104462-82-0Relevant articles and documents
Cesium Fluoride and Copper-Catalyzed One-Pot Synthesis of Benzoxazoles via a Site-Selective Amide C?N Bond Cleavage
Luo, Zhongfeng,Wu, Hongxiang,Li, Yue,Chen, Yuwen,Nie, Jingyi,Lu, Siqi,Zhu, Yulin,Zeng, Zhuo
, p. 4117 - 4125 (2019)
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.).
Iodoalkyne-Based Catalyst-Mediated Activation of Thioamides through Halogen Bonding
Matsuzawa, Akinobu,Takeuchi, Shiho,Sugita, Kazuyuki
, p. 2863 - 2866 (2016)
Halogen bonding catalysis has recently gained increasing attention as a powerful tool to activate organic molecules. However, the variety of the catalyst structure has been quite limited so far. Herein, we report the first example of the use of an iodoalkyne as a halogen bond donor catalyst. By using an iodoalkyne bearing a pentafluorophenyl group as a catalyst, thioamides were efficiently activated and reacted with 2-aminophenol to generate benzoxazoles in good yield. Mechanistic studies, including 13C NMR spectroscopic analysis and several control experiments, provided concrete evidence that this catalytic activation is based on halogen bonding. Thus, the results obtained in this study demonstrate that iodoalkynes can serve as a new scaffold for future development of halogen bonding catalysis.
Direct alkylation of heteroarenes with unactivated bromoalkanes using photoredox gold catalysis
McCallum,Barriault
, p. 4754 - 4758 (2016)
Although visible light photoredox catalysis has emerged as a powerful tool for the construction of C-C bonds, common catalysts and/or their photoexcited states suffer from low redox potentials, limiting their applicability to alkyl radical generation from substrates with activated carbon-halogen bonds. Radicals derived from these activated compounds, being highly electrophilic or stabilized, do not undergo efficient addition to heteroarenes. Herein we describe the photocatalytic generation of nucleophilic alkyl radicals from unactivated bromoalkanes as part of a universal and efficient cross-coupling strategy for the direct alkylation of heteroarenes using a dimeric gold(i) photoredox catalyst, [Au2(bis(diphenylphosphino)methane)2]Cl2. The method proves to be efficient for alkylation of arenes under mild conditions in the absence of directing groups.
One-pot green synthesis of benzoxazole derivatives through molecular sieve-catalyzed oxidative cyclization reaction
Chang, Weichieh,Sun, Yukai,Huang, Yungtzung
, (2017)
An one-pot approach to benzoxazole ring from 2-aminophenol and aldehydes utilizing molecular sieve as the catalyst have been developed. The new oxidative cyclization reaction excluded the usage of hazardous chemical reagents, transition-metal catalysts, chemical oxidants, or strong acids, and, therefore, reduced the production of toxic chemical waste. This offers an environmentally friendly pathway for the synthesis of various benzoxazole derivatives.
Method of preparing benzoxazole compound
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Paragraph 0088-0090; 0108, (2020/04/17)
The invention relates to a method of preparing a benzoxazole compound. According to the method, 2-aminophenol, olefin and carbon monoxide are used as reaction substrates, an organic solvent is used asa solvent, and the benzoxazole compound is prepared under the catalytic action of ruthenium-loaded metal oxide. The reaction process is as follows: adding an organic solvent, 2-aminophenol, olefin and a catalyst into a pressure vessel, introducing carbon monoxide, sealing, stirring, reacting at the temperature of not lower than 120 DEG C for not less than 0.5 hour, easily separating the catalystfrom the reaction system after the reaction, and recycling for many times, thereby obtaining the benzoxazole compound with the highest yield of 100%.
Sulfur-Promoted Synthesis of Benzoxazoles from 2-Aminophenols and Aldehydes
Nguyen, Le Anh,Dang, Thai Duy,Ngo, Quoc Anh,Nguyen, Thanh Binh
supporting information, p. 3818 - 3821 (2020/06/10)
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).
