Li Jia, Dong Ziyang, Liu Shuyuan, Liu Xinyu, Zhao Changgui
Key Laboratory of Radiopharmaceuticals, Ministry of Education, College of Chemistry, Beijing Normal University, Beijing, 100875, China.
Chemistry. 2025 Feb 25;31(12):e202404610. doi: 10.1002/chem.202404610. Epub 2025 Jan 27.
Optically pure monosubstituted [n]paracyclophanes are promising candidates for material synthesis, asymmetric catalysis, and drug discovery. Thus far, only a few catalytic asymmetric synthesis processes have been reported for assessing these strained atropisomers. In this study, we describe a highly enantioselective synthesis of monosubstituted [n]paracyclophanes by combining desymmetrization and kinetic resolution. The proposed protocol involves Pd-catalyzed atroposelective C-H bond olefination enabled by a monoprotected amino acid ligand, which affords a variety of monosubstituted [n]paracyclophanes with excellent enantioselectivity (≥99 %ee). Thermodynamic experiments are conducted to investigate the racemization barrier. The synthesized monosubstituted [n]paracyclophanes exhibit vivid fluorescence and impressive circularly polarized luminescence. Further, the emission color and dissymmetry factor can be tuned and controlled by switching the substituent on the benzene ring of the cyclophanes.
光学纯的单取代[n]对环芳烷是材料合成、不对称催化和药物发现领域很有前景的候选物。到目前为止，仅报道了少数用于评估这些张力阻转异构体的催化不对称合成方法。在本研究中，我们描述了一种通过去对称化和动力学拆分相结合的方法来高度对映选择性合成单取代[n]对环芳烷。所提出的方案涉及由单保护氨基酸配体实现的钯催化的阻转选择性C-H键烯烃化反应，该反应能提供各种具有优异对映选择性（≥99%ee）的单取代[n]对环芳烷。进行了热力学实验以研究外消旋化势垒。合成的单取代[n]对环芳烷表现出鲜明的荧光和令人印象深刻的圆偏振发光。此外，通过切换对环芳烷苯环上的取代基，可以调节和控制发射颜色和不对称因子。
