- A novel and efficient route for the synthesis of 5-nitrobenzo[d]oxazole derivatives
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In this paper, we report a novel and efficient route for the synthesis of 5-nitrobenzoxazole derivatives starting from 2-fluoro-5-nitroaniline and various benzoyl chloride derivatives under solvent-free conditions at 130 °C in the presence potassium carbonate. Benzoyl chlorides easily underwent nucleophilic acyl substitution followed by intramolecular cyclization via concomitant removal of fluorine to obtain the title compounds in high yields.
- Vosooghi, Mohsen,Arshadi, Hossein,Saeedi, Mina,Mahdavi, Mohammad,Jafapour, Farnaz,Shafiee, Abbas,Foroumadi, Alireza
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- Optimization of benzoxazole-based inhibitors of Cryptosporidium parvum inosine 5′-monophosphate dehydrogenase
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Cryptosporidium parvum is an enteric protozoan parasite that has emerged as a major cause of diarrhea, malnutrition, and gastroenteritis and poses a potential bioterrorism threat. C. parvum synthesizes guanine nucleotides from host adenosine in a streamlined pathway that relies on inosine 5′-monophosphate dehydrogenase (IMPDH). We have previously identified several parasite-selective C. parvum IMPDH (CpIMPDH) inhibitors by high-throughput screening. In this paper, we report the structure-activity relationship (SAR) for a series of benzoxazole derivatives with many compounds demonstrating CpIMPDH IC50 values in the nanomolar range and >500-fold selectivity over human IMPDH (hIMPDH). Unlike previously reported CpIMPDH inhibitors, these compounds are competitive inhibitors versus NAD +. The SAR study reveals that pyridine and other small heteroaromatic substituents are required at the 2-position of the benzoxazole for potent inhibitory activity. In addition, several other SAR conclusions are highlighted with regard to the benzoxazole and the amide portion of the inhibitor, including preferred stereochemistry. An X-ray crystal structure of a representative E·IMP·inhibitor complex is also presented. Overall, the secondary amine derivative 15a demonstrated excellent CpIMPDH inhibitory activity (IC 50 = 0.5 ± 0.1 nM) and moderate stability (t1/2 = 44 min) in mouse liver microsomes. Compound 73, the racemic version of 15a, also displayed superb antiparasitic activity in a Toxoplasma gondii strain that relies on CpIMPDH (EC50 = 20 ± 20 nM), and selectivity versus a wild-type T. gondii strain (200-fold). No toxicity was observed (LD 50 > 50 μM) against a panel of four mammalian cells lines.
- Gorla, Suresh Kumar,Kavitha, Mandapati,Zhang, Minjia,Chin, James En Wai,Liu, Xiaoping,Striepen, Boris,Makowska-Grzyska, Magdalena,Kim, Youngchang,Joachimiak, Andrzej,Hedstrom, Lizbeth,Cuny, Gregory D.
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p. 4028 - 4043
(2013/06/27)
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- Catalytic Staudinger/aza-Wittig sequence by in situ phosphane oxide reduction
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A Staudinger/aza-Wittig reaction sequence is described that is catalytic in phosphorus. Towards this end, the phosphane oxide is reduced in situ by diphenylsilane, which allows for substoichiometric amounts of the catalyst 5-phenyldibenzophosphole to be used. The substrate scope is investigated and benzoxazoles, benzodiazepine imidates and a 2-methoxypyrrole were successfully synthesized. These investigations show that a fast aza-Wittig reaction is required to obtain high yields. A catalytic Staudinger/aza-Wittig reaction sequence, involving in situ phosphane oxide reduction, was successfully developed. Benzoxazoles, benzodiazepine imidates and 2-methoxypyrrole were synthesized without phosphane oxide waste products. Copyright
- Van Kalkeren, Henri A.,Te Grotenhuis, Colet,Haasjes, Frank S.,Hommersom,Rutjes, Floris P. J. T.,Van Delft, Floris L.
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p. 7059 - 7066
(2013/11/06)
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- Amberlyst-15-catalyzed synthesis of 2-substituted 1,3-benzazoles in water under ultrasound
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A clean and general method has been developed for the synthesis of benzothiazole, benzoxazole, and benzimidazoles using Amberlyst-15 as a recyclable catalyst under ultrasound irradiation in water. The methodology is operationally simple, free from the use of hazardous organic solvents, and does not require the use of inert or anhydrous atmosphere. A number of 1,3-benzazole derivatives were prepared in good to excellent yields by using this methodology.
- Rambabu,Murthi, P. Radha Krishna,Dulla, Balakrishna,Basaveswara Rao,Pal, Manojit
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supporting information
p. 3083 - 3092
(2013/09/12)
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- Palladium-catalyzed direct arylation of benzoxazoles with unactivated simple arenes
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Using CuBr2 as an additive, the Pd-catalyzed intermolecular C-H-C-H cross-coupling between benzoxazoles and unactivated simple arenes has been developed. This protocol provides a straightforward approach for the biological activity of 2-arylbenzoxazole derivatives.
- Wu, Ge,Zhou, Jun,Zhang, Min,Hu, Peng,Su, Weiping
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supporting information
p. 8964 - 8966
(2012/11/14)
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- Direct arylation of benzoxazole C-H bonds with iodobenzene diacetates
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A Pd (OAc)2-catalyzed direct arylation of benzoxazole C-H bonds has been achieved with iodobenzene diacetates as the arylation reagent in moderate to good yields. The procedure tolerates a series of functional groups, such as methoxy, nitro, cyano, chloro, and bromo groups.
- Yu, Peng,Zhang, Guangyou,Chen, Fan,Cheng, Jiang
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supporting information; experimental part
p. 4588 - 4590
(2012/09/22)
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- Microwave-assisted one-pot synthesis of benzothiazole and benzoxazole libraries as analgesic agents
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Microwave-assisted synthesis of benzothiazole and benzoxazole libraries via PIFA promoted cyclocondensation of 2-aminothiophenols/2-aminophenols with aldehydes under one-pot condition in good to excellent yields was achieved. Twenty compounds have been investigated for their analgesic activity and showed moderate to good activity. Indian Academy of Sciences.
- Praveen,Nandakumar,Dheenkumar,Muralidharan,Perumal
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experimental part
p. 609 - 624
(2012/08/28)
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- Reaction of N-nitro-O-(4-nitrophenyl)hydroxylamine with phosphorus pentoxide in the presence of nitriles. New method for the generation of aryloxenium ion
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A reaction of N-nitro-O-(4-nitrophenyl)hydroxylamine with nitriles RCN (R = Me, Et, Ph) in the presence of P4O10 in excess amount at 0°C leads to the formation of 2-R-5-nitro-1,3-benzoxazoles. The reaction presumably takes place through the intermediate (phenoxy)oxodiazonium ion [NO2C6H4O-N=N=O]+, which eliminates an N2O molecule to form the aryloxenium ion [NO2C 6H4O]+. The latter reacts with nitriles RCN at the ortho-carbon atom of the phenyl ring giving 2-R-5-nitro-1,3-benzoxazoles.
- Klenov, M. S.,Churakov, A. M.,Strelenko, Yu. A.,Tartakovsky, V. A.
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p. 2429 - 2431,3
(2020/08/31)
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- Palladium-catalyzed desulfitative C-arylation of a benzo[d]oxazole C-H bond with arene sulfonyl chlorides
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A palladium-catalyzed direct desulfitative C-arylation of a benzo[d]oxazole C-H bond with arene sulfonyl chlorides is described. The procedure tolerates halo, cyano, nitro, trifluoromethyl, acetyl and acetylamino groups on the phenyl ring of sulfonyl chlorides, providing the arylation products in moderate to good yields. It represents a practical and attractive alternative for the synthesis of 2-aryl benzoxazoles.
- Zhang, Manli,Zhang, Shouhui,Liu, Miaochang,Cheng, Jiang
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supporting information; experimental part
p. 11522 - 11524
(2011/11/12)
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- Mechanistic study of oxidative aromatization using activated carbon-molecular oxygen system in the synthesis of 2-arylbenzazoles:focus on the role of activated carbon
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Nineteen activated carbons, including sixteen tailor-made and three commercially available ones, were employed to investigate their role in the one-pot synthesis of 2-arylbenzazoles starting from 2-aminophenol, 1,2-diaminobenzene, or 2-aminobenzenethiol, and aldehyde via oxidative cyclization of intermediate phenolic Schiff base promoted by the activated carbon-molecular oxygen system. Tailor-made activated carbons were prepared from wood, coconut shell, and coal by the steam activation method or the chemical activation method. All activated carbons were characterized to clarify their properties, such as metal contaminants, specific surface area, porosity, and surface functionality. After examining their effects on reactivity in the oxidative aromatization, we found that the essential role of activated carbon in this oxidation system is concerned not with metal contaminants, specific surface area, pore volume, mean pore diameter, and surface oxygen groups evolving as CO2 at 900 °C but with surface oxygen groups evolving as CO during heating at 900 °C, such as carbonyl groups on the surface of activated carbon. Additionally, in the synthesis of 2-arylbenzoxazole, it was found that activated carbon would also promote the cyclization of the intermediate Schiff base.
- Kawashita, Yuka,Juichi, Yanagi,Fujii, Tatsuo,Hayashi, Masahiko
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supporting information; experimental part
p. 482 - 488
(2009/08/07)
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- Synthesis, biological evaluation and 2D-QSAR analysis of benzoxazoles as antimicrobial agents
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A new series of 5(or 6)-nitro/amino-2-(substituted phenyl/benzyl)benzoxazole derivatives (1a-1m, 2a-2l) were synthesized and evaluated for antibacterial and antifungal activities against Staphylococcus aureus, Bacillus subtilis, Klebsiella pneumoniae, Pse
- Ertan, Tugba,Yildiz, Ilkay,Tekiner-Gulbas, Betul,Bolelli, Kayhan,Temiz-Arpaci, Ozlem,Ozkan, Semiha,Kaynak, Fatma,Yalcin, Ismail,Aki, Esin
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experimental part
p. 501 - 510
(2009/09/05)
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- Iron-catalyzed intramolecular O-arylation: Synthesis of 2-aryl benzoxazoles
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(Chemical Equation Presented) A practical iron-catalyzed intramolecular O-arylation reaction and its application in the synthesis of benzoxazole derivatives, starting from the readily available 2-haloanilines, is presented. The key cyclization step involves the use of a combination of the cheap and environmentally friendly FeCl3 and 2,2,6,6-tetramethyl-3,5 heptanedione (TMHD) as the catalyst system.
- Bonnamour, Julien,Bolm, Carsten
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supporting information; experimental part
p. 2665 - 2667
(2009/05/27)
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- Mechanistic evidence for a ring-opening pathway in the Pd-catalyzed direct arylation of benzoxazoles
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The direct Pd-catalyzed arylation of 5-substituted benzoxazoles, used as a mechanistic model for 1,3-azoles, was investigated experimentally and computationally. The results of the primary deuterium kinetic isotope effect, Hammett studies, and H/D exchange were shown to be inconsistent with the rate-limiting electrophilic or concerted palladation. A mechanism, proposed on the basis of kinetic and computational studies, includes generation of isocyanophenolate as the key step. The DFT calculations suggest that the overall catalytic cycle is facile and is largely controlled by the C-H acidity of the substrate. Copyright
- Sanchez, Rafael S.,Zhuravlev, Fedor A.
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p. 5824 - 5825
(2008/02/09)
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- Novel anti-inflammatory and analgesic heterocyclic amidines that inhibit nitrogen oxide (NO) production
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Heterocyclic amidines with anti-inflammatory and analgesic activity that inhibit nitrogen oxide production, of formula (I): in which:G1 and G2 are hydrogen, halogen, hydroxyl, C1-C4 alkoxy, C1-C4 alkyl, and an amidino substituent of formula Q, provided that, for each compound of formula (I), only one of the two substituents G1 or G2 is an amidino substituent of formula Q: and in which the substituents W, Y and X are combined to form 9- or 10-membered bicyclic heteroaromatic derivatives containing up to 2 hetero atoms in the same ring; andZ is an aryl or heteroaryl group, a linear or branched C1-C6 alkyl or alkenyl chain, a C1-C4 alkyl-aryl group or a C1-C4 alkyl-heteroaryl group.
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Page/Page column 31
(2010/02/13)
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- Novel anti-inflammatory and analgesic heterocyclic amidines that inhibit nitrogen oxide (NO) production
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Heterocyclic amidines with anti-inflammatory and analgesic activity that inhibit nitrogen oxide production, of formula (I): in which: G1 and G2 are hydrogen, halogen, hydroxyl, C1-C4 alkoxy, C1-C4 alkyl, and an amidino substituent of formula Q, provided that, for each compound of formula (I), only one of the two substituents G1 or G2 is an amidino substituent of formula Q: and in which the substituents W, Y and X are combined to form 9- or 10-membered bicyclic heteroaromatic derivatives containing up to 2 hetero atoms in the same ring; and Z is an aryl or heteroaryl group, a linear or branched C1-C6 alkyl or alkenyl chain, a C1-C4 alkyl-aryl group or a C1-C4 alkyl-heteroaryl group.
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Page/Page column 22
(2010/02/13)
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- Direct and practical synthesis of 2-arylbenzoxazoles promoted by activated carbon
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(Matrix presented) 2-Arylbenzoxazoles were directly synthesized from substituted 2-aminophenols and aldehydes in the presence of activated carbon (Darco KB) in xylene under an oxygen atmosphere.
- Kawashita, Yuka,Nakamichi, Natsuki,Kawabata, Hirotoshi,Hayashi, Masahiko
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p. 3713 - 3715
(2007/10/03)
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- Parallel synthesis of benzoxazoles via microwave-assisted dielectric heating
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A facile route to benzoxazoles has been developed using microwave-assisted dielectric heating. The ease of synthesis and workup allowed the parallel synthesis of a 48-membered library of benzoxazoles quickly and efficiently.
- Pottorf, Richard S.,Chadha, Naresh K.,Katkevics, Martins,Ozola, Vita,Suna, Edgars,Ghane, Hadi,Regberg, Tor,Player, Mark R.
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p. 175 - 178
(2007/10/03)
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- 4,5-azolo-oxindoles
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Disclosed are novel 4,5-azolo-oxindoles having the formula These compounds inhibit cyclin-dependent kinases (CDKs), in particular CDK2. Thus, these compounds and their pharmaceutically acceptable salts, and prodrugs of said compounds, are anti-proliferative agents useful in the treatment or control of cell proliferative disorders, in particular cancer. Also disclosed are pharmaceutical compositions containing these compounds, and methods for the treatment and/or prevention of cancer, particularly in the treatment or control of solid tumors using these compounds, as well as intermediates useful in the preparation of compounds of formula I.
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- Novel benzoxazole 2,4-thiazolidinediones as potent hypoglycemic agents. Synthesis and structure-activity relationships
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A new series of benzoxazole 2,4-thiazolidinediones was synthesized and evaluated for hypoglycemic activity in genetically obese and diabetic yellow KK mice. 2-Arylmethyl- and 2-(heteroarylmethyl)benzoxazole derivatives showed far more potent activity than known 2,4-thiazolidinedione derivatives such as ciglitazone, troglitazone and pioglitazone. A facile synthesis of benzoxazole 2,4-thiazolidinediones was also established using aminophenol 2,4- thiazolidinedione (11) as a key intermediate. Details of synthesis and structure-activity relationships for this series are described.
- Arakawa, Kenji,Inamasu, Masanori,Matsumoto, Mamoru,Okumura, Kunihito,Yasuda, Kosuke,Akatsuka, Hidenori,Kawanami, Saburo,Watanabe, Akishige,Homma, Koichi,Saiga, Yutaka,Ozeki, Masakatsu,Iijima, Ikuo
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p. 1984 - 1993
(2007/10/03)
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- The vicarious nucleophilic substitution of hydrogen and related reactions in nitrobenzoxazoles
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5- and 6-nitrobenzoxazoles 3 and 4 react with nucleophiles exclusively at C-2, giving ring opening products. If position 2- is blocked with phenyl substituent the reaction takes place in the carbocyclic ring affording the VNS products. 2-Methylthio-5-nitrobenzoxazole 7 and its 6-nitro isomer 8 give products which result from addition of a nucleophile to the carbocyclic ring (VNS) as well as to the heterocyclic ring (S(N)Ar and ring cleavage). 2-Methylthiobenzoxazoles can be readily converted to the corresponding benzoxazolones via oxidative hydrolysis.
- Makosza, Mieczyslaw,Stalewski, Jacek
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p. 7277 - 7286
(2007/10/02)
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- Benzoxazole derivatives
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Novel benzoxazole derivative of the formula: STR1 wherein R is a substituted or unsubstituted phenyl group, a substituted or unsubstituted naphthyl group, a substituted or unsubstituted cycloalkyl group or a substituted or unsubstituted heterocyclic group; Alk is single bond, a substituted or unsubstituted lower alkylene group, a lower alkenylene group or a lower alkynylene group; the group STR2 is a group of the formula: --CH2 -- or --CH=, and a pharmaceutically aceptable salt thereof are disclosed. Said derivative (I) and a salt thereof are useful as therapeutic agents for diabetes.
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- Aryloxenium Ions. Generation from N-(Aryloxy)pyridinium Tetrafluoroborates and Reaction with Anisole and Benzonitrile
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N-(Aryloxy)pyridinium tetrafluoroborates (4) decompose thermally at 180-200 deg C in anisole and benzonitrile to form products of intermolecular C-O-C and C-C bond formation.With anisole, diphenyl ethers (5) and hydroxybiphenyls (6) are formed; with benzonitrile, the main product is benzoxazole (14).A homolytic process was ruled out by showing that none of these products were formed when perbenzoyl p-nitrophenyl carbonate (18) was decomposed in these solvents.The main products in this case were those of homolytic phenylation (and benzoyloxylation with anisole).A concerted SN2-type heterolytic process was ruled out by showing that the nature of the substituent in the pyridine ring had no effect on the isomer ratios of 5 and 6 in the thermolysis of 4 (X = p-NO2) in anisole.The results are explained in terms of a unimolecular heterolysis of 4 to give the pyridine and aryloxenium ion 2 which now attacks solvent molecules.When an electron-withdrawing substituent is present in 2, more C-O-C than C-C products are formed in anisole.When it is absent only products of C-C bond formation are found.PhO+ is apparently electrophilic enough to attack anisole and give the four possible hydroxymethoxybiphenyls (10-13).
- Abramovitch, Rudolph A.,Alvernhe, Gerard,Bartnik, Romuald,Dassanayake, Nissanke L.,Inbasekaran, Mutiah N.,Kato, Shiego
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p. 4558 - 4565
(2007/10/02)
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