- Dowex 50W: A green mild reusable catalyst for the synthesis of 2-aryl benzoxazole derivatives in aqueous medium
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In this work simple efficient, one pot and environmentally friendly method was developed for the synthesis of 2-Aryl-1H-benzoxazole derivatives at 80oC using ortho-aminophenol and various aldehydes. It has been found that Dowex 50W is an effective catalyst to prepare moderate to high yield of a variety of benzoxazole derivatives through a clean and simple process. Aqueous medium, green methodology, rapid reaction, reusability of heterogeneous catalyst are the great advantages of this protocol.
- Datta, Arup
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p. 341 - 347
(2021/05/19)
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- An efficient rapid synthesis of benzoxazoles and benzothiazoles using pma.Sio2 at room temperature under heterogeneous conditions
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Treatment of 2-aminophenol (or 2-aminothiophenol) with aromatic aldehydes in the presence of phosphomolybdic acid on silica at room temperature affords the corresponding benzoxazoles (or benzothiazoles) in excellent yields (88-96%) under heterogeneous conditions. Benzoxazoles and benzothiazoles are formed in less than 10 min.
- Sudhakar, Chithaluri,Shekhar, Vanam,Shyamsunder, Manchi,Suryakumari, Adurthi,Manojkumar, Vala
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p. 583 - 587
(2021/09/30)
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- Bimetallic Cooperative Catalysis for Decarbonylative Heteroarylation of Carboxylic Acids via C-O/C-H Coupling
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Cooperative bimetallic catalysis is a fundamental approach in modern synthetic chemistry. We report bimetallic cooperative catalysis for the direct decarbonylative heteroarylation of ubiquitous carboxylic acids via acyl C-O/C-H coupling. This novel catalytic system exploits the cooperative action of a copper catalyst and a palladium catalyst in decarbonylation, which enables highly chemoselective synthesis of important heterobiaryl motifs through the coupling of carboxylic acids with heteroarenes in the absence of prefunctionalization or directing groups. This cooperative decarbonylative method uses common carboxylic acids and shows a remarkably broad substrate scope (>70 examples), including late-stage modification of pharmaceuticals and streamlined synthesis of bioactive agents. Extensive mechanistic and computational studies were conducted to gain insight into the mechanism of the reaction. The key step involves intersection of the two catalytic cycles via transmetallation of the copper–aryl species with the palladium(II) intermediate generated by oxidative addition/decarbonylation.
- Liu, Chengwei,Ji, Chong-Lei,Zhou, Tongliang,Hong, Xin,Szostak, Michal
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supporting information
p. 10690 - 10699
(2021/04/09)
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- Photocatalytic green synthesis of benzazoles from alcohol oxidation/toluene sp3C-H activation over metal-free BCN: effect of crystallinity and N-B pair exposure
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Porous borocarbonitride (P-BCN), with the characteristics of enhanced crystallinity and improved N-B pair exposure, was prepared with a simple KCl-assisted molten salt strategy. Efficient heterogeneous photocatalytic tandem synthesis of benzazoles from alcohol oxidation/toluene sp3C-H activation was achieved firstly over the metal-free P-BCN using visible light and the green oxidant O2, with only water as a by-product. Variouso-thio/hydroxy/aminoanilines and alcohols or toluenes could be converted to the corresponding 2-substituted benzothiazoles, benzoxazoles and benzimidazoles with good to excellent photocatalytic performance. The improved photocatalytic performance in comparison to bulk BCN should be due to the crystallinity-enhancement-induced improvement in charge separation and transmission. The increased N-B pair exposure promoted superoxide radical generation due to the electron-enriched N atoms, as well as improved oxidation ability due to the valence band constructed by the B 2p orbital. This work presents a green and efficient synthetic strategy towards benzazoles and other fine chemicalsviametal-free heterogeneous photocatalysis.
- Cheng, Hongmei,Gao, Xue,Jiang, Heyan,Sun, Bin,Zang, Cuicui
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p. 7955 - 7962
(2021/12/27)
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- 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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- Sulfur-Promoted Synthesis of Benzoxazoles from 2-Aminophenols and Aldehydes
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Elemental sulfur (S8) was found to be an excellent stoichiometric oxidant to promote oxidative condensation of 2-aminophenols with a wide range of aldehydes, including aliphatic aldehyde such as cyclohexanecarboxaldehyde. The reactions were catalyzed by sodium sulfide in the presence of DMSO as an additive. The benzoxazole products were obtained in satisfactory yields. The reaction conditions could be applied to larger syntheses (10–50 mmol).
- Nguyen, Le Anh,Dang, Thai Duy,Ngo, Quoc Anh,Nguyen, Thanh Binh
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supporting information
p. 3818 - 3821
(2020/06/10)
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- Visible Light-Induced Copper-Catalyzed C—H Arylation of Benzoxazoles?
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A general method for visible light-induced copper-catalyzed arylation of sp2 C—H bonds of azoles has been developed. The method employs aryl halide as the coupling partner, lithium alkoxide as base. A variety of azoles including benzooxazole and benzothiazole can be arylated. Furthermore, electron-poor heterocycles such as thiophene possessing one electron-withdrawing group can also be arylated.
- Ma, Xiaodong,Zhang, Guozhu
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p. 1299 - 1303
(2020/08/05)
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- Iron(0)-Catalyzed Transfer Hydrogenative Condensation of Nitroarenes with Alcohols: A Straightforward Approach to Benzoxazoles, Benzothiazoles, and Benzimidazoles
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The iron-catalyzed hydrogen transfer strategy has been applied to the redox condensation of o-hydroxynitrobenzene with alcohol, leading to the formation of benzoxazole derivatives. A wide range of 2-substituted benzoxazoles were synthesized in good to excellent yields without the addition of an external redox agent. A series of control experiments provided a plausible mechanism. Furthermore, the reaction system was successfully extended to the synthesis of benzothiazoles and benzimidazoles.
- Putta, Ramachandra Reddy,Chun, Simin,Choi, Seung Hyun,Lee, Seok Beom,Oh, Dong-Chan,Hong, Suckchang
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p. 15396 - 15405
(2020/12/02)
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- Method for synthesizing benzoxazole through microwave radiation of benzamide compound in water phase
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The invention discloses a method for synthesizing benzoxazole through microwave radiation of a benzamide compound in a water phase. The benzamide compound is added into the water phase under the microwave condition to be subjected to a cyclization reaction for generating the benzoxazole under the alkali condition, and the method for preparing the benzoxazole is environmentally friendly, easy and convenient to operate, safe, low in cost and efficient. Compared with the prior art, the method can be applied to a large number of functional groups, the yield is high, the number of by-products is small, and the method is easy to operate, safe, low in cost and environmentally friendly. (Please see the specifications for the formula).
- -
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Paragraph 0047
(2019/03/08)
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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.
- -
-
Paragraph 0062; 0072
(2019/01/21)
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- Transition-Metal-Free Alkylation/Arylation of Benzoxazole via Tf2O-Activated-Amide
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A transition-metal-free approach to the alkylation/arylation of benzoxazole was developed by employing Tf2O-activated-amide as the alkylating/arylating reagent. The mild reaction conditions, and particularly insensitivity to air and water, further enhance the synthetic potential in pharmaceutical synthesis. (Figure presented.).
- Niu, Zhi-Jie,Li, Lian-Hua,Liu, Xue-Yuan,Liang, Yong-Min
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supporting information
p. 5217 - 5222
(2019/11/13)
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- Cesium Fluoride and Copper-Catalyzed One-Pot Synthesis of Benzoxazoles via a Site-Selective Amide C?N Bond Cleavage
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We report herein a two-step one-pot strategy for the synthesis of benzoxazoles from amides by using cesium fluoride/copper as catalysts. This approach involves the in situ generation of acyl fluorides from the corresponding amides, and the acyl fluorides undergo transamidation and cyclization to give benzoxazoles in good yields. In this work, the amide C?N bonds are activated by CsF to form the acyl fluoride intermediates, which further react with o-bromoanilines to efficiently yield benzoxazoles. Notably, this methodology demonstrates a broad substrate scope, as primary/secondary benzamides are well tolerated, and this process might facilitate the development of one-pot transformations of amides. (Figure presented.).
- Luo, Zhongfeng,Wu, Hongxiang,Li, Yue,Chen, Yuwen,Nie, Jingyi,Lu, Siqi,Zhu, Yulin,Zeng, Zhuo
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supporting information
p. 4117 - 4125
(2019/08/01)
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- Pd/Cu bimetallic co-catalyzed direct 2-arylation of benzoxazole with aryl chloride
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An efficient Palladium/Copper bimetallic co-catalyzed direct 2-arylation of benzoxazoles with aryl chlorides is presented. The Pd(OAc)2/CuI/NiXantphos-based catalyst enables the installation of various aryl and heteroaryl groups in good to excellent yields (75–99%). Preliminary mechanism investigation indicates that Pd/Nixantphos complex activates C-Cl bond of aryl chlorides via oxidative addition, and Cu/Nixantphos complex chelates with nitrogen atom to lower the pKa of the 2-H in benzoxazoles.
- Zheng, Ling-Li,Yin, Bo,Tian, Xing-Chuan,Yuan, Ming-Yong,Li, Xiao-Huan,Gao, Feng
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supporting information
(2019/11/13)
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- Oxidative NHC Catalysis for the Generation of Imidoyl Azoliums: Synthesis of Benzoxazoles
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N-Heterocyclic carbene (NHC)-catalyzed intramolecular cyclization of aldimines generated from 2-amino phenols and aromatic aldehydes leading to the synthesis of 2-arylbenzoxazoles under mild conditions is presented. The reaction proceeds via the generation of the aza-Breslow intermediates from imines and NHC, which under oxidative conditions form the key imidoyl azoliums and a subsequent intramolecular cyclization furnishes the product. The reaction tolerates a broad range of functional groups, and the products are formed in generally good yields.
- Patra, Atanu,James, Anjima,Das, Tamal Kanti,Biju, Akkattu T.
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p. 14820 - 14826
(2019/01/03)
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- Palladium(II) Immobilized Onto the Glucose Functionalized Magnetic Nanoparticle as a New and Efficient Catalyst for the One-pot Synthesis of Benzoxazoles
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Palladium(II) have been immobilized into the nano magnetic Fe3O4 which was functionalized with glucose in order to achieve a one-pot synthesis of 2-substituted benzoxazole derivatives with high yields in the diverse range of organic solvents. The nano catalyst is highly dispersive in polar solvents and can be easily recovered and reused for 6 runs without significant loss of its activity. Finally, the catalyst was fully characterized by FT-IR, TGA, CHN, SEM, EDX and atomic absorption spectroscopy.
- Moghaddam, Firouz Matloubi,Saberi, Vahid,Kalhor, Sepideh,Veisi, Nazila
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- A benzoxazole for the arylation method (by machine translation)
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The invention relates to a benzoxazole for the arylation method, comprises the following steps: under the protection of the inert gas, the benzoxazole, aryl/heteroaryl tosylates, catalyst nitrogen heterocyclic carbene - palladium complex, alkaline material, reaction solvent, in the 80 - 150 °C reaction 12 - 24 H of the reaction liquid obtained, then processing reaction liquid to obtain product, to obtain 2 - aryl benzoxazole. The invention discloses a benzoxazole for the arylation method development of novel catalytic system, catalyst stability, is easy to obtain, can make the stable, low price of the aryl/heteroaryl tosylates participate in the reaction, reaction operation is simple, low cost, product yield and purity and the like, has good value for research and industrial application produces the scenery. (by machine translation)
- -
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Paragraph 0058
(2018/11/03)
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- Synthesis and characterization of a novel oxo-bridged binuclear iron(iii) complex: Its catalytic application in the synthesis of benzoxazoles using benzyl alcohol in water
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In the present work, the synthesis and characterization of a novel binuclear oxo-bridged iron(iii) complex, (FeLAPIP)2O, where LAPIP is the deprotonated form of a tetradentateo-aminophenol-iminopyridine ligand, is described. The iron complex was characterized using different techniques including X-ray crystallography, infrared spectroscopy, UV-Vis, magnetic susceptibility and cyclic voltammetry. The X-ray structure analysis revealed that in the structure of the (FeLAPIP)2O complex, each iron(iii) is coordinated in a distorted square pyramidal arrangement by an oxo group, three amine nitrogens and one oxygen atom of the o-aminophenolate ligand. The variable-temperature magnetic measurement exhibits strong antiferromagnetic coupling between two iron(iii) centers. Cyclic voltammetry measurements showed two kinds of quasireversible events, suggesting the formation of a phenoxyl radical species in the region of the anodic peaks and a metal-centered redox (FeIII/FeII) process at low potential. The catalytic activity of this Fe-complex was evaluated in coupling of 2-aminophenol and benzyl alcohols for the one-pot synthesis of benzoxazoles. The catalyst system showed high catalytic activity in this transformation and benzoxazole derivatives were obtained in good to excellent yields. tert-Butyl hydroperoxide was used as an oxidant and 1.2 mol% of catalyst was needed to accomplish the reaction in water as the green solvent.
- Safaei, Elham,Alaji, Zahra,Panahi, Farhad,Wojtczak, Andrzej,Jagli?i?, Janez Zvonko
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supporting information
p. 7230 - 7236
(2018/05/07)
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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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- AgPd Nanoparticles Deposited on WO2.72 Nanorods as an Efficient Catalyst for One-Pot Conversion of Nitrophenol/Nitroacetophenone into Benzoxazole/Quinazoline
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We report a seed-mediated growth of 2.3 nm AgPd nanoparticles (NPs) in the presence of 40 × 5 nm WO2.72 nanorods (NRs) for the synthesis of AgPd/WO2.72 composites. The strong interactions between AgPd NPs and WO2.72 NRs make the composites, especially the Ag48Pd52/WO2.72, catalytically active for dehydrogenation of formic acid (TOF = 1718 h-1 and Ea = 31 kJ/mol) and one-pot reactions of formic acid, 2-nitrophenol, and aldehydes into benzoxazoles in near quantitative yields under mild conditions. The catalysis can also be extended to the one-pot reactions of ammonium formate, 2-nitroacetophenone, and aldehyde for high yield syntheses of quinazolines. Our studies demonstrate a new catalyst design to achieve a green chemistry approach to one-pot reactions for the syntheses of benzoxazoles and quinazolines.
- Yu, Chao,Guo, Xuefeng,Xi, Zheng,Muzzio, Michelle,Yin, Zhouyang,Shen, Bo,Li, Junrui,Seto, Christopher T.,Sun, Shouheng
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supporting information
p. 5712 - 5715
(2017/05/04)
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- Synthesis and Antitumor Activity Evaluation of New 2-(4-aminophenyl) benzothiazole/oxazole/imidazole Derivatives
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A NEW series of 2-(4-aminophenyl)benzothiazole and related structure compounds, bearing thiocyanate, thiol in the 3′postion as well as new condensed benzothiazoles and related structure compounds having thiazolones, tetrazole, oxadiazole have been synthesized. All the newly synthesized compounds were screened for their anti-tumor activities. The results revealed promising effects against most of the cancer cell lines.
- El-Arab, Elham Ezz,El-Said,Amine,Moharram
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p. 967 - 984
(2017/04/17)
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- Synthesis and antitumor activity evaluation of NEW 2-(4-aminophenyl) benzothiazole/oxazole/imidazole derivatives
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A NEW series of 2-(4-aminophenyl)benzothiazole and related structure compounds, bearing thiocyanate, thiol in the 3'postion as well as new condensed benzothiazoles and related structure compounds having thiazolones,tetrazole, oxadiazole have been synthesized. All the newly synthesized compounds were screened for their anti-tumor activities. The results revealed promising effects against most of the cancer cell lines.
- El-Arab, Elham Ezz,El-Said,Amine,Moharram
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p. 967 - 984
(2017/04/17)
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- High-Throughput Screening Protocol for the Coupling Reactions of Aryl Halides Using a Colorimetric Chemosensor for Halide Ions
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Mercury complex of 4-(2-pyridylazo)resorcinol (PAR-2Hg2+), a halide-ion chemosensor, was prepared and its efficiency as a tool for high-throughput screening (HTS) of transition-metal-catalyzed coupling reactions was investigated. It showed a high selectivity for halide ions. When the PAR-2Hg2+ complex was used in the Suzuki coupling reaction and C-H activated coupling reaction with aryl bromides, the quantitative and qualitative conversions of aryl halides were obtained from the reaction mixture color change.
- Eom, Min Sik,Noh, Jieun,Kim, Han-Sung,Yoo, Soyeon,Han, Min Su,Lee, Sunwoo
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supporting information
p. 1720 - 1723
(2016/05/19)
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- Ag@TiO2 nanocomposite; Synthesis, characterization and its application as a novel and recyclable catalyst for the one-pot synthesis of benzoxazole derivatives in aqueous media
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In the present study, we use a Ag@TiO2 nanocomposite for the efficient synthesis of benzoxazole derivatives via the one-pot condensation of 2-aminophenol and several aromatic aldehydes or orthoesters or carboxylic acids or amides or acyl chlorides in water at room temperature. In all situations the preferred products were synthesized with excellent yields. The short reaction times, high yields, safety and mild conditions, simplicity, non-toxicity and easy workup are the main merits of this protocol.
- Maleki, Behrooz,Baghayeri, Mehdi,Vahdat, Seyed Mohammad,Mohammadzadeh, Abbas,Akhoondi, Somaieh
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p. 46545 - 46551
(2015/06/16)
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- Copper-catalyzed synthesis of 2-arylbenzoxazoles from o-aminophenol derivatives with arylmethyl chlorides
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A facile and efficient synthesis of 2-arylbenzoxazoles via copper-catalyzed tandem condensation/oxidative reaction of o-aminophenol derivatives with arylmethyl chlorides was developed. Note that this reaction utilized arylmethyl chlorides as a new type of simple and cheap acyl sources and KNO3 as a readily available and low-cost benign oxidant.
- Zhang, Guodong,Wang, Peng,Yang, Fan,Wu, Yangjie
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supporting information
p. 57 - 63
(2015/02/02)
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- Palladium-Catalyzed C-H Arylation of (Benzo)oxazoles or (Benzo)thiazoles with Aryltrimethylammonium Triflates
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The C-H arylation of (benzo)oxazoles or (benzo)thiazoles with aryltrimethylammonium triflates was carried out via Pd-catalyzed C-H/C-N cleavage. Oxazoles, thiazoles, benzoxazole, and benzothiazole were arylated using activated and deactivated aryltrimethylammonium triflates to give 2-aryl(benzo)oxazoles or 2-aryl(benzo)thiazoles in reasonable to excellent yields.
- Zhu, Feng,Tao, Jian-Long,Wang, Zhong-Xia
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supporting information
p. 4926 - 4929
(2015/10/12)
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- Access to 2-(het)aryl and 2-styryl benzoxazoles via palladium-catalyzed aminocarbonylation of aryl and vinyl bromides
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A sequential one-pot procedure for the synthesis of either 2-(hetero)aryl or 2-styryl benzoxazoles is reported, starting from aryl and vinyl bromides, respectively, involving an initial aminocarbonylation with 2-aminophenols as nucleophiles followed by an acid mediated ring closure to generate the heterocycle. The methodology displays a broad substrate scope in moderate to excellent yields and can be exploited for 13C-isotope labeling. Finally, this carbonylative protocol was applied to the synthesis of a potential Alzheimer's plaque binder and a selective PPAR antagonist including site-specific labeling with 13C-carbon monoxide.
- Neumann, Karoline T.,Lindhardt, Anders T.,Bang-Andersen, Benny,Skrydstrup, Troels
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supporting information
p. 2094 - 2097
(2015/05/13)
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- Palladium-catalyzed coupling of azoles or thiazoles with aryl thioethers via C-H/C-S activation
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Palladium-catalyzed cross-coupling via the Csp2-S bond activation of aryl thioethers and the C-H bond activation of azoles or thiazoles was carried out. Electron-deficient and -rich aryl methyl thioethers and diaryl thioethers can be employed as the coupling partners and the reaction tolerates a range of functional groups including MeO, CF3, CN, PhCO, CONEt2, and Py groups.
- Zhu, Feng,Wang, Zhong-Xia
-
supporting information
p. 1601 - 1604
(2015/03/30)
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- Iodine-catalyzed ammoxidation of methyl arenes
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The development of organic transformation using cheap and readily available substrates under mild conditions will be pivotal for green and sustainable synthetic organic chemistry. Concerning our continued interest in the cyanation reaction, a metal-free direct ammoxidation of readily available methyl arenes leading to nitriles was established under mild conditions. A series of aryl methanes especially heteroaryl methanes (30 examples) were applicable in moderate to good yields with good functionality tolerance.
- Guo, Songjin,Wan, Gen,Sun, Song,Jiang, Yan,Yu, Jin-Tao,Cheng, Jiang
-
supporting information
p. 5085 - 5088
(2015/03/30)
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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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- Magnetically separable nano CeO2: A highly efficient catalyst for ligand free direct C-H arylation of heterocycles
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An efficient, ligand free, nano CeO2-Fe3O4 catalyzed direct C-H arylation of heteroarenes such as benzoxazole and benzothiazole has been carried out with aryl halides in DMSO or arenediazonium salts in water. The catalyst exhibited high activity with moderate to excellent product yields under mild reaction conditions. Nano CeO2-Fe3O4 was synthesized and characterized by SEM, TEM, EDAX, XRD, FTIR, DSC-TGA, and ICP-MS analyses. The catalytic activity and stability of the catalyst were excellent, even after the ten cycle of recyclability
- Shelkar, Radheshyam S.,Balsane, Kishor E.,Nagarkar, Jayashree M.
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supporting information
p. 693 - 699
(2015/01/30)
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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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- Sonicated assisted synthesis of benzimidazoles, benzoxazoles and benzothiazoles in aqueous media
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Ammonium nickel sulphate [(NH4)2SO4.NiSO4.6H2O] was found as a new catalyst to synthesis 2-aryl benzimidazole, 2-aryl benzothiazole and 2-aryl benzoxazole in aqueous media under sonication irradiation. The procedure is an eco-friendly, efficient and provides simple workup and good yield.
- Pardeshi, Sandeep D.,Sonar, Jayant P.,Pawar, Shivaji S.,Dekhane, Deepak,Gupta, Sunil,Zine, Ashok M.,Thore, Shivaji N.
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p. 2335 - 2340
(2014/07/22)
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- Synthesis of 2-substituted pyrimidines and benzoxazoles via a visible-light-driven organocatalytic aerobic oxidation: Enhancement of the reaction rate and selectivity by a base
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An efficient visible-light-driven photocatalytic oxidation of various 2-substituted dihydropyrimidines and phenolic imines has been achieved using an organic photocatalyst eosin Y bis(tetrabutyl ammonium salt) (TBA-eosin Y) and inexpensive oxidant molecular oxygen. With the aid of a base, significantly enhanced photoinduced electron transfer from substrates dihydropyrimidines or phenolic imines to the excited state of TBA-eosin Y has enabled the aerobic oxidation to yield 2-(methylthio)pyrimidines or 2-arylbenzoxazoles selectively. This journal is the Partner Organisations 2014.
- Wang, Lin,Ma, Zhi-Gang,Wei, Xiao-Jing,Meng, Qing-Yuan,Yang, Deng-Tao,Du, Shao-Fu,Chen, Zi-Fei,Wu, Li-Zhu,Liu, Qiang
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p. 3752 - 3757
(2014/08/05)
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- Palladium-catalyzed synthesis of benzoxazoles by the cleavage reaction of carbon-carbon triple bonds with o-aminophenol
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A novel and mild procedure for efficient synthesis of benzoxazoles by the cleavage reaction of carbon-carbon triple bonds with o-aminophenol in the presence of a catalytic amount of palladium chloride has been successfully developed, which provides rapid and efficient access to benzoxazoles. the Partner Organisations 2014.
- Xie, Hou-Zhi,Gao, Qi,Liang, Ying,Wang, Heng-Shan,Pan, Ying-Ming
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supporting information
p. 2132 - 2135
(2014/04/17)
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- Copper-catalysed intramolecular O-arylation: A simple and efficient method for benzoxazole synthesis
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A wide range of 2-substituted benzoxazoles can be efficiently synthesized from N-(2-iodo-/bromo-phenyl)benzamides, and even the less reactive N-(2-chlorophenyl)benzamides, via Cu-catalysed intramolecular coupling cyclization reactions using methyl 2-methoxybenzoate as the ligand under mild reaction conditions. In addition, the benzoxazoles can be easily prepared from the primary amides coupling with o-dihalobenzenes in a single step. This journal is
- Wu, Fengtian,Zhang, Jie,Wei, Qianbing,Liu, Ping,Xie, Jianwei,Jiang, Haojie,Dai, Bin
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supporting information
p. 9696 - 9701
(2015/02/19)
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- Nickel-catalyzed ligand-free synthesis of benzoxazoles and oxazolines via isocyanide insertion
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A novel and efficient route to benzoxazoles and oxazolines involving a nickel-catalyzed three-component coupling reaction of iodobenzene, an amino alcohol and tert-butyl isocyanide has been developed. A wide array of products have been prepared in good to excellent yields in the absence of ligand.
- Wang, Jin-Mei,Jiang, Xiao,Tang, Ting,Zhu, Yong-Ming,Shen, Jing-Kang
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p. 1441 - 1453
(2014/07/07)
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- Synthesis of 2-arylbenzoxazoles through oxidation of C-H bonds adjacent to oxygen atoms
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A practical and simple synthesis of benzoxazoles from easily available substrates was developed. The protocol is triggered by an iron-catalyzed tandem oxidative process from simple ether derivatives. A practical and simple synthesis of benzoxazoles from easily available substrates is developed. The protocol is triggered by an iron-catalyzed tandem oxidative process from simple ether derivatives. Copyright
- Gu, Lijun,Wang, Wei,Xiong, Yong,Huang, Xiangzhong,Li, Ganpeng
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p. 319 - 322
(2014/01/23)
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- Direct C-H bond arylation of (benzo)oxazoles with aryl chlorides catalyzed by N-heterocyclic carbene-palladium(II)-1-methylimidazole complex
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The direct C-H bond arylation of (benzo)oxazoles with aryl chlorides was achieved catalyzed by a well-defined NHC-Pd(II)-Im complex. Under the optimal conditions, various aryl chlorides were successfully applied as the arylating reagents to achieve the 2-aryl (benzo)oxazoles in acceptable to high yields, providing a convenient and alternative method for the direct C-H bond arylation of (benzo)oxazoles and enriching the chemistry of the NHC-Pd(II) complex in organic synthesis.
- Shen, Xiao-Bao,Zhang, Yun,Chen, Wen-Xin,Xiao, Zheng-Kang,Hu, Ting-Ting,Shao, Li-Xiong
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supporting information
p. 1984 - 1987
(2014/05/06)
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- Room-temperature palladium-catalyzed direct 2-arylation of benzoxazoles with aryl and heteroaryl bromides
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An efficient room-temperature palladium-catalyzed direct 2-arylation of benzoxazoles with aryl bromides is presented. The Pd(OAc)2/ NiXantphos-based catalyst enables the introduction of various aryl and heteroaryl groups, via a deprotonative cross-coupling process (DCCP) in good to excellent yields (60-99%). This journal is the Partner Organisations 2014.
- Gao, Feng,Kim, Byeong-Seon,Walsh, Patrick J.
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supporting information
p. 10661 - 10664
(2014/10/15)
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- Ligand-free direct C-arylation of heterocycles with aryl halides over a metal-organic framework Cu2(BPDC)2(BPY) as an efficient and robust heterogeneous catalyst
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A crystalline porous metal-organic framework Cu2(BPDC) 2(BPY) was synthesized and characterized by X-ray powder diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), atomic absorption spectrophotometry (AAS), hydrogen temperature-programmed reduction (H2-TPR), and nitrogen physisorption measurements. The Cu2(BPDC)2(BPY) exhibited high catalytic activity in direct CH arylation reactions between heterocyles and aryl halides. The Cu 2(BPDC)2(BPY)-catalyzed CH arylation reaction could proceed to higher conversion than that of the reaction using Cu 3(BTC)2, Cu(BDC), Cu(BPDC), and Cu2(BDC) 2(BPY) as catalyst. Furthermore, under our conditions, the Cu 2(BPDC)2(BPY) also exhibited significantly higher activity than that of common copper salts, including Cu(NO3)2, CuCl, CuCl2, and CuI. Excellent reusability of the Cu-MOF in the direct heterocycle CH arylation reaction was achieved.
- Le, Hanh T.N.,Nguyen, Tung T.,Vu, Phuong H.L.,Truong, Thanh,Phan, Nam T.S.
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- Nano ceria catalyzed synthesis of substituted benzimidazole, benzothiazole, and benzoxazole in aqueous media
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A series of substituted benzimidazoles, benzothiazoles, and benzoxazoles was synthesized by combining 1,2-phenylenediamine, 2-aminothiophenol, or 2-aminophenol with aryl, heteroaryl, aliphatic, α,β-unsaturated aldehydes in the presence of nano ceria (CeO2) as an efficient heterogeneous catalyst.
- Shelkar, Radheshyam,Sarode, Sachin,Nagarkar, Jayashree
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supporting information
p. 6986 - 6990
(2013/12/04)
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- A novel strategy for the construction of substituted benzoxazoles via a tandem oxidative process
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A practical and simple synthesis of benzoxazoles from easily available substrates was developed. The protocol is triggered by an iron-catalyzed tandem oxidative process from simple toluene derivatives and 2-aminophenols. This method represents a straightforward approach to access substituted benzoxazoles. This journal is The Royal Society of Chemistry 2013.
- Gu, Lijun,Jin, Cheng,Guo, Junming,Zhang, Lizhu,Wang, Wei
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supporting information
p. 10968 - 10970
(2013/11/19)
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- Iodine-mediated arylation of benzoxazoles with aldehydes
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A simple and efficient methodology for the arylation of benzoxazoles with aldehydes using iodine as the mediator has been developed. The reaction proceeded smoothly with a range of substrates to give the corresponding arylated products in moderate to good yields.
- Teo, Yew Chin,Riduan, Siti Nurhanna,Zhang, Yugen
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supporting information
p. 2365 - 2368
(2013/09/12)
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- Poly (ethylene glycol)-bound sulphonic acid as a novel catalyst for synthesis of benzoxazoles
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ABSTRACT Ahighly efficient, simple and rapid method for the preparation of various 2-aminobenzoxazoles and other benzoxazole derivatives using a catalytic amount of poly (ethylene glycol)-bound sulphonic acid (PEG-SO3H) is described. PEG-SO3H is found to be economical and reusable catalyst with low catalytic loading. The percentage yield was found to be satisfactory, experimental set-up and purification of final products is facile and easy. GRAPHICAL ABSTRACT.
- Chikhale, Rupesh V.,Pant, Amit M.,Menghani, Sunil S.,Wadibhasme, Pankaj G.,Khedekar, Pramod B.
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p. 254 - 262
(2013/12/04)
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- A green route for the synthesis of 2-substituted benzoxazole derivatives catalyzed by Al3+-exchanged K10 clay
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A new, simple, and efficient protocol is developed for the synthesis of 2-substituted benzoxazole derivatives through N-C-O bond formation using Al 3+-exchanged K10 clay (Al3+-K10) as catalyst. A wide range of benzoxazole derivatives
- Suresh, Dhanusu,Dhakshinamoorthy, Amarajothi,Pitchumani, Kasi
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supporting information
p. 6415 - 6419
(2013/11/19)
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- Pd(OAc)2 catalyzed synthesis of 2-aryl- and 2-heteroaryl- benzoxazoles and benzothiazoles in imidazolium ionic liquids (ILs) without additives and with recycling/reuse of the IL
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A facile, high yielding, method for the synthesis of a library of 2-aryl- and 2-heteroaryl-benzoxazoles and benzothiazoles from readily available Schiff bases is reported employing catalytic amounts of Pd(OAc)2 in imidazolium ionic liquids (bmim)BF4 and (bmim)PF6 without ligands and/or additives. Simple product isolation and recycling/re-use of the IL are additional advantages of this method.
- Kalkhambkar, Rajesh G.,Laali, Kenneth K.
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supporting information; experimental part
p. 4212 - 4215
(2012/08/28)
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- Palladium-catalyzed deamidative arylation of azoles with arylamides through a tandem decarbonylation-C-H functionalization
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A highly chemo-, regio-selective, and efficient palladium-catalyzed deamidative arylation of azoles with arylamides, as an aryl metal equivalent, has been developed. The reaction proceeds smoothly to generate the corresponding products in good yields via a tandem decarbonylation-C-H activation.
- Li, Chengliang,Li, Pinhua,Yang, Jin,Wang, Lei
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supporting information; experimental part
p. 4214 - 4216
(2012/05/04)
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- A highly efficient palladium-catalyzed desulfitative arylation of azoles with sodium arylsulfinates
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A highly efficient palladium-catalyzed direct desulfitative arylation of azoles at C2-position has been developed using sodium arylsulfinates as aryl sources. Azoles including benzoxazoles, benzothiazoles, oxazoles, thiazoles, and 1,3,4-oxadiazoles reacted with sodium arylsulfinates smoothly to generate the corresponding products in good to excellent yields, and various substitution patterns were tolerated toward the reaction.
- Wang, Min,Li, Dengke,Zhou, Wei,Wang, Lei
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experimental part
p. 1926 - 1930
(2012/03/26)
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- Facile preparation of 2-substituted benzoxazoles and benzothiazoles via aerobic oxidation of phenolic and thiophenolic imines catalyzed by polymer-incarcerated platinum nanoclusters
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Platinum nanoclusters supported on a polymer/carbon black composite material was found to be an excellent catalyst for the oxidative cyclization of phenolic and thiophenolic Schiff bases to 2-substituted benzoxazoles and benzothiazoles under ambient conditions. Copyright
- Yoo, Woo-Jin,Yuan, Hao,Miyamura, Hiroyuki,Kobayashi, Shu
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supporting information; experimental part
p. 3085 - 3089
(2012/01/02)
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- Cyclopentyl methyl ether: An alternative solvent for palladium-catalyzed direct arylation of heteroaromatics
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Some ethers, such as cyclopentyl methyl ether and di-n-butyl ether, which can be considered as "greener" solvents than N,N-dimethylacetamide (DMAc) or DMF, can be advantageously employed for the palladium-catalyzed direct arylation of heteroaromatics. In the presence of such ethers and only 0.5-1 mol% of palladium catalysts at 125-150°C, the direct 5-arylation of thiazoles, thiophenes, or furans by using aryl bromides as coupling partners proceeds in moderate to high yields.
- Beydoun, Kassem,Doucet, Henri
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experimental part
p. 526 - 534
(2012/03/09)
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