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1.
T. K. Shkinyova I. L. Dalinger S. I. Molotov S. A. Shevelev 《Russian Chemical Bulletin》2000,49(9):1572-1574
A convenient procedure was developed for the synthesis of picryl-substituted 1,3,4-oxadiazoles. The nucleophilic replacement
of the nitro group in picroylacylhydrazines under the action of thiophenol was studied.
Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 1583–1585, September, 2000. 相似文献
2.
The effect of the solvent on the course of the reaction between trichloromethylarenes and thioacylhydrazines or acylhydrazines has been considered. In alcohols as solvents, alkyl arenecarboxylates form as a result of alcoholysis, while 2,5-disubstituted 1,3,4-thiadiazoles (1,3,4-oxadiazoles) form as minor products. In pyridine solutions, the major or sole products are those of reductive condensation,i.e., the correspondingN-substituted hydrazones of arenecarbaldehydes. 1,3,4-Thiadiazole or 1,3,4-oxadiazole derivatives are obtained in good yield when the reaction is carried out in a pyridine-alkanol mixture.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 1246–1249, May, 1996. 相似文献
3.
N. I. Korotkikh A. V. Kiselev A. V. Knishevitsky G. F. Raenko T. M. Pekhtereva O. P. Shvaika 《Chemistry of Heterocyclic Compounds》2005,41(7):866-871
Efficient methods have been developed for obtaining precursors of stable carbenes, viz. 5-unsubstituted 3,4-diaryl-1,2,4-triazoles
and 3,3′- or 4,4′-bridge linked bis-1,2,4-triazoles, by the recyclization of 5-unsubstituted 1,3,4-oxadiazoles or p-phenylenebis-1,3,4-oxadiazole
with anilines or aromatic diamines in the presence of trifluoroacetic acid or with aniline hydrochlorides in pyridine.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 7, pp. 1026–1032, July, 2005. 相似文献
4.
L. D. Patsenker I. G. Ermolenko O. N. Lyubenko I. A. Fedyunyaeva N. A. Popova O. S. Galkina A. V. Mazepa B. M. Krasovitskii 《Chemistry of Heterocyclic Compounds》2003,39(4):525-533
It has been shown that dimethylamino-substituted 2,5-diaryloxazoles and 2,5-diaryl-1,3,4-oxadiazoles undergo heterocyclization under Vilsmeier-Haack conditions with the participation of the dimethylamino group to form quinazolinium salts. The oxazole ring can also be formylated at the free 4 position. In alkaline medium the quinazolinium ring is readily hydrolyzed with desalkylation. 相似文献
5.
Aamer Saeed 《Chemistry of Heterocyclic Compounds》2007,43(8):1072-1075
An efficient, rapid, microwave-accelerated one-step synthesis of some 5-aryl-2-(2-hydroxy-phenyl)-1,3,4-oxadiazoles by reaction
of salicylic hydrazide with carboxylic acids in the presence of thionyl chloride under neat conditions is described.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 8, pp. 1264–1267, August, 2007. 相似文献
6.
We have studied the basicity of 2-phenyl-5-R-1,3,4-oxadiazoles (R = H, Me, CH2Ph, t-Bu, CH2Cl, CCl3, CF3) in aqueous sulfuric acid solutions. These compounds are weak organic bases (pKBH
+ is −1.8 to −5.2). The values of pKBH
+ determined on the H0 and X acidity function scales agree well with each other. The substituent at the 5 position has a substantial effect on the
basicity of the 1,3,4-oxadiazole ring.
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Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 748–756, May, 2006. 相似文献
7.
A one-pot synthesis of some unsymmetrical 2,5-disubstituted-1,3,4-oxadiazoles via cyclocondensation of benzoylhydrazines with orthoesters under solvent-free and microwave conditions are described here. The reaction is efficiently catalyzed by silica- supported sulfuric acid as it provided the title compounds in high yields and relatively short times. The catalyst is reusable and can be applied several times without considerable decrease in the yields and rates of the reactions. 相似文献
8.
Microwave-assisted as well as conventional synthesis of 2,5-disubstituted-1,3,4-oxadiazoles containing the azulene moiety was carried out, and their antifungal activity is also reported. 相似文献
9.
Agnieszka Kudelko 《Tetrahedron》2011,67(44):8502-8508
Reactions of symmetrical 1,1′-diphenylthiodiacetic acid dihydrazide and triethyl orthoesters in the presence of catalytic amount of glacial acetic acid resulted in the formation of three heterocyclic products: the appropriate bis(1,3,4-oxadiazol-2-yl-phenylmethyl) sulfides, 2-benzyl-1,3,4-oxadiazoles and 2-benzoyl-1,3,4-oxadiazoles. The presence of the latter two compounds is connected with carbon-sulfur fission in the molecule of the starting hydrazide. The identity of the unexpected fission products was confirmed by parallel syntheses of the model 1,3,4-oxadiazoles from phenylacetic acid hydrazide and 2-hydroxymethyl-1,3,4-oxadiazole derivatives. 相似文献
10.
《Tetrahedron letters》2009,50(17):1886-993
2,5-Disubstituted 1,3,4-oxadiazoles have been conveniently prepared by oxidative cyclization of N-acyl-N′-aryliden-hydrazines promoted by an excess of Dess-Martin periodinane under mild conditions (23 examples, up to 92% isolated yields). 相似文献
11.
R. L. Ushakova A. I. Mikaya V. G. Zaikin V. I. Kelarev G. A. Shveikhgeimer 《Chemistry of Heterocyclic Compounds》1986,22(4):442-446
1,2,4- and 1,3,4-Oxadiazoles containing indole substituents decompose upon electron impact due to breakage of bonds in the oxadiazole ring. Skeletal rearrangements may occur in the molecular ions of 2,5-diaryl-1,3,4-oxadiazoles due to migration of the aryl groups.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 539–543, April, 1986. 相似文献
12.
Four series of symmetrically 2,5-disubstituted 1,3,4-oxadiazoles with different lateral substituents and terminal alkoxy chain length were synthesised and characterised. Then, all these bent-shaped compounds were separately doped into the blue phase (BP) liquid crystal host and their effects on the BP range of the host were investigated, which shows that the BP ranges varied greatly with the difference in the structure of 2,5-disubstituted 1,3,4-oxadiazoles and their doped concentration. Moreover, in order to explore the influence of the inherent molecular geometry and properties of the bent-shaped molecules on the stability of BPs, the molecular structures of all the compounds were studied by using the theory of density functional theory, and the optimised structural parameters of the molecules were calculated at the B3LYP/6–31G* level. 相似文献
13.
L. I. Vereshchagin O. N. Verkhozina A. G. Proidakov A. I. Smirnov V. N. Kizhnyaev 《Chemistry of Heterocyclic Compounds》2008,44(9):1158-1163
The reaction of 5-substituted mono-and polytetrazoles with heterocyclic acid chlorides and trifluoroacetic acid anhydride
gave branched polynuclear 1,3,4-oxadiazole systems.
Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 9, pp. 1432–1437, September, 2008. 相似文献
14.
《Tetrahedron letters》2014,55(50):6776-6778
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. 相似文献
15.
Rafał Frański 《Journal of mass spectrometry : JMS》2004,39(3):272-276
The complexes of 2,5-disubstituted-1,3,4-oxadiazoles, namely 2,5-diphenyl-1,3,4-oxadiazole (1), 2,5-bis(2-pyridyl)-1,3,4-oxadiazole (2) and 2,5-bis(4-pyridyl)-1,3,4-oxadiazole (3), with copper cation were studied by electrospray ionization mass spectrometry (ESI-MS). The ability of the compounds studied to form complexes with copper (under the ESI conditions) can be ordered as 2 > 1 > 3. The compounds studied tend to form both 1 : 1 and 2 : 1 chelate complexes with both copper(II) and copper(I). The complexes with copper(I) are formed in the ESI process. The influence of solvent polarity, solution flow-rate, counter ions (Cl−, NO3−, CH3COO−, SO42−, acetylacetonates) on the type of the ions observed was studied. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
16.
Hemaka A. Rajapakse Hong Zhu Mary Beth Young Bryan T. Mott 《Tetrahedron letters》2006,47(28):4827-4830
A convenient one pot method for the synthesis of 2,5-disubstituted 1,3,4-oxadiazoles from acids and acyl hydrazides is reported. Acid activation with CDI, followed by coupling with the desired acylhydrazide and dehydration in the same pot with Ph3P and CBr4 affords the corresponding 1,3,4-oxadiazoles in good yield. The scope of the acid and acylhydrazide components is presented. 相似文献
17.
Paolo Stabile Alessandro Lamonica Damiano Castoldi Ornella Curcuruto 《Tetrahedron letters》2010,51(37):4801-4805
A mild, general, convenient, and efficient one-pot synthesis of 2-phenyl-5-substituted-1,3,4-oxadiazoles is described. Both (hetero)aryl and alkyl carboxylic acids were efficiently condensed with benzohydrazide in the presence of TBTU to give diacylhydrazine intermediates. The latter underwent a smooth TsCl-mediated cyclodehydration reaction to afford 2-phenyl-5-substituted-1,3,4-oxadiazoles in good to very good yields. 相似文献
18.
2,5-Disubstituted 1,3,4-oxadiazoles have been synthesized by oxidation of 1-aroyl-2-arylidene hydrazines with potassium permanganate on the surface of a solid mineral support as well as in mixtures of acetone and water under microwave irradiation. 相似文献
19.
《Green Chemistry Letters and Reviews》2013,6(1):55-59
Abstract Ceric ammonium nitrate in polyethylene glycol has been used as a sustainable, non-volatile, and ecofriendly catalytic medium for the green synthesis of 2,5-disubstituted 1,3,4-oxadiazoles. This protocol is effective toward various substrates having different functionalities. The easy recyclability of the reaction medium makes the reaction economically and potentially viable for commercial applications. 相似文献
20.
A series of N′-(5-aryl-1,3,4-oxadiazole-2-yl) actylthioureas have been synthesized from p-chlorophenoxyacetic acid, and then substituted 2-amino-5-aryl-1,3,4-oxadiazoles reacting with acylthiocyanoester, which are
derived from the second step, are used. Their structures are confirmed by Infrared, 1H nuclear magnetic resonance, and elementary analysis. From biological testing, it is found that some of these compounds have
good fungicidal activity.
Translated from Chemical Research and Application, 2005, 17(2) (in Chinese) 相似文献