Reductively activated “Polar” nucleophilic aromatic substitution. III
作者:Mohammed Niat、Jorge Marquet、Iluminada Gallardo、Maria Cervera、Miquel Mir
DOI:10.1016/0040-4039(94)88427-7
日期:1994.11
The nucleophilic aromatic substitutionreactions of pentafluoronitrobenzene (PFNB) and 2,3,4,5-tetrafluoronitrobenzene with methanol are both reductively activated. However, the first one is sensitive to the presence of radical scavengers but the second is not. In addition, the kinetic behavior of both reactions in the absence of stimulation is very similar suggesting they are examples of second stage
五氟硝基苯(PFNB)和2,3,4,5-四氟硝基苯与甲醇的亲核芳香取代反应均被还原活化。但是,第一个对自由基清除剂的存在很敏感,而第二个则不然。另外,在没有刺激的情况下,这两个反应的动力学行为非常相似,表明它们是确定S N Ar机制的第二阶段速率的实例。动力学研究还表明,在那些反应中不存在真正的光化学刺激。报告的事实与先前提出的(用于PFNB与甲醇的反应)S RN 2机制不兼容。讨论了新的机械原理。
Constructing a Catalytic Cycle for C–F to C–X (X = O, S, N) Bond Transformation Based on Gold-Mediated Ligand Nucleophilic Attack
replacement of Cl by a more nucleophilic tBuO anion ligand, showed higher reactivity and para selectivity in the transformation of C–F to C–OtBu bond, distinctively different from that when only KOtBu was used (ortho selectivity) under the identical condition. Mechanistic studies including density functional theory calculations suggested a gold-mediated nucleophilic ligand attack of the C–F bond pathway