- Electrochemical Synthesis of 2,5-Disubstituted 1,3,4-Oxadiazoles from α-Keto Acids and Acylhydrazines Under Mild Conditions
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1,3,4-Oxadiazoles are a kind of useful heterocycles which can be frequently found in materials and bioactive molecules. In this study, intermolecular electrochemical cyclization between α-keto acids and acylhydrazines has been developed for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles with the yield up to 91 %. This transformation can be run under mild reaction conditions in the absence of external oxidant, base and transition metal catalyst. Both symmetrical and unsymmetrical 2,5-disubstituted 1,3,4-oxadiazoles could be prepared according to the careful choice of the substrate combination. Gram scale synthesis also illustrates the potential application of this protocol in large preparation.
- Lu, Fangling,Gong, Fengping,Li, Liangsen,Zhang, Kan,Li, Zhen,Zhang, Xinwei,Yin, Ying,Wang, Ying,Gao, Ziwei,Zhang, Heng,Lei, Aiwen
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supporting information
p. 3257 - 3260
(2020/05/25)
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- Photocatalyzed facile synthesis of 2,5-diaryl 1,3,4-oxadiazoles with polyaniline-?g-C3N4-TiO2 composite under visible light
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PANI (polyaniline)-g-C3N4-TiO2 composite was prepared and found to be efficient for the synthesis of 2,5-diaryl 1,3,4-oxadiazoles under visible light. This reaction involved decarboxylation and cyclization from α-keto acids with acylhydrazines, and a broad scope of substrates were tolerated to provide the desired products in moderate to good yields. Control experiments indicated that a radical pathway was involved in the present photocatalytic reaction and a synergistic effect may exist in the ternary composite. Moreover, this semiconductor photocatalyst could be readily recovered and showed good reusability with only slight decrease in the catalytic activity after six consecutive runs.
- Wang, Liang,Wang, Yaoyao,Chen, Qun,He, Mingyang
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supporting information
p. 1489 - 1492
(2018/03/13)
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- Iron(III)/TEMPO-Catalyzed Synthesis of 2,5-Disubstituted 1,3,4-Oxadiazoles by Oxidative Cyclization under Mild Conditions
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A simple and efficient cationic Fe(III)/TEMPO-catalyzed oxidative cyclization of aroyl hydrazones has been developed for the synthesis of 2,5-disubstituted 1,3,4-oxadiazole derivatives. The reaction offers a broad scope, good functional-group tolerance, and high yields under mild conditions in the presence of O 2.
- Zhang, Guofu,Yu, Yidong,Zhao, Yiyong,Xie, Xiaoqiang,Ding, Chengrong
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p. 1373 - 1377
(2017/06/27)
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- A process for preparing 2, 5 - disubstituted - 1, 3, 4 - oxadiazoles (by machine translation)
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The invention provides a method for catalytic oxidative cyclization of formula (II) is shown in the 1, 3, 4 - oxadiazole method, said method comprising: in order to having a structure of formula (I) indicated by the formyl zong compound as a raw material, in order to air or oxygen atmosphere, in order to nitric acid the iron is catalyst, in order to 2, 2, 6, 6 - tetramethyl piperidine nitrogen oxides as initiator, under the action of the water absorbing agent, under the action of the water absorbing agent, in an organic solvent, for 25 - 60 °C lower reaction 3 - 12h, and the resulting reaction solution by the following formula (II) after treatment indicated by the 1, 3, 4 - oxadiazole compounds; the reaction of the invention speed, mild condition, easy operation, low cost, safe reaction, the whole process is friendly to the environment, pollution-free. (by machine translation)
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Paragraph 0031; 0032; 0033; 0034; 0035; 0071-0075
(2017/07/19)
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- One-pot cyclization/decarboxylation of α-keto acids and acylhydrazines for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles under transition-metal-free conditions
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A one-pot KI/TBHP-mediated oxidative cyclization of α-keto acids with acylhydrazines was developed. A series of functional 2,5-disubstituted 1,3,4-oxadiazoles were synthesized through a tandem keto amine condensation followed by oxidative cyclization and decarboxylation reactions. This procedure was achieved under transition-metal-free conditions and showed advantages including readily available materials, mild reaction conditions and good group tolerance.
- Gao, Peng,Wang, Juan,Bai, Zijing,Cheng, Hualei,Xiao, Jian,Lai, Mengnan,Yang, Desuo,Fan, Mingjin
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supporting information
p. 4616 - 4619
(2016/09/23)
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- Palladium-Catalyzed Aminocarbonylation Reaction to Access 1,3,4-Oxadiazoles using Chloroform as the Carbon Monoxide Source
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A palladium-catalyzed aminocarbonylation reaction of aryl halides with chloroform and tetrazoles has been developed, where chloroform was employed as the carbon monoxide (CO) source in the presence of cesium hydroxide. The in situ generated N-acylated tetrazoles were unstable and easily decomposed to afford 2,5-disubstituted 1,3,4-oxadiazoles. A wide range of tetrazoles and aryl halides reacted smoothly under the optimized reaction conditions to give the corresponding products in moderate to good yields.
- Li, Zhengyi,Wang, Liang
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p. 3469 - 3473
(2016/01/25)
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- Palladium-catalyzed one-pot synthesis of diazoles via tert-butyl isocyanide insertion
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An efficient one-pot palladium-catalyzed reaction for the synthesis of diazoles from readily available hydrazides and aryl halide via isocyanide insertion/cyclization sequence has been developed. This methodology efficiently constructs diazoles in good to excellent yields with the advantages of wide functional group tolerance and operational simplicity.
- Fan, Xiang-Yuan,Jiang, Xiao,Zhang, Ying,Chen, Zhen-Bang,Zhu, Yong-Ming
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p. 10402 - 10408
(2015/10/28)
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- An Improved Synthesis of 2-Aryl- and 2-Alkenyl-1,3,4-oxadiazoles by Using Copper(II) Oxide Nanoparticles as a Catalyst 1
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2-Aryl- and 2-alkenyl-1,3,4-oxadiazoles were efficiently synthesized in high yields by treatment of 1,3,4-oxadiazoles with aryl or alkenyl halides, respectively, in the presence of copper(II) oxide nanoparticles as a catalyst. The reusability of the catalyst is an important advantage in relation to practical applications of this synthesis.
- Salva Reddy,Raghavendar Reddy,Das, Biswanath
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p. 2831 - 2838
(2015/09/15)
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- Organocatalytic Oxidative Amidation of Aldehydes with Tetrazoles to Construct 2,5-Diaryl 1,3,4-Oxadiazoles
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A practical and metal-free oxidative amidation of aldehydes with tetrazoles into 1,3,4-oxadiazoles has been developed by employing tetrabutylammonium iodide (TBAI) as catalyst and tert-butyl hydroperoxide (TBHP) as oxidant. A wide range of 2,5-disubstituted 1,3,4-oxadiazoles can be conveniently generated in moderate to good yields. Gram-scale reaction was also realized in this catalytic system..
- Cao, Jing,Wang, Liang
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supporting information
p. 1239 - 1243
(2015/11/27)
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- One-Pot Synthesis of 2,5-Diaryl 1,3,4-Oxadiazoles via Di-tert-butyl Peroxide Promoted N-Acylation of Aryl Tetrazoles with Aldehydes
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A metal- and base-free protocol for one-pot synthesis of 2,5-diaryl 1,3,4-oxadiazoles via a radical-promoted cross-dehydrogenative coupling strategy was developed. This reaction involved the N-acylation of aryl tetrazoles with aryl aldehydes, followed by thermal rearrangement. A wide range of aryl tetrazoles and aryl aldehydes survived the reaction conditions to deliver the corresponding products in moderate to good yields. (Chemical Equation Presented).
- Wang, Liang,Cao, Jing,Chen, Qun,He, Mingyang
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supporting information
p. 4743 - 4748
(2015/05/13)
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- Visible-light-promoted aerobic oxidative cyclization to access 1,3,4-oxadiazoles from aldehydes and acylhydrazides
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A novel and practical access to symmetrical and unsymmetrical 2,5-disubstituted 1,3,4-oxadiazoles directly from aldehydes and acylhydrazides using visible light irradiation under an air atmosphere in the presence of eosin Y as an organophotoredox catalyst at rt is reported. This is the first example of oxidative cyclization of acylhydrazones employing air and visible light as inexpensive, readily available, non-toxic, and sustainable reagents.
- Yadav, Arvind K.,Yadav, Lal Dhar S.
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supporting information
p. 2065 - 2069
(2014/04/03)
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- 2,5-Disubstituted-1,3,4-oxadiazoles: Thymidine phosphorylase inhibitors
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A series of 2,5-disubstituted-1,3,4-oxadiazoles (1-16) were synthesized via microwave irradiation and screened against thymidine phosphorylase enzyme. Four members of the series have demonstrated thymidine phosphorylase inhibitory activities with IC50 values between 37 and 320 μM. Pyridinyl-containing 1,3,4-oxadiazoles exhibited an enhanced inhibitory potential, while phenyl analogs did not show substantial inhibitory potential. Compound 9, a dipyridinyl residue having an IC50 value of 37 ± 0.76 μM was found to be the most potent in the series superior to standard inhibitor 7-deazaxanthine (IC50 = 39.28 ± 0.76 μM). Graphical abstract: [InlineMediaObject not available: see fulltext.]
- Khan, Khalid Mohammed,Rani, Mubeen,Ambreen, Nida,Ali, Muhammad,Hussain, Sajjad,Perveen, Shahnaz,Choudhary, Muhammad Iqbal
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p. 6022 - 6028
(2013/11/06)
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- Efficient oxidative cyclization of N -acylhydrazones for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles using t-BuOI under neutral conditions
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An efficient procedure for the oxidative cyclization of N -acylhydrazones was developed utilizing tert-butyl hypoiodite (t-BuOI), which is generated in situ from t -BuOCl and NaI. A variety of 2,5-disubstituted 1,3,4-oxadiazoles were synthesized in high yields within short reaction time. The method is also suitable for cyclization of N -acylhydrazones derived from heterocyclic aldehydes and aliphatic aldehydes. Mild reaction conditions and simple workup operations make the procedure a good alternative for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles.
- Gao, Peng,Wei, Yunyang
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p. 113 - 119
(2013/05/23)
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- I2-mediated oxidative C-O bond formation for the synthesis of 1,3,4-oxadiazoles from aldehydes and hydrazides
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A practical and transition-metal-free oxidative cyclization of acylhydrazones into 1,3,4-oxadiazoles has been developed by employing stoichiometric molecular iodine in the presence of potassium carbonate. The conditions of this cyclization reaction also work well with crude acylhydrazone substrates obtained from the condensation of aldehydes and hydrazides. A series of symmetrical and asymmetrical 2,5-disubstituted (aryl, alkyl, and/or vinyl) 1,3,4-oxadiazoles can be conveniently generated in an efficient and scalable fashion.
- Yu, Wenquan,Huang, Gang,Zhang, Yueteng,Liu, Hongxu,Dong, Lihong,Yu, Xuejun,Li, Yujiang,Chang, Junbiao
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p. 10337 - 10343
(2013/11/06)
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- Pd(OAc)2 catalyzed C-H activation of 1,3,4-oxadiazoles and their direct oxidative coupling with benzothiazoles and aryl boronic acids using Cu(OAc)2 as an oxidant
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The first direct oxidative coupling of 1,3,4-oxadiazoles with benzothiazoles has been accomplished using Pd(OAc)2 as a catalyst and Cu(OAc)2 as an oxidant. The similar combination of the catalyst and the oxidant has also been applied for direct arylation of 1,3,4-oxadiazoles with aryl boronic acids. Several novel oxadiazole derivatives have been prepared in high yields following both the methods.
- Salvanna,Reddy, Gandolla Chinna,Das, Biswanath
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supporting information
p. 2220 - 2225
(2013/03/13)
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- 1,3,4-Oxadiazole formation as traceless release in solid phase organic synthesis
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Oxadiazoles were generated upon a dehydrative cyclization reaction with 2-acyl hydrazides bound to the polymeric support via one of their N atoms using TFAA as a dehydration agent.
- Cesarini, Sara,Colombo, Nicoletta,Pulici, Maurizio,Felder, Eduard R.,Brill, Wolfgang K.-D.
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p. 10223 - 10236
(2007/10/03)
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