Chiral Arene Ligand as Stereocontroller for Asymmetric C−H Activation**
Hao Liang, Weicong Guo, Junxuan Li, Ji‐Jun Jiang, Jun Wang
Abstract
Abstract Development of chiral ligands is the most fundamental task in metal‐catalyzed asymmetric synthesis. In the last 60 years, various kinds of ligands have been sophisticatedly developed. However, it remains a long‐standing challenge to develop practically useful chiral η 6 ‐arene ligands, thereby seriously hampering the asymmetric synthesis promoted by arene‐metal catalysts. Herein, we report the design and synthesis of a class of readily tunable, C 2 ‐symmetric chiral arene ligands derived from [2.2]paracyclophane. Its ruthenium(II) complexes have been prepared and successfully applied in the enantioselective C−H activation to afford a series of axially chiral isoquinolones (up to 99 % yield and 96 % ee). This study not only lays chemists’ longstanding doubts about whether it is possible to use chiral arene ligands to stereocontrol ruthenium(II)‐catalyzed asymmetric C−H activation, but also opens up a new avenue to achieve asymmetric C−H activation.