2-对氯苯氧基-5-芳基-1,3,4-噁二唑的合成

对氯苯氧乙酸乙酯与水合肼反应制得对甲基苯氧乙酰肼（2）;以碳酸钠作缚酸剂,2与卤代苯甲酰氯反应合成了N、N＇-二酰基肼（3）;在POCl3作用下,3脱水环化得2-对氯苯氧基-5-芳基-1,3,4-噁二唑,其结构经1^H NMR,IR,MS和元素分析表征,并对其裂解途径进行了探讨。     

2-芳基-5-苄氧苯基-1,3,4-噁二唑类化合物的合成

由苄氧基苯甲酰肼与各种芳酰氯反应制得N-取代苯甲酰基-4-苄氧苯酰肼(2),2在三氯氧磷存在下发生脱水闭环反应,合成了一系列2-芳基-5-苄氧苯基-1,3,4-噁二唑类化合物,其结构经1H NMR,IR,MS和元素分析表征。     

2-芳氧基-5-苯基-1,3,4-恶二唑类化合物的合成

通过芳氧基负离子在2-甲磺酰基-5-1,3,4-恶二唑上的亲核取代反应制得2-芳氧基-5-苯基-1,3,4-恶二唑.所有化合物的结构经元素分析,IR, ^1H NMR和MS确证.这些化合物表现出一定的抑制枯草芽孢杆菌繁殖的活性.     

Synthesis of 5-Trimethylsilylethynyl-1,3,4-oxadiazoles

5-Trimethylsilylethynyl-2-R-1,3,4-oxadiazoles were synthesized for the first time by intramolecular cyclocondensation of unsymmetrical N-acyl-N'-(3-trimethylsilyl-2-propynoyl)hydrazines by the action of phosphoryl chloride.     

2-苯基-5-芳基-1,3,4-噁二唑的合成与表征

苯甲酸乙酯与水合肼反应制得苯甲酰肼(1),1再分别与芳酰氯反应制得N、N′-二酰基肼(3a～3i),3a～3i在POCl3作用下脱水环化生成2-苯基-5-芳基-1,3,4-噁二唑(4a～4i)。其结构经元素分析,IR,^1H NMR和MS表征,并对其裂解途径进行了探讨。     

2-对硝基苯基-5-芳基-1,3,4-噁二唑的合成与表征

以自制的N,N′-二酰基肼在POCl3作用下脱水环化,合成了8个2-对硝基苯基-5-芳基-1,3,4-噁二唑类化合物。其结构经^1H NMR,IR,MS和元素分析表征,并对其裂解途径进行了探讨。     

2-取代氨基-5-吡唑基-1,3,4-噁二唑的合成及生物活性

取代氨基吡唑基噁二唑;2-取代氨基-5-吡唑基-1;3;4-噁二唑的合成及生物活性     

Synthesis and spectral properties of 2-methyl-5-aryl-1,3,4-oxadiazoles

By heterocyclization of 1-acyl-2-aroylhydrazines under the influence of strong dehydrating substances, a series of 2-methyl-5-aryl-1,3,4-oxadiazoles has been synthesized and their UV, IR, and PMR spectra have been investigated. Through analysis of data on the influence of substituents on the position of the maximum in the electronic absorption spectrum, together with calculated data, it has been shown that the long-wave band of 2-methyl-5-phenyl-1,3,4-oxadiazole is due to an S₀–S₁ transition of the –^* type and that it is a charge transfer band for transfer from the phenyl radical to the oxadiazole ring; the 1,3,4-oxadiazole ring as a substituent has an electron-acceptor character.Institute of Single Crystals, National Academy of Sciences of the Ukraine, Khar'kov 310001. Khar'kov State University, Khar'kov 310077. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 816–821, June, 1997.     

Synthesis and Spectral-Luminescent Properties of 2-Aryl-5-butyl-1,3,4-oxadiazoles

Russian Journal of General Chemistry - 2-Aryl-5-butyl-1,3,4-oxadiazoles have been obtained in 59–85% yield via refluxing of equimolar amounts of a benzoic acid hydrazide with trimethyl...     

2-取代-5-吡唑基-1，3，4-恶二唑类化合物的合成及生物活性

以5-吡唑甲酰肼和取代羧酸为起始物,运用"一锅煮"法合成了一系列2-取代-5-吡唑基-1,3,4-二唑.此外,还合成了1-苯酰基-2-吡唑酰基肼.初步生物活性测定结果表明,部分化合物有较好的杀菌和除草活性.     

2-(2-三氟苯基)-5-芳基-1,3,4-噁二唑类化合物的合成

2-三氟苯甲酰肼与芳酰氯反应制得N,N′-二酰肼(2)。2在三氯氧磷存在下脱水闭环,合成了一系列2-(2-三氟苯基)-5-芳基-1,3,4-噁二唑类化合物,其结构经1H NMR,IR,MS和元素分析表征。     

Synthesis and antioxidant evaluation of some new 2-benzoylamino-5-hetaryl-1,3,4-oxadiazoles

A series of new functionalized 2-benzoylamino-5-hetaryl-1,3,4-oxadiazoles were efficiently synthesized via the reaction of the versatile key intermediates, 2-benzoylamino-5-cyanomethyl-1,3,4-oxadiazole (1) and N-(5-(5-amino-3-phenylamino)-1H-pyrazol-4-yl)-1,3,4-oxadiazol-2-yl)-benzamide (13), with some appropriate electrophilic reagents. The structures of the newly synthesized compounds were established on the basis of elemental analyses, spectral data, and by alternative synthesis wherever possible. The mechanisms of the studied reactions are discussed. Also, we evaluate the antioxidant activity of some representative examples of the newly prepared compounds. Among the synthesized compounds, 2-benzoylamino-5-cyanomethyl-1,3,4-oxadiazole (1) and N-(5-(7-methyl-5-oxo-2-(phenylamino)-4,5-dihydropyrazolo[1,5-a]pyrimidin-3-yl)-1,3,4-oxadiazol-2-yl)benzamide (17) showed excellent antioxidant activity and exhibited high protection against DNA damage induced by the Bleomycin iron complex.     

High-temperature continuous flow synthesis of 1,3,4-oxadiazoles via N-acylation of 5-substituted tetrazoles

Applying continuous flow processing in a high-temperature/high-pressure regime (200-220 °C, 11-14 bar) 2,5-disubstituted-1,3,4-oxadiazoles are prepared in high yields within 5-10 min residence time by treatment of 5-substituted-1H-tetrazoles with anhydrides or acid chlorides as electrophiles (Huisgen reaction).     

A new approach to the one-pot synthesis of 5-substituted 2-methyl-1,3,4-oxadiazoles from N-tributylstannyltetrazoles

A new approach to the synthesis of 5-substituted 2-methyl-1,3,4-oxadiazoles was developed.     

Basicity of 2-phenyl-5-R-1,3,4-oxadiazoles

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 (pK_BH ⁺ is −1.8 to −5.2). The values of pK_BH ⁺ 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. __________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 5, pp. 748–756, May, 2006.     

Synthesis of picryl-substituted 1,3,4-oxadiazoles

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.     

Synthesis of steroidal extranucleo 1,3,4-oxadiazoles

Cholest-5en-3β-ol 1 , 3,3-ethylenedioxy-androst-4-en-17β-ol 2 and 17,17-ethylenedioxy-1,3,5(10)-estratrien-3β-ol 3 were converted into ethyl ester 1a, 2a and 3a by reaction with ethyl chloroacetate in the presence of potassium. The ethyl esters 1a, 2a and 3a on reaction with hydrazine gave hydrazides 1b, 2b and 3b , which on reaction with cyanogen bromide afforded 1,3,4-oxadiazoles 1c, 2c and 3c .