- UV-Induced 1,3,4-Oxadiazole Formation from 5-Substituted Tetrazoles and Carboxylic Acids in Flow
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A range of 1,3,4-oxadiazoles have been synthesized using a UV-B activated flow approach starting from carboxylic acids and 5-substituted tetrazoles. The application of UV light represents an attractive alternative to the traditional thermolytic approach and has demonstrated comparable efficiency and versatility, with a diverse substrate scope, including the incorporation of highly substituted amino acids.
- Green, Luke,Livingstone, Keith,Bertrand, Sophie,Peace, Simon,Jamieson, Craig
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supporting information
p. 14866 - 14870
(2020/11/11)
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- 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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- Synthesis of 2,5-disubstituted 1,3,4-oxadiazoles by visible-light-mediated decarboxylation–cyclization of hydrazides and diketones
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A visible-light-induced synthesis of 2,5-disubstituted 1,3,4-oxadiazoles from simple diketones and hydrazides with the assistant of the photocatalyst eosin Y catalyzed decarboxylation and cyclization under mild conditions has been discovered. The reaction tolerates a wide range of functional groups and gives a variety of valuable 1,3,4-oxadiazoles in moderate to good yields. Finally, a plausible reaction mechanism was proposed.
- Diao, Pinhui,Ge, Yanqin,zhang, Wenpei,Xu, Chen,Zhang, Nannan,Guo, Cheng
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supporting information
p. 767 - 770
(2018/02/07)
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- Ligand-free Cu(ii)-mediated aerobic oxidations of aldehyde hydrazones leading to N,N′-diacylhydrazines and 1,3,4-oxadiazoles
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A Cu(ii)-mediated synthesis of N,N′-diacylhydrazines and 1,3,4-oxadiazoles from aldehyde hydrazones has been developed. This is the first time that the synthesis of N,N′-diacylhydrazines and 1,3,4-oxadiazoles using N,N-dimethylamides as the acylation reagent and O2 in air as the oxidation reagent is reported. These reactions offered several advantages including simple workups, ligand-free inexpensive metal salts as mediators, high yields, and wide scope of substrates.
- Liu, Lei,Feng, Suliu
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supporting information
p. 2585 - 2592
(2017/04/03)
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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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- Photoinduced Copper-Catalyzed C-H Arylation at Room Temperature
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Room-temperature azole C-H arylations were accomplished with inexpensive copper(I) compounds by means of photoinduced catalysis. The expedient copper catalysis set the stage for site-selective C-H arylations of non-aromatic oxazolines under mild reaction conditions, and provides step-economical access to the alkaloid natural products balsoxin and texamine. Copper light: Room-temperature C-H arylations of heteroarenes were accomplished with inexpensive copper compounds by photoinduced catalysis. The expedient copper catalysis leads to site-selective C-H arylations of non-aromatic oxazolines under mild reaction conditions, and provides step-economical access to the alkaloid natural products balsoxin and texamine.
- Yang, Fanzhi,Koeller, Julian,Ackermann, Lutz
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supporting information
p. 4759 - 4762
(2016/04/19)
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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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- 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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- C-H arylation of azaheterocycles: A direct ligand-free and Cu-catalyzed approach using diaryliodonium salts
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An efficient and high yielding Cu-catalyzed direct C-H arylation of azaheterocycles including oxadiazoles, thiadiazoles, benzoxazoles and benzothiazoles has been achieved by employing easily accessible diaryliodonium salts. the Partner Organisations 2014.
- Kumar, Dalip,Pilania, Meenakshi,Arun,Pooniya, Savita
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supporting information
p. 6340 - 6344
(2014/08/18)
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- Oxydations d'hydrazones par le bioxyde de plomb: nouvelles syntheses d'oxadiazoles-1,3,4 et de derives de l'amino-4 triazol-1,2,4 one-5
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Aromatic aldehyde aroylhydrazones when oxidized with lead dioxide, in acetic acid, gave quickly the corresponding 1,3,4-oxadiazoles in good yields.Aromatic aldehyde carbodihydrazones on the other hand, gave derivatives of 4-amino-3-aryl-1,2,4-triazol-5-ones, in dimethylformamide as solvent.To explain these results, some radical mechanisms are proposed.
- Milcent, Rene,Barbier, Geo
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