15952-20-2Relevant academic research and scientific papers
Delivering 2-Aryl Benzoxazoles through Metal-Free and Redox-Neutral De-CF3Process
Qiao, Xinxin,Zhao, Yong-De,Rao, Mingru,Bu, Zhan-Wei,Zhang, Guangwu,Xiong, Heng-Ying
, p. 13548 - 13558 (2021/10/01)
An unexpected cleavage of the Csp3-CF3 bond of CF3-hydrobenzoxazoles has been disclosed, affording a range of 2-aryl benzoxazoles under metal-free and redox-neutral conditions. This transformation has demonstrated broad substrate scope and good compatibility of functional groups. 2-Aryl benzothiazole and 2-aryl benzoimidazole could be smoothly assembled in the same manner. On the basis of preliminary mechanistic studies, base initiated and aromatization driven β-carbon elimination was considered to be the key step for the formation of 2. This reaction offers an alternative, facile, and sustainable route to access important 2-aryl benzoxazole motifs.
Oxidative cyclization and synthesis of benzoxazole derivatives and hydrolytic phosphatase activity studies on dinuclear diphenoxo-bridged zinc(II)complexes
Kumar, Kapil,Chaudhary, Virendra Kumar,Singh,Ghosh, Kaushik
, (2021/03/01)
Diphenoxo bridged dinuclear zinc complexes, [Zn2(Phimp)2(Cl)2] (1) (PhimpH = (E)-2-((2-phenyl-2-(pyridin-2-yl)hydrazono)methyl)phenol), [Zn2(Me-Phimp)2(Cl)2] (2) (Me-PhimpH = (E)-4-methyl-2-((2-phenyl-2-(pyridin-2-yl)hydrazono)methyl)phenol), [Zn2(OMe-Phimp)2(Cl)2] (3) (OMe-PhimpH = (E)-4-methoxy-2-((2-phenyl-2-(pyridin-2-yl)hydrazono)methyl)phenol), were synthesized and spectroscopically characterized. The molecular structure of 2 was determined using X-ray crystallography. DFT and TD-DFT calculations were performed to optimize the molecular geometry, interpret the spectroscopic results and investigate the contribution of the ligands to the redox properties of the complexes. Phenoxyl radical complexes were generated in solution via chemical oxidation using ceric ammonium nitrate (CAN) and the redox properties were examined through cyclic voltammetric measurements. The hydrolysis of para-nitrophenylphosphate (PNPP) by all the dinuclear zinc complexes was investigated to mimic phosphatase activity. Catalytic oxidative cyclization by these complexes and synthesis of benzoxazole derivatives was investigated.
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).
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 (2019/08/01)
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.).
Synthesis of benzoxazoles via the copper-catalyzed hydroamination of alkynones with 2-aminophenols
Oshimoto, Kohei,Tsuji, Hiroaki,Kawatsura, Motoi
supporting information, p. 4225 - 4229 (2019/05/10)
We describe herein the synthetic method to benzoxazole derivatives via the copper-catalyzed hydroamination of alkynones with 2-aminophenols. The method produced a wide variety of functionalized benzoxazole derivatives in good yields. Preliminary mechanistic experiments revealed that the reaction would proceed through the copper-catalyzed hydroamination of alkynones and the sequential intramolecular cyclization of β-iminoketones/elimination of acetophenone promoted by the copper catalyst.
Iodine Promoted One-Pot Synthesis of 2-Aryl Benzoxazoles from Amidoximes via Oxidative Cyclization and Ring Contraction
Zhang, Yong,Ji, Min
supporting information, p. 7506 - 7510 (2019/11/28)
A molecular I2-promoted one-pot synthesis of 2-aryl benzoxazoles has been developed by using amidoximes rather than the limited 2-aminophenols or 2-haloamides as substrates. The amidoxime substrates provided unique and efficient strategies for converting readily available aniline and benzaldehyde precursors into valuable chemicals. This transformation proceeded smoothly under transition-metal-free conditions through a sequential oxidative cyclization and ring contraction, and provided a potential route for introducing certain groups at any site of the scaffold.
Sulfur-Catalyzed Oxidative Coupling of Dibenzyl Disulfides with Amines: Access to Thioamides and Aza Heterocycles
Nguyen, Thanh Binh,Nguyen, Le Phuong Anh,Nguyen, Thi Thu Tram
supporting information, p. 1787 - 1791 (2019/02/26)
In the presence of catalytic amounts of elemental sulfur, dibenzyl disulfide/DMSO was found to be an excellent thiobenzoylating agent of amines to provide a wide range of thioamides. The reaction becomes autocatalytic when anilines substituted by an o-cyclizable group were used as nucleophile, leading to the corresponding 2-aryl aza heterocycles. (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; 0118, (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.
Synthesis of benzoxazoles via an iron-catalyzed domino C-N/C-O cross-coupling reaction
Yang, Bo,Hu, Weiye,Zhang, Songlin
, p. 2267 - 2270 (2018/02/06)
An eco-friendly and efficient method has been developed for the synthesis of 2-arylbenzoxazoles via a domino iron-catalyzed C-N/C-O cross-coupling reaction. Some of the issues typically encountered during the synthesis of 2-arylbenzoxazoles in the presence of palladium and copper catalysts, including poor substrate scope and long reaction times have been addressed using this newly developed iron-catalyzed method.
Iron-catalyzed 2 - benzenes and wicked zuozuo apperception for the synthesis of the new method
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Paragraph 0019-0020; 0021-0023; 0023-0024, (2018/01/11)
The invention discloses a new synthesis method of iron-catalyzed 2-aryl benzoxazoles, which is prepared by directly performing C-N coupling and C-O coupling on benzamide and o-bromoiodobenzene serving as raw materials at a certain temperature in the presence an iron salt, a ligand and an alkali. According to the invention, a biological metal iron is introduced in synthesis of medical skeletons 2-aryl benzoxazoles, thus use of high-toxicity metals like palladium is avoided, and the application range of the method is expanded to substrates containing different substituent groups. The invention also successfully develops a catalyzing system which can have a catalysis effect on C-N and C-O coupling at the same time, and can greatly improve the safety of 2-aryl benzoxazoles in the synthesis process.
