The reaction of amidoximes with carboxylic acids or their esters under high-pressure conditions
作者:S. V. Baikov、G. A. Stashina、E. I. Chernoburova、V. B. Krylov、I. V. Zavarzin、E. R. Kofanov
DOI:10.1007/s11172-019-2391-9
日期:2019.2
Abstract3,5-Disubstituted 1,2,4-oxadiazoles were synthesized by the reaction of amidoximes with carboxylic acids or their esters under high-pressure conditions (10 kbar). The reaction proceeds without the use of other reagents or catalysts. Both aliphatic and aromatic carboxylic acids undergo this reaction. The obtained 1,2,4-oxadiazoles possess high fungicidal activity.
Improved Microwave-Mediated Synthesis of 3-(3-Aryl-1,2,4-oxadiazol-5-yl)propionic Acids and Their Larvicidal and Fungal Growth Inhibitory Properties
作者:Ricardo Antonio Wanderley Neves Filho、Cecília Aguiar da Silva、Clécia Sipriano Borges da Silva、Vanessa Passos Brustein、Daniela Maria do Amaral Ferraz Navarro、Fábio André Brayner dos Santos、Luiz Carlos Alves、Marília Gabriela dos Santos Cavalcanti、Rajendra Mohan Srivastava、Maria das Graças Carneiro-Da-Cunha
DOI:10.1248/cpb.57.819
日期:——
The synthesis of 3-(3-aryl-1,2,4-oxadiazol-5-yl)propionicacids from arylamidoximes and succinic anhydride under focused microwave irradiation conditions is described. The new synthetic method furnished the desired products in 2-3 min and good yields. Furthermore, the previously complicated purification procedure has been simplified in a manner which is quick, eco-friendly and cost-effective. Larvicidal
Disubstituted 1,2,4-oxadiazoles have been synthesized in good yields and good purity in one pot procedure by reaction of aromatic nitriles, hydroxylamine hydrochloride and sodium carbonate in ethylene glycol under heating at 195°C. The structures of different 1,2,4-oxadiazoles obtained were confirmed by 1H, 13C NMR and mass spectroscopy.
通过在195℃加热下使芳族腈,盐酸羟胺和碳酸钠在乙二醇中反应,在一个锅法中以高收率和高纯度合成了二取代的1,2,4-恶二唑。通过1 H,13 C NMR和质谱确认所获得的不同的1,2,4-恶二唑的结构。
Cycloadditions of nitrile oxides to amidoximes. A general synthesis of 3,5-disubstituted 1,2,4-oxadiazole-4-oxides.
cycloaddition of nitrile oxides to amidoximes is a general method for the sinthesis of 3,5-disubstituted 1,2,4-oxadiazole-4-oxides with the same or different substituents. The yields are only moderate since an equivalent amount of the nitrile oxide is consumed by reaction with the amine released in the fragmentation of the primary cycloadducts and reforms the amidoxime. With excess nitrile oxides the 1,2,4-oxadiazole-4-oxides
conditions to yield oxadiazolinic esters. The structures of the adducts have been confirmed by X-ray structures and spectroscopic data. A donor p-methoxyphenyl at the nitronic carbon slows down the cycloaddition rate, while an acceptor p-nitrophenyl retards the rearrangement of the exo adduct.
1,2,4-恶二唑 4-氧化物显示出与 N-甲基-C-苯基硝酮相同的硝基反应性和选择性,N-甲基-C-苯基硝酮是一种典型的无环硝酮,可提供相当数量的内-和外-5-烷氧基异恶唑烷。外型立体异构体在反应条件下容易发生重排,生成恶二唑啉酯。加合物的结构已通过 X 射线结构和光谱数据得到证实。硝基碳上的供体对甲氧基苯基会减慢环加成速率,而受体对硝基苯基会阻止外加合物的重排。