7420-86-2Relevant academic research and scientific papers
Cu-Catalyzed Synthesis of Benzoxazole with Phenol and Cyclic Oxime
Wang, Zheng-Hai,Wang, Dong-Hui
supporting information, p. 782 - 785 (2022/01/20)
A Cu-catalyzed straightforward synthesis of benzoxazoles from free phenols and cyclic oxime esters is reported. The mild reaction conditions tolerate various electron-withdrawing and electron-donating functional groups on both substrates, affording benzoxazoles in moderate to good yields. With this protocol, large-scale syntheses of Ezutromid and Flunoxaprofe in one or two steps are demonstrated. A catalytic mechanism, which includes Cu-catalyzed amination via inner-sphere electron transfer and consequent annulation, is proposed.
Dowex 50W: A green mild reusable catalyst for the synthesis of 2-aryl benzoxazole derivatives in aqueous medium
Datta, Arup
, p. 341 - 347 (2021/05/19)
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.
Stable Pd(0) Complexes with Ferrocene Bisphosphanes Bearing Phosphatrioxaadamantyl Substituents Efficiently Catalyze Selective C-H Arylation of Benzoxazoles by Aryl Chlorides
Horky, Filip,Císa?ová, Ivana,?těpni?ka, Petr
, p. 4848 - 4856 (2021/10/12)
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.
TEMPO-mediated aerobic oxidative synthesis of 2-aryl benzoxazoles via ring-opening of benzoxazoles with benzylamines
Rao, Mugada Sugunakara,Hussain, Sahid
, p. 2684 - 2694 (2021/07/26)
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.
One-Pot, Borax-mediated synthesis of structurally diverse N, S-heterocycles in water
Rao, Mugada Sugunakara,Hussain, Sahid
, (2021/05/26)
Herein, a borax–mediated convenient and efficient strategy for the synthesis of prominent structurally diverse N, S-heterocycles such as quinazolin-4(3H)-one, benzothiadiazine 1,1-dioxide, benzothioazole, and benzoxazoles from readily available 2-aminobenzamide/2-aminobenzenesulfonamide/2-aminothiophenol/2-aminophenol with α,α,α-trihalotoluenes at 100 ℃ in water is elaborated. Upon using aldehydes instead of α,α,α-trihalotoluenes, the reactions proceed through domino fashion under the catalytic effect borax to yield 2,3-dihydroquinazolin-4(1H)-one, 3,4-dihydrothiadiazine 1,1-dioxide, and benzothiazoles in one-pot at 60 ℃. The advantages of this protocol are practical simplicity, large substrate scope, moderate to excellent yields, and the use of water as the solvent.
Straightforward synthesis of benzoxazoles and benzothiazoles via photocatalytic radical cyclization of 2-substituted anilines with aldehydes
Le, Hao Anh Nguyen,Nguyen, Long Hoang,Nguyen, Quynh Nhu Ba,Nguyen, Hai Truong,Nguyen, Khang Quoc,Tran, Phuong Hoang
, (2020/08/03)
Eosin Y-catalyzed one-pot coupling and cyclization of o-substituted anilines with aldehydes to form benzoxazoles and benzothiazoles under mild condition has been developed. The reaction scope was broadly tolerant of various 2-substituted anilines and aldehydes. The desired products were obtained in high yields with the use of eosin Y as a photocatalyst under a substantial refinement of reaction conditions in comparison with previous literature. Based on the experimental results observed, a plausible mechanism involving a radical process has been proposed.
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).
Synthetic method 2 -aryl benzoxazole derivative (by machine translation)
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Paragraph 0044-0051; 0058-0061; 0063-0067; 0068-0071, (2020/06/05)
The invention discloses a synthesis method of 2 -aryl benzoxazole derivative, which comprises the following steps: reacting o-nitrophenol derivative with an aryl formaldehyde derivative in the presence of a pyridine accelerant and an elemental sulfur reducing agent to obtain 2 -arylbenzoxazole derivative. (by machine translation)
Consecutive Oxidation/Condensation/Cyclization/Aromatization Sequences Catalyzed by Nanostructured Iron(III)-Porphyrin Complex towards Benzoxazole Derivatives
Aberi, Mahdi,Aboonajmi, Jasem,Sharghi, Hashem,Shiri, Pezhman
, p. 5978 - 5984 (2020/10/02)
A facile, efficient, and eco-friendly strategy to access benzoxazole heterocyclic products has been accomplished through oxidation of catechols followed by condensation/cyclization/aromatization sequences. This process is catalyzed by nanostructured iron(III)-porphyrin complex to form desired benzoxazole derivatives at room temperature under air condition. The procedure is widely applicable to diverse amines, and can provide the heterocyclic products in a scalable fashion, as well. One of the most significant types of oxidizing agents in nature is the iron-porphyrin complexes (0.1 mol-%), existing in the structure of hemoglobin. They have benefits such as low toxicity and high oxidation potential for many substrates.
Sulfur/DABCO Promoted Reductive Coupling/Annulation Cascade Reaction between o -Hydroxy/Amino Nitrobenzenes and Benzaldehydes
Dang, Minh-Huy Dinh,Nguyen, Linh Ho Thuy,Tran, Phuong Hoang
supporting information, p. 1687 - 1694 (2020/05/25)
Sulfur/DABCO was found to be an efficient reagent in promoting- the reductive coupling/annulation of o -nitrophenols or o -nitroanilines with benzaldehydes. This method represents a simple, straightforward, and green approach to the construction of benz-oxazoles and benzimidazoles.
