Di- and Trifluorobenzenes in Reactions with Me2EM (E = P, N; M = SiMe3, SnMe3, Li) Reagents: Evidence for a Concerted Mechanism of Aromatic Nucleophilic Substitution
作者:Leonid I. Goryunov、Joseph Grobe、Duc Le Van、Vitalij D. Shteingarts、Rüdiger Mews、Enno Lork、Ernst-Ulrich Würthwein
DOI:10.1002/ejoc.200900880
日期:2010.2
fluorine substituent rate factors f o-F > f m-F , whereas for reactions that proceed through a two-step S N Ar mechanism the opposite sequence is typical. High-level quantum-chemical DFT and MP2 calculations predict that the gas-phase reactions should each proceed by a concerted mechanism with a single transition state. These predictions are in good agreement with the experimental observations, especially
而对于通过两步 SN Ar 机制进行的反应,相反的顺序是典型的。高级量子化学 DFT 和 MP2 计算预测,气相反应应该各自通过具有单一过渡态的协同机制进行。这些预测与实验观察非常吻合,特别是因为迈森海默加合物的结构特征不利于 SN Ar 机制。该提议与在 DMSO/CH 3 OH 溶剂混合物中相同底物和 MeONa 之间反应的相反顺序 (f mF > f oF ) 的观察结果一致。通过光谱 (NMR) 和光谱 (MS) 研究、硫代磷烷 Ar F PSMe 2 10-12 的制备、它们的光谱数据以及在 12 的情况下,对新型磷烷进行了表征。通过其X射线结构。膦 5-9 用双(苄腈)二氯钯(II)处理,得到相应的双(膦)二氯化钯配合物 17-21 和 23,分离产率高达 95%。