5676-58-4Relevant academic research and scientific papers
Eco-friendly syntheses of 2-substituted benzoxazoles and 2-substituted benzothiazoles from 2-aminophenols, 2-aminothiophenols and DMF derivatives in the presence of imidazolium chloride
Tian, Qingqiang,Luo, Wen,Gan, Zongjie,Li, Dan,Dai, Zeshu,Wang, Huajun,Wang, Xuetong,Yuan, Jianyong
supporting information, (2019/01/21)
A simple, economical and metal-free approach to the synthesis of 2-substituted benzoxazoles and 2-substituted benzothiazoles from 2-aminophenols, 2-aminothiophenols and DMF derivatives, only using imidazolium chloride (50% mmol) as promoter without any other additive, was reported. Various 2-substituted benzoxazoles and 2-substituted benzothiazoles were thus prepared in moderate to excellent yields.
Metal free montmorillonite KSF clay catalyzed practical synthesis of benzoxazoles and benzothiazoles under aerobic conditions
Kummari, Vijaya Babu,Chiranjeevi, Kalavakuntla,Suman Kumar, Alleni,Kumar, Rathod Aravind,Yadav, Jhillu Singh
supporting information, p. 3335 - 3342 (2019/11/11)
An efficient method for the synthesis of benzoxazoles and benzothiazoles via montmorillonite KSF clay catalyzed condensation reaction between 2-aminophenols or 2-aminothiophenols and β-diketones is reported. The efficiency of the reaction reflects from the wide substrate scope with electronic differentiation on aryls. The reaction is metal free and proceeds without the exclusion of air or moisture, and further the catalyst can be recycled up to 3–5 catalytic cycles.
Synthesis method of 2-substituted benzoxazole, 2-substituted benzothiazole and derivatives thereof
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Paragraph 0040; 0052-0053, (2019/02/10)
The invention provides a synthesis method of 2-substituted benzoxazole, 2-substituted benzothiazole and derivatives thereof. In the method, through ortho-aminophenol/2-aminothiophenol cyclization catalyzed by imidazole hydrochloride, synthesis of functionalized 2-substituted benzoxazole and 2-substituted benzothiazole is realized; the method is simple, economical and high in practicality. No othercatalysts or additives are used, the synthesis method ensures good functional group tolerance and excellent yield and purity, the reaction time is short, no harsh reaction conditions are needed, andthe method is suitable for industrial production.
Sodium dichloroiodate promoted C-C bond cleavage: An efficient synthesis of 1,3-Benzazoles via condensation of o -amino/mercaptan/hydroxyanilines with β -diketones
Bhagat, Saket B,Ghodse, Shrikant M,Telvekar, Vikas N
, (2018/02/09)
An efficient aqueous sodium dichloroiodate (NaICl 2) mediated protocol is developed for the synthesis of benzofused azoles by the cyclization of 2-amino anilines/thiophenols/phenols with β-diketone compounds. The reactions gave moderate to good yield of the corresponding 2-substituted benzimidazoles/benzothiazoles/benzoxazoles under mild conditions. This tandem process involved a C-C bond cleavage and C-N bond formation. Graphical Abstract?: SYNOPSIS A facile and single protocol for the synthesis of three versatile 1,3-benzazoles viz 2-substituted 1H-benzimidazoles, benzoxazoles and benzothiazoles from readily available starting materials, 1,3-diketones and corresponding o-amino anilines/thiophenols/phenols, by aqueous sodium dichloroiodate (NaICl 2) mediated C—C bond cleavage has been developed. The reaction provides a rapid access to these 1, 3-benzazoles in good yields, thus speeding up the drug discovery process.[Figure not available: see fulltext.].
Multicatalytic Beckmann rearrangement of 2-hydroxylarylketone oxime: Switchable synthesis of benzo[d]oxazoles and N-(2-hydroxylaryl)amides
Li, Zhen,Fang, Chengtao,Zheng, Yannan,Qiu, Guanyinsheng,Li, Xiaofang,Zhou, Hongwei
, p. 3934 - 3937 (2018/10/02)
A switchable synthesis route is developed for benzo[d]oxazole derivatives and (2-hydroxylaryl)benzamide from 2-hydroxylbenzeneketoxime using organomolecules (BOP-Cl, and CNC) and Lewis acid cocatalyzed Beckmann rearrangement (BR) reaction. Further, this reaction is switched using different organocatalysts.
A benzoxazole derivative synthesis method
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Paragraph 0052; 0054; 0055, (2017/08/25)
A synthetic method of benzoxazole derivative belongs to the technical field of organic chemistry synthesis. Raw material of a variety of o-hydroxyphenyl ketimines, an oxidant of iodobenzene diacetate and an additive of alkali are subjected to a simple process comprising one-step oxidation rearrangement, concentration and purification in a solvent at room temperature to obtain a product. This method has the characteristics of certain universality, mild reaction conditions, low production equipment requirement, simple technology, easily obtained raw materials, short reaction time and higher efficiency. Benzoxazole derivative products with high yield and good quality can be prepared by adopting the method of the invention; the method can be widely used in industrial production of benzoxazole derivatives; the products prepared by the method of the invention can be widely used as fluorescent whitening agents, dyeing agents, preservatives, rubber vulcanization accelerators and organic electroluminescent materials, as well as antistatic agent for the plastic films; therefore, the invention has good market application prospects.
Hypervalent iodine-mediated synthesis of benzoxazoles and benzimidazoles via an oxidative rearrangement
Zhang, Xiaohui,Huang, Ruofeng,Marrot, Jér?me,Coeffard, Vincent,Xiong, Yan
, p. 700 - 708 (2015/02/02)
A Beckmann-type rearrangement of o-hydroxy and o-aminoaryl N-H ketimines has been developed to prepare benzoxazoles and N-Ts benzimidazoles, respectively. The ketimine derivatives were easily prepared by condensation of ammonia with the corresponding ketones and (diacetoxyiodo)benzene was found to act as an efficient oxidant to trigger the [1,2]-aryl migration towards the formation of the desired heterocycles. Depending on the substitution pattern, the results revealed another mechanistic pathway through which benzisoxazoles or 1H-indazoles could be formed. The Beckmann-type rearrangement strategy was applied to the synthesis of benzimidazole-containing biorelevant targets such as chlormidazole and clemizole.
Acid Catalyzed Direct-Amidation-Dehydrocyclization of 2-Hydroxy-acetophenones to Benzoxazoles by a One-Pot Sustainable Synthesis
Rancan, Elia,Aric, Fabio,Quartarone, Giuseppe,Ronchin, Lucio,Vavasori, Andrea
, p. 939 - 946 (2015/08/06)
A series of 2-methyl-benzoxazoles have been synthesized starting from 2-hydroxy-acetophenones via a one-pot three steps reaction. Hydroxylamonium salt has been used as amidation agent. The reaction occurs with different anions, but the best results is achieved with hydroxylamonium hydrchloride. Despite the number of consecutive stages, the reaction is highly selective. Mild reaction conditions and various solvents can be used, but trifluoroacetic acid is the preferred. Almost, complete recovery of the trifluoroacetic acid can be achieved by vacuum distillation. The role of trifluoroacetic acid, as well as, of the hydroxylamonium salt suggests a cooperative effect leading to high selective formation of 2-methyl-benzoxazoles. Graphical Abstract: One-pot TFA catalyzed synthesis of benzoxazoles starting from 2-hydroxyacetophenones. (Chemical Equation Presented).
One-pot synthesis of benzoxazoles via the metal-free ortho-C-H functionalization of phenols with nitroalkanes
Aksenov, Nicolai A.,Aksenov, Alexander V.,Nadein, Oleg N.,Aksenov, Dmitrii A.,Smirnov, Alexander N.,Rubin, Michael
, p. 71620 - 71626 (2015/09/08)
PPA-activated nitroalkanes are employed in the design of a one-pot cascade transformation involving metal-free and oxidant-free direct ortho-C-H functionalization, followed by Beckman rearrangement and intramolecular cyclocondensation to produce benzoxazoles and benzobisoxazoles directly from easily available phenols.
Benzimidazoles and benzoxazoles via the nucleophilic addition of anilines to nitroalkanes
Aksenov, Alexander V.,Smirnov, Alexander N.,Aksenov, Nicolai A.,Bijieva, Asiyat S.,Aksenova, Inna V.,Rubin, Michael
, p. 4289 - 4295 (2015/04/14)
PPA-induced umpolung triggers efficient nucleophilic addition of unactivated anilines to nitroalkanes to produce N-hydroxyimidamides. The latter undergo sequential acid-promoted cyclocondensation with ortho-OH or ortho-NHR moieties to afford benzoxazoles
