20000-61-7Relevant articles and documents
Direct C–H Carboxylation Forming Polyfunctionalized Aromatic Carboxylic Acids by Combined Br?nsted Bases
Hanasaka, Kazuya,Izumi, Koki,Kondo, Yoshinori,Kwon, Eunsang,Nozawa-Kumada, Kanako,Shigeno, Masanori,Tohara, Itsuki,Yamakoshi, Hiroyuki
supporting information, p. 809 - 814 (2022/02/05)
CO2 fixation into electron-deficient aromatic C–H bonds proceeds with the combined Br?nsted bases LiO-t-Bu and LiO-t-Am/CsF/18-crown-6 (t-Am = CEtMe2) under a CO2 atmosphere to afford a variety of polyfunctionalized aromat
Phosphine-phosphonium ylides as ligands in palladium-catalysed C2-H arylation of benzoxazoles
Yao, Zhenyu,Lin, Xing,Chauvin, Remi,Wang, Lianhui,Gras, Emmanuel,Cui, Xiuling
, p. 3250 - 3254 (2020/05/25)
As balanced electron-rich P,C-chelating ligands, phosphine-phosphonium-ylides are considered for their ability to in situ promote palladium-catalysed direct C(sp2)–H arylation. Using methyl phosphonium salts of 2,2'-bis(diphenylphosphino)-1,1'-binaphtyl (“methyl-BINAPIUM”) as ylide precursors under optimized reaction conditions, arylation of benzoxazole was found to proceed in moderate to high yield to give functional 2-aryl benzoxazoles. A strong anion effect of the non-salt free ylide was evidenced (TfO? > I? > PF6? ≈ salt-free). This first example of phosphonium ylides as ligands in catalytic C–H activation extends the prospect of their general implementation in homogeneous transition metal catalysis.
Acid-promoted cleavage of the C–C double bond of N-(2-Hydroxylphenyl)enaminones for the synthesis of benzoxazoles
Ge, Bailu,Peng, Yanling,Liu, Jing,Wen, Si,Peng, Cheng,Cheng, Guolin
, (2019/12/09)
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.
Iron(0)-Catalyzed Transfer Hydrogenative Condensation of Nitroarenes with Alcohols: A Straightforward Approach to Benzoxazoles, Benzothiazoles, and Benzimidazoles
Putta, Ramachandra Reddy,Chun, Simin,Choi, Seung Hyun,Lee, Seok Beom,Oh, Dong-Chan,Hong, Suckchang
, p. 15396 - 15405 (2020/12/02)
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.
Transition-Metal-Free Alkylation/Arylation of Benzoxazole via Tf2O-Activated-Amide
Niu, Zhi-Jie,Li, Lian-Hua,Liu, Xue-Yuan,Liang, Yong-Min
supporting information, p. 5217 - 5222 (2019/11/13)
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.).
Method used for rapid preparation of benzo-heterocycle compound with physical grinding under solvent-free room temperature conditions
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Paragraph 0062; 0087, (2019/01/21)
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.
Method for synthesizing benzoxazole through microwave radiation of benzamide compound in water phase
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Paragraph 0052, (2019/03/08)
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).
A benzoxazole for the arylation method (by machine translation)
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Paragraph 0058, (2018/11/03)
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)
Phosphonium acidic ionic liquid: An efficient and recyclable homogeneous catalyst for the synthesis of 2-Arylbenzoxazoles, 2-Arylbenzimidazoles, and 2-Arylbenzothiazoles
Nguyen, Quang The,Thi Hang, Anh-Hung,Ho Nguyen, Thuy-Linh,Nguyen Chau, Duy-Khiem,Tran, Phuong Hoang
, p. 11834 - 11842 (2018/04/05)
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.
Deep eutectic solvent-catalyzed arylation of benzoxazoles with aromatic aldehydes
Tran, Phuong Hoang,Thi Hang, Anh-Hung
, p. 11127 - 11133 (2018/03/26)
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.
