- Iron(III) Chloride Mediated para-Selective C-H Functionalization: Access to C5-Chloro and C5,C7-Dichloro/Dianisyl Substituted 2-Arylbenzoxazoles
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Iron(III) chloride mediated para-selective C?H chlorination and subsequent annulation of 2-amidophenol to synthesize C5- and C5, C7-chlorinated benzoxazoles was developed. Further, the oxidative cross-dehydrogenative coupling of amidophenol with anisole b
- Sahoo, Kanchanbala,Panda, Niranjan
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p. 1023 - 1030
(2022/02/03)
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- A TEMPO-Functionalized Ordered Mesoporous Polymer as a Highly Active and Reusable Organocatalyst
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The properties of high stability, periodic porosity, and tunable nature of ordered mesoporous polymers make these materials ideal catalytic nanoreactors. However, their application in organocatalysis has been rarely explored. We report herein for the first time the incorporation of a versatile organocatalyst, 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO), into the pores of an FDU-type mesoporous polymer via a pore surface engineering strategy. The resulting FDU-15-TEMPO possesses a highly ordered mesoporous organic framework and enhanced stability, and shows excellent catalytic activity in the selective oxidation of alcohols and aerobic oxidative synthesis of 2-substituted benzoxazoles, benzimidazoles and benzothiazoles. Moreover, the catalyst can be easily recovered and reused for up to 7 consecutive cycles.
- Guo, Ying,Wang, Wei David,Li, Shengyu,Zhu, Yin,Wang, Xiaoyu,Liu, Xiao,Zhang, Yuan
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supporting information
p. 3689 - 3694
(2021/09/29)
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- Deep eutectic solvent-catalyzed arylation of benzoxazoles with aromatic aldehydes
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A novel and efficient methodology for the arylation of benzoxazoles with aromatic aldehydes catalyzed by deep eutectic solvent has been developed. The reaction smoothly proceeded with a wide range of substrates to give the desired products in high yields within short reaction time. Deep eutectic solvents are easily recovered and reused without significant loss of catalytic activity.
- Tran, Phuong Hoang,Thi Hang, Anh-Hung
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p. 11127 - 11133
(2018/03/26)
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- Phosphonium acidic ionic liquid: An efficient and recyclable homogeneous catalyst for the synthesis of 2-Arylbenzoxazoles, 2-Arylbenzimidazoles, and 2-Arylbenzothiazoles
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A highly efficient and green strategy for the synthesis of 2-Arylbenzoxazoles, 2-Arylbenzimidazoles, and 2-Arylbenzothiazoles catalyzed by phosphonium acidic ionic liquid has been developed via the condensation of o-Aminophenol, o-phenylenediamines, and o-Aminothiophenol, respectively, with aldehydes. The reaction has a good yield, the broad substrate scope, and mild condition. Triphenyl(butyl-3-sulphonyl)phosphonium toluenesulfonate catalyst was easily obtained from cheap and available starting materials through a one-pot synthesis. Its structure was identified by 1H NMR, 13C NMR, 31P NMR, and FT-IR techniques. Other properties including thermal stability and acidity were determined by TGA and Hammett acidity function method. Interestingly, the catalyst can maintain its constantly outstanding performance till the fourth recovery.
- Nguyen, Quang The,Thi Hang, Anh-Hung,Ho Nguyen, Thuy-Linh,Nguyen Chau, Duy-Khiem,Tran, Phuong Hoang
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p. 11834 - 11842
(2018/04/05)
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- A new superacid hafnium-based metal-organic framework as a highly active heterogeneous catalyst for the synthesis of benzoxazoles under solvent-free conditions
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A new crystalline porous superacid material was prepared by sulfation of a Hf-MOF constructed from a 6-connected Hf node and 1,3,5-benzenetricarboxylate. The new superacid MOF with the presence of sulfate groups coordinated to a Hf-oxo cluster as superacid sites was found to be an effective heterogeneous catalyst for solvent-free heterocyclization for benzoxazole synthesis.
- Nguyen, Linh H.T.,Nguyen, The T.,Nguyen, Ha L.,Doan, Tan L.H.,Tran, Phuong Hoang
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p. 4346 - 4350
(2017/10/13)
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- p-Toluenesulfonic acid-catalyzed metal-free formal [4?+?1] heteroannulation via N[sbnd]H/O[sbnd]H/S[sbnd]H functionalization: One-pot access to 2-aryl/hetaryl/alkyl benzazole derivatives
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A concise and direct one-pot [4?+?1] synthetic strategy for the construction of 2-substituted benzazoles such as benzoxazoles and benzothiazoles has been disclosed in high yields (80–98%) by cascade coupling reaction of 2-amino(thio)phenols with β-oxodithioesters. The current approach enables N[sbnd]H/O[sbnd]H/S[sbnd]H functionalization in one-pot under solventless condition leading to diverse benzazoles without use of any external metal. A wide range of 2-amino(thio)phenols and β-oxodithioesters are compatible toward this transformation with excellent functional group tolerance. Furthermore, we preempt the wider implications of this novel strategy by demonstrating its compatibility toward versatile diversification of DNA Topoisomerase-II inhibitors.
- Srivastava, Abhijeet,Shukla, Gaurav,Singh, Maya Shankar
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p. 879 - 887
(2017/01/25)
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- Copper-mediated synthesis of substituted 2-aryl-N-benzylbenzimidazoles and 2-arylbenzoxazoles via C-H functionalization/C-N/C-O bond formation
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An efficient method for the transformation of N-benzyl bisarylhydrazones and bisaryloxime ethers to functionalized 2-aryl-N-benzylbenzimidazoles and 2-arylbenzoxazoles is described. The protocol involves a copper(II)-mediated cascade C-H functionalization/C-N/C-O bond formation under neutral conditions. Substrates having either electron-donating or -withdrawing substituents undergo the cyclization to afford the target heterocycles at moderate temperature.
- Guru, Murali Mohan,Ali, Md Ashif,Punniyamurthy, Tharmalingam
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p. 5295 - 5308
(2011/08/05)
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- Copper(II)-catalyzed conversion of bisaryloxime ethers to 2-arylbenzoxazoles via C-H functionalization/C-N/C-O bonds formation
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A copper(II)-catalyzed conversion of bisaryloxime ethers to 2-arylbenzoxazoles has been developed. The reaction involves a cascade C-H functionalization and C-N/C-O bond formation under oxygen atmosphere.(Figure Presented)
- Guru, Murali Mohan,Ali, Md Ashif,Punniyamurthy, Tharmalingam
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supporting information; experimental part
p. 1194 - 1197
(2011/04/26)
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- Palladium-catalyzed carbonylative C-H activation of heteroarenes
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Not only carbonylation: The first carbonylative cross-coupling reactions towards ketones using C-H activation have been developed. Various heteroarenes, such as oxazoles, thiazoles, and imidazoles were used as coupling partners in this methodology. DBU =
- Wu, Xiao-Feng,Anbarasan, Pazhamalai,Neumann, Helfried,Beller, Matthias
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supporting information; experimental part
p. 7316 - 7319
(2010/11/05)
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- Synthesis of benzazoles by hydrogen-transfer catalysis
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Transition-metal-catalyzed hydrogen-transfer reactions have been used for the conversion of alcohols into benzimidazoles and aldehydes into benzoxazoles and benzothiazoles.
- Blacker, A. John,Farah, Mohamed M.,Hall, Michael I.,Marsden, Stephen P.,Saidi, Ourida,Williams, Jonathan M. J.
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supporting information; experimental part
p. 2039 - 2042
(2009/09/08)
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- Oxidative conversion of amines into benzoxazoles using hydrogen transfer catalysis
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Benzoxazoles are synthesised directly by oxidative condensation of primary and secondary amines with o-aminophenols under hydrogen transfer catalysis. The optimal system utilises 1 mol % of the Shvo catalyst, with dimethoxybenzoquinone as the hydrogen-acc
- Blacker, A. John,Farah, Mohamed M.,Marsden, Stephen P.,Saidi, Ourida,Williams, Jonathan M.J.
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experimental part
p. 6106 - 6109
(2009/12/26)
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- Efficient aerobic oxidative synthesis of 2-substituted benzoxazoles, benzothiazoles, and benzimidazoles catalyzed by 4-Methoxy-TEMPO
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(Chemical Equation Presented) Setting the TEMPO: The scheme shows the efficient aerobic synthesis of 2-substituted benzoxazoles, benzothiazoles, and benzimidazoles where 4-methoxy-2,2,6,6-tetramethyl-1-piperidinyloxy free radical (4-Methoxy-TEMPO) is used as the catalyst.
- Chen, Yong-Xing,Qian, Ling-Feng,Zhang, Wei,Han, Bing
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supporting information; experimental part
p. 9330 - 9333
(2009/05/15)
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- Hypervalent iodine(III) mediated synthesis of 2-substituted benzoxazoles
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2-Substituted benzoxazoles (6a-j, 7a-e, 7j-l) have been synthesized via the oxidative intramolecular cyclization of Schiff's bases (4a-j, 5a-e, 5j-l) using iodobenzene diacetate (IBD) as an oxidant in dry methanol. A one-pot procedure for the synthesis of 6a-j, 7a-e and 7j-l starting from o-aminophenol/p-chloro-o- aminophenol and aldehydes has also been developed.
- Prakash, Om,Batra, Anita,Sharma, Vijay,Saini, Rajesh K.,Verma, Rajender S.
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p. 1031 - 1034
(2007/10/03)
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- Synthesis of 2-arylbenzoxazoles via DDQ promoted oxidative cyclization of phenolic Schiff bases - A solution-phase strategy for library synthesis
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The Schiff base derived from the condensation of o-aminophenol with benzaldehydes was induced to undergo oxidative cyclization in the presence of DDQ. The resulting 2-arylbenzoxazoles were separated from the reduced DDQ by product by treatment of reaction mixture with a strongly basic ion-exchange resin. The applicability of this chemistry to spatially separate library synthesis is demonstrated by the preparation of a 352-member library.
- Chang, Junbiao,Zhao, Kang,Pan, Shifeng
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p. 951 - 954
(2007/10/03)
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- Reactions of α,N-Diarylnitrones with O-Methyl Diphenylphosphinothioate and Oxidations of N-Alkylidene-2-hydroxyanilines with Silver Oxide. Preparation of Benzoxazoles
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Reactions of α,N-diarylnitrones in the presence of O-methyl diphenylphosphinothioate at 150 deg C gave 2-arylbenzoxazoles (3) in fairly good yields.Oxidation of N-alkylidene-2-hydroxyanilines with silver oxide afforded 2-alkenyl-, 2-alkyl-, or 2-arylbenzoxazoles (7 and 3) in good yields under mild reaction conditions (at room temperature).A plausible mechanism for formation of 3 and 7 has been discussed briefly.
- Yoshifuji, Masaaki,Nagase, Rihei,Inamoto, Naoki
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p. 873 - 876
(2007/10/02)
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