The Development and Mechanistic Study of an Iron-Catalyzed Intramolecular Nitroso Ene Reaction of Nitroarenes.
The Development and Mechanistic Study of an Iron-Catalyzed Intramolecular Nitroso Ene Reaction of Nitroarenes.
复制标题
铁催化硝基芳烃分子内亚硝基烯反应的进展及机理研究。
DOI：
10.1021/acscatal.3c04483
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发表时间：
2023
期刊：
影响因子：
12.9
通讯作者：
Driver,TomG
中科院分区：
文献类型：
--
作者：
Vu,Van;Powell,JairN;Ford,RussellL;Patel,PoojaJ;Driver,TomG
以富稀土铁为催化剂，以苯基硅烷为末端还原剂，进行了分子内铁催化的亚硝烯反应，从硝基芳烃合成了六元或七元N-杂环。该反应只需3摩尔%醋酸铁和3摩尔%4，7-二甲氧基邻二氮杂菲为配体即可实现。该反应的范围很广，可以容忍硝基芳烃上的一系列放电子或拉电子取代基，并且邻位取代基可以被修饰以非对映选择性地构建苯并恶嗪、二氢苯并噻嗪、四氢喹啉、四氢喹恶啉或四氢苯并恶卓。反应机理研究表明，反应是通过亚硝基芳烃中间体进行的；动力学分析表明，催化剂、硝基芳烃和硅烷的浓度与反应的速率呈一级关系，而在醋酸酯中则呈相反的动力学关系。Ph SiH_3和PhSiD_3的反应速率之差为1.5±0.09，反应速率与温度的关系研究表明，反应的活化参数分别为ΔH‡=13.5kcal·m o l-1和ΔS‡=−39.1kalm ol-1K-1。这些数据被解释为转换限制步骤是氢化物从铁到配位的硝基芳烃的转移，它通过一个有序的过渡态发生，几乎没有Fe-H键断裂。
An intramolecular iron-catalyzed nitroso ene reaction was developed to afford six- or seven-memberedN-heterocycles from nitroarenes using an earth-abundant iron catalyst and phenylsilane as the terminal reductant. The reaction can be triggered using as little as 3 mol % iron(II) acetate and 3 mol % 4,7-dimethoxyphenanthroline as the ligand. The scope of the reaction is broad and tolerates a range of electron-releasing or electron-withdrawing substituents on the nitroarene, and theortho-substituent can be modified to diastereoselectively construct benzoxazines, dihydrobenzothiazines, tetrahydroquinolines, tetrahydroquinoxalines, or tetrahydrobenzooxazepines. Mechanistic investigations indicated that the reaction proceeds via a nitrosoarene intermediate; kinetic analysis of the reaction revealed a first-order rate dependence in catalyst, nitroarene, and silane concentration, and an inverse kinetic order in acetate was observed. The difference in rates between PhSiH3and PhSiD3was found to be 1.50 ± 0.09, and investigation of the temperature dependence of the reaction rate revealed the activation parameters to be ΔH‡= 13.5 kcal mol–1and ΔS‡= −39.1 cal mol–1K–1. These data were interpreted to indicate that the turnover-limiting step is hydride transfer from iron to the coordinated nitroarene, which occurs through an ordered transition state with little Fe–H bond breaking.