- Stable Pd(0) Complexes with Ferrocene Bisphosphanes Bearing Phosphatrioxaadamantyl Substituents Efficiently Catalyze Selective C-H Arylation of Benzoxazoles by Aryl Chlorides
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Versatile applications and unique performance of 1,1’-bis(diphenylphosphanyl)ferrocene (dppf) in coordination chemistry and catalysis prompted the search for its analogs. This contribution describes the synthesis of the first donor-unsymmetric dppf congeners bearing bulky and rigid 1,3,5,7-tetramethyl-2,4,6-trioxa-8-phosphaadamantyl (CgP) donor groups, viz. Ph2PfcPCg (1) and Ph2PfcCH2PCg (2; fc=ferrocene-1,1’-diyl). Bis-phosphanes 1 and 2 were converted into air-stable Pd(0) complexes, [Pd(ma)(L^L)] (L^L=1 and 2; ma=maleic anhydride). Together with [Pd(ma)(dppf)], these complexes were applied as catalysts in Pd-catalyzed C?H arylation of benzoxazoles with aryl chlorides in n-butanol as an environmentally benign solvent. Among all catalysts tested in this study, complex [Pd(ma)(2)] performed the best, providing a high-yield and selective synthesis of 2-arylbenzoxazoles from a range of the generally less reactive chloroarenes at low catalyst loading (typically 1 mol.%). Under similar conditions, the structurally related heterocycles (e. g., 1-methylbenzimidazole and benzothiazole) did not react.
- Horky, Filip,Císa?ová, Ivana,?těpni?ka, Petr
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p. 4848 - 4856
(2021/10/12)
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- BENZOXAZOLE DERIVATIVES AND FLUORESCENT MATERIAL COMPRISING THE SAME
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A benzoxazole derivative represented by Structural Formula 1 is provided. Thus, the present invention is not limited thereto. A fluorescent material is provided to remarkably improve fluorescence yield, to have excellent dyeing property and dispersibility, to minimize environmental pollution and to improve economic feasibility. Structural 1.
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Paragraph 0239-0242
(2021/07/13)
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- BENZOXAZOLE DERIVATIVES AND FLUORESCENT MATERIAL COMPRISING THE SAME
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The present invention relates to a benzoxazole derivative represented by structural formula 1. Accordingly, it is possible to provide a fluorescent material which has a significantly improved fluorescence yield, has excellent dyeability and dispersibility, minimizes environmental pollution by reducing the amount of use, and also can improve economic efficiency.COPYRIGHT KIPO 2020
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Paragraph 0153-0156
(2020/06/24)
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- One-pot formic acid dehydrogenation and synthesis of benzene-fused heterocycles over reusable AgPd/WO2.72 nanocatalyst
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Using nanoparticles (NPs) to catalyze multiple chemical reactions in one-pot and to achieve high-yield syntheses of functional molecules/materials is an important direction in NP chemistry, catalysis and applications. In this article, we report a nanocomposite of AgPd NPs anchored on WO2.72 nanorods (NRs) (denoted as AgPd/WO2.72) as a general catalyst for formic acid dehydrogenation and transfer hydrogenation from Ar-NO2 to Ar-NH2 that further reacts with aldehydes to form benzene-fused heterocyclic compounds. The AgPd/WO2.72 catalysis is Ag/Pd dependent and Ag48Pd52 is the most active composition for the multiple chemical reactions. The high activity of AgPd/WO2.72 arises from strong interfacial interaction between AgPd and WO2.72, resulting in AgPd lattice expansion and electron polarization from AgPd to WO2.72. The syntheses proceed in one-pot reactions among formic acid, 2-nitrophenol (or 2-nitroaniline, or 2-nitrothiophenol) and aldehydes in dioxane/water (2/1 v/v) at 80-90 °C, leading to one-pot syntheses of benzoxazoles, benzimidazoles and benzothiazoles that are key ring structures present in functional compounds for pharmaceutical, optical and polymer applications.
- Yu, Chao,Guo, Xuefeng,Shen, Bo,Xi, Zheng,Li, Qing,Yin, Zhouyang,Liu, Hu,Muzzio, Michelle,Shen, Mengqi,Li, Junrui,Seto, Christopher T.,Sun, Shouheng
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p. 23766 - 23772
(2018/12/10)
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- Direct multiple C-H bond arylation reaction of heteroarenes catalyzed by cationic palladium complex bearing 1,10-phenanthroline
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A cationic palladium complex bearing 1,10-phenanthroline ligand is found to catalyze direct C-H arylation reactions of heteroarenes with aryl iodides to give mono-, di-, or tri-arylated products selectively. The Royal Society of Chemistry.
- Shibahara, Fumitoshi,Yamaguchi, Eiji,Murai, Toshiaki
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supporting information; experimental part
p. 2471 - 2473
(2010/08/05)
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- SMALL MOLECULE INHIBITORS OF PLASMODIUM FALCIPARUM DIHYDROOROTATE DEHYDROGENASE
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Inhibitors of dihydroorotate dehydrogenase (DHODH) for the Plasmodium enzyme have been identified and characterized. The inhibitors have high specificity, submicromolar efficacy against cultured parasite strains, exhibit drug-like properties, and are not overtly cytotoxic.
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Page/Page column 44-45
(2010/01/29)
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- Direct arylation of oxazole and benzoxazole with aryl or heteroaryl halides using a palladium-diphosphine catalyst
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Through the use of PdCl(dppb)(C3H5) as a catalyst, a range of aryl bromides and chlorides undergoes coupling via C-H bond activation/functionalization reaction with oxazole or benzoxazole in good yields. This air-stable catalyst can be used at low loadings with several substrates. Surprisingly, better results in terms of substrate/catalyst ratio were obtained in several cases using electron-excessive aryl bromides than with the electron-deficient ones. This seems to be mainly due to the relatively low thermal stability of some of the 2-arylbenzoxazoles formed with electron-deficient aryl halides. With these substrates, in order to obtain higher yields of product, the reactions had to be performed at a lower temperature (100-120 °C) using a larger amount of catalyst. On the other hand, in the presence of the most stable products, the reactions were performed at 150 °C using as little as 0.2 mol% catalyst. Arylation of benzoxazole with heteroaryl bromides also gave the coupling products in moderate to high yields using 0.2-5 mol% catalyst. With this catalyst, electron-deficient aryl chloride such as 4-chlorobenzonitrile, 4-chloroacetophenone or 2-chloronitrobenzene have also been used successfully.
- Derridj, Fazia,Djebbar, Safia,Benali-Baitich, Ouassini,Doucet, Henri
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p. 135 - 144
(2008/03/30)
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- Palladium-catalysed direct C-H activation/arylation of heteroaromatics: An environmentally attractive access to bi- or polydentate ligands
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Bi- or polydentate ligands based on heterocycles can be easily prepared by palladium-catalysed C-H bond activation of heteroaromatics followed by heteroarylation with heteroaryl bromides. A variety of heteroaromatics such as furans, thiophenes, pyridines, thiazoles or oxazole derivatives have been employed and moderate to good yields were generally obtained using the air-stable complex [PdCl(dppb)(C3H5)] as catalyst. A range of functions such as acetyl, formyl, ester or nitrile on the heteroaromatics is tolerated. Wiley-VCH Verlag GmbH & Co. KGaA, 2008.
- Derridj, Fazia,Gottumukkala, Aditya L.,Djebbar, Safia,Doucet, Henri
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experimental part
p. 2550 - 2559
(2009/03/11)
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- Process for the preparation of bis-benzazolyl compounds
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The present invention provides a process for the preparation of a compound of formula (I) wherein Y represents —O—, —S— or —N(R2)—, R2 being hydrogen, C1-C10alkyl or aralkyl; Z represents a 2,5-furanyl, 2,5-thiophenyl, 4,4′-stilbenyl or a 1,2-ethyleny residue and R1 represents hydrogen, halogen, C1-C10alkoxyl, cyano, COOM or SO3M, M being hydrogen or an alkaline or alkaline earth metal, characterized by reacting a compound of formula (II) with a dicarboxylic acid of formula (III): HOOC-Z-COOH, or an ester thererof, Y, Z and R1 being as previously defined, in N-methylpyrrolidone or N,N-dimethylacetamide, in the presence of an acidic catalyst and, optionally, in the presence of a secondary solvent capable of removing water from the reaction mixture, which are useful as optical whitening agents for natural and synthetic materials.
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Page/Page column 4
(2008/06/13)
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- Eine einfache Methode zur Herstellung von Benzoxazolen
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The preparation of benzoxazoles by a facile one-pot reaction is reported.The reaction of carboxylic acids with 2-chloro-N-methyl-Δ1-pyrrolinium chloride in an excess of N-methyl-2-pyrrolidone afforded carboxylic acid chlorides which were converted subsequently to their 2-hydroxyanilides by addition of 2-aminophenols.Cyclization of the 2-hydroxy-anilides at elevated temperatures furnished the benzoxazoles in high yield and purity.
- Seha, Zdenek,Weis, Claus D
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p. 413 - 419
(2007/10/02)
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