Intramolecular Hiyama Coupling: Synthesis of 1,8,13-Trisubstituted Chiral Triptycenes with Three Different Substituents by Intramolecular Substituent Transfer

Herein, we describe Hiyama coupling via intramolecular substituent transfer from silicon on one blade of triptycenes to another to yield 1,8,13-trisubstituted chiral triptycenes. This reaction is attributed to the proximity effect of substituents on triptycene, which plays an important role in not only the formation of the oxy-palladacycle but also the activation of the silyl group to facilitate sigma-bond metathesis. After bromination and nucleophilic ring opening, the second intramolecular Hiyama coupling provided various 1,8,13-trisubstituted chiral triptycenes. The optical resolution of 1,8,13-triptycene afforded an optically active form for the first time.

Automated summary

In this study, Hiyama coupling was achieved through intramolecular substituent transfer from silicon, resulting in the formation of 1,8,13-trisubstituted chiral triptycenes based on triptycene. The proximity effect of substituents on triptycene played a crucial role in the formation of the oxy-palladacycle and the activation of the silyl group for sigma-bond metathesis. After bromination and nucleophilic ring opening, a secondary intramolecular Hiyama coupling provided diverse 1,8,13-trisubstituted chiral triptycenes. Optical resolution of 1,8,13-triptycene yielded optically active forms for the first time.