A Route to Enantiopure ( O -Methyl) 6 -2,6-Helic[6]arenes: Synthesis of Hexabromo-Substituted 2,6-Helic[6]arene Derivatives and Their Suzuki–Miyaura Coupling Reactions

作者：Jiaqi Wang, Jing Li, Geng‐Wu Zhang, Chuan‐Feng Chen · 发表于：The Journal of Organic Chemistry · 年份：2018 · DOI：10.1021/acs.joc.8b01437 · 被引用次数：23 · 研究领域：Supramolecular Chemistry and Complexes、Molecular Sensors and Ion Detection、Supramolecular Self-Assembly in Materials

A route to enantiopure ( O -methyl) 6 -2,6-helic[6]arenes (+)- P - 2 and (−)- M - 2 has been provided. By the reaction of enantiopure triptycene precursors (+)- 1 and (−)- 1 in refluxed o -DCB for 12 h in the presence of catalytic amount of FeCl 3, and then followed by treatment of the obtained oligomers under the same conditions, (+)- P - 2 and (−)- M - 2 could be obtained in 51% and 53% total yield, respectively. It was also found that racemic and enantiopure ( O -methyl) 6 -2,6-helic[6]arenes could be easily brominated by Br 2 to give the corresponding hexabromo-substituted helic[6]arene derivatives rac - 4, (+)- P - 4, and (−)- M - 4 in high yields. The crystal structure of (+)- P - 4 further confirmed the absolute configuration of the helic[6]arenes and their derivatives. Moreover, a series of hexaaryl-substituted helic[6]arene derivatives 5a – f with deepened cavities could be conveniently synthesized in 55–71% yield by Suzuki–Miyaura coupling reactions of 4 and arylboronic acids. rac - 5a could encapsulate chloroform and exhibit self-sorting stacking in solid state. Enantiopure (+)- P - 5a – f and (−)- M - 5a – f showed mirror images in their CD spectra.