Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Department of Chemistry, Korea Advanced Institute of Science and Technology (KAIST), Daejeon, 34141, Republic of Korea.
Angew Chem Int Ed Engl. 2023 Apr 3;62(15):e202300109. doi: 10.1002/anie.202300109. Epub 2023 Mar 2.
Pd-catalyzed nucleophilic fluorination reactions are important methods for the synthesis of fluoroarenes and fluoroalkenes. However, these reactions can generate a mixture of regioisomeric products that are often difficult to separate. While investigating the Pd-catalyzed fluorination of cyclic vinyl triflates, we observed that the addition of a substoichiometric quantity of TESCF significantly improved the regioselectivity of the reaction. Herein, we report a combined experimental and computational study on the mechanism of this transformation focusing on the role of TESCF . The poor regioselectivity of the reaction in the absence of additives results from the formation of LPd-cyclohexyne complexes (L=biaryl monophosphine ligand). When TESCF is added to the reaction mixture, the generation of the Pd-cyclohexyne complexes is diminished by an unexpected pathway involving the dearomatization of the ligand by nucleophilic attack from a trifluoromethyl anion (CF ).
钯催化的亲核氟化反应是合成氟代芳烃和氟代烯烃的重要方法。然而，这些反应会生成区域异构体产物的混合物，通常难以分离。在研究环状乙烯基三氟甲磺酸酯的钯催化氟化反应时，我们观察到添加亚化学计量的 TESCF 可显著提高反应的区域选择性。在此，我们报告了一项关于这种转化机制的实验和计算研究，重点关注 TESCF 的作用。在没有添加剂的情况下，反应的区域选择性较差，这是由于 LPd-环己烯配合物（L=联芳基单膦配体）的形成所致。当 TESCF 添加到反应混合物中时，通过亲核攻击三氟甲基阴离子（CF3-）使配体脱芳构化的意外途径，减少了 Pd-环己烯配合物的生成。
