电化学脱氢[3+2]环化反应合成取代的1,2,4-三氮唑衍生物

Synthesis of 1,2,4-Triazoles via the Electrochemical Oxidative[3+2]Annulation

1,2,4-三氮唑作为一种含氮五元杂环类化合物,不仅具有抗炎、抗菌等生物活性,还是一种重要的有机合成中间体,对该类化合物进行合成研究具有重要意义.以廉价易得的胺和醛芳基腙为原料,在电催化条件下,利用电化学脱氢[3+2]环化反应,一步合成了系列取代的1,2,4-三氮唑衍生物,其结构经^(1)H NMR、^(13)C NMR和HRMS确证.该反应条件温和,原子经济性高,底物范围广,避免了氧化剂、过渡金属催化剂、酸和碱的使用,为构建1,2,4-三氮唑骨架提供了一种绿色、可持续的合成途径.

1,2,4-Triazoles,standing for a class of five-membered nitrogenous heterocyclic compounds,show anti-inflammatory,anti-fungal and other biological activities.They also served as important intermediates in organic synthesis.Thus,the pursuit of general and efficient synthesis of 1,2,4-triazoles that controls the introduction of substituents in a highly regioselective fashion has been of continued interest to synthetic organic chemists.In this paper an electrochemical dehydrogenative[3+2]annulation used for the synthesis of 1,2,4-triazoles from cheap and readily available amines and hydrazones was developed.Their structures were confirmed by ^(1)H NMR,^(13)C NMR and HRMS analyses.Advantageously,this method proceeds in a transition-metal-,acid-,base-and external oxidant-free fashion to provide a variety of functionalized 1,2,4-triazoles.The reaction constitutes a new transformation from hydrazones and amines to 1,2,4-triazoles,providing a unifying,simple and environmentally friendly approach to the currently available methods.