- Synthesis method for preparing benzoxazole compound from catechol compound and amine compound
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The invention provides a method for preparing a benzoxazole compound from a catechol compound and an amine compound. The method has the characteristics of cheap and easily available raw materials, wide substrate range, simple reaction system, easy separation of the obtained target product, simple reaction operation, safety, reliability and the like. Compared with a transition metal catalyzed synthesis method, the system does not need expensive metal catalysts and ligands, so that the economic cost is reduced, and the problems of environmental pollution caused by heavy metals and metal residues in products are avoided. The reaction functional group has higher tolerance, can be used for synthesizing a series of 2-aryl, trifluoromethyl, ester group, halogen, 2-alkenyl, 2-alkynyl and 2-alkyl substituted benzoxazole derivatives, can be used for benzoxazole compounds containing various special functional group structures, and has higher application value.
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Paragraph 0078-0080
(2021/08/19)
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- TEMPO-mediated aerobic oxidative synthesis of 2-aryl benzoxazoles via ring-opening of benzoxazoles with benzylamines
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A simple and efficient TEMPO-mediated system for aerobic oxidative synthesis of 2-aryl benzoxazoles from readily available benzoxazoles and primary benzylic and hetero benzylic amines is presented in one pot. The reaction proceeds through the ring-opening of benzoxazoles and is followed by oxidative condensation with benzylamines. These metal-free, straightforward reactions worked well with a wide range of substrates, yielding moderate to good yields under mild conditions using air as an external green oxidant.
- Rao, Mugada Sugunakara,Hussain, Sahid
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p. 2684 - 2694
(2021/07/26)
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- One-pot multicomponent reaction of catechols, ammonium acetate, and aldehydes for the synthesis of benzoxazole derivatives using the fe(iii)-salen complex
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The Fe(III)-salen complex has been applied successfully as a catalyst for the novel, simple, efficient, and one-pot multicomponent synthesis of benzoxazole derivatives from catechols, ammonium acetate as the nitrogen source, and aldehydes (nontoxic and cheap alternatives of amines) for the first time. Using this procedure, a wide range of benzoxazoles was successfully synthesized in the presence of a catalyst in EtOH under mild conditions, and all products were obtained in excellent yields. To the best of our knowledge, this method is the first example of the multicomponent synthesis of benzoxazole derivatives using these starting materials. The notable features such as the use of air that is considered as a benign oxidant and EtOH as a green solvent, ease of product separation, readily available and inexpensive aldehydes, and mild conditions make our procedure more efficient and practical for organic synthesis. Moreover, the current protocol is successfully applied to synthesize desirable products on a large scale.
- Sharghi, Hashem,Aboonajmi, Jasem,Aberi, Mahdi
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p. 6567 - 6577
(2020/06/08)
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- Ni-Catalyzed C-H Arylation of Oxazoles and Benzoxazoles Using Pharmaceutically Relevant Aryl Chlorides and Bromides
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This manuscript details the development of the nickel-catalyzed arylation of oxazoles and benzoxazoles with aryl halides. A series of aryl, heteroaryl, and druglike electrophiles relevant to pharmaceutical applications were surveyed. The desired arylated products were obtained in synthetically useful yields using electronically and structurally varied aryl halides. The use of microscale high-throughput experimentation was essential for both the rapid identification of optimal reaction parameters and the investigation of the aryl halide scope.
- Larson, Helen,Schultz, Danielle,Kalyani, Dipannita
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p. 13092 - 13103
(2019/10/17)
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- Synthesis of benzoxazoles via the copper-catalyzed hydroamination of alkynones with 2-aminophenols
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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.
- Oshimoto, Kohei,Tsuji, Hiroaki,Kawatsura, Motoi
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p. 4225 - 4229
(2019/05/10)
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- Deep eutectic solvent-catalyzed arylation of benzoxazoles with aromatic aldehydes
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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.
- Tran, Phuong Hoang,Thi Hang, Anh-Hung
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p. 11127 - 11133
(2018/03/26)
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- Phosphonium acidic ionic liquid: An efficient and recyclable homogeneous catalyst for the synthesis of 2-Arylbenzoxazoles, 2-Arylbenzimidazoles, and 2-Arylbenzothiazoles
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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.
- Nguyen, Quang The,Thi Hang, Anh-Hung,Ho Nguyen, Thuy-Linh,Nguyen Chau, Duy-Khiem,Tran, Phuong Hoang
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p. 11834 - 11842
(2018/04/05)
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- N-Heterocyclic Carbene (NHC)-Catalyzed One-Pot Aerobic Oxidative Synthesis of 2-Substituted Benzo[ d ]oxazoles, Benzo[ d ]thiazoles and 1,2-Disubstituted Benzo[ d ]imidazoles
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N-Heterocyclic carbene (NHC), generated in situ from easily available N-heterocyclic imidazolium salt with air as terminal oxidant, has successfully been utilized as a cheap and efficient catalyst for one-pot aerobic oxidative synthesis of 2-arylbenzo[ d ]oxazoles, 2-substituted benzo[ d ]thiazoles, and 1,2-disubstituted benzo[ d ]imidazoles.
- Zhou, Quan,Liu, Shu,Ma, Ming,Cui, He-Zhen,Hong, Xi,Huang, Shuang,Zhang, Jing-Fan,Hou, Xiu-Feng
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supporting information
p. 1315 - 1322
(2018/03/10)
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- A new superacid hafnium-based metal-organic framework as a highly active heterogeneous catalyst for the synthesis of benzoxazoles under solvent-free conditions
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A new crystalline porous superacid material was prepared by sulfation of a Hf-MOF constructed from a 6-connected Hf node and 1,3,5-benzenetricarboxylate. The new superacid MOF with the presence of sulfate groups coordinated to a Hf-oxo cluster as superacid sites was found to be an effective heterogeneous catalyst for solvent-free heterocyclization for benzoxazole synthesis.
- Nguyen, Linh H.T.,Nguyen, The T.,Nguyen, Ha L.,Doan, Tan L.H.,Tran, Phuong Hoang
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p. 4346 - 4350
(2017/10/13)
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- Preparation method of 2-aryl benzoxazole and 2-aryl benzothiazole compounds
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The invention belongs to the technical field of organic synthesis, and in particular relates to a preparation method of 2-aryl benzoxazole and 2-aryl benzothiazole compounds. According to the invention, 2-aminophenol(2-aminothiophenol) and aromatic aldehydes are stirred at the temperature of 100 to 130 DEG C, imidazolium salt of which the molar equivalent amount is 10% to 20% and K2CO3 of which the molar equivalent amount is 25% to 50% are added, air is used as an oxidant, and then 2-aryl benzoxazole and 2-aryl benzothiazole compounds are synthesized by a reaction. According to the invention, the cheap and easily prepared imidazolium salt is taken as a catalyst and the cheap air is taken as the oxidant to synthesize target products in a high yield, so that the preparation method of the 2-aryl benzoxazole and 2-aryl benzothiazole compounds is greatly lowered in production cost and capable of adapting to the industrial application to a greater extent.
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Paragraph 0032; 0033
(2017/08/29)
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- Nickel-catalyzed C?H arylation of benzoxazoles and oxazoles: Benchmarking the influence of electronic, steric and leaving group variations in phenolic electrophiles
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Electronic, steric and leaving group effects for Ni-catalyzed direct arylations using C?O electrophiles were benchmarked. The scope of arylations with pivalates was general with respect to both the electronics on the electrophile and the azoles. Furthermore, the arylation of azoles with tosylates, mesylates and carbamates with varying electronics was explored, and showed electronic trends similar to those of the pivalate reactions. Finally, the relative rate of arylation of 5-methyl benzoxazole with two electronically-similar electrophiles bearing different leaving groups was established. The results from these studies implicate the following order of relative reactivity: mesylates>pivalates>carbamates.
- Steinberg, Deborah F.,Turk, Morgan C.,Kalyani, Dipannita
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supporting information
p. 2196 - 2209
(2017/03/24)
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- Iron(II) bromide-catalyzed oxidative coupling of benzylamines with ortho-substituted anilines: Synthesis of 1,3-benzazoles
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An iron(II) bromide-catalyzed oxidative coupling of benzylamines with 2-amino/hydroxy/mercapto-anilines has been developed, allowing the synthesis of a diversity of substituted 1,3-benzazoles in good to excellent yields. This transformation is compatible with a wide range of functional groups. The method is practical, economical and employs molecular oxygen as an oxidant.
- Gopalaiah, Kovuru,Chandrudu, Sankala Naga
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p. 5015 - 5023
(2015/03/03)
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- Palladium-catalyzed intra-and intermolecular C-H arylation using mesylates: Synthetic scope and mechanistic studies
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This paper describes the development of Pd-catalyzed inter-and intramolecular direct arylation using mesylates. Furthermore, a sequential mesylation/arylation protocol using phenols as substrates is described. These transformations are general with respect to the electronics of the C-H substrates and allow for the synthesis of diverse heterocyclic motifs in good yields. Both arenes and heteroarenes efficiently participate in these reactions. Preliminary mechanistic studies are presented for both inter-and intramolecular arylations.
- Ferguson, Devin M.,Rudolph, Stacey R.,Kalyani, Dipannita
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p. 2395 - 2401
(2014/07/21)
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- Oxidative conversion of amines into benzoxazoles using hydrogen transfer catalysis
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Benzoxazoles are synthesised directly by oxidative condensation of primary and secondary amines with o-aminophenols under hydrogen transfer catalysis. The optimal system utilises 1 mol % of the Shvo catalyst, with dimethoxybenzoquinone as the hydrogen-acc
- Blacker, A. John,Farah, Mohamed M.,Marsden, Stephen P.,Saidi, Ourida,Williams, Jonathan M.J.
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experimental part
p. 6106 - 6109
(2009/12/26)
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- Convenient synthesis of 2-arylbenzoxazoles mediated by solid-supported phenyliodine diacetate
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2-Arylbenzoxazoles were prepared in good yields through the intramolecular cyclization of phenolic Schiff's base in conjunction with poly[styrene(iodoso diacetate)], and the regenerated reagent kept the same activity in the reaction.
- Zhang, Ji-Zheng,Zhu, Qing,Huang, Xian
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p. 2175 - 2179
(2007/10/03)
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- Synthesis and microbiological activity of 5-methyl-2-benzoxazoles
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The synthesis and microbiological activity of a series of 5-methyl-2-(p-substituted phenyl)benzoxazoles 7a-7g are described.The in vitro microbiological activity of these compounds was determined against some Gram-positive and Gram-negative bacteria and C albicans.The observed minimum inhibitory concentration (MIC) values of the derivatives were compared to some other 2,5-disubstituted benzoxazoles and clinically used drugs.The in vitro microbiological data showed that the derivatives 7a-7g exhibited a broad spectrum of antibacterial activity and 7a-c and 7g were significantly active against E coli and/or K pneumoniae at an MIC of 6.2 μg/ml.
- Yalcin, I.,Sener, E.,Oezden, T.,Oezden, S.,Akin, A.
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p. 705 - 708
(2007/10/02)
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- Reactions of α,N-Diarylnitrones with O-Methyl Diphenylphosphinothioate and Oxidations of N-Alkylidene-2-hydroxyanilines with Silver Oxide. Preparation of Benzoxazoles
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Reactions of α,N-diarylnitrones in the presence of O-methyl diphenylphosphinothioate at 150 deg C gave 2-arylbenzoxazoles (3) in fairly good yields.Oxidation of N-alkylidene-2-hydroxyanilines with silver oxide afforded 2-alkenyl-, 2-alkyl-, or 2-arylbenzoxazoles (7 and 3) in good yields under mild reaction conditions (at room temperature).A plausible mechanism for formation of 3 and 7 has been discussed briefly.
- Yoshifuji, Masaaki,Nagase, Rihei,Inamoto, Naoki
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p. 873 - 876
(2007/10/02)
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