- Characterization of a new non-centrosymmetric polymorph of diphenyl-1,3,4-oxadiazole
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Diphenyl-1,3,4-oxadiazole (DPO) crystallization experiments from solutions clearly reveal the polymorphism of the substance. Besides the formerly known centrosymmetric monoclinic structure with space group P21/c (DPO I) a new monoclinic structure with the non-centrosymmetric space group Cc is found (DPO II): a = 2.4134(4) nm, b = 2.4099(3) nm, c = 1.2879(2) nm, β = 110.048(3)° and V = 7.0363(17) nm3. The asymmetric unit contains six independent molecules in a complex packing motif. A re-determination of the crystal structure of DPO I at room temperature gives lattice parameters a = 0.51885(6) nm, b = 1.8078(2) nm, β = 1.21435(14) nm, β = 93.193(3)°, and V = 1.1373(2) nm3. X-ray measurements at 363 K show a significant increase of the unit cell volume by 1.6%. Differences between both structures concerning morphology and characteristic Raman bands are outlined in detail. DSC investigations show an irreversible transition from DPO I to DPO II at 97°C. DPO II does not show any transition in the temperature range up to the melting point at 141°C. The non-centrosymmetric DPO II structure shows triboluminescence.
- Franco, Olga,Reck, Günter,Orgzall, Ingo,Schulz, Burkhard W.,Schulz, Burkhard
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Read Online
- Pd/Cu-Catalyzed C-H/C-H Cross Coupling of (Hetero)Arenes with Azoles through Arylsulfonium Intermediates
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A highly efficient method for the selective formal C-H/C-H cross-coupling of azoles and (hetero)arenes was established through arylsulfonium intermediates under transition-metal catalysis, which produced a variety of 2-(hetero)aryl azoles in good to excellent yields. Advantages of the reaction included mildness, a good functional group tolerance, a wide range of substrates, a high regio- and chemoselectivity, one-pot procedures, and the late-stage functionalization of complex molecules without the use of oxidants, offering a promising strategy for the transition-metal-catalyzed C-H arylation of azoles.
- Lin, Zeng-Hui,Tian, Ze-Yu,Zhang, Cheng-Pan
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supporting information
p. 4400 - 4405
(2021/06/27)
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- The preparation, characterization and catalytic activity of Ni NPs supported on porous alginate-g-poly(p-styrene sulfonamide-co-acrylamide)
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Herein, we report the synthesis of nickel nanoparticles under mild conditions using porous alginate-g-poly(p-styrene sulfonamide-co-acrylamide) as a protecting/stabilizing agent and sodium borohydride as a reducing agent. The porous cross-linked polymeric support was preparedviacombining the use of sol-gel, nanocasting, and crosslinking techniques, in which thep-styrene sulfonamide monomer (PSSA) andN,N′-methylene-bis (acrylamide) (MBA) cross-linker underwent copolymerization on the surface of sodium alginate in the presence of a SiO2nanoparticle (NP) template (Alg-PSSA-co-ACA). The prepared catalyst (Alg-PSSA-co-ACA@Ni) showed high catalytic activity for the one-step synthesis of 1,3,4-oxadiazoles from the reaction of hydrazides and aryl iodides through isocyanide insertion/cyclization.
- Alavinia, Sedigheh,Ghorbani-Vaghei, Ramin
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p. 29728 - 29740
(2021/10/06)
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- Catalytic application of electrochemically prepared nickel oxide nanoparticles to synthesize 2, 5–disubstituted-1,3,4–oxadiazoles
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The present work aims to synthesize 2,5–disubstituted-1,3,4–oxadiazoles using electrochemically prepared nanoparticles of nickel oxide as catalyst.The nanoparticles thus prepared using electrochemical syntheses are in appreciable yield.The tetrabutyl phosphonium bromide has been used for capping followed by UV, FTIR, XRD, SEM EDS andTEM SAED studies for the characterization. The 2,5-disubstituted-1,3,4-oxadiazoles were synthesized from substituted benzoic acids and their hydrazides in microwave synthesis system using prepared nanoparticles as a catalyst.
- Dare, Sushama B.,Gaikwad, Suresh T.,Rajbhoj, Anjali S.,Sawant, Manisha R.
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p. 300 - 308
(2020/07/03)
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- Sodium hypochlorite-mediated synthesis of 2,5-disubstituted 1,3,4-oxadiazoles from hydrazides and aldehydes
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[Figure not available: see fulltext.] A simple and convenient method for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles has been developed. Structurally divergent symmetrical and unsymmetrical 2,5-disubstituted 1,3,4-oxadiazoles can be obtained in moderate to high yields via NaOCl-mediated oxidative cyclization of N-acylhydrazones, generated in situ from aliphatic and aromatic hydrazides and aldehydes.
- Paidi, Karuna Raman,Kolli, Murali Krishna,Reddy, Eeda Koti,Pedakotla, Venkata Ramana
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p. 371 - 376
(2020/05/04)
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- Experimental and Theoretical Studies on the Mechanism of DDQ-Mediated Oxidative Cyclization of N-Aroylhydrazones
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The controversial single-electron-transfer process, frequently proposed in many 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ)-mediated reactions, was investigated experimentally and theoretically using the oxidative cyclization of aroylhydrazone with DDQ. DDQ-mediated oxadiazole formation involves several processes, including cyclization to form an oxadiazole ring and N-H bond cleavage, either by proton, hydride, or hydrogen atom transfer. The detailed mechanistic study using the M06-2X density functional theory, and the 6-31+G(d,p) basis set, suggests that the pathways involving radical ion pair (RIP) intermediates, which resulted from single-electron transfer (SET), were found to be energetically nearly identical to the pathway without the SET. The substituent-dependent reactivity of oxadiazole formation was consistent with the free energy profiles of both pathways, with or without the SET. This result indicates that in addition to the electron-transfer pathway, the nucleophilic addition/elimination pathway for DDQ should be considered as a possible mechanism of the oxidative transformation reaction using DDQ.
- Baek, Jihye,Je, Eun-Kyung,Kim, Jina,Qi, Ai,Ahn, Kwang-Hyun,Kim, Yongho
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p. 9727 - 9736
(2020/10/02)
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- 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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- PHOTOCATALYTIC SYSTEM AND APPLICATIONS THEREOF
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The present invention relates to novel poly(heptazine imides), a photocatalytic system comprising such poly(heptazine imides) and a sulfur source as well as the application thereof in photocatalytic reactions.
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Page/Page column 40
(2019/05/15)
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- Electrophilic activation of nitroalkanes in efficient synthesis of 1,3,4-oxadiazoles
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A novel methodology for general and chemoselective preparation of non-symmetric 1,3,4-oxadiazoles is developed. This unusual reaction proceeds via polyphosphoric acid-assisted activation of nitroalkanes towards nucleophilic attack with acylhydrazides.
- Aksenov, Alexander V.,Khamraev, Vladislav,Aksenov, Nicolai A.,Kirilov, Nikita K.,Domenyuk, Dmitriy A.,Zelensky, Vladimir A.,Rubin, Michael
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p. 6636 - 6642
(2019/03/14)
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- DMF as Methine Source: Copper-Catalyzed Direct Annulation of Hydrazides to 1,3,4-Oxadiazoles
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An unprecedented Cu-catalyzed direct annulation of hydrazides with N,N-dimethylformamide (DMF) was developed, providing an efficient synthesis of valuable 1,3,4-oxadiazoles. This process features the short reaction time and can be safely conducted on gram scale. The reaction also facilitated the convenient synthesis of 1,3,4-oxadiazole-2(3H)-ones. Moreover, the mechanistic studies suggest that the source of CH is from the N-methyl group of DMF. (Figure presented.).
- Wang, Shoucai,Wang, Kai,Kong, Xiangfei,Zhang, Shuhua,Jiang, Guangbin,Ji, Fanghua
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p. 3986 - 3990
(2019/07/31)
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- Harnessing Autoxidation of Aldehydes: In Situ Iodoarene Catalyzed Synthesis of Substituted 1,3,4-Oxadiazole, in the Presence of Molecular Oxygen
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Isobutyraldehyde underwent auto-oxidation in the presence of molecular oxygen to generate an acyloxy radical under a "metal-free" environment. They were subsequently exploited in situ to afford hypervalent iodines with p-anisolyl iodide which generated substituted 1,3,4-oxadiazoles in moderate to excellent yields from N′-arylidene acetohydrazides. The reaction strategy tolerated diverse substitution on the hydrazide substrates. Control experiments and literature precedence supported the formation of an in situ iodosylarene complex that facilitates the formation of products.
- Chauhan, Jyoti,Ravva, Mahesh K,Sen, Subhabrata
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p. 6562 - 6565
(2019/09/04)
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- One pot solvent-free solid state synthesis, photophysical properties and crystal structure of substituted azole derivatives
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A solvent-free solid state method has been developed to synthesize three series of substituted azole derivatives (including 1,3,4-oxadiazole, 1,3,4-thiadiazole and 1,2,4-triazole) in high yields by condensation cyclization of N,N′-bishydrazide derivatives with corresponding cyclization agents, respectively. This general method avoids the use of organic solvents, saves cost and resources, simplifies post-processing and increases reaction rates. These compounds have been fully characterized by 1H NMR, 13C NMR, elemental analysis and MS. The structure of 2,5-di (4-tertbutylphenyl)-1,3,4-oxadiazole has been determined by single crystal X-ray diffraction analysis. The cell parameters are as follows: monoclinic crystal system, Cc space group, a = 18.735 (2) ?, b = 6.3375 (8) ?, c = 16.824 (2) ? and α = γ = 90°; β = 98.292 (2). The electronic absorption and fluorescent properties of these compounds have been systematically investigated for the first time. The relationships between heterocyclic structures and photophysical properties have been discussed. The alteration of emission and absorption wavelengths can be elucidated by hybrid atoms' electronegativity and Substituents' Hammett constants. This approach proposes a novel insight to provide a great number of novel substituted azole derivatives with good photophysical properties by a general green method.
- Du, Yanting,Wan, Zilu,Chen, Lianqing,Wu, Lamei
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p. 315 - 325
(2019/05/27)
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- Synthesis method of 2,5-disubstituted-1,3,4-oxadiazole
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The invention discloses a synthesis method of a drug intermediate, namely, 2,5-disubstituted-1,3,4-oxadiazole. 2,5-disubstituted-1,3,4-oxadiazole is synthesized with a one-pot method under the photocatalytic action with simple hydrazide compounds as raw materials. 2,5-disubstituted-1,3,4-oxadiazole can be produced through a reaction at the room temperature with a common halogen lamp as a light source, eosinY as a catalyst, potassium carbonate as an additive and ethanol as a solvent. The method has the characteristics that the raw material source is simple, the reaction condition is mild and the like.
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Paragraph 0007; 0019; 0021-0025
(2018/08/04)
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- IBX/KI promoted synthesis of 2, 5-disubstituted 1, 3, 4-oxadiazoles
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Background: Oxadiazoles are privileged scaffolds in different areas of medicinal, pesticidal, polymer and material science. They act as anticancer, benzodiazepine receptor agonists, antimicrobial, analgesic, diuretic and tyrosinase inhibitors etc. A number of compounds containing an oxadiazole moiety are in late stage clinical trials including zibotentan and furamizole. Despite numerous methods are reported, the majority of them suffer from major drawbacks such as the use of strong alkaline or acidic conditions, highly toxic and corrosive reagents and also involve the use of costly reagents, elevated temperatures and longer reaction times. Inspired by the potential application of hypervalent iodonium reagents in organic synthesis, we would like to explore the readily available IBX and KI reagents for the facile synthesis of 1, 3, 4-oxadiazoles. Method: Oxidative cyclization has successfully been developed for the synthesis of 2, 5-disubstituted 1, 3, 4-oxadiazoles. Results: An efficient process for the one-pot synthesis of 2, 5-disubstituted 1, 3, 4-oxadiazoles has been developed using IBX/KI system at 25°C. The reaction was successful with a wide range of substrates such as aromatic and heterocyclic aldehyde and arylhydrazides to afford the corresponding unsymmetrical 2, 5-disubstituted 1, 3, 4-oxadiazoles. The mild reaction conditions, cost-effective reagents and short reaction time are noteworthy advantages of this methodology. Conclusion: We have developed a one-pot strategy for the synthesis of 1, 3, 4-oxadiazioles using a combination of IBX/KI at ambient temperature. This one-pot procedure proved to be quite general and worked well with a wide variety of aryl and heterocyclic aldehydes and variety of acylhydrazides. The advantage of this method lies in the simplicity of experimental procedure and the ready accessibility of the reagents, which render this, an experimentally attractive method for the preparation of unsymmetrical 1, 3, 4-oxadiazoles.
- Khan, P. Rasvan,Durgaprasad,Reddy, S. Gopal,Reddy, G. Raveendra,Hussein, Ibnelwaleed A.,Reddy, B.V. Subba
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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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- 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
(2017/07/19)
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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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- Three-component synthesis method of oxadiazole compound
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The invention relates to a synthesis method of an oxadiazole compound shown in formula (III). The method comprises steps as follows: a compound shown in formula (1), a compound shown in formula (II) and an amine source compound react at 80-100 DEG C for 6-10 h in the presence of an organic solvent, a catalyst, base and an additive, after-treatment is performed after the reaction ends, and the compound shown in formula (III) is obtained, wherein R1 is C1-C6 alkyl groups, phenyl groups or phenyl groups substituted with substitute groups, substitute groups are C1-C6 alkyl groups, C1-C6 alkoxy groups or halogen, and R2 is H, C1-C6 alkyl groups, C1-C6 alkoxy groups or halogen. A specific three-component reaction system is adopted in the method, comprehensive synergism of a specific catalytic system is combined, so that a target product can be obtained at the high yield, and the method has good application prospect and value.
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Paragraph 0030-0033
(2017/05/12)
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- One-pot synthesis of 1,3,4-thiadiazoles using Vilsmeier reagent as a versatile cyclodehydration agent
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A simple and efficient synthetic method for the one-pot synthesis of 1,3,4-thiadiazoles utilizing Vilsmeier reagent was developed. In this method carboxylic acids and hydrazine were converted to 1,3,4-thiadiazoles in the presence of Vilsmeier reagent and Lawesson's reagent. The influence of the thionation reagent, solvent, temperature and time, in this reaction was discussed. The developed methodology for 1,3,4-thiadiazole synthesis has the advantage of simplicity, ambient reaction conditions, easy purification and good to excellent yield of products.
- Zarei, Maaroof
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p. 1867 - 1872
(2017/03/11)
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- 2,5-Diaryloxadiazoles and their precursors as novel inhibitors of cathepsins B, H and L
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High levels of cathepsins indicated in various pathological conditions like arthritis, cancer progressions, and atherosclerosis explains the need to explore potential inhibitors of these proteases which can be of great therapeutic significance. We, in the present work, report the synthesis of some 2,5-diaryloxadiazoles from N-subsitutedbenzylidenebenzohydrazides. The synthesized compounds were screened for their inhibitory potential on cathepsins B, H and L. Structure Activity Relationship studies show that 2,5-diaryloxadiazoles were less inhibitory than their precursors. 1i and 2k have been found to be most inhibitory to cathepsins B and L. Their Ki values have been calculated as 11.38 × 10-8 M and 66.4 × 10-8 M for cathepsin B and 4.2 × 10-9 M and 47.31 × 10-9 M for cathepsin L, respectively. However, cathepsin H activity was maximally inhibited by compounds, 1e and 2c with Ki values of 4.4 × 10-7 M and 5.6 × 10-7 M, respectively. Enzyme kinetic studies suggest that these compounds are competitive inhibitors to the enzymes. The results have been compared with docking results obtained using iGemDock.
- Garg, Shweta,Raghav, Neera
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- Study on DDQ-promoted synthesis of 2, 5-disubstituted 1, 3, 4-oxadiazoles from acid hydrazides and aldehydes
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A facile stepwise synthesis of 2, 5-disubstituted 1, 3, 4-oxadiazoles proceeding via oxidative cyclization of N-acylhydrazones is reported. The reaction is efficiently promoted by 2, 3-dichloro-5, 6-dicyano-1, 4- benzoquinone (DDQ) to afford the desired products mostly in high yields and in relatively short times. The final 1, 3, 4-oxadiazole derivatives are also synthesized directly from acid hydrazides and aldehydes in a one-pot procedure. The substrate scope and limitations of the reported transformation are discussed in detail.
- Jasiak, Karolina,Kudelko, Agnieszka,Zieliński, Wojciech,Ku?nik, Nikodem
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- METHOD FOR PREPAREING 1,3,4-OXADIAZOL UNDER SOLVENT-FREE CONDITION
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The present invention relates to a synthesis method of 1,3,4-oxadiazol, comprising: 1) under a solvent-free condition and by means of a mechanical pulverization method, making a hydrazide compound react with an aldehyde compound and thereby synthesizing a N-acylhydrazone compound; and 2) under a solvent-free condition, adding an iodine-based oxidizing agent to the N-acylhydrazone compound to synthesize 1,3,4-oxadiazol via oxidative cyclization. The solventless synthesis method of 1,3,4-oxadiazol according to the present invention is easy to perform and handle, and has the advantage of synthesizing 1,3,4-oxadiazol at high selectivity and yield. Also, the solventless synthesis method of the present invention can prevent the formation of side products caused by the minute amount of water that usually remains in solvents, and can further prevent synthesized intermediates from being converted back into the starting materials by the water.COPYRIGHT KIPO 2016
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Paragraph 0074-0079; 0112-0113
(2017/02/24)
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- Phenyliodonium diacetate mediated carbotrifluoromethylation of: N -acylhydrazones
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A concise, efficient and direct trifluoromethylation method of aldehyde-derived N-acylhydrazones has been firstly developed by using the combination of inexpensive, stable and commercially available TMSCF3 and PhI(OAc)2 as the CF3 source under mild reaction conditions. This method provides easy access to highly functionalized trifluoromethylated N-acylhydrazones, which could be used as trifluoromethyl synthetic building blocks to be further transformed into other valuable trifluoromethyl compounds.
- Zhang, Weigang,Su, Yingpeng,Chong, Siying,Wu, Lili,Cao, Guiyan,Huang, Danfeng,Wang, Ke-Hu,Hu, Yulai
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p. 11162 - 11175
(2016/12/07)
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- Oxidation of sp3C—H bonds in N-alkylhydrazides: Access to 2,5-disubstituted 1,3,4-oxadiazole derivatives
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The oxidation of sp3C[sbnd]H bonds in N-alkylhydrazides was achieved en route to the efficient synthesis of a broad series of 1,3,4-oxadiazoles. Mechanistic studies have revealed that N-acylhydrazone is a key intermediate in this catalytic transformation.
- Zhang, Liang,Zhao, Xiaolong,Jing, Xiaobi,Zhang, Xuewen,Lü, Shiwei,Luo, Liangliang,Jia, Xiaodong
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supporting information
p. 5669 - 5672
(2016/11/29)
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- Reagent/Substituent Switching Approach for the Synthesis of Substituted 1,3,4-Oxadiazole/1,3,4-Oxadiazoline and 1,2,4-Triazole Derivatives from N-Substituted Hydrazides
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A metal-free method for the synthesis of substituted 1,3,4-oxadiazole/1,3,4-oxadiazoline and 1,2,4-triazole derivatives from a common starting material via reagent/substituent switching is reported. In the presence of 2-fluoropyridine/triflic anhydride, 1,3,4-oxadiazole derivatives were exclusively formed from N′-tert-butylhydrazides and 1,3,4-oxadiazoline derivatives were produced from N-phenylhydrazides. On the other hand, when using pyridine/triflic anhydride, salts of 1,2,4-triazoles were the sole products. (Figure presented.).
- Kotipalli, Trimurtulu,Kavala, Veerababurao,Konala, Ashok,Janreddy, Donala,Kuo, Chu-Wei,Yao, Ching-Fa
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p. 2652 - 2660
(2016/09/03)
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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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p. 4616 - 4619
(2016/09/23)
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- Metal-Free Synthesis of 1,3,4-Oxadiazoles from N′-(Arylmethyl)hydrazides or 1-(Arylmethyl)-2-(arylmethylene)hydrazines
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An efficient and versatile metal-free synthesis of 1,3,4-oxadiazoles from N′-(arylmethyl)hydrazides or 1-(arylmethyl)-2-(arylmethylene)hydrazines through oxidative dehydrogenation is reported. A range of 2,5-disubstituted 1,3,4-oxadiazoles were prepared by treating N′-(arylmethyl)hydrazides with (diacetoxyiodo)benzene in acetonitrile or by treating 1-(arylmethyl)-2-(arylmethylene)hydrazines with [bis(trifluoroacetoxy)iodo]benzene in methyl tert-butyl ether. Aldehyde N-acylhydrazones and aldazines were initially generated in situ as intermediates.
- Shang, Zhenhua,Chu, Qianqian,Tan, Sheng
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p. 1032 - 1040
(2015/03/30)
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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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- Pd-Catalyzed Csp2-H Functionalization of Heteroarenes via Isocyanide Insertion: Concise Synthesis of Di-(Hetero)Aryl Ketones and Di-(Hetero)Aryl Alkylamines
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We report herein an efficient Pd-catalyzed direct C-H bond functionalization of heteroarenes via an isocyanide insertion strategy for the synthesis of di-(hetero)aryl ketones and di-(hetero)aryl alkylamines. The methodology involves a three component reaction between an azole, a haloarene and an isocyanide resulting in the formation of an imine, which in turn is either hydrolyzed or reduced to get the desired product.
- Sharma, Upendra K.,Sharma, Nandini,Xu, Jun,Song, Gonghua,Van Der Eycken, Erik V.
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p. 4908 - 4912
(2015/03/30)
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- Ligand-free copper(0) catalyzed direct C-H arylation of 1,2,4-triazoles and 1,3,4-oxadiazoles with aryl iodides in PEG-400
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A ligand-free copper catalyzed approach has been developed to the synthesis of 3,4,5-triaryl-1,2,4-triazoles and 2,5-diaryl-1,3,4-oxadiazoles by the direct arylation of corresponding 3,4-diaryl-1,2,4-triazoles and 2-aryl-1,3,4-oxadiazoles with aryl iodides using PEG-400 as reaction medium. The procedure is experimentally simple and free from addition of external chelating ligands or co-catalysts.
- Tadikonda, Ramu,Nakka, Mangarao,Rayavarapu, Srinuvasarao,Kalidindi, Siva Prasada Kumar,Vidavalur, Siddaiah
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supporting information
p. 690 - 692
(2015/01/30)
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- Efficient synthesis of 1,3,4-oxadiazoles promoted by NH4Cl
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An efficient and inexpensive approach to the synthesis of 2-substituted and 2,5-disubstituted 1,3,4-oxadiazoles from arylhydrazides and orthoesters is reported using catalytic NH4Cl. The conditions are mild, and thus, compatible with a variety of functional groups. The optimized reaction is performed using 30 mol % of NH4Cl in 100% EtOH and is generally complete within 1 h for non-aromatic orthoesters and 2-10 h for aromatic orthoesters. The reaction permits both electron-releasing and electron-withdrawing groups on the arylhydrazide substrate. Most products are formed in high yields and require only minimal purification. Compared with earlier reports, the current reactions proceed in shorter time and require less of the orthoester.
- Gnanasekaran, Krishna Kumar,Nammalwar, Baskar,Murie, Maeghan,Bunce, Richard A.
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supporting information
p. 6776 - 6778
(2015/01/09)
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- In situ generated cetyltrimethylammonium bisulphate in choline chloride-urea deep eutectic solvent: A novel catalytic system for one pot synthesis of 1,3,4-oxadiazole
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Cetyltrimethylammonium bisulphate ([CTA]HSO4) catalysed one pot synthesis of 2,5-disubstituted-1,3,4-oxadiazoles from carboxylic acid and acid hydrazide in biodegradable deep eutectic solvent is investigated. [CTA]HSO 4 is generated in situ from cetyltrimethylammonium peroxodisulphate. Cyclization of diacylhydrazide using [CTA]HSO4 gives best alternative to traditional dehydration agents. Its remarkable features include a milder procedure, simplicity in workup and purification, good to excellent yields of products, use of inexpensive, recyclable reagents, and eco-friendly aspects by avoiding toxic catalysts/reagents and solvents. Graphical Abstract: [Figure not available: see fulltext.].
- More, Priyanka Anant,Gadilohar, Balu Laxman,Shankarling, Ganapati Subray
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p. 1393 - 1398
(2014/08/18)
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- Study of heterogeneous catalysis by iron-squarate based 3d metal organic framework for the transformation of tetrazines to oxadiazole derivatives
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We present here a simple, milder, and environmentally benign heterogeneous catalytic method for the transformation of tetrazines to oxadiazole derivatives at room temperature (25 °C) using our earlier synthesized iron-squarate based 3D metal organic framework, [Fe3(OH)3(C 4O4)(C4O4)0.5] n (FeSq-MOF).
- Goswami, Soumyabrata,Jena, Himanshu Sekhar,Konar, Sanjit
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supporting information
p. 7071 - 7073
(2014/08/05)
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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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- Electrochemical oxidation of aldehyde-N-arylhydrazones into symmetrical-2,5-disubstituted-1,3,4-oxadiazoles
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A convenient, efficient and one-pot synthesis of chemically and pharmaceutically interesting symmetrical-2,5-disubstituted-1,3,4-oxadiazoles is reported. The protocol involves anodic oxidation of aldehyde-N-arylhydrazones in anhyd. MeCN-LiClO4. Constant potential electrolysis carried out in an undivided cell and platinum electrodes leads to the formation of the corresponding oxadiazoles under ambient condition and the mechanism was deduced from voltammetry studies. The reaction proceeded smoothly with high atom economy. Springer Science+Business Media Dordrecht 2013.
- Singh, Sushma,Sharma, Laxmi K.,Saraswat, Apoorv,Siddiqui, Ibadur R.,Singh, Rana K. Pal
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p. 947 - 960
(2014/05/06)
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- Iodine-catalysed oxidative cyclisation of acylhydrazones to 2,5-substituted 1,3,4-oxadiazoles
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An environmentally benign synthesis of 2,5-disubstituted 1,3,4-oxadiazoles has been developed starting from N-aroylhydrazones and N-acetylhydrazones at room or ambient temperature using a catalytic quantity of iodine in the presence of an aqueous hydrogen peroxide oxidant.
- Majji, Ganesh,Rout, Saroj Kumar,Guin, Srimanta,Gogoi, Anupal,Patel, Bhisma K.
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p. 5357 - 5362
(2014/01/23)
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- An integration of condensation/Ullmann-type coupling/bicyclization sequences: Copper-catalyzed three-component direct synthesis of [1,2,4]triazolo[1,5-b]isoquinolin-5(1H)-ones
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A highly efficient three-component domino protocol has been developed for the synthesis of [1,2,4]triazolo[1,5-b]isoquinolin-5(1H)-ones from simple and readily available o-halogenated benzohydrazides, aldehydes and nitriles. This domino process involves sequential selective condensation, copper-catalyzed intermolecular C-arylation and bicyclization. Notably, the use of ligands and anaerobic conditions can be avoided in this reaction.
- Jia, Feng-Cheng,Xu, Cheng,Cai, Qun,Wu, An-Xin
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p. 9914 - 9916
(2014/08/18)
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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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- One-pot synthesis of 2,5-disubstituted-1,3,4-oxadiazoles based on the reaction of N,N-dimethyl amides with acid hydrazides
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Convenient and efficient one pot method for the synthesis of 2,5-disubstituted-1,3,4-oxadiazoles based on the reaction of N,N-dimethyl amides with acid hydrazides has been developed. The methodology is applied to a wide range of difference aryl hydrazide and difference N,N-dimethyl amides to 2,5-disubstituted-1,3,4-oxadiazoles yield the in good to excellent yields. It will be possible wide useful application in synthesis. Synopsis Convenient and efficient one pot method for the synthesis of 2,5-disubstituted-1,3,4- oxadiazoles based on the reaction of N,N-dimethyl amides with acid hydrazides has been developed. The methodology is applied to a wide range of difference aryl hydrazide and difference N,N-dimethyl amides to 2,5-disubstituted- 1,3,4-oxadiazoles yield the in good to excellent yields. It will be possible wide useful application in synthesis. Copyright
- Li, Qiang,Tao, Yi,Xu, Dongfang,Zhang, Haobing,Duan, Liping
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p. 665 - 670
(2014/06/24)
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- Efficient oxidative cyclisation of acid hydrazides to 2,5-disubstituted 1,3,4-oxadiazoles catalysed by Bu4NI with t-BuOOH as oxidant
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Acid hydrazides or araldehyde N-acylhydrazones can be converted in good yields to, respectively, symmetrical or unsymmetrical, 2,5-disubstituted 1,3,4-oxadiazoles at 60 °C by a Bu4NI-catalysed procedure which requires the presence of a base and 2.5 equiv. of t-butyl hydroperoxide.
- Gao, Peng,Wei, Yunyang
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p. 506 - 510
(2013/09/12)
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- Microwave-assisted one-step synthesis of 2,5-disubstituted-1,3,4- oxadiazoles using 1,4- bis(triphenylphosphonium)-2-butene peroxodisulfate
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A series of 1,3,4-oxadiazoles were efficiently synthesized from the cyclization-oxidation reaction of acyl hydrazones by using 1,4- bis(triphenylphosphonium)-2-butene peroxodisulfate as an oxidant in solvent-free medium under microwave irradiation.
- Gorjizadeh, Maryam,Afshari, Mozhgan,Nazari, Simin
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p. 1627 - 1630
(2014/05/06)
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- One-pot, three component synthesis of 2,5-disubstituted 1,3,4-oxadiazoles catalyzed by heteropolyacid
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H6[PMo9V3O40] was used as an efficient catalyst for the preparation of 1-aroyl-2-arylidene hydrazines. 2,5-Disubstituted 1,3,4-oxadiazoles have been synthesized by oxidation of 1-aroyl-2-arylidene hydrazines with CrO3 in excellent yields.
- Heravi, Majid M.,Zadsirjan, Vahideh,Bakhtiari, Khadijeh,Bamoharram, Fatemeh F.
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p. 259 - 263
(2013/03/29)
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- Electrosynthesis and screening of novel 1,3,4-oxadiazoles as potent and selective antifungal agents
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The electrochemical oxidation of aldehyde-N-aroylhydrazone has been studied in the presence of NaClO4 as supporting electrolyte in MeOH solution using cyclic voltammetry and controlled potential electrolysis. The results indicate that intramolecular cyclization of aldehyde-N-aroylhydrazone has been successfully performed at a platinum electrode in an undivided cell with good yields of the corresponding 1,3,4-oxadiazoles at ambient conditions. The reaction products were characterized by spectroscopic methods and a mechanism was deduced from voltammetry studies. The antifungal activity of the synthesized compounds was evaluated on Fusarium oxysporum, Alternaria solani, Candida albicans and Aspergillus niger. The results revealed that all the synthesized compounds have significant antifungal activity against the tested fungi. Among the synthesized derivatives 7b, 7d, 7g, 7h, 7i, 7j and 7r were found to be the most effective antifungal compounds. The Royal Society of Chemistry 2013.
- Singh, Sushma,Sharma, Laxmi Kant,Saraswat, Apoorv,Siddiqui, Ibadur R.,Kehri, Harbans K.,Singh, Rana K. Pal
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p. 4237 - 4245
(2013/05/08)
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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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