Cycloadditions of nitrile oxides to amidoximes. A general synthesis of 3,5-disubstituted 1,2,4-oxadiazole-4-oxides.
作者:Paolo Quadrelli、Anna Gamba Invernizzi、Mario Falzoni、Pierluigi Caramella
DOI:10.1016/s0040-4020(96)01088-5
日期:1997.2
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
腈氧化物与酰胺肟的环加成是合成具有相同或不同取代基的3,5-二取代的1,2,4-恶二唑-4-氧化物的通用方法。产率仅适中,因为通过与伯环加合物的裂解中释放的胺反应并转化了mid胺肟,消耗了等量的一氧化氮。与过量的腈氧化物一起,1,2,4-恶二唑-4-氧化物进行歧化反应,生成亚硝基羰基中间体和1,2,4-恶二唑。