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.
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.
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.
Pd/Cu-Catalyzed C-H/C-H Cross Coupling of (Hetero)Arenes with Azoles through Arylsulfonium Intermediates
Lin, Zeng-Hui,Tian, Ze-Yu,Zhang, Cheng-Pan
supporting information, p. 4400 - 4405 (2021/06/27)
A highly efficient method for the selective formal C-H/C-H cross-coupling of azoles and (hetero)arenes was established through arylsulfonium intermediates under transition-metal catalysis, which produced a variety of 2-(hetero)aryl azoles in good to excellent yields. Advantages of the reaction included mildness, a good functional group tolerance, a wide range of substrates, a high regio- and chemoselectivity, one-pot procedures, and the late-stage functionalization of complex molecules without the use of oxidants, offering a promising strategy for the transition-metal-catalyzed C-H arylation of azoles.
Investigation of Pd-PEPPSI catalysts and coupling partners towards direct C2-arylation/heteroarylation of benzoxazole
Gokanapalli, Anusha,Motakatla, Venkata Krishna Reddy,Peddiahgari, Vasu Govardhana Reddy
, (2021/05/13)
2-Aryl/heteroaryl-substituted benzoxazoles are important heterocyclic motifs extensively found in several bioactive molecules, pharmaceuticals and natural products. In view of the importance of these compounds, there is need to develop easiest and simplest synthetic routes. The motive of this current work is to conduct the direct C2-arylation reaction on benzoxazole with various cross-coupling partners like aryl/heteroaryl halide/carboxylic acid/diazonium tetrafluoroborate/sulfonyl chloride/boronic acids in the presence of different symmetrical and unsymmetrical Pd-PEPPSI (pyridine-enhanced pre-catalyst preparation by stabilization initiation) catalysts via C (sp2)–C (sp2) bond formation. Compared with other coupling partners, boronic acids coupled with benzoxazole very efficiently in the presence of sterically and electronically tunable bulky1,3-bis(N,N′-2,4,6-triisopropylbenzyl)benzimidazolium-Pd-PEPPSI complex in open air to offer the corresponding C2-aryl/heteroaryl benzoxazole compounds. Further, it is worthy to mention that there is no need of any external oxidant/ligand/additive for the complete conversion of starting molecules to products. The reactions progressed successfully with a wide range of substrate scope and attained the products in good to excellent yields in a short reaction time in ethanol/water (1:1) medium. Greatly, catalysts can be recovered and reused for few cycles with significant reactivity.
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.
