- TBAI/TBHP-Catalyzed Synthesis of [1,2,4]Triazolo[4,3-a]pyridines and 3,5-Diaryl-1,2,4-oxadiazoles via Oxidative Cleavage of C=C Double Bond
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Abstract: A simple and efficient protocol has been described for the synthesis of [1,2,4]triazolo[4,3-a]pyri-dines and 3,5-disubstituted-1,2,4-oxadiazoles by reacting 2-hydrazinylpyridine and benzamidoximes, respec-tively, with styrenes via TBAI/TBHP-mediated oxidative cleavage of C=C bond under ligand- and metal-free conditions.
- Matcha, S. L.,Vidavalur, S.
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p. 1479 - 1486
(2021/10/26)
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- Method for preparing 3-phenyl-[1,2,4] triazole [4,3-a] pyridine compound without metal catalysis
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The invention discloses a method for preparing a 3-phenyl-[1,2,4] triazole [4,3-a] pyridine compound without metal catalysis. The method comprises the following steps: enabling a pyridine compound, sodium azide and a benzaldehyde compound to react suffici
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Paragraph 0038-0042
(2019/10/01)
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- A Convenient One-pot Synthesis of N-Fused 1,2,4-Triazoles via Oxidative Cyclization Using Trichloroisocyanuric Acid
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A facile one-pot synthesis of N-fused 1,2,4-triazoles from heterocyclic hydrazines and aldehydes is reported. The reaction is efficiently promoted by trichloroisocyanuric acid to afford the desired products mostly in high yields and in relatively short time. The mild nature of the synthesis and short reaction time are notable advantages of the developed protocol. This protocol is effective toward various substrates having different functionalities.
- Bhatt, Ashish,Singh, Rajesh K.,Kant, Ravi
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p. 696 - 702
(2019/01/16)
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- A convenient one-pot synthesis of N-fused 1,2,4-triazoles via oxidative cyclization using chromium (VI) oxide
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A facile one-pot synthesis of N-fused 1,2,4-triazoles from heterocyclic hydrazines and aldehydes is reported. The reaction is efficiently promoted by chromium (VI) oxide to afford the desired products mostly in high yields and in relatively short time. The high yield of the products and short reaction time are notable advantages of the developed protocol. This protocol is effective toward various substrates having different functionalities.
- Bhatt, Ashish,Singh, Rajesh K.,Kant, Ravi
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supporting information
p. 22 - 31
(2019/06/19)
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- Electrochemical synthesis of 1,2,4-triazole-fused heterocycles
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A reagent-free intramolecular dehydrogenative C-N cross-coupling reaction has been developed under mild electrolytic conditions. In this atom- and step-economical one-pot process, valuable 1,2,4-triazolo[4,3-a]pyridines and related heterocyclic compounds could be synthesized efficiently from commercially available aliphatic or (hetero)aromatic aldehydes and 2-hydrazinopyridines. Various functional groups are compatible with this metal- and oxidant-free protocol which can be carried out on a gram scale easily. This novel method was applied to the synthesis of one of the top-selling drugs Xanax and late stage functionalization for generating chemical diversity in biologically relevant lead molecules.
- Ye, Zenghui,Ding, Mingruo,Wu, Yanqi,Li, Yong,Hua, Wenkai,Zhang, Fengzhi
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supporting information
p. 1732 - 1737
(2018/04/30)
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- KI-catalyzed oxidative cyclization of α-keto acids and 2-hydrazinopyridines: Efficient one-pot synthesis of 1,2,4-triazolo[4,3-a] pyridines
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A one-pot approach to substituted 1,2,4-triazolo[4,3-a]pyridines has been developed that is based on a KI-catalyzed oxidative cyclization of α-keto acids and 2-hydrazinopyridines. This transition-metal-free procedure was highly efficient and shows good economical and environmental advantages.
- Yang, De-Suo,Wang, Juan,Gao, Peng,Bai, Zi-Jing,Duan, Dong-Zhu,Fan, Ming-Jin
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p. 32597 - 32600
(2018/10/08)
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- [1,2,4]-triazol [4,3-a] pyridines compound and synthesis method thereof
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The invention discloses a [1,2,4]-triazol [4,3-a] pyridines compound and a synthesis method thereof. The compound has a structure general formula shown as the formula (I), wherein R1 is selected fromaryl and heterocyclic groups; R2 is selected from hydrogen, alkyl, alkoxy, halogen or aryl. According to the synthesis method, alpha-ketonic acid and 2-hydrazinopyridine are used as raw materials; KIis used as a catalyst; Na2CO3 is used as alkali; TBHP is used as an oxidizing agent; 1,4-dioxane is used as a solvent; after a series of serial connection cyclization and decarboxylation aromatization, the [1,2,4]-triazol [4,3-a] pyridines compound is obtained. The [1,2,4]-triazol [4,3-a] pyridines compound is prepared under the condition of no transition metal and has the advantages that the reaction is efficient and fast; the conditions are mild; the substrate is simple and can be easily obtained; the applicability is wide; the reaction time is short; the yield is high, and the like; meanwhile, the post treatment of the reaction is simple and convenient; the harm to experiment operators is reduced; the environment-friendly effect is achieved; the green chemical requirements are met.
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Paragraph 0063-0066
(2020/04/17)
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- Facile one pot synthesis of N-fused 1,2,4-triazoles via oxidative cyclisation using DDQ
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A facile and expedient one pot synthesis of N-fused 1,2,4-triazoles from 2-hydrazinopyridines or 2-hydrazinopyrazines and aldehydes is described via oxidative cyclization using DDQ as a safe and convenient oxidizing agent and polyethylene glycol as recyclable reaction medium. This protocol is effective toward various substrates having different functionalities. The easy recyclability of the reaction medium makes the process economic and potentially viable for commercial applications.
- Bhatt, Ashish,Singh, Rajesh K.,Kant, Ravi
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p. 236 - 247
(2018/11/23)
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- Facile one-pot synthesis of N-fused 1,2,4-triazoles via oxidative cyclization using manganese dioxide
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[Figure not available: see fulltext.] A facile one-pot synthesis of N-fused 1,2,4-triazoles from heterocyclic hydrazines and aldehydes is reported. The reaction is efficiently promoted by manganese dioxide to afford the desired products mostly in high yields and in relatively short times. The mild nature of the synthesis, cheap oxidizing agent, and short reaction time are notable advantages of the developed protocol. This protocol is effective toward various substrates having different functionalities.
- Bhatt, Ashish,Singh, Rajesh K.,Kant, Ravi
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p. 1111 - 1116
(2019/01/25)
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- One-pot synthesis of N-fused 1,2,4-triazoles and related heterocycles via I2/TBHP-mediated oxidative C–N bond formation
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A metal-free iodine/TBHP-mediated oxidative C–N bond formation for the one-pot synthesis of N-fused 1,2,4-triazoles and related heterocycles via cyclization has been developed. This reaction which is amenable to scale-up affords the corresponding products with good to excellent yields and tolerates a wide range of functional groups.
- Wu, Yachuang,Yang, Yifeng,Qi, Yinliang,Du, Shimei,Zhang, Yongsheng,Ding, Liang,Zhao, Yanfang
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supporting information
p. 4216 - 4220
(2018/10/26)
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- Synthesis method of 1,2,4-triazolohetercyclic compound
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The invention provides a method for synthesizing a 1,2,4-triazolohetercyclic compound. The method comprises the following steps: dissolving a 2-hydrazinohetercyclic compound (I) and an aldehyde compound (II) into acetonitrile A; stirring at 25 DEG C to 80
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Paragraph 0032; 0033
(2018/01/09)
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- RuCl3/Oxone: An efficient combination for the synthesis of 3-aryl-[1,2,4]triazolo[4,3-a]pyridines from 2-(2-arylidenehydrazinol)pyridines
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An efficient and convenient method for the synthesis of 3-aryl[1,2,4]triazolo[4,3-a]pyridines has been developed involving RuCl3/Oxone oxidative cyclization of 2-(2-arylidenehydrazinyl)pyridines, which occurs chemoselectively at the pyridine ni
- Swamy, Tallapally,Raviteja, Padma,Srikanth, Goskula,Reddy, Basi V. Subba,Ravinder, Vadde
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supporting information
p. 5596 - 5598
(2016/11/28)
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- Synthesis of 1,2,4-Triazolo[4,3-a]pyridines and Related Heterocycles by Sequential Condensation and Iodine-Mediated Oxidative Cyclization
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A facile and efficient approach to access 1,2,4-triazolo[4,3-a]pyridines and related heterocycles has been accomplished through condensation of readily available aryl hydrazines with corresponding aldehydes followed by iodine-mediated oxidative cyclizatio
- Li, Ertong,Hu, Zhiyuan,Song, Lina,Yu, Wenquan,Chang, Junbiao
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p. 11022 - 11027
(2016/07/27)
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- A novel approach for the synthesis of imidazo and triazolopyridines from dithioesters
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T3P-DMSO mediated desulfurative cyclization of in situ generated thioamides serves as an efficient and versatile method for the synthesis of imidazo[1,5-a]pyridines and [1,2,4]-triazolo[4,3-a]pyridines with good to excellent yields. Substrates such as 2-methylaminoquinoline and pyrazin-2-yl-methanamine also undergo the corresponding reactions at room temperature. This efficient protocol has several advantages such as mild conditions, short reaction time, operational simplicity and high yields.
- Ramesha, Ajjahalli B.,Sandhya, Nagarakere C.,Pavan Kumar, Chottanahalli S.,Hiremath, Mahanthawamy,Mantelingu, Kempegowda,Rangappa, Kanchugarakoppal S.
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supporting information
p. 7637 - 7642
(2016/09/09)
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- 1,1′-carbonyldiimidazole (CDI) mediated coupling and cyclization to generate [1,2,4]triazolo[4,3-a]pyridines
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An operationally efficient CDI mediated tandem coupling and cyclization reaction to generate [1,2,4]triazolo[4,3-a]pyridines has been reported. The reaction conditions and scope were investigated, and the methodology was demonstrated in batch mode as well
- Baucom, Kyle D.,Jones, Sian C.,Roberts, Scott W.
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supporting information
p. 560 - 563
(2016/02/18)
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- Cu-catalysed direct C-H (hetero)arylation of [1,2,4]triazolo[4,3-a]pyridine to construct deep-blue-emitting luminophores
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Cu-catalysed direct C-H (hetero)arylation of [1,2,4]triazolo[4,3-a]pyridine has been accomplished for the first time to streamline the synthesis of 3-aryl-[1,2,4]triazolo[4,3-a]pyridines for screening blue-emitting materials. On this basis, the photophysi
- Wu, Jie,You, Qiulin,Lan, Jingbo,Guo, Qiang,Li, Xiaoyu,Xue, Ying,You, Jingsong
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supporting information
p. 5372 - 5375
(2015/05/20)
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- A simple and efficient synthesis of 3,4,5-trisubstituted/N-fused 1,2,4-triazoles via ceric ammonium nitrate catalyzed oxidative cyclization of amidrazones with aldehydes using polyethylene glycol as a recyclable reaction medium
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An environmentally benign protocol is described for the synthesis of 3,4,5-trisubstituted 1,2,4-triazoles and N-fused 1,2,4-triazoles via ceric ammonium nitrate catalyzed oxidative cyclization of amidrazones and aldehydes using polyethylene glycol as recyclable reaction medium. This protocol is effective toward various substrates having different functionalities. The easy recyclability of the reaction medium makes the process economic and potentially viable for commercial applications.
- Nakka, Mangarao,Tadikonda, Ramu,Rayavarapu, Srinuvasarao,Sarakula, Prasanthi,Vidavalur, Siddaiah
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p. 517 - 525
(2015/02/19)
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- A mild synthesis of [1,2,4]triazolo[4,3-a]pyridines
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The reaction between 2-hydrazinopyridines and ethyl imidates was examined as a one-pot method for rapidly preparing [1,2,4]triazolo[4,3-a]pyridines. A diverse set of 2-hydrazinopyridines were cyclized with a variety of alkyl- and aryl-substituted ethyl imidates in good yields. The reaction proceeds optimally under mild conditions (50-70 C) using 1.5 equiv of acetic acid. The electronic and steric properties of the hydrazine and imidate strongly impact the rate of the reaction. When highly electron deficient 2-hydrazinopyridines were used, the products rearranged to [1,2,4]triazolo[1,5-a]pyridines.
- Schmidt, Michael A.,Qian, Xinhua
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supporting information
p. 5721 - 5726
(2013/09/24)
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- An environmentally benign and solvent-free synthesis of 3-aryl[1,2,4]triazolo[4,3-a]pyridines and 1-aryl-5-methyl[1,2,4]triazolo[4,3-a] quinolines using phenyliodine bis(trifluoroacetate) or iodobenzene diacetate
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A simple, solvent-free and effective method for oxidative cyclization of 2-pyridyl- and 2-quinolylhydrazones with phenyliodine bis(trifluoroacetate) and iodobenzene diacetate to the corresponding 3-aryl[1,2,4]triazolo[4,3-a]pyridines and 1-aryl[1,2,4]tria
- Kumar
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experimental part
p. 1237 - 1243
(2012/08/08)
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- Efficient synthesis of 3-substituted 1,2,4-triazolo[4,3-a]pyridine by [bis(trifluroacetoxy)iodo]benzene-catalyzed oxidative intramolecular cyclization of heterocyclic hydrazones
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A series of 1,2,4-triazolopyridines have been prepared by oxidative intramolecular cyclization of heterocyclic hydrazones with [bis(trifluroacetoxy) iodo]benzene. General applicability of this simple transformation was confirmed by synthesis of 1,2,4-triazolo[4,3-a]pyridine. The advantages of this protocol are the nontoxicity of catalyst and shorter reaction time to obtain good preparative yield.
- Padalkar, Vikas S.,Patil, Vikas S.,Phatangare, Kiran R.,Umape, Prashant G.,Sekar
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experimental part
p. 925 - 938
(2011/04/22)
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- Palladium-catalyzed coupling of aldehyde-derived hydrazones: Practical synthesis of triazolopyridines and related heterocycles
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The palladium-catalyzed intermolecular coupling of aldehyde-derived hydrazones with chloroazines, followed by oxidative cyclization under mild conditions afforded access to a broad variety of bicyclic heterocyclic scaffolds (see scheme) that have potentia
- Thiel, Oliver R.,Achmatowicz, Michal M.,Reichelt, Andreas,Larsen, Robert D.
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supporting information; experimental part
p. 8395 - 8398
(2010/12/25)
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- Palladium-catalyzed chemoselective monoarylation of hydrazides for the synthesis of [1,2,4]Triazolo[4,3-a]pyridines
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(Chemical Equation Presented) An efficient and convenient method for the synthesis of [1,2,4]triazolo[4,3-a]pyridines was exemplified by the synthesis of 20 analogues bearing a variety of substituents at the 3-position. The methodology involves a palladiu
- Reichelt, Andreas,Falsey, James R.,Rzasa, Robert M.,Thiel, Oliver R.,Achmatowicz, Michal M.,Larsen, Robert D.,Zhang, Dawei
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supporting information; experimental part
p. 792 - 795
(2010/04/06)
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- Hypervalent iodine mediated synthesis of 1-aryl/hetryl-1,2,4-triazolo[4,3-a] pyridines and 1-aryl/hetryl 5-methyl-1,2,4-triazolo[4,3-a]quinolines as antibacterial agents
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Oxidation of 2-pyridyl and 2-quinylhydrazones with iodobenzene diacetate (IBD) in dichloromethane yield 1-aryl/hetryl-1,2,4-trizolo-[4,3-a] pyridines (3a-f) and 1-aryl/hetryl-5-methyl-1,2,4-triazolo[4,3-a] quinolines (6a-f). Seven compounds were tested in
- Sadana, Anil K.,Mirza, Yasmin,Aneja, Kamal R.,Prakash, Om
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p. 533 - 536
(2007/10/03)
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- Electrochemical Synthesis of Heterocyclic Compounds. XV. Anodic Synthesis of s-Triazolopyridine Derivatives
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Anodic oxidation of several heterocyclic hydrazones (1a - 9a) prepared from 2-hydrazinopyridine of 2-hydrazino-4-nitropyridine and the corresponding aromatic aldehyde was performed in a CH3CN-Et4NClO4 solution with the addition of 60percent HClO4 on a platinum electrode, using controlled potentials.As a result of two-electron oxidative cyclizations, several s-triazolopyridine derivatives (1b - 9b) were prepared in yields ranging from 55 to 92percent.A mechanism rationalizing the formation of the 3-phenyl-s-triazolopyridine, 1b, has been studied by LSV, CPSV, RDE, coulometry and preparative scale electrolysis.
- Crljenak, Senka,Tabakovic, Ibro,Jeremic, Dragoslav,Gaon, Igor
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p. 527 - 536
(2007/10/02)
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