6797-15-5Relevant articles and documents
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
, (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.
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.
Facile synthesis of 2-benzoxazoles via CuI/2,2'-bipyridine catalyzed intramolecular C–O coupling of 2-haloanilides
Venu Saranya, Thachora,Rajan Sruthi, Pambingal,Anas, Saithalavi
, p. 297 - 307 (2019/01/18)
Development of newer methods for the synthesis of Benzoxazoles has of greater interest due to their wide range of biological activities and pharmaceutical importance. We herein report a facile and general method for the synthesis of 2-substituted Benzoxazoles via copper catalyzed intramolecular C–O cross-coupling of 2-haloanilides. A combination of CuI (5 mol%), 2,2'-bipyridine (10 mol%), Cs2CO3 (2 equiv.) in DMF solvent with 4 ? molecular sieves at 140 °C, illustrated the scope for tuning the reactivity of 2-haloanilides toward the selective formation of a series of 2-alkyl benzoxazole derivatives in moderate to good yields. This is the first systematic study using CuI/2,2'-Bipyridine as the catalytic system for the synthesis of 2-substituted Benzoxazoles. The outcome of the reaction was found to be significantly influenced by the aromatic and amide substituents of 2-haloanilides.
Transition-Metal-Free Alkylation/Arylation of Benzoxazole via Tf2O-Activated-Amide
Niu, Zhi-Jie,Li, Lian-Hua,Liu, Xue-Yuan,Liang, Yong-Min
supporting information, p. 5217 - 5222 (2019/11/13)
A transition-metal-free approach to the alkylation/arylation of benzoxazole was developed by employing Tf2O-activated-amide as the alkylating/arylating reagent. The mild reaction conditions, and particularly insensitivity to air and water, further enhance the synthetic potential in pharmaceutical synthesis. (Figure presented.).
Iodoalkyne-Based Catalyst-Mediated Activation of Thioamides through Halogen Bonding
Matsuzawa, Akinobu,Takeuchi, Shiho,Sugita, Kazuyuki
supporting information, p. 2863 - 2866 (2016/10/25)
Halogen bonding catalysis has recently gained increasing attention as a powerful tool to activate organic molecules. However, the variety of the catalyst structure has been quite limited so far. Herein, we report the first example of the use of an iodoalkyne as a halogen bond donor catalyst. By using an iodoalkyne bearing a pentafluorophenyl group as a catalyst, thioamides were efficiently activated and reacted with 2-aminophenol to generate benzoxazoles in good yield. Mechanistic studies, including 13C NMR spectroscopic analysis and several control experiments, provided concrete evidence that this catalytic activation is based on halogen bonding. Thus, the results obtained in this study demonstrate that iodoalkynes can serve as a new scaffold for future development of halogen bonding catalysis.
Synthesis of benzoxazoles from 2-aminophenols and β-diketones using a combined catalyst of br?nsted acid and copper iodide
Mayo, Muhammad Shareef,Yu, Xiaoqiang,Zhou, Xiaoyu,Feng, Xiujuan,Yamamoto, Yoshinori,Bao, Ming
, p. 6310 - 6314 (2014/07/21)
Cyclization reactions of 2-aminophenols with β-diketones catalyzed by a combination of Br?nsted acid and CuI are presented. Various 2-substituted benzoxazoles were obtained through these reactions. Different substituents such as methyl, chloro, bromo, nitro, and methoxy on 2-aminophenol are tolerated under the optimized reaction conditions.
A general palladium-catalyzed method for alkylation of heteroarenes using secondary and tertiary alkyl halides
Wu, Xiaojin,See, Jessica Wei Ting,Xu, Kai,Hirao, Hajime,Roger, Julien,Hierso, Jean-Cyrille,Zhou, Jianrong
supporting information, p. 13573 - 13577 (2015/01/09)
A general alkylation of heterocycles using a simple palladium catalyst is reported. Most classes of heterocycles, including indoles and pyridines, efficiently coupled with unactivated secondary and tertiary alkyl halides. An alkyl radical addition to neutral heteroarenes is most likely involved.
Samarium(III) triflate as an efficient and reusable catalyst for facile synthesis of benzoxazoles and benzothiazoles in aqueous medium
Gorepatil, Pratapsinha B.,Mane, Yogesh D.,Ingle, Vilas S.
, p. 2241 - 2244 (2013/11/06)
A simple, green, and efficient method is presented for the synthesis of benzoxazoles and benzothiazoles from reaction of o-aminophenols, o-aminothiophenols, and aliphatic or aromatic aldehydes using samarium triflate as a reusable acid catalyst under mild reaction conditions in aqueous medium. Georg Thieme Verlag Stuttgart, New York.
A general approach to substituted benzimidazoles and benzoxazoles via heterogeneous palladium-catalyzed hydrogen-transfer with primary amines
Pizzetti, Marianna,De Luca, Elisa,Petricci, Elena,Taddei, Maurizio,Porcheddu, Andrea
supporting information, p. 2453 - 2464,12 (2012/12/12)
The synthesis of benzimidazoles starting from o-phenylenediamines and amines in the presence of palladium on charcoal as catalyst is reported. Under microwave dielectric heating it is possible to use a tertiary, a secondary, and even a primary amine as the substrate for a palladium-mediated process to get 2-substituted or 1,2-disubstituted benzimidazoles, depending on the nature of the o-phenylenediamine employed. Primary amines are the most suitable reagents for the atom economy of the overall process that resulted to be general as several different substituted benzimidazoles were obtained in good yield. Benzoxazoles can be also prepared starting from primary amines and o-aminophenol. The reaction is also highly selective as no (poly)-alkylated phenylenediamines or cross-contaminated benzimidazoles are obtained starting from N-monoalkylphenylenediamines. This behavior was interpreted as a scarce aptitude to dehydrogenation of the methylene bonded to the aromatic NH of N-alkylarylamines. The experiments carried out consent to draw an almost complete picture of the reaction pathways occurring during the process. The catalyst can be recycled several times and, although far from optimal performances, catalyst TON=90 is encouraging for further large-scale optimization protocols. In addition, the palladium on charcoal-catalyzed microwave-assisted reaction of o-phenylenediamine gives de-alkylation of tertiary amines and transformation into the secondary ones. Copyright
A general approach to substituted benzimidazoles and benzoxazoles via heterogeneous palladium-catalyzed hydrogen-transfer with primary amines
Pizzetti, Marianna,De Luca, Elisa,Petricci, Elena,Porcheddu, Andrea,Taddei, Maurizio
supporting information, p. 2453 - 2464 (2013/01/14)
The synthesis of benzimidazoles starting from o-phenylenediamines and amines in the presence of palladium on charcoal as catalyst is reported. Under microwave dielectric heating it is possible to use a tertiary, a secondary, and even a primary amine as the substrate for a palladium-mediated process to get 2-substituted or 1,2-disubstituted benzimidazoles, depending on the nature of the o-phenylenediamine employed. Primary amines are the most suitable reagents for the atom economy of the overall process that resulted to be general as several different substituted benzimidazoles were obtained in good yield. Benzoxazoles can be also prepared starting from primary amines and o-aminophenol. The reaction is also highly selective as no (poly)-alkylated phenylenediamines or cross-contaminated benzimidazoles are obtained starting from N-monoalkylphenylenediamines. This behavior was interpreted as a scarce aptitude to dehydrogenation of the methylene bonded to the aromatic NH of N-alkylarylamines. The experiments carried out consent to draw an almost complete picture of the reaction pathways occurring during the process. The catalyst can be recycled several times and, although far from optimal performances, catalyst TON=90 is encouraging for further large-scale optimization protocols. In addition, the palladium on charcoal-catalyzed microwave-assisted reaction of o-phenylenediamine gives de-alkylation of tertiary amines and transformation into the secondary ones. Copyright
