835-71-2Relevant academic research and scientific papers
DMF-Assisted Radical Cyclization of o-Isocyanodiaryl Ethers via 1,5-Aryl Migration: Construction of 2-Arylbenzoxazoles
Cai, Jingyu,Ding, Qiuping,Peng, Yiyuan,Song, Zhibin,Tan, Yuxing,Ye, Xiaoling,Yuan, Sitian
, p. 1485 - 1492 (2022/01/20)
A novel DMF-assisted radical cyclization of o-isocyanodiaryl ethers via 1,5-aryl migration has been developed for the synthesis of a series of 2-arylbenzoxazoles by the FeCl3/TBHP/Et3N catalytic system in DMF. However, N,N-dimethylbenzo[d]thiazole-2-carboxamide and N,N-dimethylbenzo[d]selenazole-2-carboxamide were obtained from the corresponding substrate 2-isocyanophenyl p-methoxyphenyl thioether and 2-isocyanodiphenyl selenoether under the same conditions. A possible mechanism may involve aryl 1,5-migration and DMF-assisted radical cyclization of o-isocyanodiaryl ethers.
Novel and efficient heterogeneous polymer supported copper catalyst for synthesis of 2-substituted Benzoxazoles from 2-Haloanilides
Saranya, Thachora Venu,Sruthi, Pambingal Rajan,Raj, Veena,Anas, Saithalavi
supporting information, (2021/02/27)
A novel polymer supported copper complex is prepared by the immobilization of copper iodide on chemically modified polyacrylonitrile and its application in heterogeneous catalysis is described. The catalyst was prepared by easy method via synthetic modification of Polyacrylonitrile (PAN) using ethylene diamine followed by the complexation with CuI. After characterization, this complex was explored as a green and efficient heterogeneous catalyst for the synthesis of 2-benzoxazoles from 2-haloanilides. The reaction was performed without adding additional ligand and the catalyst shows activity over a broad range of substrates with quantitative product yields. The catalyst was easily recovered by simple filtration and reused successfully for further cycle.
An efficient rapid synthesis of benzoxazoles and benzothiazoles using pma.Sio2 at room temperature under heterogeneous conditions
Sudhakar, Chithaluri,Shekhar, Vanam,Shyamsunder, Manchi,Suryakumari, Adurthi,Manojkumar, Vala
, p. 583 - 587 (2021/09/30)
Treatment of 2-aminophenol (or 2-aminothiophenol) with aromatic aldehydes in the presence of phosphomolybdic acid on silica at room temperature affords the corresponding benzoxazoles (or benzothiazoles) in excellent yields (88-96%) under heterogeneous conditions. Benzoxazoles and benzothiazoles are formed in less than 10 min.
Syntheses, characterization, and catalytic potential of novel vanadium and molybdenum Schiff base complexes for the preparation of benzimidazoles, benzoxazoles, and benzothiazoles under thermal and ultrasonic conditions
Kargar, Hadi,Kargar, Khadijeh,Fallah-Mehrjardi, Mehdi,Munawar, Khurram Shahzad
, p. 593 - 605 (2021/06/21)
A new ONO-tridentate Schiff base ligand (H2L) derived from 3-methoxysalicylaldehyde and nicotinic hydrazide was synthesized and characterized by elemental analysis, FT-IR, 1H NMR, 13C NMR, UV–Vis, and powder XRD studies. Then, oxovanadium(V) and dioxomolybdenum(VI) Schiff base complexes, VOL and MoO2L, were also prepared and characterized by different techniques. Moreover, the catalytic activities of both complexes were investigated for the synthesis of benzimidazoles, benzoxazoles, and benzothiazoles under reflux conditions as well as through ultrasonic irradiation. The results revealed several advantages of this procedure, including high product yields, short reaction times, facile work-up procedure, simplicity in operation, eco-friendly reaction conditions, and green aspects by avoiding toxic catalysts and solvents. Graphic abstract: [Figure not available: see fulltext.]
Fluorinated phosphoric acid as a versatile effective catalyst for synthesis of series of benzimidazoles, benzoxazoles and benzothiazoles at room temperature
Mathapati, Sushil R.,Patil, Komal N.,Mathakari, Sujit S.,Suryawanshi, Appasaheb W.,Jadhav, Arvind H.
, p. 538 - 547 (2021/01/21)
The present work describes synthesis of a series of benzimidazoles, benzoxazoles and benzothiazoles through the cyclization of 1, 2-phenylenediamine, 2-aminothiophenol, or 2-aminophenol with aryl, aliphatic and heteroaryl aldehydes. The present synthetic protocol is very much efficient in presence of 5 mol % fluorophosphoric acid as a catalyst in ethanol solvent at room temperature. Shorter reaction time, simple work-up technique, high yields and easy availability are specific compensations of the present synthetic approach.
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.
Heterogeneous palladium (II)-complexed dendronized polymer: A rare palladium catalyst for the one-pot synthesis of 2-arylbenzoxazoles
George, Smitha,Sreekumar, Krishnapillai
, (2020/12/14)
The palladium complex of dendronized amine polymer (EG–Gn–Pd, n = 0, 1 and 2) having ethylene glycol-initiated polyepichlorohydrin as core was synthesized on a Merrifield resin support and was well characterized. Generally, palladium catalysts are known for carbon–carbon coupling reactions. Here, a developed catalyst was found to be good for benzoxazole synthesis. Higher generation dendronized polymer (EG–G2–Pd) was found to be better catalyst over lower generation dendronized polymers. Moreover, dendronized polymers were found to be a better catalyst over dendrigraft polymers. The catalyst reusability was checked and good yield was obtained for five cycles.
Nickel catalyzed sustainable synthesis of benzazoles and purines: Via acceptorless dehydrogenative coupling and borrowing hydrogen approach
Chakraborty, Gargi,Guin, Amit Kumar,Mondal, Rakesh,Paul, Nanda
, p. 7217 - 7233 (2021/08/30)
Herein we report nickel-catalyzed sustainable synthesis of a few chosen five-membered fused nitrogen heterocycles such as benzimidazole, purine, benzothiazole, and benzoxazole via acceptorless dehydrogenative functionalization of alcohols. Using a bench stable, easy to prepare, and inexpensive Ni(ii)-catalyst, [Ni(MeTAA)] (1a), featuring a tetraaza macrocyclic ligand (tetramethyltetraaza[14]annulene (MeTAA)), a wide variety of polysubstituted benzimidazole, purine, benzothiazole, and benzoxazole derivatives were prepared via dehydrogenative coupling of alcohols with 1,2-diaminobenzene, 4,5-diaminopyrimidine, 2-aminothiphenol, and 2-aminophenol, respectively. A wide array of benzimidazoles were also prepared via a borrowing hydrogen approach involving alcohols as hydrogen donors and 2-nitroanilines as hydrogen acceptors. A few control experiments were performed to understand the reaction mechanism.
Photocatalytic green synthesis of benzazoles from alcohol oxidation/toluene sp3C-H activation over metal-free BCN: effect of crystallinity and N-B pair exposure
Cheng, Hongmei,Gao, Xue,Jiang, Heyan,Sun, Bin,Zang, Cuicui
, p. 7955 - 7962 (2021/12/27)
Porous borocarbonitride (P-BCN), with the characteristics of enhanced crystallinity and improved N-B pair exposure, was prepared with a simple KCl-assisted molten salt strategy. Efficient heterogeneous photocatalytic tandem synthesis of benzazoles from alcohol oxidation/toluene sp3C-H activation was achieved firstly over the metal-free P-BCN using visible light and the green oxidant O2, with only water as a by-product. Variouso-thio/hydroxy/aminoanilines and alcohols or toluenes could be converted to the corresponding 2-substituted benzothiazoles, benzoxazoles and benzimidazoles with good to excellent photocatalytic performance. The improved photocatalytic performance in comparison to bulk BCN should be due to the crystallinity-enhancement-induced improvement in charge separation and transmission. The increased N-B pair exposure promoted superoxide radical generation due to the electron-enriched N atoms, as well as improved oxidation ability due to the valence band constructed by the B 2p orbital. This work presents a green and efficient synthetic strategy towards benzazoles and other fine chemicalsviametal-free heterogeneous photocatalysis.
Production process of fluorescent whitening agent OB-1
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Paragraph 0030; 0037; 0039-0047, (2021/03/11)
The invention relates to a production process of a fluorescent whitening agent OB-1. The production process specifically comprises the following steps: 1, carrying out condensation reaction on p-toluic acid and o-aminophenol to generate 4-methyl phenyl benzoxazole; 2, carrying out distillation treatment after the condensation reaction is finished, and collecting a main fraction 4-methyl intermediate; 3, adding methanol into the main fraction, keeping the temperature at 60 DEG C for 6 hours, cooling to 10 DEG C, centrifugally filtering, drying, and transferring into a vulcanization synthesis kettle; 4, carrying out a vulcanization synthesis reaction on the 4-methyl intermediate to generate OB-1, rinsing with xylene, repeatedly washing with xylene, and drying the xylene by distillation to obtain a dried OB-1 crude product; 5, adding trichlorobenzene, the OB-1 crude product and activated carbon into a refining kettle to refine OB-1; and 6, pulping and washing OB-1 with methanol, carryingout centrifugal separation, and drying a filtering cake to obtain the OB-1 product. The method is environmentally friendly, safe and high in yield.
